Novel Fabrication of Renewable Aerogels from Coconut Coir Fibers for Dye Removal

Abstract

Water pollution resulted from the discharge of the textile industry limits light penetration into the water, negatively affects the photosynthesis of aquatic organisms, and causes serious risks of cancer and genetic mutation for humans living near the emission site. The utilization of porous materials like aerogels to adsorb dye has been one of the effective methods for wastewater treatment. The fabrication of renewable materials from agricultural waste both to take advantage of its abundance and increase its value has gained research interest in recent years. In this research, this is the first time natural cellulose aerogel from coconut fibers (CFs) have successfully been developed by physically cross-linking cellulose with non-toxic binders including polyvinyl alcohol (PVA) and xanthan gum (XTG) in distilled water, followed by cost-effective freeze-drying to sublimate water and leave the hollow structure. The as-fabricated cellulose aerogel exhibits a tremendously low density (0.041 g/cm3) and high porosity (96.30 %). The aerogels are then tested for methylene blue (MB) adsorption in water to evaluate its applicability in the treatment of dye-contaminated water with varied investigated factors such as contact time, pH values, and MB initial concentrations. The MB adsorption process of the aerogels reaches equilibrium after 50 min and their adsorption isotherms follow the Freundlich model with an R-square value of 0.9453. It is worth noting that the highest adsorption capacity of the synthesized aerogels is up to 11.84 mg/g when the initial MB concentration is 25 mg/L at pH 7. The feasible procedure to synthesize recycled cellulose aerogels from CFs with green chemicals in this study has created good promise for dye adsorbents. About the potential economic benefits, the CFs are abundant agricultural wastes, easy pretreated processing involved in saving energy costs.