Applied Mechanics and Materials Vol. 768

Abstract: In order to generate powerful radicals as oxidizing species for the complete oxidation of NO, homogeneous activation of peroxymonosulfate (Oxone: PMS) by the Mn₃O₄/GO catalysts was explored. The catalytic oxidation of NO from waste gas was investigated using advanced oxidation process based on sulfate radicals that produced. The manganese oxide immobilized on graphene oxide (GO) can activate PMS for the oxidation of NO in water. We not only took advantage of the high oxidation–reduction potential of produced sulfite radicals but also an opportunity to oxidize NO on less complex compounds with low dosages. The Mn₃O₄/GO catalysis system was characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that Mn₃O₄ was well-distributed on GO. The Mn₃O₄/GO catalyst system exhibited high efficiency for NO oxidation when the Mn₃O₄/GO catalyst has an optimum Mn₃O₄ loading. In addition, the best catalytic oxidation can be achieved within 30 min with pH 4 and 6 mM PMS at 25 °C. Therefore, the results indicate promising potential for a system utilizing Mn₃O₄/PMS to oxidize NO for offgas treatment.

Abstract: In this paper, the acute toxicity test were used to study the effects of different concentrations of suspended solids on the growth of Skeletonema costatum . The research result showed that the effects of different concentration of suspended solids on the growth of Skeletonema costatum were very significantly (P <0.01);The relationship between concentration of suspended solids and the inhibition rate of Skeletonema costatum growth was linear, the half inhibition concentration of Skeletonema costatum 48h-EC50 was 1.58g/L,r =0.9769,96 h-EC50 was 2.82g/L, r=0.9927.

Abstract: In this study, a rapid and selective method has been developed to determine PENG residues in waste penicillium chrysogenum by using SPE cleanup strategy followed by HPLC. Furthermore, some parameters which influenced the extraction efficiency including extraction mode, solvent and time, while washing solution and eluting solution for SPE were systematically investigated. It should be noted that the extraction process was carried out in a single step by mixing the extraction solvent acetonitrile: formic acid in aqueous solution and chrysogenum samples under ultrasound. The SPE procedure was conducted using Oasis HLB as the clean up cartridge, n-hexane as washing solution, and mixture of acetonitrile and methanol as eluting solution. Under the optimized conditions, the linear of PENG are in the range of 0.1-2000 μg/mL, with the correlation was R²>0.99. In addition, the recoveries of PENG in these samples at three fortification levels of 800-1800mg/kg were 74.98% to 113.47% are obtained, respectively. Moreover, a limits of detection (0.006 mg/kg) and quantification (0.02 mg/kg) could be achieved.

Abstract: Samplings of PM_2.5 used to determine water-soluble anions were obtained from four representative sites of Hefei. There are High-tech zone, Binhu new area, Hupo villa, Dongpu reservoir. The other samplings of PM_2.5 used to determine metal elements came from four kinds of domestic waste combustion. There are paper, plastic, cotton, rubber. In this article, anions were detected by ion chromatography (IC). It was found that the main anions in PM_2.5 are NO₃^-, SO₄^2-. Metal elements were detected by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Fe, Mn, Zn, Cu, Cd, Cr six kinds of metal elements were detected in this article. The main metal elements in samplings of PM_2.5 are Fe and Cu element. The concentrations of Cd and Cr elements are lower in four domestic waste burning.

Abstract: Nanotechnology is intensively developing and is mostly introduced in renewable energy, cosmetics, nanomedicine, electricity and electronics thereby increasing amount of nanowaste has been challenging issue in the world. However waste management policy in Mongolia has incomplete, nanowaste regulation has to be embedded in order to protect environment and human health. Because environmental and health impact of nanomaterial is still open field for researchers. The main objectives of this study are to introduce test results of some nanomaterials, and to evaluate waste including nanowaste management policy in Mongolia. 21 nanomaterials were tested by X-Ray Diffraction analysis, Cross Correlation Analysis and the Ames test. As a result, physical sizes of 5 nanomaterials were measured at less than 100 nm, and all samples were non-mutagenic. In conclusion, the registration of imported goods in Mongolia needs to be improved in high technology products and safety data sheet for nanomaterial is necessary due to sound disposal of hazardous waste.

Abstract: For many recycled plastics, materials with different rheological properties and melting points are usually mixed together, and can not be separated. For this situation, the block of die-plate holes can be regarded as an important factor that must be taken into consideration in pelleting process. This paper discusses pelleting process in die-plate and reasons of die hole’s blocking. Finite element simulation is calculated to analyze the relationship between operation factors of pelleting process and blocking situation of die holes. Furthermore, block self-healing is realized by changing the velocity of polymer-melt in die-hole.

Abstract: In most cases, recycled plastics include lots of impurities that can not be separated in operation steps of separation and washing. Normally, these impurities should be filtrated in extrusion process with filter plate and single or twin screw extruder. In extrusion process, it is easily for impurities to block the holes of filter plate. So how to improve the performance of self-cleaning can be regarded as a very important requirement for design of filter equipment. Based on FEM simulation, this paper discusses mechanism of filter plate’s blocking, the pressure distribution and deformation of two direct flow filtrations. Specially, a side stream filtration including how to clean itself has been introduced.

Abstract: Over the past century, numbers of hydrometallurgical processing technologies have been conducted for gold leaching in mining and second resource, such as cyanidation, being with high toxicity and low reaction rate, and non-cyanide---thiosulphate leaching and thiourea leaching, etc, having relatively high reagent consumption. Recently, ammonium thiocyanate was selected as leaching reagent in the laboratory study. Just as some papers shown, thiocyanate can be complexed tightly with Au⁺ or Au³⁺ to form water-soluble complexes according to the dynamic and thermodynamic system of thiocyanate gold and regenerated or obtained as a by-product in technological processes. And the extraction process is affected by many factors, such as thiocyanate concentration, oxidant concentration, liquid-solid ratio, temperature, and reaction time, especially pH and the category of oxidants, which can be chosen properly to make the method extensively applied in industrialization. Recent studies have shown that the gold leaching with thiocyanate under alkaline conditions is also viable using oxygen as oxidant. Then this article compares and analyzes the use of different oxidants in acid or alkali environment reaching a 96% leaching efficiency and the techniques of gold recycle from thiocyanate gold solutions. However, as the restriction for post-processing cost of thiocyanate and the strict requirement for the equipment in the acidic conditions or high pressure conditions, additional research should be directed towards making incorporation with other extraction methods perfectly. Two development tendencies are presented in this paper: (1) as additive; (2) as the lixiviant under alkaline or neutral conditions.

Abstract: The present study described the application of mechano-chemical reaction on stabilization of heavy metal containing smelting ash. Extraction procedure for leaching toxicity test showed that the leaching toxicity of cadmium and lead in smelting ash decreased very significantly after grinded. The optimal condition of the mechano-chemical stabilization process was established as follow. The ball milling medium was stainless steel, the additive was the mixture of elemental sulfur and iron powder, the dosage of additive was n_(Cd):n_(Fe):n_(S)=1:3:3, and ball milling time was 3.5 hour. The results showed that the leaching toxicity of cadmium decreased from 2496 mg/L to 0.43 mg/L, compared to lead decreased from 7.30 mg/L to 0.12mg/L under the optimal condition.