Biosorption of Chromium from Spent Semi-Chrome Liquor: Part 1 Effective Pollution Abatement using Bacillus cerus

The current study focuses on the isolation of Bacillus cerus from mangrove rhizosphere and its ability to treat semi-chrome process liquor of upper leathers. This strain has been identified by its molecular characteristics (16s rRNA sequencing) and confirmation has been obtained from neighbor joining tree. Minimum inhibitory concentration of the strain has been found to be 50 ppm. The growth pattern of this organism has been investigated in the presence of chromium, which showed the bacterial strain can grow luxuriantly at 50 and 100 ppm concentration of chromium. Biosorption study has been conducted at different concentrations (50, 100, 150, 200 and 250 ppm) of chromium. The biosorption capability of Bacillus cerus has been found to be 80.78, 73.19, 65.86, 59.44 and 39.27% for 50, 100, 150, 200 and 250 ppm respectively. Chromium sorption from the semi-chrome process liquor by Bacillus cerus has also been investigated, which showed a reduction of 76.15, 68.56, 61.63, 56.29 and 36.51% against 50, 100, 150, 200 and 250 ppm of chromium. Sorption characterization has been carried out by FTIR (Fourier Transform Infra-Red spectroscopy) and SEM (Scanning Electron Microscopy) analyses and the results confirmed the presence of sorption of chromium in Bacillus cerus.

Reduction and Biosorption of Cr(VI) from Aqueous Solutions by Acid-Modified Guava Seeds: Kinetic and Equilibrium Studies

The use of guava seeds (GS) and acid-modified guava seeds (MGS) for the removal of Cr(VI) from aqueous solutions was investigated. Batch-type experiments were performed with Cr(VI) aqueous solutions and biosorbents to determine the kinetic and equilibrium sorption parameters. Results indicated that GS and MGS were capable of reducing and remove Cr(VI) from solutions, but the reduction was only observed at some experimental conditions. Infrared analysis showed that several functional groups were involved in the reduction, and biosorption of Cr(VI), particularly alcohol, phenolic, carboxylic, and methoxymethyl structures. The mechanisms of reduction and biosorption depended upon the type of biosorbent, pH, and temperature of the system. The pseudo-second-order kinetic model describes the kinetic sorption data, and the Langmuir-Freundlich (L-F) model describes the isotherm data in most cases. Significantly high total chromium biosorption capacities were obtained. Acid modification of guava seeds improves chromium biosorption performance.