Sufia Hena

Removal of chromium hexavalent ion from aqueous solutions using biopolymer chitosan coated with poly 3-methyl thiophene polymer

Adsorption capacity of Cr(VI) onto chitosan coated with poly 3-methyl thiophene synthesized chemically was investigated in a batch system by considering the effects of various parameters like contact time, initial concentration, pH and temperature. Cr(VI) removal is pH dependent and found to be maximum at pH 2.0. Increases in adsorption capacity with increase in temperature indicate that the adsorption reaction is endothermic. Based on this study, the thermodynamic parameters like standard Gibbs free energy (DeltaG degrees), standard enthalpy (DeltaH degrees) and standard entropy (DeltaS degrees) were evaluated. Adsorption kinetics of Cr(VI) ions onto chitosan coated with poly 3-methyl thiophene were analyzed by pseudo-first-order and pseudo-second-order models. The Langmuir, Freundlich and Temkin isotherms were used to describe the adsorption equilibrium studies of chitosan coated with poly 3-methyl thiophene at different temperatures. Langmuir isotherm shows better fit than Freundlich and Temkin isotherms in the temperature range studied. The results show that the chitosan coated with poly 3-methyl thiophene can be efficiently used for the treatment of wastewaters containing chromium as a low cost alternative compared to commercial activated carbon and other adsorbents reported. In order to find out the possibility of regeneration and reuse of exhausted adsorbent, desorption studies were also performed.

THIN-LAYER CHROMATOGRAPHY OF AMINO ACIDS: A REVIEW

Thin-layer chromatography is a versatile separation technique and is compatible to almost all types of compounds available in nature. This review presents numerous chromatographic systems developed for the analysis of amino acids. The stationary phases, solvent systems, and detection reagents used by the various chromatographers are incorporated in this review. From the available literature, it is obvious that amino acids have been greatly analyzed by thin-layer chromatography.

Three stage cultivation process of facultative strain of Chlorella sorokiniana for treating dairy farm effluent and lipid enhancement.

Reserve lipids of microalgae are promising for biodiesel production. However, economically feasible and sustainable energy production from microalgae requires optimization of cultivation conditions for both biomass yield and lipid production of microalgae. Biomass yield and lipid production in microalgae are a contradictory problem because required conditions for both targets are different. Simultaneously, the mass cultivation of microalgae for biofuel production also depends extremely on the performance of the microalgae strains used. In this study a green unicellular microalgae Chlorella sorokiniana (DS6) isolated from the holding tanks of farm wastewater treatment plant using multi-step screening and acclimation procedures was found high-lipid producing facultative heterotrophic microalgae strain capable of growing on dairy farm effluent (DFE) for biodiesel feedstock and wastewater treatment. Morphological features and the phylogenetic analysis for the 18S rRNA identified the isolated strains. A novel three stage cultivation process of facultative strain of C. sorokiniana was examined for lipid production.

Micellar TLC of Inorganic Ions: Simultaneous Separation of Lead(II), Zinc(II), and Cobalt(II) and Spectrophotometric Estimation of Zinc(II)

Micellar thin-layer chromatography has been used to investigate the separation and migration behavior of metal ions. Thin layers (0.25 mm) of silica gel G on glass plates (5 cm × 20 cm) were used as adsorbent. Ascending development of the plates was performed with aqueous sodium dodecyl sulfate (SDS) and two-component mixtures of aqueous SDS (0.2 m) and 0.04 m, 0.08 m, or 0.1 m carboxylic acids in different ratios (1:9, 1:1, and 9:1) as mobile phases. The RF values of metal ions were measured. The mobile phase 0.2 m SDS—0.08 m tartaric acid 1:1 was best for separation and identification of Pb2+, Zn2+, and Co2+. The order of mobility (RF) was Pb2+ < Zn2+ < Co2+. On-plate identification of Pb2+, Zn2+, and Co2+in the presence of impurities was achieved. The method was successfully applied to identification and separation of Pb2+, Zn2+, and Co2+in drugs, river water, sea water, and tap water. TLC-spectrophotometry was used for quantitative analysis of Zn2+in spiked drug samples with preliminary separation from Pb2+, and Co2+. The detection limits for Pb2+, Zn2+, and Co2+were also evaluated.

