The Study On The Degradation Of Salicylichydroxamic Acid By Fe(?)-Carboxylate Under Ultraviolet Light

In the mining and production of non-ferrous metal mineral resources,various flotation reagents are widely used.Salicylichydroxamic acid(SHAM),as a new type of chelating collector,is widely used in the mining process of tin ore,iron ore and rare earth minerals.The heavy metal ions in mine wastewater are difficult to remove,and the addition of collectors causes the compound pollution of heavy metal ions and organics in mine wastewater to become more severe.This study takes SHAM as the target pollutant,and simulates the use of Fe³⁺that is abundant in mine wastewater to form a stable Fe(?)-SHAM chelate.Then,adding oxalic acid(Oxa)and citric acid(Cit)to the solution can reduce the Fe³⁺in the chelate.It is separated to form Fe(?)-carboxylate complex,which forms a photo-Fenton reaction through the LMCT mechanism under ultraviolet light irradiation,and finally degrades SHAM.This paper discusses the effects of different Fe³⁺and carboxylate concentrations,different initial pH of the solution,different ratios of Fe³⁺/Oxa(Cit),and different anion concentrations on the photodegradation of SHAM.It simulates and analyzes the existence of Fe³⁺under different conditions.The degradation mechanism and path were studied.The main research conclusions are as follows:The degradation of SHAM in the UV-Fe(?)-carboxylate system conforms to the pseudo first-order kinetic model.The results show that SHAM can be degraded by 19.5%after 60 min of UV irradiation.Appropriately increasing the concentration of Fe³⁺and carboxylate can increase the degradation rate of SHAM.In the exploration experiment with different ratios of Fe³⁺/Oxa(Cit),when Fe³⁺/Oxa(Cit)=1:15,the degradation rate of SHAM is the highest,the degradation rates are92.7%and 89.3%respectively.In the mixed system where Oxa and Cit are added at the same time,Fe³⁺/Oxa/Cit=1:5:5 is the best condition,and the degradation rate is 95.9%.The Fe³⁺concentration under the three best systems is the same,all 0.2 m M.In the exploration experiment of the initial pH of different solutions,under the Fe(?)-Oxa system,the best initial pH=4.In the Fe(?)-Cit system,the best initial pH=5.and under the Fe(?)-Oxa-Cit system,the best initial pH=4.SO₄^2-shows a greater promotion effect on the photodegradation of SHAM.HCO₃^-,NO₃^-,and Cl^-all show an inhibitory effect.In the experiments of tap water and actual mine water samples,the degradation of SHAM was affected by anions and organic matter,showing a slight inhibitory effect,and its degradation rate was reduced by 1.8%and 5.8%respectively compared with the ultrapure water system.but compared with UV irradiation,it increased by 74.6%and 70.6%respectively.The degradation of SHAM detected 6 intermediate products.In summary,UV-Fe(?)-carboxylate system degrades the chelating collector SHAM is highly effective and feasible,among which Fe³⁺and Oxa(Cit)are cheap and easy to obtain.At the same time,it provides a theoretical basis for the treatment of mine organic wastewater,and has broad prospects in mine wastewater treatment.