Study On The Removal Performance Of Biomass-Based Materials For Micropollutants In Water

Helical carbon fibers are a new kind of fascinating carbon material,its unique three-dimensional spiral structure exhibits unique electrical,magnetic and mechanical properties,including high specific surface area,super elasticity,excellent stability,electrical conductivity and electromagnetic wave absorption.Therefore,the controlled synthesis and performance research of helical carbon fibers have attracted widespread attention from scientists in many countries.On the other hand,while the society is developing rapidly,the problems such as energy demand and environmental pollution become increasingly serious.In particular,the misconduct(landfill and incineration,etc.)of biological wastes(such as leaves and straws,etc.)not only destroyed the ecological environment of the city but also caused the public safety hazards and waste of resources.Hence,the efficient treatment and resource utilization of biological wastes are widely concerned.Biomass carbon provides a technical approach for the sustainable resource utilization of biological wastes.This paper proposes a new idea of extracting high-purity spiral vessels from biomass by physical-chemical process using waste biomass as raw materials.Based on the biomass template method,an idea for optimizing the microcosmic pore structure and enhancing the performance of the porous helical carbon fibers was proposed by studying the carbonization and activation processes.The preparation and performance of biomass-bass porous helical carbon fibers are researched and the potential applications of porous helical carbon fibers in adsorption field are discussed,these studies make useful explorations on the high value conversion and utilization of biomass wastes.This paper mainly conducts innovative research in the following aspects:1.Using the inherent complex and fine structure of biomass,the high-purity spiral vessels with helical shape were extracted by chemical dispersion effect of alkaline reagents and aggregation effect of physical ultrasound waves.The influence of different extraction processes on the morphology and purity of spiral vessels was discussed,and a new idea for preparing helical carbon fibers at low cost was constructed.Then helical carbon fibers were obtained by a bio-template carbonization process using the high purified spiral vessels as the template.2.KOH was used as the activator to prepare the spiral vessels-based porous helical carbon fibers(SV ACFs)with multistage pore structure by simply mixing and grinding of KOH and helical carbon fibers through activation process.The effect of the ratio of KOH activator on the structure and performance of porous SV ACFs was investigated.As the spiral vessels were carbonized and the mild activation condition was applied,the three-dimensional structure of spiral vessels was fully preserved.Three-dimensional spiral structure of the carbon fibers is beneficial to the full contact between the activator and helical carbon fibers'inside and outside the surface,resulting porous SV ACFs with high specific surface area.The BET results of the porous SV ACFs show that the specific surface area and total pore volume of the SV ACFs further increase with the increase of the ratio of activator,this is because that the augment of activator ratio increases the etching strength.The specific surface area of the prepared porous SV ACFs is greater than 3000m2 g-1.3.The adsorption capacities of sulfamethoxazole(SMX)on porous SV ACFs with four activation ratios(the porous carbon with activation ratios of 1:1,1:3,1:5 and 1:7 were labeled as SV ACFs 1-1,SV ACFs 1-3,SV ACFs 1-5 and SV ACFs 1-7,respectively)were shown as follows:SV ACFs 1-5 and SV ACFs 1-7 have similar adsorption capacities and are far greater than that of SV ACFs 1-1 and SV ACFs 1-3,this is because SV ACFs 1-5 and SV ACFs 1-7 possess ultrahigh specific surface area and high levels of nanopore(1nm-3nm).The high content of pores(1-3 nm)not only guarantees the accessibility of the surface for SMX storage but also provide easily approachable SMX channels for SMX transmission.The influences of pH value,ion strength and humic acid were shown as follows:the adsorption capacity of SMX by SV ACFs 1-7 increased first and then decreased with the increase of pH value,and reached the highest adsorption capacity(318mg/g)at pH value of 4.With the increase of humic acid concentration,the adsorption capacity of SMX on SV ACFs 1-7 firstly increases and then decreases.Na+ promotes the adsorption of SMX on SV ACFs 1-7,while Ca2+ inhibits the adsorption of SMX by SV ACFs 1-7.4.The theoretical adsorption capacities calculated by the pseudo-second-order kinetic model are more consistent with the experimental adsorption capacities,and the correlation coefficients are closer to 1,so this model is more in line with the adsorption behavior of SMX on SV ACFs 1-7.The correlation coefficients of the Langmuir model at all temperatures were greater than 0.99 and far exceeded that of the Freundlich model,demonstrating the adsorption isotherms data of SMX on SV ACFs 1-7 were more in line with the Langmuir model and the adsorption type is monolayer adsorption.The adsorption of SMX on SV ACFs 1-7 is an exothermic process,and low temperature will create an conducive adsorption of SMX on SV ACFs 1-7.5.Through the analysis of characterization and adsorption data,inferring that the adsorption mechanism mainly includes electrostatic interaction,pore filling,hydrogen bonding,hydrophobic interaction and ?-? EDA interaction.The disappearance of C=O support the occurrence of reaction between SMX and the surface of SV ACFs 1-7,it is possible that the C=O of carbonyl and carboxyl groups on the surface of SV ACFs 1-7 has reaction with the amino group of aniline group in SMX.