A potentially low-cost modified sawdust (MSD) effective for rapid Cr(vi) and As(v) removal from water

Abstract

The study was carried out to evaluate the effectiveness of a diethylenetriamine (DETA)-crosslinked adsorbent prepared from pine sawdust for removing Cr(VI) and As(V) from aqueous solutions. The maximum adsorption capacity of Cr(VI) and As(V) by MSD was highly enhanced from 7.04 mg L⁻¹ to 238.6 mg g⁻¹ and from 4.88 to 71.23 mg g⁻¹ at pH 6.0, respectively. The surface characterization of the MSD proved that the grafted amino groups were responsible for the good affinity towards Cr(VI) and As(V). The uptake of Cr(VI) and As(V) was highly dependent on the pH and was facilitated in acidic solutions. Batch experiments were conducted as a function of pH, temperature and contact time. Both Cr(VI) and As(V) adsorption equilibrium could be quickly attained within 1 h and the process followed the Redlich–Peterson isotherm model. As(V) uptake was more sensitive to an individual coexisting anion (Cl⁻, SO₄²⁻, NO₃⁻, HCO₃⁻) in the system than Cr(VI). The mechanism of adsorption was characterized by the electrostatic attraction between the positively charged surface of sawdust and Cr(VI)/As(V) anions.