Studies on the removal of basic fuchsin dye from aqueous solution by HCl treated malted sorghum mash

The efficacy of using hcl-modified malted sorghum mash to remove basic fuchsin dye from aqueous solution was investigated through batch adsorption studies. the quantity of dye removed by the adsorbent increased with increase in contact time and optimum adsorption was achieved in 30 min. the adsorption process was dependent on ph of aqueous solution with optimum removal of dye occurring between ph = 4 and ph = 9. the adsorption of dye by the adsorbent increased with increase in initial dye concentration but decreased with an increase in adsorbent dose. adsorption equilibrium data were fitted with langmuir,freundlich,dubinin-radushkevich and temkin equations to describe the isotherms. the langmuir and temkin models described the experimental data better than the dubinin-radushkevich and freundlich models. the maximum adsorption capacity of hcl-modified malted sorghum mash was 58.48 mg.g-1 at 304 k. the kinetic data were fitted with the pseudo-first order,pseudo-second order,intraparticle diffusion and elovich models. the pseudo-second order model yielded a much better fit than the other kinetic models. the free energy of adsorption (δg°) was evaluated as -22.54 kj.mol-1. the negative value of δg° confirmed the feasibility of the process and the spontaneous nature of adsorption.