Characterization and adsorption performance of chitosan/diatomite membranes for Orange G removal

Abstract

Novel chitosan/diatomite (CS/DM) membranes were prepared by phase inversion technique to remove anionic azo dyes from wastewater. The fabricated composite membranes exhibited the combined advantages of inorganic substances, diatomites, and polysaccharides. These composite membranes were characterized through Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction analysis. The mechanical properties of the membranes were also evaluated. Adsorption experiments were conducted under varied initial dye concentration, solution pH values, contact time, and adsorbent dosage. The results indicate that pH 3 is the optimal pH value for Orange G adsorption. The CS/DM membranes exhibit the highest adsorption capacity of 588 mg g -1 and removal rate of 94% under an initial dye concentration of 200 mg l -1 , contact time of 6 h, and membrane dosage of 8 mg. Langmuir, Freundlich and Redlich-Peterson adsorption models were applied to describe the equilibrium isotherms at different dye concentrations. The equilibrium data was found to be fitted well to the Redlich-Peterson isotherm. Pseudo-first-order and pseudo-second-order kinetics models were used to describe the adsorption of membranes. The adsorption data were well explained by pseudo-secondorder models, and also followed by the Elovich model. In addition, these membranes display high adsorption capacity and mechanical performance even after reused for seven times.

Preparation of Diatomite-Chitosan Composites for Loading and Release of Diphenhydramine HCl

“…The bands around 1582 cm -1 belonging to chitosan disappeared in the formulations. This indicates that the peaks of the weaker amide and amine groups of chitosan compared to diatomite are absorbed by the dominant peaks of the diatomite (Wu et al, 2016). Dominant peaks of DPH molecules were also detected in the formulations.…”

Combination of photocatalytic degradation and adsorption in dye removal by TiO2-chitosan-glycerol beads under natural sunlight

“…Furthermore, it is noted that the dyes have negatively charged sulfonic groups in acidic conditions. Therefore, these groups could be adsorbed by TiCsG beads [24]. On the other hand, with the pH value less than pHpzc of TiO2 Degussa P25 (pHpzc = 6.5) [25], the surface of TiO2 particles gain a positive charge (TiOH2 + ) [26] and also attracted negative dye more and faster.…”

Enhancing economic and environmental friendliness of xylonic acid bioproduction from corncob hydrolysate by the combined recycling-technology of detoxifying-resin and catalyzing-cell

“…Adsorption is a commonly used purification and detoxification technology in industrial production (Dong et al, 2018;Huang et al, 2020;Wu et al, 2016). An adsorbent with selective adsorption capacity is a good choice to remove acetic acid and other inhibitors from the hydrolysate (Castaldo et al, 2021).…”