Ismail Md. Mofizur Rahman

Abstract: Plants experience water stress either when the water supply to their roots becomes limiting or when the transpiration rate becomes intense. Water stress is primarily caused by the water deficit, i.e. drought or high soil salinity. Each year, water stress on arable plants in different parts of the world disrupts agriculture and food supply with the final consequence � famine. Hence, the ability to withstand such stress is of immense economic importance. Plants try to adapt to the stress conditions with an array of biochemical and physiological interventions. This multi authored edited compilation attempts to put forth an all-inclusive picture on the mechanism and adaptation aspects of water stress. The prime objective of the book hence is to deliver a thoughtful mixture of viewpoints, which would be useful to workers in all areas of plant sciences. We trust that the material covered in this book will be valuable in building strategies to counter water stress in plants.

Abstract: The first application of solid phase extraction (SPE) started approximately five decades ago, and until then development of SPE materials is continued, and it seems to be a never-ending story. Lately, research is focused in developing more explicit materials to achieve meticulous separation of ions from solutions containing complex matrices with high concentrations of interfering ions. One group of SPE materials includes those with macrocyclic ligands immobilized on a silica or polymer support; this type of SPE has been reportedly available for ion-selective separation and pre-concentration of ions, and the technique is commonly known as molecular recognition technology (MRT). In MRT, the designed �host� materials possess a high degree of recognition to specific ions or groups of ions called �guest�, and the recognition capability remains effective at the very low concentrations of the �guest� ion or when those present in complex matrices. In this book, application of different MRT-SPE materials for the selective separation of trace ecotoxic ions from the aqueous matrix are described, and the effects of the various chemical species or forms on MRT-based separations are discussed.

Abstract: Ex-situ soil washing with synthetic extractants such as, aminopolycarboxylate chelants (APCs) is a viable treatment alternative for metal-contaminated site remediation. EDTA and its homologs are widely used among the APCs in the ex-situ soil washing processes. These APCs are merely biodegradable and highly persistent in the aquatic environments leading to the post-use toxic effects. Therefore, an increasing interest is focused on the development and use of the eco-friendly APCs having better biodegradability and less environmental toxicity. The paper deals with the results from the lab-scale washing treatments of a real sample of metal-contaminated soil for the removal of the ecotoxic metal ions (Cd, Cu, Ni, Pb, Zn) using five biodegradable APCs, namely [S,S]-ethylenediaminedisuccinic acid, imminodisuccinic acid, methylglycinediacetic acid, DL-2-(2-carboxymethyl) nitrilotriacetic acid (GLDA) and 3-hydroxy-2,2'-iminodisuccinic acid. The performance of those biodegradable APCs was evaluated for their interaction with the soil mineral constituents in terms of the solution pH and metal-chelant stability constants, and compared with that of EDTA. Speciation calculations were performed to identify the optimal conditions for the washing process in terms of the metal-chelant interactions as well as to understand the selectivity in the separation ability of the biodegradable chelants towards the metal ions. A linear relationship between the metal extraction capacity of the individual chelants towards each of the metal ions from the soil matrix and metal-chelant conditional stability constants for a solution pH greater than 6 was observed. Additional considerations were derived from the behavior of the major potentially interfering cations (Al, Ca, Fe, Mg and Mn), and it was hypothesized that use of an excess of chelant may minimize the possible competition effects during the single-step washing treatments. Sequential extraction procedure was used to determine the metal distribution in the soil before and after the extractive decontamination using biodegradable APCs, and the capability of the APCs in removing the metal ions even from the theoretically immobilized fraction of the contaminated soil was observed. GLDA appeared to possess the greatest potential to decontaminate the soil through ex-situ washing treatment compared to the other biodegradable chelants used in the study.

Abstract: The protonation and complex formation equilibria of two biodegradable aminopolycarboxylate chelants (DL-2-(2-carboxymethyl)nitrilotriacetic acid (GLDA) and 3-hydroxy-2,2´-iminodisuccinic acid (HIDS)) with Ni2+, Cu2+, Zn2+, Cd2+ and Pb2+ ions was investigated using the potentiometric method at a constant ionic strength of I = 0.10 mol.dm�3 (KCl) in aqueous solutions at 25 ± 0.1C. The stability constants of the proton-chelant and metal-chelant species for each metal ion were determined, and the concentration distributions of various complex species in solution were evaluated for each ion. The stability constants (logKML) of the complexes containing Ni2+, Cu2+, Zn2+, Cd2+ and Pb2+ ions followed an identical order of logKCuL>logKNiL>logKPbL>logKZnL>logKCdL when using GLDA (13.03>12.74>11.60>11.52>10.31) as when using HIDS (12.63>11.30>10.21>9.76>7.58). In each case, the constants obtained for metal-GLDA complexes were higher in magnitude than the corresponding constants for metal-HIDS complexes. The conditional stability constants (logK´ML) of the metal-chelant complexes containing GLDA and HIDS were calculated in terms of pH, and compared with the stability constants for EDTA and other biodegradable chelants.

