Degradation Of Tetracycline By Fe/Ni Bimetallic Nanoparticles And The Physicochemical Transformation Of Nanoparticles In Aqueous Environment

Nanoparticles,especially nanoscale zero-valent iron?NZVI?,had drawn much attention in in-situ remediation of underground water for its high reactivity and decontamination capacity.However,NZVI tend to be deactivated,leading to the reducing of reactivity.To solve the problem,Fe/Ni bimetallic nanoparticles?Fe/Ni BNPs?were used to remove contaminant.The adding of Ni could reduce the reaction activation energy and accelerate the producing of hydrogen.And then the removal rate of Fe/Ni BNPs to TC was enhanced.In this paper,tetracycline?TC?was chosen as the target canmaminnat.The main contents of the paper include the following two parts:1.Removal of tetracycline by Fe/Ni bimetallic nanoparticles?Fe/Ni BNPs?in aqueous solution.The comparison of NZVI and Fe/Ni BNPs for the removal of TC confirmed that Fe/Ni BNPs are indeed having better performance than NZVI.The removal rate of TC by Fe/Ni BNPs decreased with the rising of pH and the initial concentration of TC.Four typical anions(NO₃^-,H₂PO₄^-,SO₄^2-and HCO₃^-)exhibited varying degree of inhibitory effect.NO₃^–had the maximal effect and HCO₃^-had the least influence.According to the analysis of degradation products,we affirmed that TC was not only removed by adsorption but also removed by degradation.The main transformation products resulted from hydrogenation,dehydration,loss of some groups and cleavage of carboatomic and benzene rings of TC.2.Physicochemical transformation of Fe/Ni BNPs during aging in simulated groundwater and the consequent effect on contaminant removal.In the short time aging process?within 5 d?,pH,ORP and the concentration of total concentration of soluble Fe in filtrate of aged samples were all increased sharply i n the first several hours and then keep stable in a value.The color of solution changed from black suspensions to green,indicating the corrosion reaction occurred during the short time aging.In the long time aging process?up to 90 d?,the shape of Fe/Ni BNPs transformed from spherical to rod-like,sheet-like,flaky-like and needle-like.The XRD revealed that Fe/Ni BNPs were completely transformed to magnetite?Fe₃O₄?and/or maghemite??-Fe₂O₃?.The analysis of EDS manifested that the transformation of Fe occurred throughout the aging time.Most of Ni was capsuled by iron oxide instead of leaching out to external environment during the aging time.Thus,Fe/Ni BNPs couldn't cause secondary pollution and is a safe and efficient remediation material.