| With the depletion of non-renewable petroleum-based resources and the worsening environment, agricultural and forest biomass has attracted more and more attentions due to the good biodegradability, easy availability, biocompatibility and renewability. Pre paration of novel and functional biomaterials and biopolymers from lignocellulo sic biomass has been considered to be an effective approach to solve these problems derived from energy and environment. However, most of agricultural and forest biomass have not been effectively exploited. In order to broaden the application of agricultural and forest biomass and achieve the transformation of agricultural and forest biomass to high value-added products, two novel biomass-based adsorption materials were prepared and their adsorption property for heavy metal ions and creatinine was discussed in this work.1. Sugarcane bagasse-based hydrogels were prepared by grafting acrylic acid(AA) and acrylamide(AM) onto the backbone of sugarcane bagasse(SB) under the presence of a crosslinker(N, N-methylene-bis-acrylamide, MBA) using the free radical graft copolymerization. The influences of reaction conditions on the water absorbency w ere studied. It was found that the optimal synthesis conditions for the water absorbency were an ammonium persulfate(APS) amount of 10%(based on the bagasse weight), a MBA amount of 2.5%(based on SB weight), and a AM/(AA+AM) weight ratio of 0.5 and a monomers/SB weight ratio of 3.0, the corresponding maximum reached to 269 g/g for the water-swelling ratio. These hydrogels also had the great water retention capacity. The water-retention rates at 5 oC, 25 oC and 35 oC were 92.7%, 81.7% and 76.8% for 44 h, and 83.7%, 58.6% and 47.1% for 116 h, respectively. Sugarcane bagasse-based hydrogels could have the potential application in the waste-water treatment and the agricultural and horticultural industries.2. The removal of metal ions from an aqueous solution using highly efficient sugarcane bagasse-based hydrogel adsorbents was investigated. The effects of p H, contact time and initial concentration of metal ion on the adsorption capacity were discussed. The adsorption data were fit to often-used adsorption kinetics and isotherms. The present study demonstrates that the adsorption of sugarcane bagasse-based hydrogel adsorbent for Pb2+, Cd2+and Cu2+ was p H-dependent, and the maximum adsorption for Pb2+, Cd2+ and Cu2+ was achieved at p H 6.0. The adsorption equilibrium time for Pb2+, Cd2+ and Cu2+ was 60, 90 and 180 min, respectively. The maximum adsorption capacities were 268 mg/g for Cu2+, 700 mg/g for Pb2+ and 320 mg/g for Cd2+. The experimental results were also well fitted to the pseudo-second-order equation and Langmuir adsorption isotherms. After five cycles, the recovery rates of Pb2+, Cd2+ and Cu2+ only dropped to 95%, 96% and 92%, respectively. This phenomenon showed that the hydrogels had good cycle performance. Sugarcane bagasse-based hydrogels were confirmed to be an effective adsorbent of heavy metal ions and had highly efficient recovery and regeneration performance. These prepared hydrogels could have great potential applications in the waste water treatment.3. A new xylan-based biomaterial as a creatinine adsorbent was prepared by the homogeneous acylation of xylan with 3, 5-dinitrobenzoyl chloride in 1-butul-3-methylimidazolium chloride ionic liquid. The effects of reaction conditions including reaction time, temperature and the molar ratio of 3,5-dinitrobenzoyl chloride to anhydroxylose units in xylan on the degree of substitution(DS) on xylan-based adsorbent were discussed. When the ratio of 3, 5-dinitrobenzoyl chloride to anhydroxylose units in xylan was 7:1, reaction time was 70 min, the reaction temperature was 100 oC, the maximum DS of 1.77 for the resulting product was obtained. The physicochemical properties of obtained products are characterized by Fourier transform infrared(FTIR) and 13C nuclear magnetic resonance(NMR) spectroscopies and results indicated the successful attachment of 3, 5-dinitrobenzoyl groups onto xylan.4. The adsorption capacities of xylan-based adsorbent for creatinine were examined. The influences of contact time, contact temperature, initial concentration of creatinine and p H on the adsorption capacity were studied. The results showed that the adsorption capacity of xylan esters(DS =1.77) for creatinine was 1.84 mg/g at 37 oC, p H 7.0 and a creatinine concentration of 100 mg/L. The maximum adsorption capacity of xylan esters for creatinine was 2.45 mg/g at 23°C, p H 9.0 and a creatinine concentration of 300 mg/L. And the adsorption data were fit with Freundlich equation very well, indicating that the sorption process mainly was controlled by the chemical adsorption... |
PDF Full Text Request