Reserch On The Effect And Mechanism Of Degradation Of Phenol By CuCo@MgAl Hydrotalcites-based Catalysis Of PS

Removal of organic contaminants is one of the major objectives in the remediation of water resource. Persulfate?PS?-based advanced oxidation processes?AOPs? have attracted considerable attentions since AOPs can degrade organic contaminants quickly and effectively, and only simple equipments are required in the process. However, huge consumption of energy in heat activation, corrosive issues in alkali activation, and leeching of the transition metal ions in homogenous catalytic activation are still challenging in this process. Thus, employing a effective and stable heterogeneous catalyst is attempted in this study. Layered Double Hydroxide?LDH? was chosen as the support onto which copper and cobalt oxides are introduced as the heterogeneous catalyst,forming PS/CuCo@MgAl-LDH system for the treatment of phenol-contaminated wastewater. The highly catalytic activity of CuCo@MgAl-LDH leads to good performance of degradation of organic pollutants without heating, while leaching of ions is significantly reduced to avoid secondary pollution. The main contents and results are as follows:?1? CuCo@MgAl-LDH has the typical charactor of MgAl-LDH hydrotalcite-like structure, and shows large surface area and crystal integrity, which was indicated by BET, XRD, FT-IR, SEM.?2? The influence of different temperatures?10 ? ⁴0 ?? on the degradation of phenol was studied, and the results showed that the degradation of phenol by persulfate increased along with the raise of temperature. The degradation kinetic fits the first-order model with lnk= ? 7981.1/T+24.086, R2=0.96, and the activation energy of phenol oxidation was calculated to be Ea=66.35KJ/mol.?3? The influence of pH0 on the degradation of phenol was studied. Results revealed that the performance of PS/CuCo@MgAl-LDH is well maintained in a wide pH window?3-12? for the degradation of phenol. Meanwhile the influence of humic acid, Cl^-, Br^-,NO₃^-, CH₃COO^-, SO₄^2-, CO₃^2-, HCO₃^-, HPO₄^2- and other anions on the degradation of phenol by PS/CuCo@MgAl-LDH were also studied. Humic acid and various anions inhibit the degradation of phenol, and related inhibition from weak to strong can be listed as: Cl^- <Br^- < NO₃^- < CH₃COO^- < SO₄^2- < CO₃^2- < HCO₃^- < HPO₄^2-, halogen ions have almost no effect on the degradation of phenol.?4? Analyzed by Roman, ATR-FTIR, XPS, EPR, radical scavenger experiments and fluorescence study, the active radicals in the AOPs are identified as: in the condition of pH=5, SO₄·^- is the domain radical, in the case of pH=7, SO₄·^-, ·OH and O₂·^- are the domain radicals, while pH=10, ·OH and O₂·^- are the domain radicals in the PS/CuCo@MgAl-LDH system.