Study On The Removal Of Typical Organic Pollutants In Water By The Iron-copper Co-modified Biochar Catalyst/Peroxymonosulfate System

With the rapid development of industry and improvement of human living standards,various wastewater containing organic pollutants is discharged into natural water bodies through multiple pathways.Because most organic pollutants are difficult to degrade and are toxic,they have become a potential threat to aquatic ecosystems and human health.Among various water pollution treatment technologies,advanced oxidation technology based on persulfate has attracted attention due to its high oxidation ability and environmental friendliness.In recent years,biochar-based catalysts have also been extensively studied due to their simple preparation and low cost.In present paper,two iron-copper co-modified biochar catalysts were prepared using iron-copper chemical reagents and natural minerals containing iron and copper,and heterogeneous peroxymonosulfate（PMS）catalytic systems were constructed to remove typical organic pollutants in water.Through a variety of characterization and the batch experiments,the efficiencies and mechanisms of two biochar-based materials to activate PMS degrading organic pollutants in water bodies were clarified,which provided a theoretical basis for the application of biochar-based catalysts and the removal of organic pollutants in water bodies.The main research contents and results are as follows:（1）Using corn stalks as the biomass raw material,selecting chemical reagents modification and natural chalcopyrite modification prepared two kinds of iron-copper co-modified biochar catalysts（FeCu-MSBC and 10%NCBC500）,respectively.Through various characterization methods explored morphology,structural characteristics and differences of two composite materials.The results showed that the yield of FeCu-MSBC was significantly lower than 10%NCBC500,but its specific surface area and pore volume were much higher than 10%NCBC500.The pore structure of FeCu-MSBC was mainly micropores and mesopores,while10%NCBC500 only had mesoporous structure,but the average pore size was larger.The metal on FeCu-MSBC existed in the form of metal oxide particles,and the particle size was only tens of nanometers.The metal on 10%NCBC500 mainly existed in the form of Cu FeS₂,and a small amount of metal oxides were distributed on its surface,besides,the particle size was significantly higher than FeCu-MSBC.（2）The PMS catalytic system was constructed using FeCu-MSBC as a catalyst to explore the removing performance,the activation and degradation mechanisms as well as practical application potential for Rhodamine B（RhB）in water.According to results,compared with MSBC,2Fe-MSBC and 2Cu-MSBC,FeCu-MSBC showed the highest removal efficiency and degradation rate for activating PMS to degrade RhB,which was mainly due to the unique synergistic effect derived form introducing Fe and Cu into FeCu-MSBC.The efficiency of degrading RhB in FeCu-MSBC/PMS system increased with the increase of material dosage,PMS and humic acid（HA）concentration.The system has a wider pH range（2.0～10.0）,and was not easy to affect by the complex components in the actual water body.Besides,the system still performed good removal ability for RhB in Tap water and Yellow River water,and had a faster degradation rate in domestic sewage.Meanwhile,FeCu-MSBC showed good regeneration performance.The copper,iron,defective sites and C=O on FeCu-MSBC played an important role in activation of PMS and degradation of pollutants.The system selectively degraded electron-rich pollutants through non-radical pathways（¹O₂ and electron transfer）,while was difficult to degrade electron-deficient pollutants.（3）The PMS catalytic system was constructed using 10%NCBC500 as a catalyst to explore the performance,activation and degradation mechanism,and practical application potential for removing carbamazepine（CBZ）in water.The results indicated that the adsorption ability of 10%NCBC500 for CBZ was weak,but it could efficiently activate PMS to degrade CBZ.Under optimal conditions,98.3%of CBZ could be removed after 2.5 h reaction.The initial pH of solution had little effect on the degradation of CBZ,the addition of SO₄^2-,NO₃^-,HCO₃^-and humic acid slightly inhibited the degradation of CBZ,however the addition of Cl^-accelerated the degradation process.The 10%NCBC500/PMS system had a wider range of pollutant degradation species,while it was susceptible to interference from complex components in the actual environment.Furthermore,the iron,copper,sulphur,C=O and defective sites on 10%NCBC500 played important roles in the activating PMS and degrading CBZ.During the reaction,low-valent sulfur(S^2-and S₂^2-)could reduce Fe³⁺and Cu²⁺to produce Fe²⁺and Cu⁺active sites,promoted the redox cycle of elemental iron and copper,thereby improved ability for formation of free radicals and degradation of pollutants.The system degraded pollutants mainly through free radical pathways(^·OH and SO₄^·￣),and the generation of^·OH and SO₄^·￣was affected by O₂^·￣and ¹O₂.