Application of heat-activated peroxydisulfate process for the chemical cleaning of fouled ultrafiltration membranes

Na Cl O has been widely used to restore membrane flux in practical membrane cleaning processes,which would induce the formation of toxic halogenated byproducts.In this study,we proposed a novel heatactivated peroxydisulfate(heat/PDS)process to clean the membrane fouling derived from humic acid(HA).The results show that the combination of heat and PDS can achieve almost 100%recovery of permeate flux after soaking the HA-fouled membrane in 1 mmol/L PDS solution at 50℃ for 2 h,which is attributed to the changes of HA structure and enhanced detachment of foulants from membranes.The properties of different treated membranes are characterized by scanning electron microscopy(SEM),atomic force microscope(AFM),attenuated total reflection Fourier transform infrared spectroscopy(ATRFTIR),and X-ray photoelectron spectroscopy(XPS),demonstrating that the reversible and irreversible foulants could be effectively removed by heat/PDS cleaning.The filtration process and fouling mechanism of the cleaned membrane were close to that of the virgin membrane,illustrating the good reusability of the cleaned membrane.Additionally,heat/PDS which can avoid the generation of halogenated byproducts shows comparable performance to Na Cl O on membrane cleaning and high performance for the removal of fouling caused by sodium alginate(SA),HA-bovine serum albumin(BSA)-SA mixture and algae,further suggesting that heat/PDS would be a potential alternative for membrane cleaning in practical application.

Activation of sulfite by ferric ion for the degradation of 2,4,6-tribromophenol with the addition of sulfite in batches

In this work,the removal of 2,4,6-tribromophenol(TBP)by ferric ion-activated sulfite[Fe(Ⅲ)/S(Ⅳ)]process was systematically investigated with determining the intermediate products and evaluating the influences of some operational conditions and water matrices.Our results show that batching addition of S(Ⅳ)benefits the S(Ⅳ)utilization efficiency and TBP removal,with SO_(4)^(-)being the primary reactive radical accounting for TBA degradation.The maximum TBP removal in the Fe(Ⅲ)/S(Ⅳ)process was observed at pH 4.0 and oxygen is essential in this process.With increasing Fe(Ⅲ)and S(Ⅳ)dosages from 0.05 and 0.1 mmol/L to 0.2 and 2.0 mmol/L,respectively,TBP removal followed trends of first increase then decrease.As the acute toxicity of the TBP solution was significantly reduced,the Fe(Ⅲ)/S(Ⅳ)process was believed to be a good choice in the treatment of TBP.