Jinping Jia

Catalytic Oxidation of Elemental Mercury over the Modified Catalyst Mn/α-Al2O3 at Lower Temperatures

In order to facilitate the removal of elemental mercury (Hg(0)) from coal-fired flue gas, catalytic oxidation of Hg(0) with manganese oxides supported on inert alumina (alpha-Al2O3) was investigated at lower temperatures (373-473 K). To improve the catalytic activity and the sulfur-tolerance of the catalysts at lower temperatures, several metal elements were employed as dopants to modify the catalyst of Mn/alpha-Al2O3. The best performance among the tested elements was achieved with molybdenum (Mo) as the dopant in the catalysts. It can work even better than the noble metal catalyst Pd/alpha-Al2O3. Additionally, the Mo doped catalyst displayed excellent sulfur-tolerance performance at lower temperatures, and the catalytic oxidation efficiency for Mo(0.03)-Mn/alpha-Al2O3 was over 95% in the presence of 500 ppm SO2 versus only about 48% for the unmodified catalyst. The apparent catalytic reaction rate constant increased by approximately 5.5 times at 423 K. In addition, the possible mechanisms involved in Hg(0) oxidation and the reaction with the Mo modified catalyst have been discussed.

Capture of gaseous elemental mercury from flue gas using a magnetic and sulfur poisoning resistant sorbent Mn/γ-Fe2O3 at lower temperatures

A series of Mn/γ-Fe(2)O(3) were synthesized to capture elemental mercury from the flue gas. Mn(4+) cations and cation vacancies on the surface played important roles on elemental mercury capture by Mn/γ-Fe(2)O(3). Furthermore, the reaction route of elemental mercury oxidization was dependent on the ratio of Mn(4+) cations to cation vacancies. As a result, the capacities of 15%-Mn/γ-Fe(2)O(3)-250 for elemental mercury capture were generally higher than those of 30%-Mn/γ-Fe(2)O(3)-400. SO(2) mainly reacted with ≡Fe(III)-OH and only a small amount of ≡Mn(4+) reacted with SO(2), so the presence of a high concentration of SO(2) resulted in an insignificant effect on elemental mercury capture by 15%-Mn/γ-Fe(2)O(3)-250 at lower temperatures. The capacities of 15%-Mn/γ-Fe(2)O(3)-250 for elemental mercury capture in the presence of 2.8 g N m(-3) of SO(2) were more than 2.2 mg g(-1) at <200°C. Meanwhile, 15%-Mn/γ-Fe(2)O(3)-250 can be separated from the fly ash using magnetic separation, leaving the fly ash essentially free of sorbent and adsorbed HgO. Therefore, 15% Mn/γ-Fe(2)O(3)-250 may be a promising sorbent for elemental mercury capture.

Degradation of dye solution by an activated carbon fiber electrode electrolysis system

Degradation of 29 dyes by means of an activated carbon fiber (ACF) electrode electrolysis system was performed successfully. Almost all dye solutions tested were decolorized effectively in this ACF electrolysis process. Internal relationships between treatment mechanisms and chemical composition of the dye have been discussed in this paper. Generally, it is shown that higher solubility leads to greater degradation in the process. Dyes with many -SO3-, COO-, -SO2NH2, -OH, hydrophilic groups, and azo linkages are susceptible to reduction. However, dyes with many -C=O, -NH-and aromatic groups, and hydrophobic groups, tend to be adsorbed. For dyes with -SO3-, COOH and -OH groups, if their molecules linearly spread in solution and have a significant tendency to form colloids by hydrogenous bonding, they also tend to be adsorbed and flocculated. Typical dynamic electrolysis of dye Acid Red B, Vat Blue BO and Disperse Red E-4B shows how the two major mechanisms, degradation and adsorption, act differently during treatment. Reduction occurs evenly during treatment. During the dominant adsorption process, after certain amount of iron is generated, colloid precipitation occurs and TOC and color are rapidly removed.

