Chromium Absorption Experiments

Biosorption of Chromium Using A. towneri and R. eutropha

J. Aravind

Asst. Prof. (SrG), Department of Biotechnology, Kumaraguru College of Technology, Coimbatore-641049

G. Ligi Elezabeth, T. Mariya

ABSTRACT

Chromium is one of the toxic heavy metals which are discharged into the environment from various industries which causes serious threat to human health as well as environment. Biosorption is one of the effective methods for removal of chromium which uses dead or inactive biological matter. In the present study, batch biosorption experiments were carried out using Acinetobacter towneri and Ralstonia eutropha. Various parameters affecting biosorption such as temperature, pH, adsorbent dosage, contact time and initial metal ion concentration

6: Effect of pH on chromium biosorption (adsorbent dosage 25 mg, volume 25 ml, temperature 37◦C, initial metal concentration 30 mg/l, contact time 180 min)

Effect of temperature

Temperature affects biosorption process only to a smaller extent within a range from 27 – 37 ◦C. Higher temperature usually increases the sorption process due to increase in kinetic energy of molecules. Fig 7 shows the effect of temperature on biosorption. It suggests that 37 ◦C is optimum for biosorption for both A. towneri and R. eutropha. Most of the literature suggests an effective biosorption within a range of 30- 35 ◦C (Veglio and Beolchini, 1997). Fig. 7: Effect of temperature on chromium biosorption (Adsorbent dosage 25 mg, pH 2, volume 25 ml, initial metal concentration 30 mg/l, contact time 180 min)

Isotherm data analysis

The equilibrium biosorption of chromium was modeled by Langmuir, Freundlich and Temkin isotherms. The affinity of sorbent towards sorbate was between the distribution in solid and liquid phases.From the table1 the Langmuir constants Q0 and K were calculated and found to be more for R. eutropha ie 303 mg/g. The value of Freundlich exponent is 1.7 for A. towneri and 1.205 for R. eutropha , in the range of 1-10, indicates favorable adsorption. These results were comparable with the studies conducted by Hassan, (2013) using Spirulina sp. Out of these three adsorption isotherms Temkin model was found to have highest regression value for A. towneri aand Langmuir model for

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