Reduction Efficiency Increase Research Articles

N, S co-doped carbon quantum dots/TiO2 composite for visible-light-driven photocatalytic reduction of Cr (VI)

A novel carbon quantum dots (CQDs) sensitized TiO2 (N, S-CQDs/TiO2) composite was prepared and used as a visible-light-active photocatalyst for the reduction of Cr (VI), one of the most toxic heavy metal ions. Experimental results from the batch reaction process indicated that the composite was able to completely reduce Cr (VI) to Cr (III) at pH 2.0 after 3 h′ exposure to visible light with the initial Cr (VI) concentration being 20.0 mg/L and a catalyst dosage of 1.0 g/L. It was also found that lower pH and lower initial concentration of Cr (VI) led to high reduction efficiency. Compare with pure TiO2, a four-fold increase in reduction efficiency of Cr (VI) was achieved by the N, S-CQDs/TiO2 composite under the same reaction conditions. The prepared composite also demonstrated good reusability and stable photocatalytic performance in real water samples. Results from this study confirm that sensitization of TiO2 with CQDs is efficient in broadening the light absorption range of TiO2, expanding its application in visible-light-driven photocatalysis.

The Effect of Dead Load Chemicals in the Kraft Pulping and Recovery System

"The primary dead load chemicals are sodium carbonate from incomplete conversion during causticizing, and sodium sulfate from low reduction efficiency in the recovery boiler, but thiosulfate and chloride also are potentially important. The difference between a low and high dead load operation might amount to as much as 125kg/metric tons of pulp (mtp). A 1% increase in causticizing efficiency reduces dead load by 6-7 kg/mtp, and a 1% increase in reduction efficiency decreases dead load by 2-3 kg/mtp. Costs associated with dead load include increased internal energy use, greater chemical losses, reduced equipment capacity, and operating problems. The differences in energy use between a low and high dead load operation can be as much as 0.7 GJ/mtp. Evaporators are likely to be affected most, but the green and white liquor system and recovery boiler also could be affected. This paper provides some guidelines for minimizing the effects of dead load."

Study on NO heterogeneous reduction with coal in an entrained flow reactor

The effects of coal types with a wide range of volatile matter content including lignite, bituminous coal, and lean coal, as well as the effects of reaction temperature, coal particle size, the primary-zone stoichiometry (SR1) and reburning-zone stoichiometry (SR2), etc. on NO reduction efficiency were carried out systematically in an entrained flow reactor. The heterogeneous NO reduction mechanism was analyzed. The results indicate that the NO reduction efficiencies increase with decreasing SR2 and coal particle size, and with increasing reaction temperature. The char contributions to the total NO reduction efficiency increase with increasing proximate volatile matter, coal particle size, and with decreasing reaction temperature. The char contribution can be reached more than 40% when SR2 is larger than 1.06 or less than 0.92 for XLT lignite. The char contribution at the conditions of SR1 = 1.0 and SR1 = 1.2 is significantly larger than that at SR1 = 1.1 for coals with high-volatile matter at a fixed reburning fraction.

Direct electron transfer between a chemically, viologen-modified glassy-carbon electrode and ferredoxins from spinach and Megasphaera elsdenii

Direct reversible electron transfer between an electrode and ferredoxins has been described by several authors [l-8]. Recently, we have shown that at the dropping mercury electrode the efficiency of reduction of both 4Fe-4FS and 2Fe-2S ferredoxins can be enhanced drastically [8]. This increase in reduction efficiency was obtained by addition of a positively charged polymer or surfactant to the negatively charged ferredoxins, indicating that electrostatic effects play an important, if not a predominating role. Authors in [5,6] have reported on the reduction and oxidation of spinach ferredoxin at a gold electrode on which a polymeric form of methyl viologen was adsorbed. Authors in [7] have described the direct reversible