Abstract: A new technique for the separation and preconcentration of dissolved Fe(III) from the ligand-rich aqueous system is proposed. A solid phase extraction (SPE) system with an immobilized macrocyclic material, commonly known as molecular recognition technology (MRT) gel and available commercially, was used. Synthetic Fe(III) solution in aqueous matrices spiked with a 100-fold concentration of EDTA was used. Dissolved iron that was �captured� by the MRT gel was eluted using hydrochloric acid and subsequently determined by graphite furnace atomic absorption spectrometry. The effect of different variables, such as pH, reagent concentration, flow rate and interfering ions, on the recovery of analyte was investigated. Quantitative maximum separation (~100%) of the dissolved Fe(III) from synthetic aqueous solutions at a natural pH range was observed at a flow rate of 0.2 mL min�1. The extraction efficiency of the MRT gel is largely unaltered by the coexisting ions commonly found in natural water. When compared with different SPE materials, the separation performance of MRT gel is also much higher.

Abstract: A combination of solid phase extraction (SPE) columns was used for selective separation of water-soluble arsenic species: arsenite, arsenate, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). The SPE columns, namely AnaLig TE-01 (TE-01), AnaLig AN-01 Si (AN-01) and AnaLig As-01 PA (As-01), contain immobilized macrocyclic material as the sorbent and commonly known as molecular recognition technology (MRT) gel. The retention, extraction and recovery behavior of the MRT gel SPE columns were studied at pH 4�10. Fortified deionized water spiked with 100 µM of arsenic species were treated at the flow rate of 0.2 mL min�1. HNO3 (1.0 and 6.0 M) was used as eluent to recover the retained arsenic species from TE-01 and AN-01 SPE columns. Arsenic species retained in the As-01 column were eluted with HNO3 (0.1 M) followed by NaOH (2.0 M). Likely interference from the various coexisting ions (Na+, K+, Ca2+, Mg2+, Cl�, NO3�, CH3COO�, PO43�, SO42�, ClO4�) (10 mM) were negligible. Quantitative separation of As(III), As(V), MMA and DMA was achieved based on the differences in extraction and recovery behavior of the MRT gel SPE columns with pH for different arsenic species. Complexation between arsenic species and MRT gel is the core phenomenon of the proposed technique as the complexation of MRT gels is expected to be stronger than the resin-based separation processes. MRT gel SPE columns are advantageous as compared with other reported SPE columns in terms of its performance with As(III). Effortless regeneration and unaltered separation performance of the sorbent materials for more than 100 loading and elution cycles are other sturdy characteristics to consider the MRT gel SPE columns for sensitive and selective arsenic species separation.

Abstract: The concern over ensuing fresh water scarcity has forced the developing countries to delve for alternative water resources. In this study we examined the potential of stagnant surface water bodies (SSWBs) as alternative fresh water resources in the densely populated Chittagong metropolitan area (CMPA) of Bangladesh � where there is an acute shortage of urban fresh water supply. Water samples, collected at one month intervals for a period of one year from 12 stations distributed over the whole metropolis. Samples were analyzed for pH, water temperature (WTemp), turbidity, electrical conductivity (EC), total dissolved solids, total solids, total hardness, dissolved oxygen (DO), chloride, orthophosphates, ammonia, total coliforms (TC) and trace metal (Cd, Cr, Cu, Pb, As and Fe) concentrations. Based on these parameters different types of water quality indices (WQIs) were deduced. WQIs showed most of CMPA-SSWBs as good or medium quality water bodies while none were categorized as bad. Moreover, it was observed that the minimal water quality index (WQIm), computed using five parameters: WTemp, pH, DO, EC and turbidity gave reliable estimate of water quality. The WQIm gave similar results in 72% of the cases compared with other WQIs which were based on larger set of parameters. Based on our finding, we suggest the wider use WQIm in developing countries for assessing health of SSWBs as it will minimize the analytical cost to overcome the budget constraints involved in this kind of evaluations. It was observed that except turbidity and TC content, all other quality parameters fluctuated within the limit of World Health Organization suggested standards for drinking water. From our findings we concluded that if the turbidity and TC content of water from SSWBs in CMPA are taken care of, they will become good candidates as alternative water resources all round the year.

