Removal of cationic dye from aqueous solution using recombinant gellan gum-coated MgO nanoparticles

Gellan gum is a linear, water-soluble anionic polymer formed by tetrasaccharides in the molar ratio 2:1:1 of repeating d-glucose, d-glucuronic acid and l-rhamnose. Sphingomonas paucimobilis ATCC 31461 is currently employed for the industrial synthesis of gellan gum. GG-MgO nanoparticles were synthesized and employed to decolorize dye effluent. The adsorption capacity of GG-MgO has been investigated for cationic malachite green dye. The physio-chemical characteristics of the GG-MgO nanoadsorbent were analyzed by utilizing SEM, DLS, FTIR, TGA, DSC and XRD. Characterization by SEM confirmed GG-MgO has a rough structure. The incorporation of MgO nanoparticles over the gellan gum surface was validated by XRD, DSC and FTIR. Thermogravimetric examined the thermal stability of the nanoadsorbent. DLS exhibited the steady form of MgO Nps in the gellan matrix. The test parameters like pH, temperature, stirring speed, contact time, adsorbent dosage and initial dye concentration were assessed during the batch studies to estimate the percentage elimination of malachite green by GG-MgO nanoadsorbent. The maximum malachite green removal of 98% was achieved using GG-MgO during the optimum pH 7, temperature 60 degrees C, malachite green concentration 5 mg/l, adsorbent dose 0.2 g, contact time 30 min and stirring speed 100 rpm. The isotherm examinations evaluated the best fit. The malachite green adsorption on the nanoadsorbent suits well with the Langmuir and the highest monolayer adsorption of 92.5 mg/g was observed. This research rendered a promising approach of biopolymeric incorporation for enhancing the metal oxide nanoadsorbent adsorption capacity.