Volatile organic compounds (VOCs) are atmospheric pollutants that have been of concern for researchers in recent years because they are toxic, difficult to remove, and widely sourced and easily cause damage to the environment and human body. Most scholars use low-temperature plasma biological treatment, catalytic oxidation, adsorption, condensation, and recovery techniques to treat then effectively. Among them, catalytic oxidation technology has the advantages of a high catalytic efficiency, low energy consumption, high safety factor, high treatment efficiency, and less secondary pollution; it is currently widely used for VOC degradation technology. In this paper, the catalytic oxidation technology for the degradation of multiple types of VOCs as well as the development of a single metal oxide catalyst have been briefly introduced. We also focus on the research progress of composite metal oxide catalysts for the removal of VOCs by comparing and analyzing the metal component ratio, preparation method, and types of precursors and the catalysts' influence on the catalytic performance. In addition, the reason for catalyst deactivation and a correlation between the chemical state of the catalyst and the electron distribution are discussed. Development of a composite metal oxide catalyst for the catalytic oxidation of VOCs has been proposed.

Research Progress of a Composite Metal Oxide Catalyst for VOC Degradation.

The performances of two hybrid wastewater treatment methods were compared to determine which method is more effective for improving the reusability of textile industry wastewater as irrigation water. In the hybrid treatment processes, either adsorption or catalytic wet air oxidation (CWAO) was performed subsequent to the electrocoagulation. The performances of the adsorption and catalytic wet air oxidation methods were evaluated according to the irrigation water criteria. Rice husk based activated carbon (RHAC) was used as adsorbent and catalyst support material in the adsorption and CWAO, respectively. BiNiO3-RHAC catalyst was prepared and used in CWAO process. The irrigation water criteria for total organic carbon (TOC), turbidity, and color were met and 91 % TOC reduction was achieved after the sequential application of electrocoagulation and adsorption. Freundlich isotherm and second order adsorption kinetics were regarded as the most suitable models to fit the adsorption data. The application of electrocoagulation and catalytic wet air oxidation yielded 62 % TOC removal whereas the oxidation reaction followed a two-step second order reaction kinetics.

Performance investigation of the hybrid methods of adsorption or catalytic wet air oxidation subsequent to electrocoagulation in treatment of real textile wastewater and kinetic modelling

Oxidative degradation of acid red 73 in aqueous solution over a three-dimensional OMS-2 nanomaterial

Oxygen vacancy defect (OVD) as one of the crystal defects is critical to the reactivity of heterogeneous catalyst surface for catalytic NO reduction with NH₃ (NH₃-SCR). Here, we propose a simple and feasible method to enhance OVDs through Ce doping manganese oxide octahedral molecular sieves (Ce-K-OMS-2), where it was proven that Ce mainly enters the framework structure of K-OMS-2. The robust NH₃-SCR catalytic test showed that the presence of Ce could lower the catalytic temperature and activity for NO conversion (∼100%) across a wide temperature span of 140–230 °C. The characterization results indicated the distortion of octahedral units after Ce substitution and the subsequent introduction of OVDs. Moreover, we demonstrated by density functional theory (DFT + U) calculations that the unique nanostructure of Ce doping K-OMS-2 with OVDs in the framework can alter the local bond lengths and the density of states, thereby obviously accelerating the low-temperature NH₃-SCR. NH₃ prefers to be adsorbed at the Ce site of Ce-K-OMS-2, while NO is much more likely to adsorb on the O site of Ce-K-OMS-2, following the Langmuir–Hinshelwood mechanism.

Insight into Low-Temperature Catalytic NO Reduction with NH₃ on Ce-Doped Manganese Oxide Octahedral Molecular Sieves

Evaluation of degradation and mineralization of glyphosate pollutant in wastewater using catalytic wet air oxidation over Fe-dispersed carbon nanofibrous beads

A series of MnCeOx catalysts for the catalytic wet air oxidation (CWAO) of phenol is developed by a redox-precipitation preparation method. Among them, Mn9Ce1Ox (Mn/Ce = 9:1) shows excellent activity and stability which can achieve TOC conversion of 88.1 % in 60 min at 70 °C and retain stable for five consecutive runs. Even at 50 °C, Mn9Ce1Ox can reach a phenol conversion of 84. 2% and a TOC conversion of 73.8 %. The roles of Mn valence state and Ce modification in the catalytic performance of Mn9Ce1Ox are extensively investigated by XRD, BET, Raman, H2-TPR and XPS. It is found that high Mn4+ concentration favors phenol adsorption and oxidation while high Mn3+ concentration favors oxygen activation. Ce optimizes the Mn4+/Mn3+ ratio and thus enhances catalytic activity. Additionally, Ce retains the structure of the catalyst and prevents Mn4+ and Mn3+ from being reduced to Mn2+, which contributes the good stability.

Synergistic effect between Mn and Ce for active and stable catalytic wet air oxidation of phenol over MnCeOx

Tissue engineering using adipose-derived mesenchymal stem cells (ADSCs) promotes the regeneration of articular cartilage. However, insulin-like growth factor 1 (IGF-1), which is used to induce the differentiation of ADSCs into chondrocytes during treatment, is prone to instability and short tissue retention. Nap-FFG-GYGSSSRRAPQT was used as an IGF-1 mimicking molecule. MTT and CCK-8 assays were performed to evaluate the proliferation ability of ADSCs. QRT-PCR and Western blot assays were used to assess the expression of cartilage-related genes. International Cartilage Regeneration and Joint Preservation Society (ICRS) scoring was used for the evaluation of cartilage repair. Repaired tissues were analyzed by hematoxylin-eosin, Safranin-O and immunohistochemical staining. Nap-FFG-GYGSSRRAPQT stimulated the proliferation and migration of ADSCs through the activation of IGF-1 receptor. Gel Nap-FFG-GYGSSRRAPQT treatment upregulated the expression of cartilage-related genes in ADSCs. ADSCs/Gel Nap-FFG-GYGSSRRAPQT treatment significantly promoted the regeneration of cartilages. Self-assembled IGF-1 peptide, Nap-FFG-GYGSSRRAPQT, can induce ADSC differentiation and proliferation to repair cartilage injury. 

Self-assembled insulin-like growth factor 1 peptides induce adipose stem cell differentiation to repair cartilage injury.

The invention provides a catalytic wet-type oxidation catalyst, and relates to the field of catalysts. The oxidation catalyst comprises an active component and a carrier, wherein the active componentcomprises Au and a modified metal; the modified metal is one or more of Ru, Rh, Pd, Pt, Fe, Co, Ni and Cu; the mass ratio of Au in the active component to the carrier is (0.01-5.0):(85-100); and the mass ratio of the modified metal in the active component to the carrier is (0.05-10.0):(85-100). The catalytic wet-type oxidation catalyst provided by the invention is used for performing catalytic wetoxidation bio-safety treatment on wastewater, the catalyst has good anti-leakage performance and can simultaneously remove ammonia nitrogen and organic pollutants in the wastewater, and the conversion rate of ammonia nitrogen in the wastewater is greater than 84.3%, and the removal rate of COD is greater than 85.9%.

Jihao Yang

Papers

Synergistic effect between Mn and Ce for active and stable catalytic wet air oxidation of phenol over MnCeOx

Self-assembled insulin-like growth factor 1 peptides induce adipose stem cell differentiation to repair cartilage injury.

Catalytic wet-type oxidation catalyst as well as preparation method and application thereof