Preparation Of Coated/Loaded Ferrate Composite Material And Its Carbamazepine Removal Efficiency

In recent years,trace and stubborn new organic substances such as Pharmaceutical and Personal Care Products?PPCPs?have been widely used and directly enter the surface water environment or even the groundwater environment from the urban residential water system through the urban sewage treatment plant without treatment.Therefore,PPCPs has become a highly detectable substance in tap water,reclaimed water and surface water,posing a great threat to the safety of aquatic ecosystems.This kind of substance is difficult to be effectively removed by traditional biological treatment technology in sewage treatment plant,and the concentration in effluent water can be effectively reduced only by process optimization or advanced treatment.Potassium ferrate?K₂FeO₄?is a kind of green multifunctional water treatment agent with strong oxidation,which can be used as oxidant,disinfectant and flocculant.However,due to its strong instability in aqueous solution,potassium ferrate is also prone to self-decomposition and deterioration during storage,resulting in low content of active ingredients,which can not fully play its role in water treatment and thus is limited in application.In this paper,adsorption is integrated on the basis of strong oxidation of ferrate,and adsorption-oxidation integrated composite material is prepared.Coated potassium ferrate and loaded potassium ferrate are synthesized based on coating and loading.The removal efficiency of carbamazepine?CBZ?in reclaimed water is investigated,and the degradation mechanism and approach are studied.Through preliminary exploration on the synthesis of composite materials,potassium ferrate and ?-cyclodextrin??-CD?are determined as raw materials for preparing coated potassium ferrate,potassium ferrate and biomass char are used as raw materials for preparing loaded potassium ferrate,which are respectively prepared by melting suspension condensation method and high-energy ball milling method,and the prepared products are tested for slow release performance,stability,water absorption and a series of physical characteristics.The slow release test shows that the maximum release rates of the two composites in alkaline solution for 120 min are 53.62% and 62.13% respectively.The minimum residual percentage in air after 40 days was 73.44% and 63.8% respectively.After 10 days,the maximum wat er absorption rate was 9.86% and 6.79% respectively.Overall,the properties of the two composite materials have been greatly improved compared with potassium ferrate,which shows that the two processes have played a role in protecting and slowly releasing potassium ferrate.The removal efficiency of pollutants CBZ was tested on two kinds of composite materials,and compared with potassium ferrate oxidation effect,biomass char and ?-CD adsorption effect.Under the same experimental conditions,compared with potassium ferrate,the degradation rate of CBZ of the two composite materials can be increased by 49.1% and 44.5% at the highest,and the adsorption effect accounts for about 15%-20% and the oxidation degradation effect accounts for about 80 %-85% in the composite material adsorption-oxidation degradation system,indicating that the oxidation effect in the system plays a major contribution to the degradation rate.The optimal conditions for CBZ removal by composite potassium ferrate were obtained through optimization of conditions: reaction time 30 min,concentration of potassium ferrate 5mg/L,reaction temperature of coated potassium ferrate 40 ?,reaction temperature of loaded potassium ferrate 50?,initial p H of solution 8.0-9.0.After exploring the degradation efficiency and optimal reaction conditions,the mechanism and approach of CBZ degradation by composite materials were further explored.Samples at different reaction times were determined by liquid chromatography-mass spectrometry?LC-MS?.Four intermediate products of CBZ were estimated based on the total ion diagram,mass spectrum diagram and spectral library data,and the molecular structure of CBZ was estimated based on the mass-tocharge ratio,thus the degradation pathway was estimated.According to the degradation pathway,it can be seen that the degradation of CBZ by the adsorption-oxidation integrated composite material is mainly a process of potassium ferrate destroying the double bond of CBZ olefin and continuously adding oxygen through oxidation to make it undergo ring-opening recombination.The degradation process is consistent with the law of pseudo-first-order kinetics.To sum up,this paper realizes the effective removal of CBZ in reclaimed water through potassium ferrate composite materials,which provides a new idea for ferrate composite materials to remove PPCPs and guarantees the water quality safety of reclaimed water.