Research on the process of modifying the bio-adsorbent of Sauropus androgynus to treat ion heavy metals Pb2+ in water

Abstract

Sauropus androgynus (SA) leaves contain many compounds such as cellulose, hemicellulose, lignin and pectin, which can form bonds with metal ions thanks to functional groups such as hydroxyl (-OH), carboxyl (-COOH), secondary amides (-CONH), amines (-NH, NH2). However, the intact leaf surface only provides a few adsorption sites. In this study, the surface of SA leaves was modified with NaOH solution, resulting in a new biological adsorbent referred to as modified Sauropus androgynus (MSA). The results showed that the adsorption performance of MSA increased from 49.64 to 80% within 30 min at a pH6, using 0.1 g of material at room temperature. To characterise the structural morphology, the samples were analysed by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR). The surface modification process significantly changed the structure and adsorption capacity of MSA. In addition, a temperature of 40^oC, a stirring time of 2 hours and a NaOH concentration of 0.1 M were determined as optimal conditions for surface modification. These experimental results not only demonstrated that the adsorption capacity of MSA was significantly superior to that of the SA, but also highlighted the further potential studies on the improvement of biological adsorbents through surface modification techniques.