Photocatalytic Fuel Cell (PFC) and Dye Self-Photosensitization Photocatalytic Fuel Cell (DSPFC) with BiOCl/Ti Photoanode under UV and Visible Light Irradiation

A fuel cell that functioned as a photo fuel cell (PFC) when irradiated with UV light and as a dye self-photosensitization photo fuel cell (DSPFC) when irradiated with visible light was proposed and investigated in this study. The system included a BiOCl/Ti plate photoanode and a Pt cathode, and dye solutions were employed as fuel. Electricity was generated at the same time as the dyes were degraded. 26.2% and 24.4% Coulombic efficiency were obtained when 20 mL of 10 mg · L(-1) Rhodamine B solution was treated with UV for 2 h and visible light for 3 h, respectively. Irradiation with natural and artificial sunlight was also evaluated. UV and visible light could be utilized at the same time and the photogenerated current was observed. The mechanism of electricity generation in BiOCl/Ti PFC and DSPFC was studied through degradation of the colorless salicylic acid solution. Factors that affect the electricity generation and dye degradation performance, such as solution pH and cathode material, were also investigated and optimized.

Significance of RuO2 Modified SCR Catalyst for Elemental Mercury Oxidation in Coal-fired Flue Gas

Catalytic conversion of elemental mercury (Hg(0)) to its oxidized form has been considered as an effective way to enhance mercury removal from coal-fired power plants. In order to make good use of the existing selective catalytic reduction of NO(x) (SCR) catalysts as a cobenefit of Hg(0) conversion at lower level HCl in flue gas, various catalysts supported on titanium dioxide (TiO(2)) and commercial SCR catalysts were investigated at various cases. Among the tested catalysts, ruthenium oxides (RuO(2)) not only showed rather high catalytic activity on Hg(0) oxidation by itself, but also appeared to be well cooperative with the commercial SCR catalyst for Hg(0) conversion. In addition, the modified SCR catalyst with RuO(2) displayed an excellent tolerance to SO(2) and ammonia without any distinct negative effects on NO(x) reduction and SO(2) conversion. The demanded HCl concentration for Hg(0) oxidation can be reduced dramatically, and Hg(0) oxidation efficiency over RuO(2) doped SCR catalyst was over 90% even at about 5 ppm HCl in the simulated gases. Ru modified SCR catalyst shows a promising prospect for the cobenefit of mercury emission control.

Nanosized Cation-Deficient Fe-Ti Spinel: A Novel Magnetic Sorbent for Elemental Mercury Capture from Flue Gas

Nonstoichiometric Fe-Ti spinel (Fe(3-x)Ti(x))(1-δ)O(4) has a large amount of cation vacancies on the surface, which may provide active sites for pollutant adsorption. Meanwhile, its magnetic property makes it separable from the complex multiphase system for recycling, and for safe disposal of the adsorbed toxin. Therefore, (Fe(3-x)Ti(x))(1-δ)O(4) may be a promising sorbent in environmental applications. Herein, (Fe(3-x)Ti(x))(1-δ)O(4) is used as a magnetically separable sorbent for elemental mercury capture from the flue gas of coal-fired power plants. (Fe(2)Ti)(0.8)O(4) shows a moderate capacity (about 1.0 mg g(-1) at 250 °C) for elemental mercury capture in the presence of 1000 ppmv of SO(2). Meanwhile, the sorbent can be readily separated from the fly ash using magnetic separation, leaving the fly ash essentially free of sorbent and adsorbed mercury.

Treatment of mature landfill leachate by internal micro-electrolysis integrated with coagulation: A comparative study on a novel sequencing batch reactor based on zero valent iron

A comparative study of treating mature landfill leachate with various treatment processes was conducted to investigate whether the method of combined processes of internal micro-electrolysis (IME) without aeration and IME with full aeration in one reactor was an efficient treatment for mature landfill leachate. A specifically designed novel sequencing batch internal micro-electrolysis reactor (SIME) with the latest automation technology was employed in the experiment. Experimental data showed that combined processes obtained a high COD removal efficiency of 73.7 ± 1.3%, which was 15.2% and 24.8% higher than that of the IME with and without aeration, respectively. The SIME reactor also exhibited a COD removal efficiency of 86.1 ± 3.8% to mature landfill leachate in the continuous operation, which is much higher (p<0.05) than that of conventional treatments of electrolysis (22.8-47.0%), coagulation-sedimentation (18.5-22.2%), and the Fenton process (19.9-40.2%), respectively. The innovative concept behind this excellent performance is a combination effect of reductive and oxidative processes of the IME, and the integration electro-coagulation. Optimal operating parameters, including the initial pH, Fe/C mass ratio, air flow rate, and addition of H(2)O(2), were optimized. All results show that the SIME reactor is a promising and efficient technology in treating mature landfill leachate.

