An ingenious construction of porous sodium alginate/TEMPO-oxidized cellulose composite aerogels for efficient adsorption of crystal violet dyes in wastewater

Since caustic dyes are a major component of wastewater used in printing and dyeing, they represent a significant risk to human health. It's getting harder to get rid of them efficiently. An appealing solution to this issue is adsorption based on biomass material aerogel. Here, using the sol-gel process and freeze-drying, an inventive three-dimensional porous aerogel (STA) was created using sodium alginate (SA) and TEMPO-oxidized cellulose (TOC) as raw materials, with the dual cross-linking effects of glutaraldehyde (GA) and Ca2+. Various characterization approaches and analytical methods were used to study STA. The results indicated that the addition of TOC resulted in the excellent pore structure, thermal stability, charge characteristic and adsorption capacity of STA. The adsorption capacity of STA was investigated by selecting crystalline violet (CV) as a typical cationic dye. Thereafter, the adsorption capacity was comprehensively analyzed by varying temperature, pH and adsorption time. The adsorption process conformed to the pseudo-second-order kinetic model, and the Langmuir isothermal adsorption model has a better fit, which was a single-molecule layer chemisorption process. The highest adsorption capacity reached 505.9 mg/g. Moreover, STA also possessed outstanding competitive adsorption capacity and cyclic adsorption performance. Sodium alginate and TEMPO-oxidized cellulose were combined innovatively, and the application scope of bio-based materials was expanded.A double cross-linking reaction was achieved in the presence of Ca2+ and glutaraldehyde.The largest porosity reached 95.6% as a result of the three-dimensional porous structure.The maximum adsorption capacity for CV reached 505.98 mg/g. Recycling times and competitive adsorption capacity are excellent.The thermal stability was enhanced to some extent due to the addition of TOC.