| Rice husks are a by-product of the rice processing process,and the quantity is huge.With rice husk cellulose as the skeleton,the synthesis of rice husk cellulose water-absorbing and hygroscopic materials is a way to utilize agricultural waste resources.In this paper,the preparation and properties of rice husk cellulose water-absorbent resin are studied from two aspects: heterogeneous and reversed-phase suspension polymerization.main tasks as follows:(1)Rice husk pretreatmentThe rice husks were pretreated with Na OH solution.The single-factor test was used to analyze the effects of pretreatment conditions on the rice husks.The reaction temperature,the mass ratio of Na OH to rice husk,Na OH concentration,and reaction time on rice husk moisture,ash content,volatile matter and fixed carbon.Under the experimental system,it was shown that the mass ratio of Na OH to rice hull = 1,20 wt.% Na OH,reaction temperature 65℃,reaction time 8h was the reaction conditions after optimization.the moisture,ash content,volatile matter and fixed carbon of the rice husks pretreated were 8.00%,2.77%,72.02% and 17.21%,respectively.(2)Preparation and properties of rice husk / acrylic acid-sodium acrylate composite water-absorbing resinPreparation and properties of rice husk / acrylic acid-sodium acrylate composite water-absorbing resin.The pretreated rice husk was graft polymerized with acrylic acid and sodium acrylate monomers.The single factor experiment obtained the influence law of reaction temperature,monomer dosage,initiator dosage and crosslinking agent dosage on the product liquid absorption rate,grafting rate,grafting efficiency,repeated water absorption rate,water retention rate and water loss rate.The single-factor optimal preparation process conditions are: 0.45 g / g rice husk for initiator,10 g / g rice husk for monomer,0.1g / g rice husk for crosslinker,and reaction temperature 70 ℃ Orthogonal orthogonal test determined that the best preparation conditions are initiator dosage 0.3g / g rice husk,monomer dosage 10 g / g rice husk,crosslinker dosage 0.1g / g rice husk,reaction temperature 70 ℃,reaction time 1h.The water absorbing resin prepared under this condition has a water absorption ratio of 235 g / g in deionized water.(3)Preparation of rice husk / sodium acrylate resin by reverse phase polymerization and its water and moisture absorption propertiesIn the experiment,orthogonal experiment was used to analyze the influence of reaction conditions on the hygroscopic performance of the hygroscopic resin.According to the orthogonal experiment,the primary and secondary factors were determined as monomer dosage> initiator dosage> reaction time> reaction temperature> crosslinker.The best preparation conditions: initiator dosage 0.3 g / g rice husk,monomer dosage 12 g / g rice husk,crosslinking agent dosage 0.05 g / g rice husk,reaction temperature 70 ℃,reaction time 1h.Under these conditions,the hygroscopic resin prepared under RH = 33%,RH = 65%,and RH = 84%,the moisture absorption rate of 5d was 59.43%,68.46% and 73.11%,respectively.(4)Preparation of rice husk / acrylic acid-sodium acrylate resin by reverse phase polymerization and its water and moisture absorption propertiesIn the experiment,single factor experiment analysis was used to select the best suspension solution ratio.The ratio of emulsifier in reverse phase polymerization was selected to obtain a water ring ratio of 1: 2,Tween 60 was 0.01 g / g cyclohexane,and Span 80 was 0.035 g / g.Cyclohexane,the stability of the suspension in this ratio is the most stable compared to other ratios.The optimal conditions for the preparation of water-absorbent resin are the amount of samples generated by the reverse phase polymerization reaction.The deionized water,tap water and 0.9wt.% Brine ratio are 182.96 g / g,96.25 g / g and 29.96 g / g respectively.The hygroscopic materials prepared by reverse-phase polymerization method have a hygroscopic rate of 70.12%,66.32% and 57.43% at RH = 33%,RH = 65% and RH = 84%,respectively. |
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