Dialdehyde Cellulose Fabric Membranes Enable Chemical Adsorption of Amino-Containing Dyes for Wastewater Treatment

Abstract

Dialdehyde cellulose fabric (DACF) membranes with varying degrees of oxidation were fabricated using periodate oxidation and were employed for the chemical adsorption of amino-groups containing dyes from wastewater. The aldehyde group contents of DACF membranes were adjusted by altering oxidation time, which was confirmed by titration experiments. The chemical structure and morphology of DACF membranes were characterized using ATR-FTIR, TGA, SCA, SEM, XPS, and XRD measurements. The optimized DACF membrane, which was treated for an oxidation time of 24 h and has an aldehyde content of 2.97 mmol/g, was used for the chemical adsorption of amino-containing dye molecules. This process relies on the Schiff base reaction between the amino groups of the target dye molecule and the aldehyde groups of the membrane. Two typical cationic dyes, fuchsin basic and chrysoidine, containing aromatic amino groups, were chosen to determine the adsorption capacity of the DACF membrane. The adsorption kinetics, isotherms, and thermal dynamics of the DACF membrane were investigated comprehensively, while both pseudo-first- and pseudo-second-order kinetics models fit well, indicating the complicated chemical/diffusion adsorption process, where the hydrophobic properties of the DACF membrane retarded the adsorption rate. The maximum adsorption capacities of the DACF membrane against fuchsin basic and chrysoidine were 108.69 and 46.29 mg/g, respectively, as determined by Langmuir isotherm simulations. Various competing ions such as Na+, Ca2+, Cl−, and SO42− at high concentrations of 10,000 ppm were used to challenge the adsorption capability of the DACF membrane, with negligible effects observed. A new adsorption mechanism based on chemical/diffusion interaction was proposed. Bovine serum albumin (BSA), fuchsin basic, and chrysoidine were mixed to simulate the multicomponent wastewater containing dissolved organic nitrogen (DON) and demonstrated the adsorption process; the direct adsorption capacity of the DACF membrane was up to 63.0%. This work offers a new method for the highly efficient removal of organic pollutants by a chemical reaction approach.