A novel adsorbent of bentonite modified chitosan-microcrystalline cellulose aerogel prepared by bidirectional regeneration strategy for Pb(II) removal

Traditional chitosan aerogel (CSA) could be used to chelate heavy metal ions due to its large specific surface area, high porosity and rich amino groups. However, the CSA was rarely applied in practical application because of its easy hydrolysis, low mechanical strength and slow adsorption rate. In this study, we developed a novel method for increasing the anti-hydrolytic ability and mechanical strength of CSA by bidirectional regeneration of chitosan and microcrystalline cellulose to synthesize chitosan-microcrystalline cellulose aerogel (CS-MCCA). In addition, bentonite (BT) was introduced in the regeneration process to enhance the adsorption rate of CSA, and an efficient adsorbent of bentonite-chitosan-microcrystalline cellulose aerogel (BT-CS-MCCA) for Pb(II) removal was developed, and the maximum adsorption amount and adsorption equilibrium time of Pb(II) on BT-CS-MCCA were 256.24 mg g(-1) and 60 min, respectively. Additionally, it was found that with the increase of Na+ or K+ concentration in the solution from 0 mol L-1 to 0.1 mol L-1, the adsorption capacity of BT-CS-MCCA was enhanced, because the Ca2+ in BT was substituted by Na+ or K+, and then the ion-exchange ability of BT-CSMCCA was improved. Moreover, the preparation method of BT-CS-MCCA possessed merits of simple operation, low cost and hypotoxicity. Thus, the BT-CS-MCCA had a broad potential application for the purification of Pb(II) in wastewater, and the bidirectional regeneration strategy might offer a brand-new path for the utilization of biomass resources.

Automated summary

In this study, a novel method for increasing the anti-hydrolytic ability and mechanical strength of traditional chitosan aerogel (CSA) was developed by bidirectional regeneration of chitosan and microcrystalline cellulose to synthesize chitosan-microcrystalline cellulose aerogel (CS-MCCA). Bentonite (BT) was introduced in the regeneration process to enhance the adsorption rate of CSA, leading to the development of an efficient adsorbent for Pb(II) removal, bentonite-chitosan-microcrystalline cellulose aerogel (BT-CS-MCCA). The bidirectional regeneration strategy of biomass resources presented a brand-new path for utilization in wastewater treatment.