The Preparation Of Bamboo Fiber Based Porous Adsorbent Materials And The Application On Wastewater Treatment

Due to the rapid development of industrialization,abundant of organic dye and heavy metal wastewater has been discharged into the environment,such as methylene blue（MB）,congo red（CR）and Cu²⁺.It has caused serious pollutions to water ecosystem.Bamboo fiber is a renewable biomass resource.The cellulose in fiber contains a large number of hydroxyl groups,which can be used as the active site for the adsorption of organic dyes and grafting modification sites.Therefore,bamboo fiber resources can be applied as adsorbents for wastewater treatment.In this work,bamboo fiber/polyurethane foam and bamboo fiber based aerogel bead were prepared to remove MB,CR and Cu²⁺.The preparation and properties of the two porous materials were characterized by FTIR,XPS,SEM,TGA and BET.The effects of p H,adsorbent dosage,contact time,initial dye concentration and temperature on the removal of MB,CR and Cu²⁺were investigated,and the adsorption mechanism was studied as well.The main findings are as follows:（1）The preparation of bamboo fiber/polyurethane foam adsorption material and the adsorption of cationic pollutantsThe bamboo fiber waste was prepared to bamboo fiber resources（i.e.,original fiber,bambooα-cellulose fiber and bamboo nanocellulose fiber）.Bamboo fiber/polyurethane（PU）foam adsorbents were prepared by loading bamboo fiber resources into polyurethane foam matrix.The results showed that the PU foam adsorbent with 1 g of nanocellulose（PUN₁）had high removal efficiencies for MB（95.52%）and Cu²⁺（100%）in low concentration aqueous solutions.The PU foam adsorbent with 1 g of bamboo fiber（PUB₁）also displayed an excellent removal efficiency for MB（98.61%）at p H 11,initial concentration=15 mg/L.Meanwhile,100%removal of Cu²⁺was obtained by PUB₁at p H7（initial content=15 mg/L）.Furthermore,the PUN₁had a good reusability,evidenced by61.25%removal of MB after five adsorption-desorption cycles.It suggested that PUN₁is a promising renewable adsorbent for cationic pollutants.（2）The preparation of bamboo fiber based double-cross-linked aerogel bead and the adsorption of anionic and cationic dyesWaste bamboo paper and chitosan were used as raw materials.Double-cross-linked bamboo fiber based aerogel bead（DCBA bead）was prepared by physical and chemical cross-linking methods.FTIR,XPS,SEM-EDS,TGA and BET analysis showed that DCBA bead was successfully obtained.DCBA bead had a good stability due to its double cross-linked structure.The MB and CR adsorption capacities of DCBA bead increased with increasing adsorbent dosage,contact time,temperature and initial dye concentration.With increasing solution p H,the MB adsorption capacity increased,while that for CR increased first and then decreased.When the initial dye concentration was 50 mg/L,the maximum removal efficiencies of MB and CR were 91.4%and 94.7%,respectively.The maximal adsorption capacities for MB and CR were 653.3 and 559.6 mg/g,respectively,in the single system.The thermodynamic analysis results showed a spontaneous and endothermic adsorption process.DCBA bead had a good stability and reusability with the removal efficiencies of 49.4%and 60.6%for MB and CR,respectively,after five cycles of adsorption-desorption.In the binary system,the adsorption of MB was inhibited by CR,while the removal of CR was enhanced by MB.Therefore,DCBA bead was an excellent candidate to remove MB and CR dye from wastewater.