Abstract: Separation of trace levels of lead from concentrated-matrix electroless nickel plating (ENP) waste solutions is required to meet the increasingly stringent environmental regulations. A solid phase extraction (SPE) system using a molecular recognition technology (MRT) gel was used for the selective separation of trace levels of lead (Pb) from the waste discharge of ENP operations, followed by subsequent analysis with inductively coupled plasma optical emission spectrometry (ICP-OES). Two SPE-MRTs, AnaLig® Pb-01 and AnaLig® Pb-02, packed in 3 mL polypropylene cartridges were used to treat the synthetic metal-waste solutions that were used to simulate the typical metal mixture in ENP bath waste. The fortified solutions contained 100�1000 µg L�1 of Pb in an HNO3 matrix with pre-added Ni, Cu and other interfering elements (1000 mg L�1). After the sample treatment, the SPE-MRT cartridges were washed with water and 0.1 M nitric acid, followed by elution with 0.03 M EDTA. The matrix elements (e.g., Ni, Cu) were completely removed at the washing step, while the �captured� Pb was quantitatively eluted, as determined by ICP-OES measurements. The detection limit of the proposed method was 2.6 µg L�1. �Real� samples from commercial ENP operations were used to assess the validity of this method, and almost quantitative Pb recovery was observed. The excellent Pb selectivity of the SPE-MRT system indicates the potential of the proposed technique for trace-level Pb separation from the Pb-containing high matrix aqueous waste discharge.

Abstract: Viscosities of binary liquid mixtures of butan-2-one with benzene were measured at a number of mole fractions at T = (303.15, 313.15, and 323.15) K and atmospheric pressure. The viscometric behavior is discussed on the basis of structural and geometrical effects between the components. In addition, kinematic viscosities were calculated using the UNIFAC�VISCO model. The predicted kinematic viscosities are in good agreement with the experimental ones.

Abstract: Aminopolycarboxylate chelants (APCs) are extremely useful for a variety of industrial applications, including the treatment of toxic metal-contaminated solid waste materials. Because non-toxic matrix elements compete with toxic metals for the binding sites of APCs, an excess of chelant is commonly added to ensure the adequate sequestration of toxic metal contaminants during waste treatment operations. The major environmental impacts of APCs are related to their ability to solubilize toxic heavy metals. If APCs are not sufficiently eliminated from the effluent, the aqueous transport of metals can occur through the introduction of APCs into the natural environment, increasing the magnitude of associated toxicity. Although several techniques that focus primarily on the degradation of APCs at the pre-release step have been proposed, methods that recycle not only the processed water, but also provide the option to recover and reuse the metals, might be economically feasible, considering the high costs involved due to the chelants used in metal ion sequestration. In this paper, we propose a separation process for the recovery of metals from effluents that contain an excess of APCs. Additionally, the option of recycling the processed water using a solid phase extraction (SPE) system with an ion-selective immobilized macrocyclic material, commonly known as a molecular recognition technology (MRT) gel, is presented. Simulated effluents containing As(V), Cd(II), Cr(III), Pb(II) or Se(IV) in the presence of APCs at molar ratios of 1:50 in H2O were studied with a flow rate of 0.2 mL min-1. The �captured� ions in the SPE system were quantitatively eluted with HNO3. The effects of solution pH, metal-chelant stability constants and matrix elements were assessed. Better separation performance for the metals was achieved with the MRT-SPE compared to other SPE materials. Our proposed technique offers the advantage of a non-destructive separation of both metal ions and chelants compared to conventional treatment options for such effluents.

Abstract: Densities and viscosities of the binary systems of phenylmethanol with 2�butanone were measured for the entire composition range at T = (303.15, 308.15, 313.15, 318.15 and 323.15) K and at the atmospheric pressure. The excess molar volumes were derived from the experimental data, and were fitted with the Redlich�Kister equation to obtain their coefficients and standard deviations. The Grunberg�Nissan equation was used to correlate the viscosity data. Furthermore, kinematic viscosities were compared with those predicted by UNIFAC�VISCO model. The cause of relatively large deviations between the experimental and predicted kinematic viscosities was explored by comparing combinatorial and residual term of UNIFAC�VISCO model.

Abstract: A simple flow-based method was developed for the simultaneous separation of some transition metal ions (Co, Ni, Cu, Zn, Cd) from aqueous systems which show ecotoxic effects when present at elevated concentrations. A silica-gel-bonded macrocycle system, commonly known as molecular recognition technology (MRT) gel, was used for solid phase extraction (SPE) of the target analytes. The collection behavior of the MRT-SPE system was studied in terms of pH. Fortified deionized water samples containing 250 µg L�1 of each of the elements were treated at the flow rate of 1 mL min�1. The collected analytes were then eluted by 3 M HNO3, and introduced for inductively coupled plasma optical emission spectrometry determination. The detection limits of the proposed technique were in the range of 0.004�0.099 µg L-1 for the studied metal ions. The validity of the proposed separation technique was checked with spiked �real� water samples and satisfactory recoveries (96�102%) were observed. The non-destructive nature and highly selective ion-extraction capability of the SPE material are some focal points of the proposed method.

