Preparation of bead-type NiO x (OH) y catalyst for hypochlorite conversion and reactive brilliant red K-2BP degradation

In order to develop a low-cost NaClO/NiO x (OH) y process instead of Fenton method for treating refractory wastewater, a convenient bead-type hypochlorite conversion NiO x (OH) y catalyst was prepared by simply impregnating Ni-precursor over alumina and then oxidizing with persulfate (PS) in strong alkali solution. The influence of catalyst preparation conditions on the synthesis of NiO x (OH) y was studied. A series of batch experiments were carried out to verify the effective conversion of NaClO and investigate the influence of different parameters. Orthogonal test showed that Ni 2+ concentration had the greatest effect on the catalyst performance, while PS dosage had the least effect. The best combination of catalyst preparation parameters is impregnation of the γ-Al 2 O 3 beads in 1.5 M Ni 2+ solution followed by oxidation in a mixture of 5 % PS and 1.94 % NaOH. The best catalyst sample was characterized by XRD, SEM and FTIR. XPS tests showed that the oxygen content in the catalytic layer increased with the Ni 2+ solution concentration, and the oxygen content in the catalytic layer with the best performance reached 90.22 %. S BET of the samples is 283−292 m 2  g −1 ; Ni(OH) 2 accounted for ∼2/3 of the nickel content and NiOOH accounted for ∼1/3. The catalyst significantly improved COD and color removal rate of reactive brilliant red (RBR) K-2BP with low operation cost. The scavenger furfuryl alcohol proves the important role of atomic oxygen in decolorization of RBR K-2BP by NaClO/NiO x (OH) y system. During the reuse of the catalyst, the catalytic performance did not decline. The prepared catalyst has great potential in wastewater treatment.