Muhammad Ali Zulfikar

Abstract: The aim of this study was to investigate the use of liver moss (Dumortiera hirsute Sw. nees) as an alternative adsorbent for the removal of nickel, copper and cadmium from aqueous solution. The results showed that equilibrium contact time was 60 min and acidic pH was favourable for removal of metal ions. Higher initial metal ion concentrations led to lower removal. The data were fitted well both Langmuir and Freundlich isotherms. The monolayer adsorption capacities were 30.675, 35.971 and 53.476 mg/g for nickel, copper and cadmium, respectively. The presence of metal ions such as sodium, potassium and magnesium at concentration of 10 mM was found to have no significant effect on the removal of nickel, copper and cadmium. The removal of nickel, copper and cadmium was markedly inhibited, however, in the presence of calcium ion and heavy metal ions mixture in solutions. The kinetic data for removal processes were described by the pseudo-second-order model. The liver moss shows high potential as an economic and abundant material for the removal of metal ions from aqueous solution.

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Abstract: Batch adsorption of lignosulfonates using untreated powdered eggshell under the influences of mixing time, pH, particle size and dose of powdered eggshell was investigated. Adsorption isotherms of lignosulfonates onto powder eggshell were also studied. Eggshells were collected from the Balubur traditional market in Bandung, Indonesia, washed with distilled water, air dried, and then ground into powder of different particle sizes. Kinetic studies found that equilibrium time was as high as 90 minutes. From experiments carried out at different pH, it was observed that pH plays an important role in the adsorption of lignosulfonate compounds. It was also observed that particles size has no significant effect on the adsorption of lignosulfonate compounds. The optimum dosage of powdered eggshell was 30 g/100 mL of 500 mg/L lignosulfonate solution. Adsorption isotherms studied through the use of graphical methods revealed that the adsorption of lignosulfonates onto powdered eggshell follows the Langmuir model.

Abstract: A complete analysis of municipal solid waste landfill leachate which coming from the old landfill, Leuwigajah (LG) and the new landfill, Rajamandala (RM) were performed using X-ray fluorescence (XRF), X-ray diffraction (XRD) and other physico-chemical analysis. The results of landfill leachate at different age were compared and observed both similarities and differences. It is our first report of landfill leachate analysis in environmental study at Indonesia. Our results indicated that the new landfill which is less than 5 years, have no significant influence to water quality, although already started polluting the surrounding area. © EuroJournals Publishing, Inc. 2012.

Abstract: Immobilization of enzymes is one of the most promising methods in enzyme performance enhancement, including stability, recovery, and reusability. However, investigation of suitable solid support in enzyme immobilization is still a scientific challenge. Polyethersulfone (PES) and aminated PES (PES-NH 2) were successfully synthesized as novel materials for immobilization. Membranes with various pore sizes (from 10-600 nm) based on synthesized PES and PES-NH 2polymers were successfully fabricated to be applied as bioreactors to increase the immobilized lipase performances. The influence of pore sizes, concentration of additives, and the functional groups that are attached on the PES backbone on enzyme loading and enzyme activity was studied. The largest enzyme loading was obtained by Mucor miehei lipase immobilized onto a PES-NH 2 membrane composed of 10% of PES-NH 2, 8% of dibutyl phthalate (DBP), and 5% of polyethylene glycol (PEG) (872.62 μg/cm 2). Hydrolytic activity of the immobilized lipases indicated that the activities of biocatalysts are not significantly decreased by immobilization. From the reusability test, the lipase immobilized onto PES-NH 2 showed a better constancy than the lipase immobilized onto PES (the percent recovery of the activity of the lipases immobilized onto PES-NH 2 and PES are 97.16% and 95.37%, respectively), which indicates that this novel material has the potential to be developed as a bioreactor for enzymatic reactions. © 2012 by the authors; licensee MDPI, Basel, Switzerland.

