Sodium Alginate and Chitosan Based Amphoteric Nanocomposites Modified with Graphene Oxide and Bentonite as an Efficient Adsorbent for Both Anionic and Cationic Dyes

For hazardous dye removal, this research developed a promising adsorbent based on chitosan (CH) and sodium alginate (ALG) nanocomposite modified with graphene oxide (GO) and bentonite (BN). The amphoteric characteristics of the obtained nanocomposite with both positive and negative charges were used to exclude anionic and cationic dyes from waste aqueous solutions. The synthesized nanocomposite was characterized by XRD, FTIR, FESEM, and reaction parameters were optimized to compare the swelling capacity of both the synthesized nanocomposite. The adsorption capacity of CH/ALG/GO and CH/ALG/BN nanocomposites was compared by adsorbing the xylenol orange (XO) (anionic) and methylene blue (MB) (cationic) dye. For MB removal, CH-ALG-GO nanocomposite adsorbed 91% with 0.5 g whereas CH-ALG-BN adsorbed 96% with 0.5 g adsorbent dose in neutral pH solution. For XO removal, CH-ALG-GO nanocomposite adsorbed 85% with 0.5 g whereas CH-ALG-BN adsorbed 93% with 0.5 g adsorbent dose in neutral pH solution. The resultant porous nanocomposite can effectively remove cationic and anionic dyes such as methylene blue (MB) and xylenol orange (XO) from wastewater. With adsorption maxima of 0.731 mg/g and 0.195 mg/g, respectively, the CH-ALG-BN nanocomposite was able to remove both cationic dye (MB) and anionic dye (XO) as an adsorbent.Graphical Abstract