Abstract: Although the excellent metal-binding capacities of aminopolycarboxylate chelants (APCs) facilitate their extensive use, pre- and post-toxicity of APCs and their high persistence in aquatic environments evoke concerns. Several treatment techniques with a principal focus on the degradation of APCs at the pre-release step have been proposed. Here, we report a technique for the separation of metal ions from waste solution containing excess APCs using a solid phase extraction system with an ion-selective immobilized macrocyclic material, commonly known as a molecular recognition technology (MRT) gel. Synthetic metal solutions with 100-fold chelant content housed in H2O matrices were used as samples. The MRT gel showed a higher recovery rate compared with other SPE materials at 20 °C using a flow rate of 0.2 mL min-1. The effects of solution pH, metal-chelant stability constants and ionic radii were assessed for 32 metals. Compared to the conventional treatment options for such waste solutions, our proposed technique has the advantage of non-destructive separation of both metal ions and chelants.

Abstract: Densities and viscosities of binary liquid mixtures of hexan-1-ol + o-xylene, or + m-xylene, or + p-xylene were measured at a number of mole fractions at T = (308.15 and 318.15) K and atmospheric pressure. The excess volumes and the viscosity deviations from the mole fraction average were calculated from the experimental density and viscosity data. The experimental data were correlated with Redlich-Kister equation. Variations in the calculated excess and deviation properties for the liquid mixtures were studied in terms of intermolecular interactions.

Abstract: Densities and viscosities for the binary mixtures of hexan-1-ol with p-xylene have been measured at a number of mole fractions at T = (303.15, 313.15, and 323.15) K. The excess molar volumes and viscosity deviations have been calculated from the experimental results and have been fitted to the Redlich-Kister polynomial equation.

Abstract: Experimental values of density of binary liquid mixtures of methyl ethyl ketone (MEK) with n-hexane, cyclohexane, and benzene have been measured at a number of mole fractions at T = (303.15, 313.15, and 323.15) K. The excess molar volumes VmE have been calculated from the density data. These quantities are further fitted to the appropriate polynomial equations. The sign and magnitude of the calculated excess values have been discussed in terms of the nature of the solvent�solvent interactions in binary mixtures.

Abstract: Moringa oleifera Lam. seed oil of the indigenous-cultivar of Bangladesh was extracted using n-hexane (H), light petroleum ether (b.p. 40�60C) (LPE) and chloroform/methanol (50:50, v/v) mixture (CM). The oil content ranged from 37.50% (H) to 40.20% (CM). The moisture, protein, ash and crude fiber contents of seed residues, and the density, refractive index, color, acidity, saponification value, iodine value, unsaponifiable matter content, oxidative state, sterols, tocopherols and fatty acid composition of the extracted oil were determined. The oil contained a high amount of oleic acid (C18:1) of up to 74.41% and a high ratio of monounsaturated to saturated fatty acids with moderate oxidative stability. The results of the present study were compared with those reported in literature for different regional habitats, and species variants.

Abstract: Muscle Lipid of Hilsha (Tenualosa ilisha) was solvent extracted and characterized with respect to various physical constants e.g. refractive index, moisture, crude fat, crude fibre and ash contents; and chemical parameters e.g. saponification value, saponification equivalent value, acid value, iodine value, acetyl value, peroxide value, thiocyanogen value, reichert�meissl value, polenske value, henher value etc. and compared with those of different oils. Results also compared with the data available in literature about pharmacological aspects of Hilsha fish lipid. The oil contain high percentage of palmitic acid followed by myristic acid, palmitoleic acid, stearic acid, oleic acid, respectively, as confirmed by chromatographic examinations. However, investigation of the lipid sample against the microbial species was inconclusive.

Abstract: Volumetric and viscometric properties of the binary mixture of hexan-1-ol with m-xylene at T = (303.15, 313.15, and 323.15) K have been investigated. The excess volumes and viscosity deviations from the mole fraction average were calculated and correlated by a Redlich�Kister type equation.

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Abstract: New pentadentate Schiff base ligand of S,S-dimethyldithiocarbazate was prepared after condensing with 2,6-diacetyl Pyridine and its Ni(II), Cu(II), Zn(II) complexes were obtained while reacted with corresponding metal salts. The ligand and its metal complexes were screened for antimicrobial activity against plant microbes� viz. Aspergillus sp., Fusarium solani, Penicillium sp., Verticillum sp. and Rhizobium sp. Observed action was moderate against Aspergillus sp., Fusarium solani, Penicillium sp., Verticillum sp. while for Rhizobium sp. it was negative or minute. Metal chelation increased the inhibitory competence of the ligand in most of the cases.

Abstract: Exposure to arsenic through tubewell water in Bangladesh has become a major health problem at mass level. Current investigation was carried out to assess the extent of arsenic (As) and its correlations with some water quality parameters e.g., Ca-hardness, Total Dissolved Solids (TDS), chloride, phosphate (PO43--P), silica and iron (Fe) in the groundwater of Cox�sBazar District (CBD), a representative administrative block of Bangladesh. Mean of Ca-hardness, TDS, chloride, PO43--P, silica, Fe and As content in the groundwater samples from CBD were 13.4, 8343.5, 141.9, 12.7, 21.1, 6.7 and 0.027 ppm, respectively. Arsenic content in the CBD-groundwater found to have non-significant negative correlation with Ca-hardness, TDS, chloride, silica and Fe content at 5% level while the correlation was positive for PO43--P. One-sample t-test showed variability among the samples was significant at 1% level for TDS, chloride, PO43--P, silica and Fe.