Abstract: Synthetic dye-containing wastewaters from textile, paper, plastic and leather-tanning industries are a most common organic pollutant. Such dyes may be toxic not only to aquatic life, but also to human beings. Consequently, dye removal from wastewater significantly benefits the environment. The aim of this study was to investigate the effectiveness of phyrophyllite as an adsorbent for Congo Red dye from wastewater. Dye sorption rates were investigated in bench-scale studies. Evaluation of adsorption performance of phyrophyllite on Congo Red necessitated the determination of Langmuir and Freundlich isotherms. Adsorption of Congo Red on phyrophyllite was found to be in conformity with both isotherms. The adsorption capacity for phyrophyllite was found to increase with decrease in particle size and with increase in temperature and intensity of agitation. The results indicated that phyrophyllite was a good adsorbent for Congo Red from wastewaters. © 2010 Taylor & Francis.

Abstract: Hybrid organic-inorganic membranes were fabricated using sol-gel technique using poly(methyl methacrylate) (PMMA) and tetraethyl orthosilicate (TEOS) with 80/20 (w/w) ratios with THF solvent. The thin films were then characterized using FTIR, SEM, EDX, DSC, TGA, water permeability and also its molecular weight cut-off. From the preliminary characterization, the hybrid membrane was found to have nano and ultra scale tight pore ranges. FT-IR spectroscopy uncovered all the signature peaks characteristic of silicate structures in the near-surface regions. Fingerprints of Si{single bond}O{single bond}Si groups in cyclic and linear molecular substructures are present. The SEM image clearly shows that hybrid membranes have homogenous and smooth surface. EDX analysis shows the composition of particles in the membrane. DSC analysis of the membrane shows interesting phenomenon regarding glass transition temperature (Tg). The hybrid membrane was found to have higher Tg than pure PMMA. From TGA analysis, the hybrid membranes were observed to have higher thermal stability than pure PMMA. © 2006 Elsevier B.V. All rights reserved.

Abstract: In this paper, hybrid organic-inorganic membranes were prepared using three different solvents and characterized. The hybrid membranes were fabricated using sol-gel technique, which had polymethyl-methacrylate (PMMA) and tetraethyl orthosilicate (TEOS) as materials, with 80/20 ratio. The thin films were then characterized using FTIR, SEM, EDX, and mapping techniques. From the preliminary characterization, hybrid membranes were found to have nano and ultra scale tight-pores ranges, which was influenced by the solvent used. The SEM images clearly show that hybrid membranes have homogenous and smooth surface. FTIR spectroscopy uncovered all the signature peaks characteristic of silicate structures in the near-surface regions. Fingerprints of Si-O-Si groups in cyclic and linear molecular substructures were also present. From DSC analysis, the Tg value of the PMMA moieties in hybrids membranes was in the order H-15-Toluene < Pure PMMA < H-15-THF < H-15-DMF. Furthermore, from TGA analysis it was found that the hybrid membranes have higher thermal stability compared with that of pure PMMA. EDX and mapping analysis showed that the composition and distribution of particles in the membranes were different and dependent on the solvents used. © 2005 Wiley Periodicals, Inc.

Abstract: Poly(methyl methacrylate) (PMMA)-SiO2 composite membranes were prepared by casting ternary solutions obtained by adding additional amounts of TEOS to PMMA solutions. Methods to obtain an intimate dispersion of the inorganic particles in the PMMA solutions were developed. Various samples of hybrid membranes were prepared by varying some of the preparative parameters such as the PMMA solvent (tetrahydrofuran, and N,N-dimethyl formamide) and the PMMA/TEOS ratio in the ternary solution. Membranes were also cast from a binary solution of PMMA and solvent for comparison. The membranes were characterized by water permeability, scanning electron microscope observations, DSC and TGA analysis and ultrafiltration tests. The effects of the above-mentioned preparative parameters on the structure, thermal behavior, flux and dextran retention properties of the membranes are discussed. © 2006.

Abstract: Hybrid organic-inorganic membranes were fabricated using sol-gel technique using PMMA and TEOS with 80/20 (w/w) ratio at various solvents. The thin membrane films were then characterized using DSC and TGA. From DSC analysis, the Tg value of the PMMA moieties in hybrids membranes was in the order H-15-Toluene < Pure PMMA < H-15-THF < H-15-DMF. Furthermore, from TGA analysis it was found that the hybrid membranes have higher thermal stability compared to pure PMMA, and the type of solvents used play an important role in their degradation behavior.