Chandrajit B. Majumder

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 ...

Growth of three bacteria in arsenic solution and their application for arsenic removal from wastewater

The present paper compares the arsenic removal capacities of three bacterial strains namely, Ralstonia eutropha MTCC 2487, Pseudomonas putida MTCC 1194 and Bacillus indicus MTCC 4374 form wastewater (simulated acid mine drainage) containing arsenic (As(III):As(V)::1:1), Fe, Mn, Cu and Zn in the concentration of 15 mg/l, 10 mg/l, 2 mg/l, 5 mg/l and 10 mg/l respectively, in bulk liquid phase. Growth patterns of these bacteria in presence of arsenic in solution as well as under starvation have also been investigated as the acid mine drainage normally does not contain organic carbon and also contains high arsenic. At the nutrient broth concentration of 1.25 g/l and in presence of 15 mg/l arsenic sufficient growth of these strains have been observed. However, growth of Ralstonia eutropha MTCC 2487 has been found slightly more than Pseudomonas putida MTCC 1194 and Bacillus indicus MTCC 4374. Arsenic removal capacities of Ralstonia eutropha MTCC 2487, Pseudomonas putida MTCC 1194 and Bacillus indicus MTCC 4374 from simulated acid mine drainage are ∼67%, 60% and 61% respectively. It has also been observed that arsenic concentration of 15 mg/l prolongs the stationary phase of these strains. pH and temperature for the above studies have been maintained at 7.1 ± 0.1 and 29 ± 1 °C, respectively. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Bioconversion of Hemicellulosic Fraction of Perennial Kans Grass (Saccharum spontaneum) Biomass to Ethanol by Pichia stipitis: A Kinetic Study

Ethanol is a promising alternative energy source for the limited crude oil and can be produced from abundantly available lignocellulosic biomass. Utilization of acid hydrolysate of Kans grass (Saccharum spontaneum), a perennial grass native to South Asia, has been investigated for ethanol production. The dilute acid treatment was applied to hydrolyze the Kans grass biomass for releasing maximum hemicellulosic sugars. The aim of this work was to develop a fermentative system utilizing Kans grass hemicellulose acid hydrolysate as a substrate for ethanol production by Pichia stipitis. It was found that 74% of xylose was converted to ethanol with a yield of 0.429 gp gs −1 and productivity of 0.231 gp l−1 h−1. The appropriate mathematical models for cell and ethanol production rate have been developed to explain theoretically the bioconversion of Kans grass hemicellulose acid hydrolysate to ethanol and validated statistically with the experimental results carried out in the laboratory. The present study revealed that the degradation of sugar, activation and inhibition of cells, and ethanol production were strictly coupled during the bioconversion process of hemicellulosic fraction of Kans grass to ethanol.

Modelling and kinetic aspects of a BTEX contaminated air-treating biofilter

In this study, the overall performance of a biofilter was evaluated in terms of its elimination capacity by using 3-D mesh techniques. The overall results indicate that the agreement between experimental data and model predictions is excellent for benzene, toluene, ethylbenzene and o-xylene (BTEX). In this study, the maximum removal rate (r max) values for BTEX were 0.0117, 0.0126, 0.0081 and 0.0146 g m–3 h–1, and the half-saturation constant (KS ) values were calculated to be 0.269, 0.297, 0.156 and 0.394 g m–3, respectively. For this system, the coefficients of determination (r 2) of BTEX compounds were greater than 0.97. The BTEX concentration profiles along the depth were also determined using a convection–diffusion reactor (CDR) model. The sums of squares of the errors (SSEs) of BTEX were 0.0078, 0.0059, 0.0129 and 0.0269, respectively, with r 2 values greater than 0.99 for all four compounds at low concentrations.