Optimized preparation of Ni-Fe bimetallic particles by ball milling NiSO and iron powder for efficient removal of triclosan.

The excessive usage and emissions of triclosan (TCS) pose a serious threat to aquatic environments. Iron-based bimetallic particles (Pd/Fe, Ni/Fe, and Cu/Fe, etc.) were widely used for the degradation of chlorophenol pollutants. This study proposed a novel synthesis method for the preparation of Ni/Fe bimetallic particles (Ni-Fe) by ball milling microscale zero valent iron ZVI (mZVI) and NiSO. Ball-milling conditions such as ball-milling time, ball-milling speed and ball-to-powder ratio were optimized to prepare high activity Ni-Fe bimetallic particles. During the ball-milling process, Ni was reduced to Ni and formed a coupled structure with ZVI. The amount of Ni on ZVI significantly affected the activity of Ni-Fe bimetallic particles. The highest activity Ni-Fe bimetallic particles with Ni/Fe ratio of 0.03 were synthesized under optimized conditions, which could remove 86.56% of TCS (10 μM) in aerobic aqueous solution within 60 min. In addition, higher particle dosage, lower pH condition and higher reaction temperature were more conducive for TCS degradation. The higher corrosion current and lower electron transfer impedance of Ni-Fe bimetallic particles were the main reasons for its high activity. The hydrogen atom (•H) on the surface of Ni-Fe bimetallic particles was mainly contributed to the removal of TCS, as reductive transformation products of TCS were detected by LC-TOF-MS. Notably, a small amount of oxidation products were discovered. The total dechlorination rate of TCS was calculated to be 39.67%. After eight reaction cycles, the residual Ni-Fe bimetallic particles could still degrade 28.34% of TCS within 6 h. Low Ni leaching during reaction indicated that Ni-Fe bimetallic particles did not pose potential environmental risks. The prepared environmental-friendly Ni-Fe bimetallic particles with high activity have great potential in the degradation of other chlorinated organic compounds in wastewater.