A Study On The Degradation Of Trichloroethylene In Groundwater Using Carboxymethyl Cellulose Stabilized Sufidated Nanoscale Fe/Ni

Groundwater remediation has always been a hot topic in the field of environmental geochemistry,Nano zero-valent iron technology is one of the frontier technologies in the field of groundwater in-situ remediation.In this paper,sulfidated nano zero-valent iron(S-Fe)and its modified materials were used to degrade trichloroethylene(TCE)in groundwater,in order to explore the remediation effect and mechanism of sulfidated nano zero-valent iron on TCE degradation,and the influence of common coexisting metal ions in groundwater on TCE degradation activity by sulfidated nano zero-valent iron.The results show that the degradation rate of TCE by S-Fe/Ni is 1.6～3.7 times higher than that by S-Fe,when the dosage of S-Fe/Ni and S-Fe was 1g/L,94.4%TCE could be degraded by S-Fe/Ni within 3.5 hours,while the removal rate of TCE by S-Fe was only 53.6%,due to the catalytic effect of noble metal Ni,which can accelerate the hydrodechlorination process of TCE and accelerate the electron transfer.In order to improve the migration ability of S-Fe and S-Fe/Ni,carboxymethyl cellulose(CMC)was used as a stabilizer to coat sulfidated nano zero-valent iron materials,and the coated materials CMC@S-Fe、CMC@S-Fe/Ni were explored the degradation ability of TCE.The results show that the coating of CMC can slightly inhibit the degradation efficiency of TCE by S-Fe and S-Fe/Ni,but even if CMC reaches 1gc/L,the ratio of CMC to Fe is 1:1,the removal rate of TCE by CMC@S-Fe can still reach 87.11%within 16 hours.Therefore,CMC modified sulfidated nano zero-valent iron is a kind of groundwater in-situ material with good mobility and reactivity.In the actual groundwater pollution,many kinds of pollution often exist together,so this paper explores the influence of common coexisting metal ions on TCE degradation by sulfidated nano zero-valent iron.The results showed that Ni(Ⅱ)promoted the degradation of TCE by S-Fe,Cu(Ⅱ),Cr(Ⅵ)and CD(Ⅱ)could inhibit the degradation of TCE to a certain extent,and the inhibition was stronger with the increase of ion concentration.Among them,Cd(Ⅱ)has the most obvious inhibitory effect on the degradation of TCE by S-Fe,which is due to the substitution reaction between Cd(Ⅱ)and FeS to form stable CdS on the surface of S-Fe,thus slowing down the electron transfer rate.