Abstract: Kinetics of the reaction between polyethylene glycol (PEG) and hexamethylene diisocyanate (HDI) have been studied at 80°C in bulk and also in dioxan, nitrobenzene and toluene used as solvent/diluent. Two PEG samples having molar masses 4019 and 9947 respectively have been used and reactions were conducted without any addition of catalyst. The kinetic study observed from the plots showed that all these non-catalyzed spontaneous reactions are deviated from second order kinetics. Autocatalytic effect due to the product polyurethane is assumed to be the major cause for this deviation. However, the dielectric constant of the solvent, especially nitrobenzene and the viscosity of the reaction media were found to affect the kinetics.

Abstract: Performance of two indigenous arsenic (As) removal techniques-Safi filter and Home-based filters (Chari/Pitcher filter)-designed to serve household drinking water requirement have been evaluated at field conditions and compared with those reported in literature. Moderate to good As removal efficiency (>73%) with the diminution of its concentrations below Bangladesh standard of 0.05 mg L-1 were observed. Results revealed occurrence of gradual decrease in removal efficiency with the increase of As concentration in the feed water. Though these filters are rated as user friendly and readily available, lessening in flow rate of water with the progression of time is a major hindrance to the efficiency of the techniques as observed by the users.

Abstract: Oil extracted from Swietenia mahagoni seed was studied with a view to finding out its suitability for ethnomedical uses with special focus on antimicrobial and toxic behavior. Some of its physical and chemical properties were examined and compared with those of standard oils: olive, sunflower, cotton seed, Linseed, soybean, coconut, palm and castor. The refined oil was found to show good to moderate activity against disease causing bacteria viz. Shigella dysenterial, Salmonella typhi, Staphylococcuss aureus and fungal pathogens viz. Macrophomina phascolma, Alternaria alternata, Curvularia lunata. Different extracts from Swietenia mahagoni seed showed minimal toxic effect while applied on predatory fish�s viz. Heteropneustes fossilis and Anabas testudineus.

Abstract: A new tridentate Schiff base synthesized by condensing di-2-pyridylketone with S-benzyldithiocarbazate and its mono- and bis-chelated Ni(II), Cu(II) & Zn(II) complexes were screened for antifungal activity against four plant pathogens viz. Aspergillus sp., Fusarium solani, Penicillium sp. and Verticillum sp. The Schiff base ligand was found to exhibit moderate to good antifungal activity against all the tested fungi except Fusarium solani next to which no or minute activity was observed. The metal complexes of the Schiff base ligand showed greater % inhibition in comparison to that of the ligand indicating the enhancement of antifungal capability of the ligand through metal chelation. Study on comparative and average antifungal behaviour of the metal complexes reveals that Verticillum sp. is the fungus that inhibited more than the others, similar to that observed for the ligand.

Abstract: Water samples from discharge canals in the Kalurghat Industrial Area of Chittagong (KIAC) and Karnaphuli River (KR) have been analyzed for about two years for various physico-chemical parameters such as pH, conductance, alkalinity, hardness, dissolved solids, chloride, sulphate, phosphate, nitrite, nitrate, DO and trace metals such as chromium, copper, cadmium, lead and zinc to assess the environmental impact of the effluents from KIAC on KR water. The values of the parameters and trace metal concentrations at a certain collection point depend on the industry near which it is located. There is also some seasonal variation. The water samples are found alkaline throughout having high dissolved solids, phosphate, chloride and nitrite contents. DO is below the limit for healthy aquatic life in almost all places. Trace metal concentrations are also above acceptable limit for agricultural use, fish culture and other purposes.

Abstract: Arsenic (As) has been estimated in the groundwater samples extracted from shallow tubewells of the Mirsharai Thana, Sitakundu Thana and Chittagong Metropolitan Area of the Chittagong District. Some samples from Bera Thana of Pabna District have also been analyzed for comparison. The samples were collected at random. The inorganic As was converted into Arsine and estimated by visible spectrophotometry using Silverdiethyldithiocarbamate in hexamethylenetetramine-chloroform mixture. On the basis of the analytical data, the situation seems alarming in the Mirsharai Thana and a matter of concern in the Sitakundu Thana, as well as in Bera Thana. The situation in the Chittagong Metropolitan Area is not bad. Surprisingly, not a single case of As poisoning has yet been detected from the areas of Chittagong district under investigation. Arsenic contamination is, therefore, either a recent development or if old, has not yet shown its effect in these areas. No correlation was found between As and Fe-content of water and tubewell depths.

