Enhanced methylene blue adsorption from aqueous solution by corn stalk/diatomite gel porous materials

Abstract

Corn stalk and diatomite were cross-linked by N,N'-Methylenebisacrylamide (MBA) to obtain gel porous materials for methylene blue adsorption, which improved the multi-element pores effect. The process solved the difficult recovery problem of powder adsorbents as well. Results showed that the optimal preparation conditions of corn stalk/diatomite gel porous materials were: 1 mL of glutaraldehyde, 6 g of acrylic acid, 150 mg of MBA and 100 mg of potassium persulfate. The adsorption process conditions were optimized: At the pH = 8, 8 mg of gel porous material was adsorbed for 1 hour. Under the optimal conditions, the removal percentage was 93.65% and the adsorption capacity reached 288.43 mg/g. The characterization results indicated that the corn stalk was successfully combined with diatomite. Corn stalk/diatomite gel porous materials had a three-dimensional network structure with more active sites. The adsorption isotherms fit the Langmuir model. Furthermore, the adsorption kinetics fit the pseudo-second-order model. The adsorbent surface is uniform and the adsorption process is mostly monolayer adsorption. The adsorption process includes chemical and physical adsorption. The maximum saturated adsorption capacity was 657.89 mg/g. Corn stalk/diatomite gel porous materials maintained good adsorption performance after cyclic adsorption. The adsorbent prepared in this study has a good regeneration cycle and methylene blue removal capacity.