Experimental study on adsorption of Congo red wastewater by EDTA-modified chitosan/graphene oxide

To improve the adsorption performance of CS/GO, the EDTA-CS/GO composite adsorbent was prepared by the solution mixing method and used to treat Congo red wastewater. The optimal reaction conditions were determined by single-factor testing and response surface methodology. The results of SEM, XRD, and FTIR characterization showed that EDTA was successfully grafted onto CS/GO, the surface of EDTA-CS/GO was rougher, and the specific surface area of the composite increased, thereby improving its adsorption capacity. The results of the single factor test and response surface optimization showed that at an adsorbent dose of 0.12 g, stirring speed of 302 rpm, and pH of 7.4, the chromaticity and COD removal rates were 92.64% and 71.34%. Under optimal conditions, the adsorption capacity of EDTA-CS/GO composites only decreased by 4.91% after five reuse times, indicating that the composites had good stability and recycling performance. This study provides an effective strategy for producing efficient adsorbents and their application in dye wastewater treatment.