Abstract: Cellulose acetate samples, CA�1 and CA�2 with different degrees of substitution, DS = 2.38 & 2.89, respectively have been prepared from �-cellulose isolated from rayon grade bamboo pulp by a single stage acetylation process followed by hydrolysis in the former case. The polymer samples have been characterized with respect to DS, viscosity average molar mass and solubility in different solvents. Viscometric behaviours of the polymer samples have been studied in appropriate solvents such as CH3COCH3, 1,4-dioxane, CHCl3, CH2Cl2 and CH2Cl2:EtOH (4:1, v/v) mixture at different temperatures. The behaviours have been discussed in the light of modified Fox-Flory treatment. Some abnormal viscosity behaviour of the highly substituted CA sample (DS = 2.89) has been observed in CH2Cl2 and CH2Cl2-EtOH mixture.

Abstract: The kinetics of the polymerization between polyethylene glycol, PEG (molar mass 1040) and hexamethylene diisocyanate, HDI have been studied in three different solvents � dimethylformamide, DMF, nitrobenzene and toluene at 35°C and 70°C without any added catalyst. Varying amount of solvents were used in reaction carried out at the same temperature. Some non-catalysed or spontaneous reactions which were found very slow were also conducted in presence of an added catalyst, 1,4-diazabicyclo(2,2,2-)octane, DABCO. Second order kinetics plots of all the reactions, non-catalysed or catalysed showed positive deviation with time. The deviations were found much higher in non-catalysed reactions. Autocatalytic effect due to the product, polyurethane is assumed to be major cause of this deviation. The rate constants in catalysed reactions are much higher than in spontaneous reactions in the same medium. Dielectric constants of the solvents especially DMF and nitrobenzene were also found to affect the kinetics.

Abstract: Sodium carboxymethylcellulose, CMC with a degree of substitution, DS = 0.73 has been prepared by a single-stage carboxymethylation from alpha-cellulose isolated from rayon grade bamboo pulp. The polymer sample has been characterized with respect to DS, viscosity average molar mass, and solubility in different solvents. The viscometric behaviours of the CMC have been studied in water, aq. NaCl, H2O:EtOH and H2O:CH3COCH3 mixed solvents at different temperatures. The polymer followed Huggin�s equation in concentrated and dilute aq. NaCl, H2O:EtOH (50:50 v/v) and H2O:CH3COCH3 (50:50 v/v) but did not do so in very dilute aq. NaCl of concentration <0.001 M, water and H2O:CH3COCH3 (75:25 v/v). The variation of limiting viscosity numbers with temperatures in the solvents studied has been found to be consistent with that of the stiff-chain polymers.

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Abstract: Electronic wastes have become the foremost stream of solid waste in almost all the countries of the world over a short span of last few years. The digital information and communication technology (ICT) revolution that the mankind is undergoing now has substantially contributed in creating this scenario. Popularly abbreviated as E-wastes, electronic waste comprises of all out-of-date discarded or otherwise unused electronics and peripherals thereof � the bulk being computers of many descriptions, consumer electronics and mobile phones. Necessarily, a huge amount of electronics is replaced by individuals and organizations each year but people are increasingly purchasing more electronics than they really need with the rapid introduction of cheaper, sleeker and alluring gadgets. The technology and trends are changing quite rapidly rendering usable electronics obsolete and make us to go for newer versions of the same thing thereby adding up to the volume of outmode electronics. Bulk of these ends up into landfills, for USA 80-85% of e-wastes goes to landfills as estimated by US-EPA. Volume of e-wastes is a big concern but the high content of heavy metals, e.g. lead, chromium, cadmium and mercury, etc., along with harmful organic compounds in the electronic products is a bigger concern for mankind. To some, the name �e-waste� is ironic as it contains over 60% recyclables including iron, copper, aluminum, gold and other metals let alone the polymers from casings of disposed electronic products. The increasing flow of e-wastes naturally stimulated various solution responses, one of which is the boom in e-waste recycling business, in the form of formal industry in developed part of the world while manual and archaic disassembly of wastes in developing countries most of which are imported from developed countries for recycling. The non-recyclable parts of these wastes, including the toxicants, are finding their way into the environment which has led to the formulation of Basel Ban, an amendment to the Basel Convention to restrict trans-boundary movement of e-waste. However, the e-waste flux from developed to developing countries is on the rise due to win-win economics of informal recycling. Our knowledge about the chemistry of distribution, speciation, transport and environmental fate of these hazardous elements in and outside landfills are still sketchy though some researchers have initiated in-depth studies to assess and predict the eco-environmental consequences of the toxicants from disposed e-wastes. The incineration at the informal reprocessing sites contaminates the air and soils with polychlorinated and polybrominated dibenzo-p-dioxins and dibenzofurans, polycyclic aromatic hydrocarbons, etc. On the other hand, acid leaching processes contaminate the freshwater sources and sediments with heavy metal, which is exacerbated through the entry of these pollutants into the food cycle. Besides the contamination of the surroundings, the recycling process itself poses health risks to the workers due to the chemicals used in recycling and hazardous byproducts from the recycled wastes. Within the scope of this chapter, we will provide a brief overview, in light of the recent findings, of the toxic environmental releases from the e-waste disposal and recycling processes and their effects.

