Functional Modification Of Cellulose And Its Performance Study On Adsorption And Catalysis Degradation

Heavy metal ions and organic dyes have posed a serious threat to human health and ecosystem health in the water environment.With the increasing prevalence of water pollutants and the high cost of treatment process,there is a need for more efficient,economic viability and environmental friendliness methods of water purification.Currently,adsorption and catalytic degradation play an important role in wastewater treatment,and adsorbents and catalysts are the core of the two technologies respectively.Due to its unique characteristic,such as biodegradability,low-cost,and environmental friendliness,cellulose can be used as an adsorbent and catalyst carrier.However,cellulose is not usually used directly in adsorption and catalysis field due to the problem that it has few types of surface functional groups and low catalytic activity.Therefore,functional modification of cellulose to prepare new adsorption and catalytic materials is of great significance in the field of water purification.1.Cellulose powder（CH）was prepared by hydrothermal method using extracted cellulose as raw material,which has good dispersibility and uniform particle size.Then,amine-functionalized cellulose（CH@DETA）was prepared by facile single step method and applied in the adsorption of anionic dye Congo red（CR）.The results showed that CH@DETA has a good adsorption capacity for CR,and the maximum adsorption capacity was 826.45 mg/g at25°C and p H=7.CH@DETA has a good regeneration performance,the removal rate remained87.53%after five cycles.The main adsorption mechanism was that the protonated CH@DETA removed anionic dyes by electrostatic action.2.To improve the separation efficiency and recovery performance of the adsorbent,prevent adsorbent induced secondary pollution.And expand the contact area between the adsorbent and the pollutant.A macroscopic composite bead with three-dimensional porous structure was constructed by combining cellulose nanofiber（CNF）,sodium alginate（SA）and polyethylenimide（PEI）using iron ion and glutaraldehyde mediated cross-linking process and yielding a porous hollow bead（CS-Fe@PEI）.The results showed that:The maximum adsorption capacity of CS-Fe@PEI for Cr（VI）was 526.32 mg/g at 25°C and p H=2.The removal rate of Cr（VI）reached 91.68%after five cycles,indicating that CS-Fe@PEI has good structural stability and regeneration ability.FT-IR,Zeta and XPS analysis revealed that the mechanism of Cr（VI）adsorption by CS-Fe@PEI was mainly attributed to electrostatic action,and part of the adsorbed Cr（VI）with high toxicity could be reduced to Cr（III）with low toxicity.3.In order to improve the powder catalytic material is difficult to recycle,and the dye molecules recovered by adsorption method still need other technologies to achieve molecular degradation.In this paper,Cu Mn O₂ catalyst was prepared by hydrothermal reaction.Cu Mn O₂,CNF,PEI and SA were combined using calcium ion and glutaraldehyde mediated cross-linking process and yielding a composite bead（CS-Ca@PEI/Cu Mn O₂）with adsorption and catalytic effect.The solid-liquid heterogeneous oxidation system was prepared by using CS-Ca@PEI/Cu Mn O₂ as a catalyst to activate peroxymonosulfate（PMS）.The performance of CS-Ca@PEI/Cu Mn O₂ for CR oxidative degradation was affected by p H,PMS concentration,temperature and other factors.The results showed that CS-Ca@PEI/Cu Mn O₂ has excellent degradation capacity,the degradation rate of CR reached 83.27%after adsorption equilibrium.The results of XPS and electron spin resonance spectroscopy（EPR）showed that CS-Ca@PEI/Cu Mn O₂ had the ability of activating PMS to generate free radicals,which could effectively degrade organic dyes.