Process And Mechanism Of 5-Hydroxymethylfurfural Derived From Phytoremediation Plant Wastes Under Mechanicalchemistry-microwave Hydrothermal Treatment

As a special biomass resource for the treatment of heavy metal pollution,the environmentfriendly resource utilization of phytoremediation waste is worth exploring.This research explored the feasibility of mechanochemistry combined with microwave hydrothermal directed conversion of 5-hydroxymethylfurfural（HMF）from phytoremediation waste.First of all,using plant waste as raw materials,the impact of mechanical ball milling conditions on its resource utilization was investigated.The study found that ball milling（BM）with microwave hydrothermal（MHT）treatment of plant waste is feasible.The conditions of ball milling include ball milling time,ball-solid ratio and rotational speed can effectively affect conversion of HMF,a product of green plant waste recycling.Secondly,based on the catalytic effect of metal ions in MHT process,the HMF conversion potential of BM-MHT process was further explored with typical metal-occurring restorative plants such as Phytolacca acinosa Roxb,Sedum alfredii Hanceand,Commelina commelina and Pteris vittata L.Finally,the mechanism of lignocellulosic and metal ion coupling system promoting HMF directional transformation under mechanical BM-MHT system was explored.The study found that under the best BM conditions,the ball milling time is 237.42 min,the ball-solid ratio is 39.37:1,the rotational speed is 401.25 rpm,and the best microwave hydrothermal conditions are the temperature of 150℃ and the holding time of 1 min,the optimal HMF yield is 1.82%.The economic analysis further shows that the yield rate of BM-MHT resource of plant waste is obviously higher than other technologies,and the profit of plant waste can be 85,000 yuan per ton,indicating a great prospect of resource utilization.The results showed that the material structure and metal ions had significant effects on the yield of HMF,and the plant with high cellulose and hemicellulose content had the highest potential of HMF conversion,with a yield of 2.07%±0.11%.After phytoremediation,metal ions can further catalyze the conversion of phytoremediation waste to HMF in MHT process.The HMF yield of Commelina commelina containing 1 g/kg Zn²⁺at 210℃ reaches 3.11±0.14%,which is 1.6 times higher than that before phytoremediation.From the perspective of solid phase products,Commelina commelina with 500 mg/kg Zn2+at 210℃for 10 minutes,the yield of hydrochar was as high as 63.38%.It was found that the reaction system could promote the hydrolysis of lignocellulosic polymer to monosaccharide,in which the hydrolysis of cellulose to glucose was the most significant,and the saccharification rate reached 3.75%.Lewis acid metal can promote cellulose hydrolysis and conversion of dehydrated sugars and secondary dehydrated products,and alkaline earth metal can induce carbohydrate dehydrated substances to produce furfural compounds.The possible mechanism of metal complexes and crystal co-promoting lignocellulosic directional transformation of HMF was proposed.The results obtained in this study can provide new ideas for resource disposal of restorative plants.