Lalitagauri Ray

Adsorption profile of lead on Aspergillus versicolor: A mechanistic probing

The adsorption of lead on Aspergillus versicolor biomass (AVB) has been investigated in aqueous solution with special reference to binding mechanism in order to explore the possibilities of the biomass to address environmental pollution. AVB, being the most potent of all the fungal biomasses tested, has been successfully employed for reducing the lead content of the effluents of battery industries to permissible limit (1.0 mg L(-1)) before discharging into waterbodies. The results establish that 1.0 g of the biomass adsorbs 45.0 mg of lead and the adsorption process is found to depend on the pH of the solution with an optimum at pH 5.0. The rate of adsorption of lead by AVB is very fast initially attaining equilibrium within 3h following pseudo second order rate model. The adsorption process can better be described by Redlich-Peterson isotherm model compared to other ones tested. Scanning electron micrograph demonstrates conspicuous changes in the surface morphology of the biomass as a result of lead adsorption. Zeta potential values, chemical modification of the functional groups and Fourier transform infrared spectroscopy reveal that binding of lead on AVB occurs through complexation as well as electrostatic interaction.

Studies on Cr(VI), Pb(II) and Cu(II) adsorption-desorption using calcium alginate as biopolymer

Abstract The aim of this study was to investigate the Cr(VI), Pb(II) and Cu(II) biosorption potential of calcium alginate from aqueous solution and to screen a variety of desorbing agents, in order to access the efficiency of desorption and regeneration of the biosorbent in multiple sorption-desorption cycles. Calcium alginate beads was found to remove heavy metal ions efficiently from aqueous solution with selectivity in the order of Cr(VI)>Cu(II)> Pb(II).The biosorption of metal ions by calcium alginate beads decreased as the initial concentration of metal ions increased in the medium. The maximum heavy metal ions adsorbed was found to be 238,154,120 mg/g calcium alginate beads for Cr(VI), Cu(II) and Pb(II) respectively. The maximum uptake of metal ions was obtained at pH 2.0. Above pH 2.0, biosorption of metal ions by calcium alginate beads was found to be relatively constant for Pb(II) and Cu(II) ions, biosorption of Cr(VI) still increased upto pH 3.0 having 86% removal efficiency. At temperature 35°C, the biosorption of metal ions was found to be highest, with increase or decrease in temperature resulted in a decrease in the metal ions uptake capacity. The sorption data of all three metal ions conformed well the Langmuir isotherm. The bound metal ions could be eluted successfully using 0.1 M EDTA. The successive sorption-desorption studies employing calcium alginate beads indicated that the beads could be regenerated without showing the significant loss in adsorption capacity even after second cycle of adsorption -desorption. The results suggest that calcium alginate beads can be used as a biosorbent for an efficient removal of heavy metal ions from aqueous solution.

Performance Study of Chromium (VI) Removal in Presence of Phenol in a Continuous Packed Bed Reactor by Escherichia coli Isolated from East Calcutta Wetlands

Organic pollutants, like phenol, along with heavy metals, like chromium, are present in various industrial effluents that pose serious health hazard to humans. The present study looked at removal of chromium (VI) in presence of phenol in a counter-current continuous packed bed reactor packed with E. coli cells immobilized on clay chips. The cells removed 85% of 500 mg/L of chromium (VI) from MS media containing glucose. Glucose was then replaced by 500 mg/L phenol. Temperature and pH of the MS media prior to addition of phenol were 30°C and 7, respectively. Hydraulic retention times of phenol- and chromium (VI)-containing synthetic media and air flow rates were varied to study the removal efficiency of the reactor system. Then temperature conditions of the reactor system were varied from 10°C to 50°C, the optimum being 30°C. The pH of the media was varied from pH 1 to pH 12, and the optimum pH was found to be 7. The maximum removal efficiency of 77.7% was achieved for synthetic media containing phenol and chromium (VI) in the continuous reactor system at optimized conditions, namely, hydraulic retention time at 4.44 hr, air flow rate at 2.5 lpm, temperature at 30°C, and pH at 7.

Biosorption of Malathion by immobilized cells of Bacillus sp. S14

Abstract Biosorption is potentially an attractive technology for the treatment of wastewater by removing pesticide molecules from dilute solutions. This study investigated the feasibility of an isolated Bacillus sp. S14 immobilized in calcium alginate that was used as a biosorbent for Malathion removal from aqueous solutions in batch mode. The highest value of Malathion uptake by isolated Bacillus sp. S14 (1.33g L−1, dry basis) immobilized in 3% calcium alginate was 64.4% at 25°C and pH7.0 when the initial Malathion concentration was 50 mg L−1. Equilibrium was attained at 8h. The sorption data conformed well to the Fruendlich isotherm model.

Adsorption of nickel onto Bacillus cereus M116: A mechanistic approach

ABSTRACT Adsorption characteristics of nickel on Bacillus cereus M116 biomass have been studied under varied environmental conditions to explore the potentiality of the biomass for controlling water pollution due to nickel. The optimized parameters for adsorption process are as follows: pH: 7.0, temperature: 40°C, biomass dosage: 2 g L–1. The process is best fitted to Redlich–Peterson isotherm model and follows pseudo-second order rate model. The combination of zeta potential measurement, SEM – EDXA, XRD, XPS, FTIR, TGA, and DSC studies allow a more comprehensive characterization of biomass to understand the mechanisms involved in nickel (II) adsorption in aqueous system.

