Treatment of High Nitrate-Containing Wastewaters by Sequential Heterotrophic and Autotrophic Denitrification

The treatment performance of sequential heterotrophic and autotrophic denitrification process was evaluated using synthetic wastewaters containing high nitrate concentrations. The effluents from two sequentially connected reactors, for heterotrophic denitrification and sulfur-based autotrophic denitrification, were analyzed for more than 200 days. Experimental results indicated that higher than 95% of the nitrate removal could be achieved with volumetric nitrate loading rates of 2.16, 3.24, and 4.32 kg/m3?d. The maximum denitrification rates, with 1,000 mgN/l influent nitrate concentrations, for the heterotrophic and sulfur-packed autotrophic reactors, were found to be 2.47 and 3.61 kg/m3?d, respectively. A sequential heterotrophic and autotrophic denitrification process is considered a good alternative for the sole autotrophic denitrification process, providing excellent nitrate removal, especially for nitrate-rich wastewaters with very low organic contents.     

Control of Molybdenum Emission by Sorbents: Equilibrium Analysis

Emissions from fossil fuel combustion containing various heavy metals such as molybdenum are of public concern due to their adverse effects on human health and the environment. In this study, thermodynamic analyses were applied to determine the potential of sorbent technology to control molybdenum emissions from combustion sources. The effectiveness of four sorbents (Ca, Fe, Mg and Na based) was assessed for a wide range of temperatures. The adverse effects of chlorine and sulfur were also examined. Ca and Na-based sorbents were identified to be effective.     

Modeling Water and Sulfuric Acid Transport through Coated Cement Concrete

The behavior of coated cement concrete in water and sulfuric acid was investigated over a three-year period. Two epoxy-based coatings were selected and cylindrical concrete specimens were coated and used in this investigation. The concrete-to-coating mass transfer coefficient ratio varied from 8 to 10. The penetration of liquids through bulk coating materials and coated concrete with and without holidays (pinholes) was studied. The mass change of the specimens was measured at regular intervals and a total of 64 coated specimens were tested. Coated concrete specimens with and without holidays had different performance with long-term immersion in deionized (DI) water and 3% sulfuric acid. Mass transfer models were developed using film and bulk concepts and were used to predict the increase in mass in coated concrete in nonreactive DI water and reactive 3% sulfuric acid solutions. The mass transfer model parameters for various solution-coating combinations were obtained from experiment data. The parameters of the effect of holiday size on the liquid transport process were also identified based on the experiment results.     

Shape‐Controlled Synthesis of High‐Quality Cu7S4 Nanocrystals for Efficient Light‐Induced Water Evaporation

Copper sulfides (Cu_2–xS), are a novel kind of photothermal material exhibiting significant photothermal conversion efficiency, making them very attractive in various energy conversion related devices. Preparing high quality uniform Cu_2‐xS nanocrystals (NCs) is a top priority for further energy‐and sustainability relevant nanodevices. Here, a shape‐controlled high quality Cu₇S₄ NCs synthesis strategy is reported using sulfur in 1‐octadecene as precursor by varying the heating temperature, as well as its forming mechanism. The performance of the Cu₇S₄ NCs is further explored for light‐driven water evaporation without the need of heating the bulk liquid to the boiling point, and the results suggest that as‐synthesized highly monodisperse NCs perform higher evaporation rate than polydisperse NCs under the identical morphology. Furthermore, disk‐like NCs exhibit higher water evaporation rate than spherical NCs. The water evaporation rate can be further enhanced by assembling the organic phase Cu₇S₄ NCs into a dense film on the aqueous solution surface. The maximum photothermal conversion efficiency is as high as 77.1%.     

