Evaluation of biomass type blue Cyanophyta algae for the sorption of Cr (III), Zn (II) and Ni (II) from aqueous solution using batch operation system: Kinetics and thermodynamic studies

The biosorption of Cr (III), Zn (II) and Ni (II) ions from aqueous solution by dead blue algal biomass (Cyanophyta) was investigated in single metal system and batch conditions. Experimental parameters included contact time (0-140 min), pH (2-8), sorbent dose (0.1-2.0 g), initial concentrations (10-120 mg/L), agitation speeds (50-300 rpm) and temperatures (298-232K) were investigated. The best values of pH were found 4 for Cr+3, Zn+2 and 5 for Ni+2, respectively. The biosorption process was relatively fast and equilibrium established after 90 min. Equilibrium isotherm experiments data were analyzed by Langmuir and Freundlich isotherm models and Langmuir isotherms gives the best fit to the experimental data. Biosorption kinetic models were used for the single metal system using the dead blue algal biomass, good matching was found between pseudo second order kinetic model and experimental data for Cr (III), Zn (II), and Ni (II) ions systems. Thermodynamic parameters included Go; Ho and So during the process were calculated, the results show that the biosorption process applied to remove Cr (III), Zn (II) and Ni (II) ions using blue algal biomass (Cyanophyta) is feasible, spontaneous and exothermic at 10 – 30 °C. The results indicated that blue algal biomass (Cyanophyta) could be used as a good sorbent for treatment of industrial effluents containing Cr (III), Zn (II) and Ni (II) ions in single metal system.