Fabrication And Properties Of Novel Corn Stalk/Clay Composite Hydrogels

In order to solve the environmental problems such as land desertification,industrial wastewater pollution and air pollution caused by straw burning,we chose the discarded corn stalks as the major ingredient to synthesize a series of new functional materials,carboxymethyl cellulose?CMC?/clay composite hydrogels which can improve the available value of discarded corn stalks,and be applied to the field of nutrient conservation of farmland and treatment of industrial sewage as well.During the experiments,the polymerization mechanism and the synthesis conditions were explored,further,the novel hydrogels with high swelling ability and adsorption capacity were obtained.Then,the target products were tested and analyzed.As for the CMC-based hydrogel,we found:?1?The maximum water absorption was144.04 g/g,and the salt absorption was 30.60 g/g.?2?There were gullies and fissures in a local area,which resulted in the rough surface;the network skeletons of the hydrogels were clearly observed after swelling.?3?The swelling properties of the cationic salt solution in same concentrations were different following the order of swelling ratio,i.e.,Na⁺>Mg²⁺>Ca²⁺>Al³⁺;the distinct?overshooting effect?swelling-deswelling phenomenon was shown in the swelling within the CaCl₂ and AlCl₃ solutions.?4?Good ability to water absorption and water retention.As for the CMC/OMMT composite hydrogel,we found:?1?After the whole ultrasonic treatment?40 KHz?,the maximum water absorption was 173.08 g/g,and the salt absorption was 34.80 g/g.?2?The microstructure of the hydrogels after swelling was stereoscopic in the microscope,and more fine structures can be observed after amplification.?3?The stimuli-responsive of this material on the different cationic salt solutions and temperature changes were different.?4?The results showed that 99.70%MB dye was removed with the initial dye concentration of 10 mg/L,hydrogel dose of 0.20 g/L,oscillation rate of 100 r/min,contact time of 240 min,and temperature of 50°C.This adsorption was a multistep process,including the intraparticle diffusion and the film diffusion,which fit well with the pseudo-second-order kinetic model.As for the CMC/ATP composite hydrogel,we found:?1?The maximum water absorption was 396.67 g/g,and the salt absorption was 120.80 g/g.?2?The removal rate of three kinds of dyes,such as crystal violet,methylene blue,and malachite green were above 94%.The adsorption process was suitable for the pseudo-second-order kinetic model.?3?The adsorption capacity of heavy metal Cu?II?was as high as 430.23 mg/g with the hydrogel dose of 0.10 g/L,initial dye concentration of 600 mg/L,oscillation rate of 100 r/min,contact time of 240 min and temperature of 50°C.This adsorption was spontaneous endothermic reaction,which fitted well with the pseudo-second-order kinetic model and the Langmuir isothermal model.At different temperatures,?G was less than 0,and?S was greater than 0.?4?The material was recyclable,and before the first three times,the regeneration rate was 80%or more.