Polysaccharides-based adsorbents for removal of Congo red dyes from wastewater

Abstract

Gums Arabic (GA) and Xanthan (GX) are natural polysaccharides that can be extracted by natural means for applications, such adsorption of pollutants. Structural modifications such as carboxymethylation on bio-adsorbent materials, can be performed to improve its adsorptive properties. Development of polymeric nanoparticles is an economical and favorable option for the adsorption of Congo red dye, which has high toxicity and is resistant to traditional removal processes. In this work, it was developed nanoparticles (NPs) of natural GA (NPGA) and GX (NPGX) and their carboxymethylated forms (NPCMGA and NPCMGX) aiming to evaluate the adsorption of Congo red (CR) dye. NPs are sized from 133 to 1099 nm at an average zeta potential of -13 mV, suggesting stability to absorb dyes. NPGX and NPCMGX absorbed a substantially higher amount of dye than the other NPs. The kinetic studies showed that adsorption process follow pseudo-second order model, suggesting that chemisorption control the process, and the isotherm test revealed that samples fit Langmuir model, with a homogeneous adsorption profile for the two carboxymethylated samples with a maximum adsorption capacity of 182,82 mg/g for NPCMGX and 757,58 mg/g for NPGX. These findings indicate that NPs from Xanthan Gum can be used for removal CR in contaminated water and wastewater.