Enhanced methylene blue sequestration using an eco-friendly carboxymethyl cellulose/xanthan gum-based biocomposite...

Lately, several attempts have been made to involve agricultural waste as an abundant source for the design of ecological materials for environmental applications. In this pursuit, arundo donax biomass (ADS), carboxymethyl cellulose (CMC) and xanthan gum (Xth) were combined in presence of lauroyl sarcosinate surfactant to prepare a potential bioadsorbent for methylene blue dye removal from synthetic wastewater. CMC/Xth/ADS biocomposite was characterized using XRD, FTIR, SEM, EDX and TGA techniques. Various physico-chemical parameters including contact time, dye concentration, adsorbent dosage, pH, and temperature were explored to optimize the overall process. Adsorption equilibrium data were best fitted to Langmuir isotherm, with a maximum adsorption capacity of 48.31 mg g^-1. The elimination process reached equilibrium after 4 h, obeying the pseudo-second order kinetic model. Thermodynamic parameters revealed that MB adsorption onto the biocomposite was spontaneous, endothermic with increased randomness at the adsorbent/adsorbate interface. The biocomposite showed a good selectivity for MB and cationic dyes generally, and maintained its adsorption performance in presence of various inorganic salts. The mechanism of MB binding was found to be dominated by electrostatic interactions and hydrogen bonding. After five cycles of use, adsorption remained sufficient (78 %), indicating that CMC/Xth/ADS is durable and effective for long-term MB removal.