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Process And Mechanism Of 5-hydroxymethylfurfural Derived From Plant Solid Wastes Under Microwave Hydrothermal Treatment

Posted on:2021-05-29Degree:MasterType:Thesis
Country:ChinaCandidate:Y C ShaoFull Text:PDF
GTID:2381330623458956Subject:Environmental Science and Engineering
Abstract/Summary:PDF Full Text Request
Plant solid waste is an important biomass resource.Therefore,it is worthwhile to explore the new ideas of sustainable and environmentally friendly treatment in addition to traditional technology such as incineration and landfill.This study investigated the transformation process of plant solid waste under microwave hydrothermal method.Firstly,the feasibility of microwave hydrothermal treatment for the green waste selected as the typical plant solid waste was researched.The result showed this technology was not only feasible for plant solid waste treatment,but also discovered the holding temperature,holding time and liquid-to-solid ratio can significantly affect the recycling of green waste.The yield of solid-phase product?i.e.hydrochar?was up to 50.4%under the optimal microwave hydrothermal condition?i.e.holding temperature of 190?,holding time of 1 h and liquid-to-solid ratio of 8:1?.Its calorific value of 23.01 MJ/kg same as that of standard coal and its porous structure characteristics indicated this method has a considerable prospect for resource and energy.Comparing with the hydrochar,the detection of HMF in liquid-phase product was a bigger highlight.However,its yield of 0.5%was low and need to further optimization and improvement.The result of economic analysis showed the added value of product obtained by microwave hydrothermal treatment reached at 30033 yuan/t.This showed the huge prospect of resource recycling and it is necessary to further explore the higher yield of HMF.Secondly,HMF in liquid phase was taken as the target product and the optimization of microwave hydrothermal conditions in a low-cost and environmentally friendly system was used to obtain a higher yield.The results showed that the type of raw material had obvious influence on the HMF yield under microwave hydrothermal treatment.The bagasse with high sugar content had more advantages than watermelon peel in HMF production.The highest HMF yield could be increased to 5.7%under the same hydrothermal condition.The solvent of acidic seawater can further enhance the potential of conversion of bagasse into HMF.The acidic seawater circumstance significantly promoted the hydrolysis of bagasse into glucose and fructose,and effectively inhibited the conversion of HMF into LA.The HMF yield was up to 8.1%at the holding temperature of 149?,holding time of 4 min and liquid-to-solid ratio of 12:1.Finally,glucose and fructose as the direct precursor of HMF was used to explore the mechanism of HMF production and conversion under microwave hydrothermal circumstance.The high HMF yield produced by fructose and glucose as well as the high conversion rate of raw materials under acidic seawater circumstance were discovered.This study verified the above inference that monosaccharide was the key for HMF formation.The process of HMF conversion was sequentially undergone the dehydration reaction and decarboxylation reaction to form hydrochar with typical structure whose average formula of C5.2H4.2O2.1.1 and C5.3H4.4O2.0.During microwave hydrothermal process,the conversion balance between precursors,target product,downstream products and hydrochar was obviously different.In the dehydration stage,the conversion rate of HMF into hydrochar was 5.5 times higher than that of fructose,which was worthy of further exploration.The results obtained in this study can provide a new method for expanding the high value of biomass waste.
Keywords/Search Tags:Plant solid waste, microwave hydrothermal, hydrochar, 5-hydroxymethylfurfural
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