Crystallinity and electrical conductivity of sulfur-containing microcrystalline diamond thin film

Hydrogen sulfide (H₂S) was introduced into a microwave plasma chemical vapor deposition of microcrystalline diamond thin film. Secondary-ion mass spectroscopy showed that sulfur concentration was controlled from 2 × 10¹⁵ to 9 × 10¹⁷ cm^− 3 by controlling the H₂S/CH₄ ratio, while that of hydrogen concentration was around 5 × 10²⁰ cm^− 3 and was independent of the H₂S/CH₄ ratio. Electrical conductance increased linearly as the S concentration increased from 2 × 10¹⁵ to 3 × 10¹⁶ cm^− 3 without significant deterioration of film crystallinity, i.e., the amount of sp² phase did not increase. Non-ohmic conduction was converted to ohmic conduction when the S concentration reached 9 × 10¹⁷ cm^− 3 by increasing the H₂S/CH₄ ratio to 30,000 ppm. This modification was consistent to the formation of a graphitic phase by heavy S-doping, which was identified by Raman spectra and surface morphology.     

烟火药剂中硫磺含量测定方法的研究

确定了烟火药剂中硫磺含量的测定方法,将烟火药剂洗去有机粘合剂后,用稀盐酸充分溶解、过滤,用浓硝酸将硫磺氧化成硫酸,加入过量的钡离子,然后用EDTA容量法测定过量的钡离子,进而得到硫磺含量.试验表明,本文提出的方法回收率在98.22%～99.79%.     

浅谈金川高冰镍传统精炼工艺技术改方案和镍产品结构调整

论述了金川有色金属公司现行高冰镍精炼工艺技改的必要性。在综合国内外高冰镍精炼技术的基础上,结合金川有色金属公司的实际,重点阐述了高冰镍硫酸湿法精炼和氯化精炼工艺的优缺点。指出,现行高冰镍精炼工艺的改造应吸取氯化精炼和硫酸湿法精炼两种工艺的长处,稳妥地向高冰镍全湿法精炼过渡。文中还对该公司镍产品结构调整提出看法。     

利用原料1生产金属化阳极板试验研究

本文介绍了利用原料1在合金硫化炉进行金属化阳极板试验的过程。通过在合金硫化炉中进行原料1硫化、吹炼等试验过程,达到提镍降硫的目的。并在试验过程中摸索出了生产金属化阳极板的关键参数,同时对金属化阳极板中化学成分、镍直收率、钴直收率等关键指标进行了分析,为金属化阳极板的工业化生产提供了理论依据。     

Electrochemical properties of lithium sulfur cells using PEO polymer electrolytes prepared under three different mixing conditions

Lithium sulfur cells were prepared by composing with sulfur cathode (PEO)₆LiBF₄ polymer electrolyte and lithium anode. (PEO)₆LiBF₄ polymer electrolyte was prepared under three different mixing conditions: stirred polymer electrolyte (SPE), ball-milled polymer electrolyte (BPE) and ball-milled polymer electrolyte with 10 wt%Al₂O₃ (BCPE). The effects of ball milling and additive were investigated by discharge test according to depth of discharge. The initial discharge capacity of lithium sulfur cell using BCPE was 1670 mAh g⁻¹-sulfur, which was better than those of SPE and BPE, and approximately equal to the theoretical capacity. The cycle performance of Li/(PEO)₆LiBF₄/S cell was remarkably improved by the addition of Al₂O_3.     

Y type zeolites/PI membranes for sulfur-free hydrogen source and for fuel cell applications

Sulfur removal is significant for fuels used as hydrogen source for modern fuel cell applications and to avoid sulfur poisoning of therein used catalysts. Novel membranes for the polymer–zeolite system with well-defined transport channels are proposed for the sulfur removal. Membranes are fabricated using polyimide (PI) as matrix material and Y zeolites as adsorptive functional materials. By detailed analysis of FT-IR, morphology and adsorption performance of membranes, the process-structure-function relationship is obtained. The results show that the functional zeolites particles are incorporated into three-dimensional channels. For all cases, the inlet fuel can be desulfurized to below 0.1 mg L⁻¹, which means that the outlet fuel can be used as sulfur-free hydrogen source for fuel cell applications. The proposed membranes adsorber may be applied as sulfur trap before the reformer for fuel cells on-board or on-site, and it may be applied in a periodically replaceable form. The desulfurization efforts by membrane are likely to play an influential role for the development of sulfur-free hydrogen source and fuel cell area.