Photodegradation Of HBCD By Fe(â…¢)-Carboxylate Complex In Aqueous Solutions

HBCD is the third most widely used brominated flame retardants, it belongs to thepersistent organic pollutants, it has harmful effects such as bioaccumulation, neurotoxic,and genotoxic on organisms, it’s a threat to human health and safety. Many researches hasproved HBCD is widely present in the soil, water, air, animals, and the human body, theexistence of HBCD in water has great biological impact, therefore, the control andremoval of residual HBCD in water environment is of great significance, but the watertreatment and sewage treatment process cannot effectively remove HBCD, so researchingthe HBCD effective biodegradation in water environment at this stage is an importantdirection. Further more, Fe(Ⅲ), oxalate, citrate, and other substances are widelydistributed in nature, researches indicates that the Fe(Ⅲ)-carboxylate complex system playan important role on the photodegradation of organic pollutants.In this paper, degradating of Hexabromocyclododecane is in Fe(Ⅲ)-carboxylatecomplex system under simulated sunlight, and exploring the optimal process conditionsand its photocatalytic mechanism to provide an energy-efficient method for HBCDwastewater. The main contents and results of the experimental study are as follows:The photodegradation of HBCD in the Fe(Ⅲ)-carboxylate complex system,exploring the effects of the ratio of Fe (Ⅲ)-carboxylalt, pH, and other factors in thedegradation system, and the optical degradation mechanism of HBCD. Results suggested:(1) The photodegradation efficiency decreased with increasing pH at fixed Fe(Ⅲ)-ox ratioand follow the order of pH7.05.03.0; the photodegradation efficiency changed withvariable pH at fixed Fe(Ⅲ)-citrate ratio and follow the order of pH3.07.05.0,Fe(Ⅲ)-citrate system has a preferably degradation effect of HBCD in the nearly neutralcondition.(2) with the increase of the carboxylic acid, HBCD degradation enhanced in thefixed pH and Fe(Ⅲ).(3) OH is the main factor of the HBCD photodegradation in theFe(Ⅲ)-carboxylate complex system, and in the Fe(Ⅲ)-cit system, there’s other factors acton the degradation, the O2has little impact on it. Degradation of HBCD in the Fe(Ⅲ)-citrate/H2O2complexes system under simulatedsunlight research suggests:(1) The HBCD degradation rate of three degradation systemare of as follows: Fe(Ⅲ)-citrate <Fe(Ⅲ)/H2O2system <Fe(Ⅲ)-citrate/H2O2system, theaddition of H2O2on the Fe(Ⅲ)-citrate system plays an significant role in promotingdegradation of HBCD, and adding citrate in the Fenton system will also greatly promotethe degradation of HBCD.(2) At the fixed pH, H2O2and Fe(Ⅲ) concentration, with theincrease of citric, HBCD degradation efficiency is enhanced.(3) Adding H2O2inFe(Ⅲ)-citrate system can increased the reaction rate, but a high concentration of H2O2canreduce the efficiency of HBCD degradation.(4) The degradation trend of HBCD is pH3.57.05.0with the change of pH in a fixed Fe (Ⅲ)-citrate/H2O2ratio, it has a preferablydegradation effect of HBCD in the nearly neutral condition.(5) OH is the main factor ofthe HBCD photodegradation in the Fe(Ⅲ)-cit/H2O2system, but not the only one, and theO2has little impact on it.This study shows that the Fe(Ⅲ)-carboxylate system and the Fe(Ⅲ)-citrate/H2O2system has a good degradation rate in the HBCD-containing wastewater treatment, it haspractical significance for the HBCD-containing wastewater treatment.