Amino-mediated interfacial regulation of alkalized Ti3C2Tx to enhance urea adsorption capacity

Abstract

Urea is widely used in agricultural fertilizer production, but there is a risk of it flowing into soil and water sources. Excessive urea can cause algal blooms or toxic algal blooms, which can accumulate in food sources and poison wildlife and even humans. Effective removal of urea is the key to ensuring environmental safety. Here, we propose a scheme of introducing carboxymethyl chitosan (CMC) onto the surface of alkalized Ti₃C₂T_x using amino groups as bridges. There is electrostatic attraction between the positive charge carried by chitosan and the negative charges generated by urea ionization. This electrostatic interaction promotes the adsorption of urea by chitosan. CMC reacts with the amino groups on the surface of Ti₃C₂T_x to form amide bonds, which can stabilize the CMC. The urea adsorption capacity of CMC-L/Ti₃C₂T_x was tested under different experimental conditions. The results showed that CMC-L/Ti₃C₂T_x can adsorb urea at super-fast speed, and the adsorption equilibrium can be reached in 20 min, with a maximum adsorption capacity of 108.54 mg/g, and has good stability. After 5 cycles, the removal rate of urea was still above 60 %. Therefore, introducing carboxymethyl chitosan on the surface of Ti₃C₂T_x has high potential for environmental protection.