Construction And Performance Study Of Fenton-like Functionalized Wood Veneer

With the increasing water pollution problem and the widespread application of membrane technology in wastewater treatment,the renewable,low cost,green and efficient membrane materials are the current goals of membrane material design and also become the key issues for industrial application of membrane technology.As one of natural resource,wood has the advantages of being cheap and easy to obtain,green and environmentally friendly,and good processability.As a commercial furniture facing material,the wood veneer sliced from natural wood has the characteristics of thin thickness,good flexibility and special pore structure,which can be regarded as a very ideal membrane material.In this paper,the sliced wood veneers of poplar wood and Chinese fir were used as research objects.Firstly,the basic properties of the two woods and the feasibility of using them for filtration membranes were analyzed by microscopic observation,SEM observation,BET surface area analysis and mechanical tensile test,and their performance in filtering and retention methylene blue were tested.Secondly,based on the above study,wood membranes with Fenton-like catalysts were prepared by hydrothermal synthesis.The morphological structure,composition and mechanical strength of the membranes were characterized and analyzed by SEM,XRD,XPS,FTIR and mechanical tensile tests,and their catalytic retention properties were investigated.At the same time,the catalytic degradation mechanism was further analyzed.The main results can be summarized as follows:(1)The study results of the basic properties of the two untreated wood veneers and their use for the filtration of methylene blue show that poplar wood and Chinese fir both have interconnected micro-and nano-scale three-dimensional pore structured cellular channels,which provides rich water transfer path for fluid transport.The tensile strength parallel to the grain of poplar wood and Chinese fir in the air-dried state is about 1.3 times and 1.2-1.9 times higher than that in the water-saturated state,respectively.Both woods show excellent corrosion resistance in HCl,HNO3 and NaOH solution.The retention test of methylene blue revealed that wood species,wood veneer thickness and filtration pressure all have an effect on the retention rate of methylene blue.Due to the presence of larger vessel channels in poplar wood,the flux of poplar wood membrane was 95.7%higher than Chinese fir wood membrane,while the different in the removal performance of methylene blue was 25.8%.When the membrane thickness was increased from 0.2 mm to 0.6 mm,the flux of poplar wood membrane showed a decrease of 84.3%,while Chinese fir membrane showed a decrease of 98.4%,and the increase in retention rate was smaller for the former and larger for the latter(11.1%).When the filtration pressure was increased from 0.005 MPa to 0.030 MPa,the fluxes of both were improved by 2.05 and 5.38 times,respectively,and the retention rate of poplar wood membrane was reduced from 59.6%to 43.4%,the Chinese fir membrane was reduced from 95.0%to 75.9%,which significantly reduced the removal effect.(2)The wood membranes with Fenton-like catalytic function were successfully prepared by hydrothermal synthesis MnO2 nanoparticles into wood.The SEM results showed that the treated wood membranes still maintained their structural integrity relatively well,and the MnO2 nanoparticles were relatively uniformly immobilized the cell lumen surface,mainly in the form of thin solid layers of nanowires and particles.The results of XRD and XPS indicated the presence of other impurities in the synthesized manganese dioxide.Compared to the untreated poplar wood membrane and Chinese fir membrane,the strength of the MnO2/wood membranes obtained by hydrothermal treatment decreased 11.4%and 49.8%in the air-dried state,and decreased 55.1%and 61.8%in the water-saturated state,respectively.But it still has relatively excellent mechanical strength and good bending properties,which can meet the application requirements.(3)The results of filtration tests of functionalized wood membranes on methylene blue solution showed that had good performance in removing and catalytic degradation methylene blue dye molecules,and the Fenton-like effect in the reaction system effectively delays the blockage of membrane pores and fast decline of flux.And the wood species,wood veneer thickness,amount of KMnO4,pH,with or without H2O2 all had effects on the retention performance of methylene blue.After five times of repeated use,the retention rates of the two functionalized wood membranes can be maintained at more than 5 5%and 85%,respectively.The difference in the structure of the wood itself allow MnO2/poplar wood membrane and MnO2/Chinese fir membrane to have similar trend in terms of flux and retention rates compared to the untreated wood membranes.When the membrane thickness increased from 0.2 mm to 0.6 mm,the flux of MnO2/poplar wood membrane decreased from 13748.54 L/m2h to 2090.13 L/m2h,and the retention rate increased from 63.6%to 84.3%,while the flux of MnO2/Chinese fir wood membrane decreased from 40.88 L/m2h to 3.18 L/m2h,but its retention rate basically remained at around 95%-98%.At the same time,when the amount of KMnO4 was increased from 0 to 0.10 mol/L,the flux of MnO2/poplar wood membrane decreased 47.4%and its retention rate(61.9%-63.6%)remained basically unchanged,while the flux of MnO2/Chinese fir wood membrane decreased 96.4%and the retention rate increased from 87.7%to 98.7%.The study also found that under acidic conditions,the losses of the catalyst is not favorable for the increase of the retention rate.