Abstract: Phytoremediation utilizes different plant species as a media of containment, destruction, or extraction of contaminants from different matrices including soil and water. Plants require essential metals i.e. Cu, Mn, Fe, Zn, Mo, etc. for growth and as such they are capable of accumulating these metals. Plants can also accumulate Cd, Cr, Pb, Co, Ag, Se, Hg, etc., which are apparently non-essential for their growth and survival. This metal-accumulating property of plants has made them very popular in recent days in the remediation of metal-contaminated soil. This approach of remediation has the benefit of cost savings compared to the conventional treatment options. Plants capable of concentrating metal pollutants at enhanced rate - the hyperaccumulators - are commonly used for metal-polluted soil remediation. But, the bioavailability of the metals limits the performance of hyperaccumulators since a large proportion of metals in contaminated soils exist in �non-labile� state. There came the application of synthetic chelants to enhance the mobility and phytoavailability of metals to remediating plants. Various chelants are available which forms bioavailable and water-soluble stable metal complexes facilitating phytoextraction of these metals at enhanced rates by plants. While chelants are used because of their powerful metal solubilizing properties, it is the same characteristic which gives them the potential of becoming an eco-environmental threat. Environmental concerns are evoked due to the high persistency and poor photo-, chemo- and biodegradability of metal-chelant complexes. Different approaches have been proposed to combat the eco-environmental concerns raised by the use chelants in phytoremediation. Within the scope of this chapter, we will focus on the chelant assisted phytoremediation approaches for the removal of heavy metal contaminants from soil and eco-environmental consequences associated with it.

Abstract: Humans are exposed to arsenic (As) from many sources including foods, water, and air. Although As contaminated drinking water is considered as the main route of exposure, As has also been reported in many foods. Populations who ingest contaminated groundwater excrete more As in urine that the intake from drinking water alone, suggesting that they are exposed to As from sources other than drinking water. Therefore, dietary exposure has been implicated as a significant source of As in the human body. Bioavailability and forms of As in foods are important from a toxicological point of view. Inorganic species, As(III) and As(V), are the main constituents in foods, and are toxic to humans. Cooking methods and ingredients used for cooking of foods can affect the retention of As in cooked foods, and hence in the dietary intake. In many Asian countries with arsenic in drinking water problems, the basic diet consists mainly of rice and vegetables. A substantial amount of As is absorbed or concentrated in cooked rice and vegetables from contaminated cooking water primary in inorganic forms.

Abstract: A large number of sites worldwide are contaminated by arsenic (As) as a result of human activities as well as from natural sources. Arsenic is a vital environmental and health concern due to its known chronic and epidemic toxicity. The main arsenic exposures to humans are through water pathway and food contamination originates from natural processes. Many of the available remediation technologies lost economic favor and public acceptance because of some unavoidable limitations of those technologies. Therefore, phytoremediation, a plant-based green technology, becomes an emerging and alternative technology that aims to extract or inactivate As in the environment. However, two approaches have been proposed in literature for the phytoremediation of arsenic: continuous or natural phytoremediation, and chemically enhanced phytoremediation. The first one is based on the use of natural hyperaccumulator plants having the ability to accumulate very high concentration of As in their shoots with exceptionally higher tolerance to As toxicity. On the other hand, As uptake in high biomass crop plants is increased using some chelating ligands in chemically enhanced phytoremediation technology. Freshwater and seawater around the world have been contaminated by As from various anthropogenic activities and natural sources over time. Therefore, remediation of As-contaminated aquatic systems is important as it is for terrestrial system. Aquatic macrophytes could be used to remediate the aquatic system. The use of aquatic macrophytes or other floating plants in phytoremediation technology is commonly known as phytoextraction. This cleanup process involves biosorption and accumulation of As. Recently, aquatic macrophytes and some other small floating plants such as Spirodela polyrhiza L., Lemna spp., Azolla pinnata, Salvinia natans, Eichhornia crassipes have been investigated for the remediation of As-contaminated aquatic systems. Compared to the As-phytoremediation in terrestrial system, less work has been done in aquatic systems. In this chapter, process and prospect of As phytoremediation by aquatic macrophytes is discussed.