BIOSORPTION OF CHROMIUM (VI) BY A MUTATED STRAIN OF Bacillus cereus M116

The removal of chromium, a highly toxic metal causing environmental pollution from dilute aqueous solution, was studied in the present work using growing and washed cells of a mutant strain of Bacillus cereus (M 1 16 ) isolated from tannery waste. Particularly, the effects of pH, temperature, metal ion concentration and contact time on removal of chromium were studied. About 40% chromium removal, was observed by growing cells of the selected strain at pH 6.5, temperature 30 o ±1 o C, inoculum size 3%, medium volume 50 ml/250 ml Erlenmeyer flask, and initial chromium concentration 50 ppm. Using resting cells 98.02% and 78.34% chromium removal was possible with initial chromium concentration of 25 and 50 ppm, respectively, at pH 3.0, temperature 25-35 o C and 2.73 g/L biomass concentration. It was found that the overall adsorption process was best described by pseudo-second order kinetics. Freundlich and Langmuir adsorption models were found suitable for describing the short-term biosorption of chromium (VI). IR spectral analysis of the biomass was carried out to find out the functional groups responsible for chromium (VI) biosorption.

Optimization of fermentation conditions for green pigment production from Bacillus cereus M116 (MTCC 5521) and its pharmacological application

Optimal culture conditions for the production of green pigment was investigated. The optimal culture condition for the production of an extracellular green pigment by growing Bacillus cereus M116 (MTCC 5521) in a complex medium containing (g l−1) Peptone‐4·0, Beef Extract‐9·0, NaCl‐7·0, MgSO4·7H2O‐1·0 and KH2PO4‐5·0 was as follows pH‐7·0 at 30°C for 72 h in a 5 l fermenter. Aeration rate and agitator speed had no effect on the pigment production. Thin layer chromatogram of the pigment extracted from the fermented broth with chloroform on silica gel GF254 using ethyl acetate and hexane (1 : 1) as solvent showed three fractions. The major fraction (C3) was separated out and identified as 9‐methyl‐1, 4, 5, 8‐tetra‐azaphenanthrene. Acute toxicity test revealed the nontoxic nature upto a dose of 2000 mg kg−1, b.wt., of mice. MTT assay showed the cytotoxic nature in HL60 cells having an IC50 of 2·47 mmol. So, this biopigment may have application in food, textile colorant and pharmaceutical industry.

Continuous removal of malathion by immobilised biomass of Bacillus species S14 using a packed bed column reactor

Abstract Biosorption of malathion from aqueous solution was studied using Bacillus sp. S14 immobilised on calcium alginate (3%) using a packed bed column reactor at a temperature of 25 °C and a pH of 7.0. The experiments were conducted to study the effect of important design parameters such as bed height, flow rate and influent malathion concentration. Maximum removal capacity (57%) was found at 4 mL min-1 flow rate, 6.0 cm bed height and 25 mg L-1 influent malathion concentration. The Adam-Bohart model, Wolborska model, Thomas model, Yoon-Nelson model were employed to determine characteristic parameters such as saturation concentration, external mass transfer coefficient, Thomas rate constant, the maximum solid phase concentration of the solute, rate constant, and the time required for 50% adsorbate breakthrough time, which are all useful for process design. Experimental data were well fitted with Adam–Bohart model at the lower region of effluent/influent malathion concentration values but at higher region values data fitted well with the Thomas and Yoon-Nelson models.

Adsorption behaviour of cadmium by Bacillus cereus M116: some physical and biochemical studies

Abstract Adsorption behaviour of cadmium from its aqueous solution by growing and non-growing cells of a mutant strain of Bacillus cereus M116 has been studied to explore the possibility of the biomass to address environmental pollution due to this toxic metal. The results establish that about 75% and 88% of the cadmium can be removed by growing and non-growing cells of the selected strain respectively from its aqueous solution at pH 6.8 ± 0.2, temperature 30 ± 1°C and 120 rpm shaking speed. For growing cells, inoculum size 2% and medium volume 50 mL is found to be optimum. The adsorption rate of cadmium on the biomass is very fast initially and attains equilibrium within 60 min following pseudo second-order rate model (R2 = 0.99). The equilibrium adsorption isotherm can be best described by Langmuir–Freundlich dual model (R2 = 0.99) indicating that both physisorption and chemisorption take place simultaneously. Cadmium can be desorbed from the loaded biomass using mineral acids (0.1 M).

Enzymes- An Existing and Promising Tool of Food Processing Industry

BACKGROUND The enzyme catalyzed process technology has enormous potential in the food sectors as indicated by the recent patents studies. It is very well realized that the adaptation of the enzyme catalyzed process depends on the availability of enzyme in affordable prices. OBJECTIVE Enzymes may be used in different food sectors like dairy, fruits & vegetable processing, meat tenderization, fish processing, brewery and wine making, starch processing and many other. Commercially only a small number of enzymes are used because of several factors including instability of enzymes during processing and high cost. METHOD More and more enzymes for food technology are now derived from specially selected or genetically modified microorganisms grown in industrial scale fermenters. Enzymes with microbial source have commercial advantages of using microbial fermentation rather than animal and plant extraction to produce food enzymes. CONCLUSION At present only a relatively small number of enzymes are used commercially in food processing. But the number is increasing day by day and field of application will be expanded more and more in near future. The purpose of this review is to describe the practical applications of enzymes in the field of food processing.