Various spinel-type catalysts AB2O4 (where A = Mg, Ca, Mn, Co, Ni, Cu, Cr, Fe, Zn and B = Cr, Fe, Co) were prepared and characterized by XRD, BET, TEM and FESEM-EDS. The performance of these catalysts towards the decomposition of N2O to N2 and O2 was evaluated in a temperature programmed reaction (TPR) apparatus in the absence and the presence of oxygen. Spinel-type oxides containing Co at the B site were found to provide the best activity. The half conversion temperature of nitrous oxide over the MgCo2O4 catalyst was 440 °C and 470 °C in the absence and presence of oxygen, respectively (GHSV = 80,000 h−1). On the grounds of temperature programmed oxygen desorption (TPD) analyses as well as of reactive runs, the prevalent activity of the MgCo2O4 catalyst could be explained by its higher concentration of suprafacial, weakly chemisorbed oxygen species, whose related vacancies contribute actively to nitrous oxide catalytic decomposition. This indicates the way for the development of new, more active catalysts, possibly capable of delivering at low temperatures amounts of these oxygen species even higher than those characteristic of MgCo2O4.

N2O catalytic decomposition over various spinel-type oxides

Novel micro-structured carbon-based adsorbents for notorious arsenic removal from wastewater

Recent Progress on Electrocoagulation Process for Wastewater Treatment: A Review

Electrocoagulation (EC) is one of the emerging technologies in groundwater and wastewater treatment as it combines the benefits of coagulation, sedimentation, flotation, and electrochemical oxidation processes. Extensive research efforts implementing EC technology have been executed over the last decade to treat chemical oxygen demand (COD)-rich industrial wastewaters with the aim to protect freshwater streams (e.g., rivers, lakes) from pollution. A comprehensive review of the available recent literature utilizing EC to treat wastewater with high COD levels is presented. In addition, recommendations are provided for future studies to improve the EC technology and broaden its range of application. This review paper introduces some technologies which are often adopted for industrial wastewater treatment. Then, the EC process is compared with those techniques as a treatment for COD-rich wastewater. The EC process is considered as the most privileged technology by different research groups owing to its ability to deal with abundant volumes of wastewater. After, the application of EC as a single and combined treatment for COD-rich wastewaters is thoroughly reviewed. Finally, this review attempts to highlight the potentials and limitations of EC. Related to the EC process in batch operation mode, the best operational conditions are found at 10 V and 60 min of voltage and reaction time, respectively. These last values guarantee high COD removal efficiencies of > 90%. This review also concludes that considerably large operation costs of the EC process appears to be the serious drawback and renders it as an unfeasible approach for handling of COD rich wastewaters. In the end, this review has attempted to highlights the potential and limitation of EC and suggests that vast notably research in the field of continuous flow EC system is essential to introduce this technology as a convincing wastewater technology.

A critical review of state-of-the-art electrocoagulation technique applied to COD-rich industrial wastewaters.

Removal of inorganic pollutants using electrocoagulation technology: A review of emerging applications and mechanisms

Electrocoagulation processes: A general review about role of electro-generated flocs in pollutant removal

Combined metal/air fuel cell and electrocoagulation process: Energy generation, flocs production and pollutant removal.

The invention discloses a method for treating wastewater by coupling an original battery and electric flocculation. The method comprises the following steps: conductivity of wastewater is adjusted, and the pH value is adjusted to 2-10 for carrying out a galvanic reaction; and when the pH value of the wastewater reaches 5-10, power is supplied by a primary battery for carrying out an electric flocculation reaction, wherein the ratio of the time for the electric flocculation reaction to the time for the galvanic reaction is 1:(1-8). According to the invention, the primary battery is coupled withthe electric flocculation, so that on one hand, a problem of filler hardening in an existing micro-electrolysis reaction is effectively avoided, and on the other hand, the galvanic reaction can generate Fe and Fe , rich metal cations are provided for the subsequent electric flocculation reaction, and the yield of floc is effectively improved with the combination of the electric flocculation reaction. In addition, the primary battery reacts to generate electric energy, high power density is output for the electric flocculation reaction, and electric energy loss is reduced.

Method for treating wastewater by coupling original battery and electric flocculation

The invention discloses a device and a method for repairing polluted soil. The device comprises an electric repairing device and an electric flocculation device, wherein the electric repairing devicecomprises an anode and a cathode; and the electric flocculation device is positioned between the anode and the cathode of the electric repairing device and is at the position 1/3-1/10 away from the cathode or anode of the electric repairing device. The method comprises the following steps: during the repairing process, arranging the electric repairing device and the electric flocculation device insoil, switching on the electric repairing device to carry out electric repairing for 0.5-20 days, and at 1/3-1/2 of the electric repairing time period, switching on the electric flocculation device for repairing simultaneously until the repairing is finished. The device is compact in structure and high in stability, avoids the problem that adsorption of an adsorbent is saturated, does not need tochange a permeation reaction wall, and avoids the problem that the pore passage of an adsorbing material is blocked and passivated; and in addition, during the repairing process, the capacity for removing heavy metal is high, and compared with the existing method, the heavy metal removing effect is improved by 20-30%, and the cost is saved by 35-50%.

Xu Qiuling

Papers

Electrocoagulation processes: A general review about role of electro-generated flocs in pollutant removal

Combined metal/air fuel cell and electrocoagulation process: Energy generation, flocs production and pollutant removal.

Method for treating wastewater by coupling original battery and electric flocculation

Device and method for repairing polluted soil