LAUSR

The degradation of nitro and azo compounds has attracted wide attention due to their high toxicity and stability in water. Here, we reported the fast degradation of nitro and azo compounds by the direct injection of high-concentration noble-metal ions (Au 3+ , Ag + , Pd 2+ , or Pt 4+ ) and discussed the degradation mechanism. The rate constants of the nitro and azo compounds degradation followed the order: K 4-NP > K 2-NP > K 3-NP > K 2-NR > K MR > K MO , explained by the substituent effect. The maximum of the degradation rate constant could reach up to 16 min −1 , which can be attributed to the atom-nano catalysis motivated by the direct injection of high-concentration ions. Furthermore, based on the method, the highlighted conflicts shown in the nitro and azo compounds degradation could be resolved. Meanwhile, the recovery method (centrifugation, dissolution, and purification) of noble-metal ions was proposed by means of various characterization techniques, and then noble-metal ions were recovered and recycled for five cycles. Obviously, the above degradation technology can have great potential for applications in water pollutant removal and environmental remediation.