Preparation of the ramulus mori-based adsorbent and its adsorption performance for heavy metals ions

Abstract

The waste Ramulus Mori generated from sericulture process was chemically modified with succinic acid to prepare Ramulus Mori-based absorbent for removal of heavy metals from aqueous solution. The as-prepared adsorbent was characterized by Fourier Transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The isoelectric point, specific surface area and oxygenic groups of the as-prepared adsorbent were measured and the adsorption behavior for heavy metals including Pb2+, Cu2+, Cd2+, Zn2+ were investigated. The results show that a lot of oxygenic groups were grafted into the as-prepared adsorbent. The Ramulus Mori-based absorbent exhibited highly efficient and rapid adsorption for heavy metals. The adsorption isotherm of the four heavy metals could be well fitted by Langmuir and Temkin model and the maximum adsorption capacity of the prepared adsorbent for Cd2+, Cu2+, Pb2+ and Zn2+ was estimated, by Langmuir model, to be 67.57, 50.25, 46.95 and 50.51mg/g, respectively. The adsorption may be governed by chemisorption involving coordination between heavy metals and the oxygen in oxy groups on the surface of the absorbent and ion exchange between cationic heavy metals and carboxylic group on the surface of the absorbent by electrostatic attraction. The competitive adsorption between the four heavy metals was in the order of Cd2+> Cu2+ >Pb2+ > Zn2+. The Ramulus Mori-based absorbent could be regenerated effectively and reused.