Screening of facultative strains of high lipid producing microalgae for treating surfactant mediated municipal wastewater

This study discusses a novel approach to simultaneously remove two types of hazardous chemicals, surfactants and nutrients, from municipal wastewater by culturing selected microalgae. A total of 76 strains of microalgae were separated from different sampling sites situated in the Island of Penang, Malaysia, using a 48-well tissue culture plate. Screening and acclimation procedures were performed to select facultative heterotrophic microalgae strains capable of growing in surfactant-mediated wastewater for simultaneous wastewater treatment and lipid production. Only eleven out of thirty-six facultative strains were demonstrated to be tolerant towards surfactant-mediated municipal wastewater (SMMW). The selected eleven strains were further characterized according to the rate of cell growth, biomass production, lipid accumulation and fatty acid profile. The six best strains, identified as Scenedesmus sp., Chlamydomonas sp., Chlorococcum humicola, Botryococcus braunii and two Chlorella sp., were chosen for further studies because of their ability to grow in surfactant mediated municipal wastewater (SMMW) with high growth rates (0.354–0.501 d−1) and their higher lipid accumulations (21.54–41.98% of dry biomass).

Treatment of coal gasification wastewater by anaerobic SBR–aerobic SBR process for elimination of toxic organic matters-a lab scale study

As a typical refractory industrial wastewater, coal gasification wastewater has a high toxicity and poor biodegradability. In this paper, an anaerobic SBR–aerobic SBR process was used to treat coal gasification wastewater. Average removal efficiency of COD, total phenols, volatile phenols, NH4+–N were 65.1%, 79.6%, 99.5% and 99.39%, with final concentration in the effluent were 380 mg L−1, 45.2 mg L−1, 0.52 mg L−1 and 0.32 mg L−1, respectively. There are 72 kinds of organic matters in the influent, a total of 10 categories. After biological treatment, the types and concentration of organic matters in the effluent of A (anaerobic 48 h effluent), B (anaerobic 48 h–aerobic 48 h effluent), C (anaerobic 24 h effluent), D (anaerobic 24 h–aerobic 48 h effluent) has dropped significantly and the types of organic compounds were reduced to simpler 42, 45, 46 and 61 kinds, respectively. The process showed ascendancy in the treatment of toxic matters. Organics degradation and transformation were analysed by GC-MS. Additionally, microbial community analysis in anaerobic sludge was investigated by means of polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) along with SEM, revealed that it had a great variety of bacterial dominant species. The study demonstrated that hydrolytic acidification at SBR anaerobic 24 h + aerobic 48 h could be a technically feasible method to enhance NH4+–N, COD, TP removal and degradation of complex organic compounds in coal gasification wastewater.

Identification and separation of lead (II), nickel (II), and cobalt (II) on silica gel 60 F254 high-performance thin-layer chromatographic plates with mixed aqueous sodium dodecyl sulfate-oxalic acid solvent system

The chromatographic separation of three metal cations was performed on high-performance thin-layer plates (silica gel 60F254) with mixed sodium dodecyl sulphate (SDS) and oxalic acid. The effect of concentration of surfactant and additive effect of different carboxylic acids on the mobility of metal ions were investigated. The resolution of a mixture of Pb2+, Ni2+, and Co2+ was achieved by using 0.2 M SDS plus 0.08 M oxalic acid, 1:9, v/v as a solvent system. The developed method was utilized to identify these metal ions in different spiked water samples after their preliminary separation.

New T-Shape Polyurethanes: Synthesis, Thermal and Mechanical Properties

A series of new T-shaped polyurethanes were prepared from various diisocyanates and 2,5-dihydroxybenzelidene aniline (azomethine bisphenol). The latter compound was synthesized by the reaction of 2,5-dihydroxy-benzaldehyde with aniline. The structures of azomethine bisphenol and T-shaped polyurethane were confirmed by FT-IR, 1H-NMR, 13C-NMR Spectroscopy and elemental analysis (CHN). The mechanical properties were characterized by tensile strength, tear strength and shore hardness. Thermal properties were also studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Mechanical and thermal studies showed that the synthesized polyurethanes possess good mechanical and thermal properties.