| As the largest production and usage of brominated fla me retardants (BFRs),tetrabromobisphe no l A (TBBPA) have been ma inly used as important add itive fla meretardants, which have been directly pla yed an role of flame retardants in ABS plasticthat to delay or to prevent the burning. During the productio n, usage and d isposalprocess products conta ining TBBPA, a certain amo unt o f TBBPA and its metabolitesmay inevitab ly re lease to the environme nt through various means.Nanoscale iron is a superfineness iron powder materia l with partic le size of1to100nm. With s ma ll partic le size, specific surface area, high reactivity as well asenvironme nt-friend ly features, NZVI materials showed an obvio us advantage andutilization potentia lity in the degradation of persiste nt organic polluta nts. While theagglo meratio n and oxidation of the nanoscale iron is ofte n unavo idable due to thesma ll particle size, it is necessary to study the dispersion and stability of nanoscaleiron. In this paper, montmorillonite was used as a porous-based support materia l forsynthes ized nanoscale iron. In order to overcome the adverse hydrophiliccharacteristics of montmorillonite, Organo montmorillonite(CM T) prepared by io nexchange method can overcome the adverse hydrophilic characteristics ofmontmorillo nite and improve the processing capacity o n the adsorption o fhydrophobic organic compounds and also serve as nanoscale iron exce lle nt loadmed ia for synthes ized nanoscale iron(NZVI-CMT).In this e xperime nt, based on the remo va l capacity o f montmorillonite andnanoscale iron, characterizatio n and degradation, a adsorption reduction process wasemp loyed to re move TBBPA by synthetic materia ls which supported NZVI onorgano montmorillo nite(NZVI-CMT) through a series of tests inc lude synthes is.Besides, degradation byproducts and reactio n mecha nis ms was stud ied and analyzed.The results shown that, the remova l rate by NZVI-CMT reached97.5%in12hoursunder25℃, when the initia l concentratio n of TBBPA was10mg·L-1. And the remova lrate of NZVI-CMT was higher than the rate of two s imple materia ls, name ly organobentonite (CMT) and nanoscale zero va lent iron (NZVI), as well as the sum of thosetwo simple materia ls. In additio n, NZVI-CMT exhib ited a better reusable attribute,and the rate of the materia ls still exceeds90%after be ing used3times. Highertemperature fa vored the debrominatio n effic ient, while the tota l remo val rate washigher when te mperature was low. With the increase of TBBPA initia l concentration,the degradation rate decreased and the absolute a mount of degradation increased. Even the initia l concentration attained to15mg L-1, the remova l rate was still86.8%. Lower pH played a positive role in TBBPA debro mination steps and re mova leffic ie ncy as we ll. Based on the identification of degradation products and ana lyzingthe remova l of TBBPA by NZVI-CMT, the ma in reactio n mecha nis m was suggested asadsorption and debrominnatio n, and higher reaction temperature was bene fit todebrominnation. Reduction k inetics of TBBPA by NZVI-CMT was described by apseudo first-order reactio n. Comparing the TBBPA re move reactio n rate undercond itions o f d ifferent impact factor system, it turned out that the rate of reactio nincreased with increasing reactio n temperature and materia l dosage, and reduced withris ing TBBPA initial concentration and pH. |
