Biosorption of Chromium (VI) from an aqueous solution onto citrus limonium peel

The effective removal of Cr (VI) from an aqueous solution in a batch system using of low-cost biosorbent Citrus limonium peel was studied. The effect of process parameters including solution pH, biosorbent dosage, initial Cr (VI) concentration, contact time, biosorbent size and temperature was studied. The optimum solution pH for Cr (VI) biosorption by biosorbent was 6 with the optimal removal of 91.82 %. The biosorbent dosage 0.1 g was enough for optimal removal. The equilibrium was achieved at 75 min of contact time. The equilibrium data were well described by Langmuir, Freundlich,Dubinin- Redushkevich and Temkin biosorption isotherms. Sorption equilibrium exhibited better fit to Freundlich isotherm (R2 = 0.994) than Langmuir isotherm (R2 = 0.984), Dubinin-Redushkevich isotherm (R2 = 0.979) and Temkin isotherm (R2 =0.968). Furthermore, to determine the biosorption mechanism, a detailed analysis has been conducted by testing kinetic models such as pseudo-first-order, pseudo-second-order, Elovich equation, Intra-particle diffusion and Boyd equation. Results clearly indicate that the pseudo second-order kinetic model was found to be correlate the experimental data strongest than other kinetic models