Abstract: Arsenic (As) is widely distributed in aquatic environments in various forms. In natural waters, the dominant inorganoarsenicals (iAs) are incorporated into microorganisms such as phytoplankton, and are converted to methylarsenicals and/or more high order organoarsenicals. In addition, the organoarsenicals are mineralized to iAs and methylarsenicals by bacteria. The cycling of As species would depend on the bioactivity of organisms. Microorganisms, such as phytoplankton and organisms of higher trophic levels, produce methylarsenicals in natural waters with maximum concentrations in summer. The degradation and mineralization of organoarsenic compounds are thought to depend mostly on bacterial activities, which influence the As cycling in aquatic environment. Arsenic metabolism in aquatic organisms results in the occurrence of thermodynamically unstable arsenite and methylarsenic compounds in natural waters. The inorganic forms (As(V) and As(III)) and the methylated forms (methylarsonic acid (CH3AsO(OH)2); MMAA(V) and dimethylarsinic acid ((CH3)2AsO(OH)); DMAA(V)) are the main arsenic species present in natural waters. Although the predominant form of methylarsenicals is consistently DMAA(V) followed by MMAA(V), the existence of trivalent methylarsenic species in the environment has also been reported. Researchers reported the correlation between As(III)/methylarsenicals and chlorophyll-a concentrations and/or phytoplankton density, while others found that the seasonal changes of DMAA concentration is related to the temperature rather than the biological activity of phytoplankton. Eutrophication increases the concentration of nutrient salts and multiplies the primary producers, such as phytoplankton, in lake water. Lakes progress through the oligotrophic, mesotrophic and eutrophic process in the natural environment, and these transitions are very slow. Recently, the transition speed became faster because of discharged pollutants and nutrients from human activities, and the eutrophication affects the As circulation in lakes. Very recently, reports showed that the eutrophication influences As speciation in lake water too. In this chapter, the influence of eutrophication on arsenic speciation will be discussed.

Abstract: Toxic elements e.g. arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), and zinc (Zn) are the chief environmental pollutants which can cause deleterious health effects in humans. Inhalation and consumption of metal-contaminated food are the major pathways of metal entrance into human body. Cultivation of crop plants in the metal-contaminated soils induces the bioaccumulation of toxic elements in the food chain. Among different food items, vegetables have major contribution in the daily diet, and the heavy metal contamination of vegetables poses a threat to human health with the prevalence of skin and gastrointerestinal cancer. The uptake and bioaccumulation of toxic elements in vegetables are influenced by a number of factors such as atmospheric deposition, metal concentrations in soil, soil characteristics, and duration of cultivation. Cultivation areas near highways are exposed to atmospheric pollution in the form of metal containing aerosols which can be deposited on leaves of vegetables and then absorbed. The magnitude of heavy metal deposition on vegetable surfaces varied with morpho-physiological nature of the vegetables. Post-harvest activities, such as transportation, marketing, cooking, etc., may also influence the deposition of toxic elements in vegetables. Incorporation of toxic elements during transportation and marketing of vegetable can be occurred due to the use of contaminated water. Higher heavy metal content in vegetables from urban area then those from rural areas may be due to the contribution of urban activities which elevates heavy metal loads in atmospheric deposition and consequently in the edible part of the vegetables. Cooking has definite influence to the content of toxic elements in cooked items if the heavy metal concentrations in the cooking water are high. Vegetable consumption varies with age group, food habit, as well as vegetable availability. For example the mean daily vegetable consumption among the European people is 153 g (ranged between 109-241 g) while it is around 250g among the South Asian people. Vegetables occupy a substantial proportion of the daily diet for the South-East Asian people, especially the Japanese, Korean and Chinese people. Thus, whatever the metal contents in vegetables are, their intake in human is, off course, dependent on the total vegetable consumption. In this review, the contribution of vegetables in dietary intake of toxic elements has been discussed from a common platform.

Abstract: The arsenic calamity of Bangladesh is the largest known mass poisoning in the history. Edible vegetables, medicinal and aromatic plants grown in arsenic contaminated soil may uptake and accumulate significant amount of arsenic in their tissue which has been studied in this paper. The plants studied during the present investigation were Lablab niger (Bean), Lycopersicon esculentum (Tomato), Solanum melongena (Brinjal), Cucurbita maxima (Sweet gourd), Amaranthus gangeticus (Red amaranth), Carica papaya (Green papaya), Capsicum sp. (Chilli), Lagenaria siceraria (Bottle gourd), Momordica charantia (Bitter gourd), Mentha viridis (Mint), Vigna sesquipedalis (String bean), Abelmoschus esculentus (Okra), Trichosanthes dioica (Palwal), Basella alba (Indian spinach). Mean arsenic concentration in the selected plants in the area studied was 0.113 mg/g. The minimum was found in T. dioica (0.026 mg/g) and the maximum in M. viridis (0.566 mg/g) followed by V. sesquipedalis, Capsicum sp. (0.400, 0.200 mg/g, respectively) while arsenic content in A. esculentus, B. alba and C. papaya was below detectable limit. The average dietary intake of arsenic from the plants in the study area was estimated to be 14.69 mg/d. Correlation with the groundwater arsenic status and statistical significance of variations has also been determined.

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