Hydroxylamine Enhanced Degradation Of Orange G And Sulfamethoxazole With Hydrogen Peroxide/Peroxydisulfate Activated By Fe(Ⅲ) Complexes

In recent years,organic wastewater discharged from textile printing and dyeing industry,medical treatment and personal care has become the main source of water pollution in China.Dye wastewater has toxicity,carcinogenicity and teratogenicity due to its complex composition,while PPCPs wastewater may induce the emergence of drug-resistant bacteria,so both of these two types of wastewaters will cause harm to human health and the ecosystem.Therefore,it is necessary to degrade them before they enter the environment.However,due to the complex organic components and poor biodegradability of dye wastewater,and the antibacterial properties of antibiotics in PPCPs,the traditional sewage treatment technology cannot effectively remove the pollutants.Thus,it is very important to develop an efficient,economical,green and environmentally friendly treatment technology to remove dye wastewater and PPCPs wastewater.In this paper,orange G（OG）,a typical azo dye,was selected as the target pollutant,and sulfamethoxazole（SMX）,was used as the representative of PPCPs pollutants.The degradation of organic pollutants in water by Fe（Ⅲ）-trisodium nitrilotriacetate（NTA）/hydroxylamine（HAm）/hydrogen peroxide（H₂O₂）、Fe（Ⅲ）-NTA/HAm/peroxydisulfate（PDS）and alginate iron（SA-Fe（Ⅲ））/HAm/PDS was investigated.The main contents are as followed:（1）The degradation mechanism and influencing factors of OG in Fe（Ⅲ）-NTA/HAm/H₂O₂ system were studied,the degradation efficiency of three types of PPCPs,the degradation mechanism,influencing factors and degradation products of SMX were investigated preliminarily.The results showed that Fe（Ⅲ）-NTA/HAm/H₂O₂ system could degrade OG effectively under neutral conditions,and the removal rate was 90.54%within 30 min.The main active species in this system was HO^·,which mainly attacked azo bonds and naphthalene rings in OG molecular structure.The degradation reaction could be promoted by increasing the reagents concentration and temperature,while the degradation reaction could be inhibited by excessive dose of reagents.Cu（Ⅱ）could promote the removal of pollutants,while Co（Ⅱ）had little effect on the reaction.HCO₃^-and NOM could inhibit OG degradation.The system could effectively degrade different types of PPCPs,and the removal rate was more than 80%,suggesting the stability and universality of this system.Eight degradation products were detected in Fe（Ⅲ）-NTA/HAm/H₂O₂ system during the degradation of SMX,and three degradation pathways were proposed including hydroxylation,amino oxidation and bond breaking.（2）PDS,which is more stable,was used to replace H₂O₂ to degrade OG.The degradation mechanism and influencing factors of OG in Fe（Ⅲ）-NTA/HAm/PDS system were studied,the degradation efficiency of three types of PPCPs,the degradation mechanism,influencing factors and degradation products of SMX were investigated preliminarily.The results showed that Fe（Ⅲ）-NTA/HAm/PDS system could degrade OG effectively under neutral conditions,and 86.41%OG was removed within 15 min.Compared with Fe（Ⅲ）-NTA/HAm/H₂O₂ system,Fe（Ⅲ）-NTA/HAm/PDS system could obtain higher degradation efficiency in shorter time.The main active species in the system were HO^·and SO₄^·-,which mainly attacked azo bonds and naphthalene rings in OG molecular structure.Compared with HO^·in Fe（Ⅲ）-NTA/HAm/H₂O₂system,SO₄^·-has higher selectivity and half-life,which might lead more obvious advantages in the degradation of OG under same conditions.The degradation reaction could be promoted by increasing the reagents concentration and temperature,while the degradation of OG could be inhibited by excessive dose of the reagents.Cu（Ⅱ）,Co（Ⅱ）and Cl^-could promote the removal of pollutants,while HCO₃^-and NOM could inhibit OG degradation.This system could effectively degrade different types of PPCPs,and the removal rate was more than90%,suggesting the stability and universality of this system.Eight degradation products were detected in Fe（Ⅲ）-NTA/HAm/PDS system during the degradation of SMX,and three degradation pathways were proposed,including hydroxylation,amino oxidation and bond breaking.（3）A new kind of green,economical and efficient heterogeneous material SA-Fe（Ⅲ）was prepared to replace NTA in order to reduce COD from the source and further recycle Fe（Ⅲ）.The basic morphologic structure of SA-Fe（Ⅲ）,the degradation mechanism and influencing factors of SA-Fe（Ⅲ）/HAm/PDS system on OG were studied,the degradation efficiency of three types of PPCPs and the degradation of SMX in actual water bodies were investigated preliminarily.The results showed that SA-Fe（Ⅲ）is a kind of stable material with uniform distribution of Fe（Ⅲ）,good cycling ability,and less Fe（Ⅲ）dissolution after reaction.SA-Fe（Ⅲ）/HAm/PDS system could degrade OG effectively under neutral conditions,and 96.24%OG was degraded in 20 min.The degradation efficiency of SA-Fe（Ⅲ）/HAm/PDS system was higher than that of Fe（Ⅲ）-NTA/HAm/PDS system using less dose of reagent within the same time.The main active species in the system were HO^·and SO₄^·-,which mainly attacked azo bonds and naphthalene rings in OG molecular structure.The degradation reaction could be promoted by increasing the reagents dose and temperature,while the degradation could be inhibited by excessive dose of reagents.Cu（Ⅱ）and Cl^-could promote the removal of pollutants,while Co（Ⅱ）had no effect on the reaction.HCO₃^-and NOM could inhibit OG degradation.The system could effectively degrade different types of PPCPs,suggesting its stability and universality.The degradation of SMX was inhibited in actual waters,therefore,the operational parameters should be adjusted in practical applications.In conclusion,Fe（Ⅲ）-NTA/HAm/H₂O₂,Fe（Ⅲ）-NTA/HAm/PDS and SA-Fe（Ⅲ）/HAm/PDS can effectively remove OG and SMX from water.NTA and SA can effectively complex Fe（Ⅲ）to broaden the p H reaction range.HAm plays a role of reducing agent in promoting the effective circulation of Fe（Ⅲ）/Fe（Ⅱ）in the system to reduce the addition of Fe（Ⅲ）and improve the utilization rate of Fe（Ⅲ）.