Vijay Kumar Agarwal

Enzymatic mechanism and biochemistry for cyanide degradation: A review

Cyanides are fast-acting poisons, can be lethal if exposed in excess. In spite of fact, cyanides are discharged as effluents in large scale from industries every year. Certain bacteria, fungi, algae and plants produce cyanides. It has been observed that microbes and plant systems can degrade cyanides to less toxic compounds. There are many enzymes, which are produced by microorganisms that utilize cyanides as substrate to make alanine, glutamic acid, alfa-amino-butyric acid, beta-cyanoalanine, etc. Present paper deals with different enzymes, their mechanisms and corresponding pathways with respect to the known biochemistry of enzyme and feasibility for the use in treatment of cyanides containing industrial effluents.

Design and optimization of simultaneous biosorption and bioaccumulation (SBB) system: a potential method for removal of Zn(II) ion from liquid phase

Abstract This study has dealt with the design of simultaneous biosorption and bioaccumulation (SBB) batch system for Zn(II) ion removal from liquid phase. Cedrus deodara sawdust was used as carrier to immobilize Zinc sequestering bacteria “VMSDCM” accession number HQ108109. This methodology was adopted for SBB of metal ion zinc from liquid phase. The surface texture of the biomass was studied through scanning electron microscopy and Fourier transformation infra red spectrum analysis. Physico-chemical analysis of the biomass was performed through proximate carbon, hydrogen, nitrogen and sulphur analysis coupled with measurement of the surface area by Brunauer–Emmett–Teller (BET) method, obtained after the adsorption and desorption of nitrogen gas on the sample. Various isotherm models such as Langmuir (Type I to IV), Freundlich, and Temkin isotherm models have been used in the present work. A modified model was proposed to elucidate the better explanation of the sorption of Zn(II) on the surface of Zinc se...

Sorption of Zn(II) ion onto the surface of activated carbon derived from eucalyptus bark saw dust from industrial wastewater: isotherm, kinetics, mechanistic modeling, and thermodynamics

Abstract The activated carbon was derived from base (0.2 M NaOH)-mediated activation of biomass followed by thermal treatment at 1,123 K. The utmost metal ion uptake capacity and sorption percentage of activated carbon derived from eucalyptus biomass were 1.42 mmol g−1 and 93.42%, respectively. Freundlich isotherm model proved to be superior with higher linear correlation coefficient R 2 = 0.96–0.98. Similarly, it was observed that pseudo-second-order reaction model with lower χ 2 (0.002703–0.009351) and sum of square errors (0.0001–0.0144) value together with higher R 2 (0.98–0.99) ruled in all the possibilities of sorption of Zn(II) ion on activated carbon surface as chemisorption. Bangham’s model (R 2 = 0.93–0.95) applicability in the present investigation demarcated the fact that the main rate-controlling step in the sorption of Zn(II) ions on activated carbon surface was film diffusion rather than intraparticle diffusion. The results of diffusivity coefficients (D f = 7.16 × 10−6 cm2 s−1) reproduced ...

ADSORPTIVE TREATMENT OF CYANIDE-BEARING WASTEWATER: A PROSPECT FOR SUGAR INDUSTRY WASTE

The biosorption of cyanide ions from aqueous solution by bagasse was studied in a batch adsorption system with pH, contact time, cyanide ion concentration, metal ion concentration, and adsorbent dosage as variables. XRD, FT-IR spectroscopy, CHN, proximate, ultimate, and TG/DTG thermal analyses were used for the characterization of bagasse. The biosorption capacities and rates of biosorption of cyanide ions onto bagasse were evaluated. The Langmuir and Freundlich adsorption models were applied to describe the isotherms and isotherm constants. Biosorption isothermal data were interpreted by the Langmuir model followed by the Freundlich model with maximum adsorption capacity of 98% of cyanide ion on bagasse. The kinetic experimental data were properly correlated with the first- and second-order kinetic model.

Physico-mechanical properties of coir fiber/LDPE composites: Effect of chemical treatment and compatibilizer

Coir fiber/low density polyethylene (LDPE) composites were fabricated with different fiber loading (10-30 wt%) using compression molding technique. A fiber loading of 20 wt% was found optimum, with maximum mechanical properties. Further, the effect of fiber treatment (alkali and acrylic acid) and compatibilizer (MA-g-LDPE) incorporation on the mechanical and water absorption properties of the LDPE composites were studied and compared. The results showed that MA-g-LDPE incorporation into untreated and treated fiber composites led to improved mechanical properties and water resistance compared with the same composite formulation without MA-g-LDPE. However, treated fiber composites with MA-g-LDPE showed lower mechanical properties than untreated fiber without MA-g- LDPE, due to the removal of hydroxyl groups from the hemicellulose and lignin region of the fiber and degradation of fibers by chemical attack. From SEM studies on the tensile fractured composite samples, a good relationship has been observed between the morphological and mechanical properties.

Hybridization effect of coir fiber on physico-mechanical properties of polyethylene-banana/coir fiber hybrid composites

Abstract In this paper, an attempt has been made to investigate the effect of coir fiber addition along with the banana fiber in low-density polyethylene (LDPE) to develop cost-effective and high-performance composite material. The composite samples were prepared at fixed fiber content (25 wt%) and with varying relative weight fraction of banana and coir fiber using compression molding technique. The effect of hybridization was analyzed through the mechanical properties (tensile, flexural, and impact), thermal stability, morphological behavior, and water absorption behavior. Additionally, scanning electron microscopy studies had been carried out on the tensile fractured surface for all composite samples to examine the fracture behavior of the composite samples. The results showed that the incorporation of coir fiber into the banana fiber composites of up to 50% by weight led to enhancement of the mechanical properties and thermal stability and to reduction of the water absorption capacity of the banana fiber/LDPE composites.

Thermal degradation of coir fiber reinforced low-density polyethylene composites

Abstract In the present study, the effect of fiber surface treatments (alkali and acrylic acid) on the thermal degradation behavior of coir fiber (CF)-low-density polyethylene (LDPE) composites with or without compatibilizer (maleic anhydride grafted LDPE, MA-g-LDPE) using thermogravimetric and derivative thermogravimetric analyses (TG/DTG) was analyzed and compared with those of untreated fiber composites. The TG/DTG results revealed that the thermal stability of the CF improved after the chemical treatments. However, the composite containing treated fiber showed lower thermal stability and started to degrade at a faster rate above 380°C in comparison to composites containing untreated fiber composites. Furthermore, the addition of MA-g-LDPE led to improvement in the thermal stability of both treated and untreated fiber composites in comparison to the same composite formulation without MA-g-LDPE. The composite containing untreated fiber and MA-g-LDPE demonstrated superior thermal stability among all the formulated composites, indicating strong fiber-matrix adhesion.