A facile method for the highly efficient hydrodechlorination of 2-chlorophenol using Al–Ni alloy in the presence of fluorine ion

An integrated low-cost alloy and corrosive anion system was attempted to perform aqueous hydrodechlorination (HDC) of biorefractory chlorinated organics. Several influencing factors were investigated for HDC of 2-chlorophenol (2-CP) including anion species, alloy categories, and their dosages. Al–Ni alloy presented the remarkably highest reactivity to remove 2-CP under the action of aqueous fluorine ion (F−) compared with other anions and alloys used in this study. Increasing Al–Ni alloy dosage or initial concentration of F− could enhance of 2-CP HDC efficiency. The optimized results showed that 0.389 mM of 2-CP in solution could be completely dechlorinated into phenol using 10 g L−1 of Al–Ni alloy and 39.7 mM initial concentration of F− within 120-min reaction. The used Al–Ni alloy after each HDC reaction could almost be reactivated to the original activity level of raw Al–Ni alloy for HDC after Ca(OH)2 treatment to remove the adsorbed species such as AlF3 on alloy surface during three cycle reaction. Moreover, after Ca(OH)2 activation, F− in the effluent solution could also be effectively removed to under 0.8 mg L−1 due to the formation of insoluble CaF2. The maintenance and regeneration of Al–Ni alloy activity for HDC was mainly attributed to the effects of Ca(OH)2 activation to remove adsorbed species on Al–Ni surface, inherent structure of alloy with Ni droplets homogeneously dispersed into Al substrate, and the change of its surface morphology with more active sites produced by F− corrosion.

► 2-Chlorophenol was effectively dechlorinated with an Al–Ni alloy and F− system.
► The reaction mechanism relied on corrosion effect of F− on Al–Ni alloy surface.
► Inherent structure of Al–Ni alloy ensured its sustained dechlorination activity.
► The regeneration of Al–Ni activity was attributed to Ca(OH)2 activation effect.
► The remained aqueous F− was effectively removed with the Ca(OH)2 activation.