Adsorption of Heavy Metals by Graphene Oxide/Cellulose Hydrogel Prepared from NaOH/Urea Aqueous Solution.

By taking advantage of cellulose, graphene oxide (GO), and the process for crosslinking using epichlorohydrin (ECH), we propose a simple and novel method to prepare GO/cellulose hydrogel with good potential to adsorb metal ions. GO nanosheets containing carboxyl and hydroxyl groups were introduced into the surface of the cellulose hydrogel with retention of the gel structure and its nanoporous property. Due to the introduction of GO, the GO/cellulose composite hydrogels exhibited good compressive strength. Adsorption capacity of Cu2+ significantly increases with an increase in the GO/cellulose ratio and GO/cellulose hydrogel showed high adsorption rates. The calculated adsorption capacities at equilibrium ( q e cal ) for GO/cellulose hydrogel (GO:cellulose = 20:100 in weight) was up to 94.34 mg·g-1, which was much higher than that of the pristine cellulose hydrogels. Furthermore, GO/cellulose hydrogel exhibited high efficient regeneration and metal ion recovery, and high adsorption capacity for Zn2+, Fe3+, and Pb2+.

Protic acid resin enhanced 1-butyl-3-methylimidazolium chloride pretreatment of Arundo donax Linn.

To improve the cellulose digestibility of energy crop Arudo donax Linn. with cost-efficient, a novel pretreatment of protic acid resin Amberlyst 35DRY catalyzed inexpensive ionic liquid (IL) 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) was developed in this work. The pretreatment was performed at 160°C with [C4mim]Cl for 1.5h, followed by Amberlyst 35DRY catalyzed at 90°C for 1h. The IL-Amberlyst pretreatment was demonstrated to be effective, evidenced by the reduction in cellulose crystallinity (31.4%) and increased porosity caused by extensive swelling the undissolved biomass and partial depolymerization of the longer cellulose chain of the dissolved biomass by Amberlyst. Consequently, a higher glucose yield (92.8%) was obtained than for the single [C4mim]Cl pretreatment (42.8%) at an enzyme loading of 20 FPU/g substrate. Overall, the enhanced pretreatment was competitive by using inexpensive and recyclable IL-Amberlyst 35DRY pretreated system with shorter processing time and reduced enzyme usage.

Chemical composition, properties, and antimicrobial activity of the water-soluble pigments from Castanea mollissima shells.

Agricultural residues Castanea mollissima shells represent a promising resource for natural pigments for the food industry. This study provides a comprehensive and systematic evaluation of water-soluble pigments (CSP) from C. mollissima shells, which were obtained by 50% ethanol with microwave-assisted extraction. Spectroscopic techniques (UV, FT-IR, (13)C NMR), elemental analysis, and chromatographic techniques (HPAEC, GPC) revealed that the main components in the CSP were flavonoids procyanidin B3 (condensed tannin), quercetin-3-O-glycoside, and steroidal sapogenins. As a consequence, CSP was water-soluble and presented significant DPPH scavenge capacity (EC50 value was 0.057 mg/mL). Specially, CSP gave excellent antibacterial activity, and even better than 5% aqueous phenol in some case. Moreover, CSP was practically nontoxic and exhibited good stability with temperature, natural light, and metal ions. These outstanding properties will enlarge the application of CSP for natural food additives production.