Adsorption of Ni(II) from Aqueous Solution by Wheat Straw Modified with Mercaptopropionyl Functional Groups

Mercaptopropionyl wheat straw (MPWS) was prepared as an adsorbent by modifying wheat straw with mercaptopropionyl groups, and the ability of MPWS for the removal of Ni(II) from aqueous solution was examined. The removal of Ni(II) by using MPWS was identified through investigating the impacts of MPWS dosage, adsorption temperature, and adsorption time. Different models for the adsorption isotherm and kinetics were utilized to fit the experimental results and elucidate the mechanism of MPWS for Ni(II). Environmental interference factors, including initial Ni(II) concentration, pH value, inorganic matters, and organic matters in wastewater, were examined to evaluate the antienvironmental disturbance capability of MPWS during Ni(II) adsorption. A removal rate of Ni(II) as high as 99.02% was achieved at pH 6.0 with an adsorption temperature of 30 °C and a contact time of 100 min. The experimental results exhibited excellent alignment with both pseudo-second-order kinetic model, Freundlich isothermal model, Redlich-Peterson model, and Hill model. Furthermore, coexisting substances in the environment could inhibit the adsorption process of Ni(II) by MPWS; however, this inhibition could be mitigated or eliminated by increasing the amount of absorbent MPWS. Overall, MPWS displays remarkable resistance against environmental interference during its application for removing Ni(II) from wastewater.