The development of a novel iron-microorganism composite adsorbent and its removal of tris(2-chloroethyl)phosphate: Preparation, performance and mechanism

Tris (2-chloroethyl) phosphate (TCEP) was one of widely used chlorinated organophosphate flame retardants (Cl-OPFRs) in the industrial production, had received increasing attention for its potential bio-toxicity and widespread in environment. In this study, a novel iron-microorganism composite biosorbent (Z/ZVI-N 1 ) was synthesized by zeolites/zero-valent iron and Novosphingobium tardaugens (N 1 ) for TCEP removal . That the process could be fitted to the pseudo-first order equation and Freundlich model, which meant it was a multilayer heterogeneous physisorption process, while chemisorption was also present. Besides, the optimal operating conditions for Z/ZVI-N 1 were 30 ℃ and pH 7. The results of FTIR, XPS and XRD analysis showed that there were some functional groups of alcohols and FeO(OH) on Z/ZVI-N 1 and the charge of iron ions changed as reaction proceed, all of which proved that Z/ZVI-N 1 participated the degradation of TCEP. The degradation products analysis further confirmed that TCEP was really degraded through two pathways. First was the reduction reaction, which the C Cl bond of TCEP broke down by Z/ZVI, and finally generated the triethyl phosphate (TEP). The second was bio-hydrolysis by Novosphingobium tardaugens , which made the O P bond of TCEP to be fractured, and monochloroethyl phosphate (MCEP) was generated. • The removal ability of the new composite biosorbent (Z/ZVI-N 1 ) for TCEP was proved. • Z/ZVI-N 1 was synthesized by zeolites/zero-valent iron and Novosphingobium tardaugens . • The Z/ZVI-N 1 not only could adsorb TCEP, but also decompose it. • The adsorption of TCEP on Z/ZVI-N 1 were multi-layer physical and chemical adsorption. • The removal of TCEP by Z/ZVI-N 1 through synergistic REDOX and bio-hydrolysis.