Freeze-thaw as a route to build manageable polysaccharide cryogel for deep cleaning of crystal violet

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 396; p. 125354
• Main Authors: Hu, Xinyu, Yan, Linlin, Wang, Yongmei, Xu, Man
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.09.2020
• Subjects: Deep cleaning of CV; Locust bean gum; Manageable; Monolayer chemisorption mechanism; Novel cryogel; Salecan; Locust bean gum; Monolayer chemisorption mechanism; Novel cryogel; Salecan; Manageable; Deep cleaning of CV
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2020.125354

•Freeze-thaw of salecan and locust bean gum (LBG) into cryogel without crosslinkers.•Cryogel properties could be accurately tuned by adjusting salecan/LBG ratio.•The maximum adsorption of crystal violet onto cryogel can even reach 309.5 mg/g.•Adsorption followed the pseudo-second-order kinetic and Langmuir isotherm models.•Cryogel can be reused and adsorption capacity retained over 95% after 5 cycles. Crystal violet (CV) is one of the most toxic organic dyes, thus there is a critical need to remove it from wastewater before discharging into the environment. To tackle this challenge, new resources should be exploited to construct green and environmentally friendly adsorbents. Herein, we designed a novel cryogel by freeze-thaw of naturally derived polysaccharides salecan and locust bean gum (LBG) without any toxic and organic cross-linkers. Their three-dimensional network structure was established by strong hydrogen bonding interactions between the two polysaccharides and has been characterized systematically. More specially, salecan/LBG ratio could be accurately tuned to enhance the storage modulus, and to adjust the hydrophilicity and pore architecture of these cryogels. Batch experiments with the subject of salecan/LBG ratios, pHs, initial dye concentrations as well as contact time were studied. The adsorption equilibrium data could be well-fitted with pseudo-second-order model and Langmuir model, revealing monolayer chemical adsorption mechanism. The maximum CV adsorption capacity calculated by Langmuir equation was 309.5 mg/g, higher than many reported CV adsorbents. Notably, the regenerated cryogel could be easily reused with high adsorption capacity for at least five cycles. This work provided a facile avenue to develop sustainable cryogel adsorbent for deep cleaning of CV in wastewater.