Potential of amino-riched nano-structured MnFe2O4@cellulose for biosorption of toxic Cr (VI): Modeling, kinetic, equilibrium and comparing studies

In this work, amine riched MnFe2O4-cellulose was employed to remove toxic Cr (VI). To find out the optimum conditions R (3.3.1) software was used. The results of Cr (VI) adsorption onto three-step adsorbents were compared by interpreting kinetic and isotherm studies. The kinetic studies reveal that the adsorption of Cr (VI) onto cellulose and magnetic cellulose (MC) followed pseudo-first order model whereas the adsorption of Cr (VI) onto amine modified cellulose (AFMC) followed pseudo-second order kinetic model. From the obtained intraparticle diffusion model results it is evident that the adsorption is an external surface process. The adsorption isotherm parameters for Cr (VI) adsorption onto MC and AFMC showed that the correlation coefficient (R2: 0.96, 0.88) of Freundlich isotherm is more than that of Langmuir isotherm (R2: 0.50, 0.76); hence, it is suggested that the adsorption of Cr (VI) onto these sorbents occurs in multilayer possessing heterogeneous sorption sites whereas the adsorption onto cellulose followed Langmuir model. The maximum adsorption capacities of cellulose, MC and AFMC under optimum conditions were found to be 25, 125 and 250 mg/g, respectively; thus, it is confirmed that adsorption efficiency has been improved after modification steps.