The performance of iodine on the removal of elemental mercury from the simulated coal-fired flue gas

In order to facilitate the removal of elemental mercury (Hg(0)) in flue gas, iodine was used as the oxidant to convert Hg(0) to the oxidized or particulate-bound form. The removal of Hg(0) by the homogenous gas phase reaction and the heterogeneous particle-involved reactions was investigated under various conditions, and a method to test the particle-involved reaction kinetics was developed. Iodine was found to be efficient in Hg(0) oxidation, with a 2nd-order rate constant of about 7.4(+/-0.2)x10(-17)cm(3)molecules(-1)s(-1) at 393 K. Nitric oxide showed significant inhibition in the homogenous gas reaction of Hg(0) oxidation. The oxidation of Hg(0) with iodine can be greatly accelerated in the presence of fly-ash or powder activated carbon. SO(2) slightly reduced Hg(0) removal efficiency in the particle-involved reaction. It was estimated that Hg(0) removal efficiency was as high as 70% by adding 0.3 ppmv iodine into the flue gas with 20 g/m(3) of fly-ash. In addition, the predicted removal efficiency of Hg(0) was as high as 90% if 10mg/m(3) of activated carbon and 0.3 ppmv iodine were injected into the flue gas with fly-ash. The results suggest that the combination of iodine with fly-ash and/or activated carbon can efficiently enhance the removal of Hg(0) in coal-fired flue gas.

Visible Light Assisted Heterogeneous Fenton-Like Degradation of Organic Pollutant via α-FeOOH/Mesoporous Carbon Composites

A novel α-FeOOH/mesoporous carbon (α-FeOOH/MesoC) composite prepared by in situ crystallization of adsorbed ferric ions within carboxyl functionalized mesoporous carbon was developed as a novel visible light assisted heterogeneous Fenton-like catalyst. The visible light active α-FeOOH nanocrystals were encapsulated in the mesoporous frameworks accompanying with surface attached large α-FeOOH microcrystals via C-O-Fe bonding. Assisting with visible light irradiation on α-FeOOH/MesoC, the mineralization efficiency increased owing to the photocatalytic promoted catalyzing H2O2 beyond the photothermal effect. The synergistic effect between α-FeOOH and MesoC in α-FeOOH/MesoC composite improved the mineralization efficiency than the mixture catalyst of α-FeOOH and MesoC. The iron leaching is greatly suppressed on the α-FeOOH/MesoC composite. Interestingly, the reused α-FeOOH/MesoC composites showed much higher phenol oxidation and mineralization efficiencies than the fresh catalyst and homogeneous Fenton system (FeSO4/H2O2). The XPS, XRD, FTIR, and textural property results reveal that the great enhancement comes from the interfacial emerged oxygen containing groups between α-FeOOH and MesoC after the first heterogeneous Fenton-like reaction. In summary, visible light induced photocatalysis assisted heterogeneous Fenton-like process in the α-FeOOH/MesoC composite system improved the HO• production efficiency and Fe(III)/Fe(II) cycle and further activated the interfacial catalytic sites, which finally realize an extraordinary higher degradation and mineralization efficiency.

Optimization and application of TiO2/Ti–Pt photo fuel cell (PFC) to effectively generate electricity and degrade organic pollutants simultaneously

A TiO2/Ti-Pt photo fuel cell (PFC) was established to generate electricity and degrade organic pollutants simultaneously. The electricity generation was optimized through investigation the influences of photoanode calcination temperature and dissolve oxygen on the resistances existing in PFC. TiO2 light quantum yield was also improved in PFC which resulted in a higher PC degradation efficiency. Two kinds of real textile wastewaters were also employed in this PFC system, 62.4% and 50.0% Coulombic efficiency were obtained for 8 h treatment. These refractory wastewaters with high salinity may become good fuels in PFC because a) TiO2 has no selectivity and can degrade nearly any organic substance, b) no more electrolyte is needed due to the high salinity, c) the energy in wastes can be recovered to generate electricity. The electricity generated by the PFC was further applied on a TiO2/Ti rotating disk photoelectrocatalytic reactor. A bias voltage between 0.6 and 0.75 V could be applied and the PC degradation efficiency was significantly improved. This result was similar with that obtained by a 0.7 V DC power.