Highly Efficient Adsorption of Heavy Metals and Cationic Dyes by Smart Functionalized Sodium Alginate Hydrogels

In this paper, functionalized sodium alginate hydrogel (FSAH) was prepared to efficiently adsorb heavy metals and dyes. Hydrazide-functionalized sodium alginate (SA) prepared hydrazone groups to selectively capture heavy metals (Pb2+, Cd2+, and Cu2+), and another functional group (dopamine grafting), serves as sites for adsorption methylene blue (MB), malachite green (MG), crystal violet (CV). Thermodynamic parameters of adsorption indicated that the adsorption process is endothermic and spontaneous. The heavy metals adsorption by FSAH was physical adsorption mainly due to Delta H-theta < 40 kJ/mol, and the adsorption of cationic dyes fitted with the Langmuir models, which indicated that the monolayer adsorption is dominated by hydrogen bonds, electrostatic interactions, and pi-pi interactions. Moreover, the adsorption efficiency maintained above 70% after five adsorption-desorption cycles. To sum up, FSAH has great application prospect.

Automated summary

In this study, functionalized sodium alginate hydrogel (FSAH) was prepared for efficient adsorption of heavy metals and dyes. The results showed that FSAH mainly adsorbed heavy metals through physical adsorption, and cationic dyes through hydrogen bonds, electrostatic interactions, and pi-pi interactions. Additionally, FSAH exhibited good adsorption cycle stability.