Papers by Keyword: Pre-Treatment

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Authors: Chen Cui, Da Zhi Wang, Xiang Tao Li, Feng Zuo Qu, Tong Kuan Xu
Abstract: The purpose of this paper is to study the anti-corrosion properties of a novel pre-treatment CeO2/ZrO2 nanometric film coating on the surface of cold-rolled plate at room temperature. A novel coating agents involved elements Zr,Ce and additional surfactants were prepared and used in the field of cold-rolled plate pretreatment. The surface of the coating sample was investigated by using X-ray Photon Spectrum (XPS), X-ray Diffraction (XRD) and Scanning Electronic Microscope (SEM),respectively. The Ce3+ doted ZrO2 nanofilm could improve the anti-corrosion performance of coated plate. This dipping coating process satisfied the energy-saving and green chemistry requirement of modern cold-rolled plate pre-treatment technology.
Authors: So Young Kang, Jong Un Lee, Kyoung Woong Kim
Abstract: Pseudomonas aeruginosa biomass was used to investigate the biosorption properties of heavy metals in wastewater. The biosorption isotherm of Co2+ was best described by the Langmuir model when washed cells were employed, and results obtained utilizing heat-treated P. aeruginosa were also adequately represented by a Langmuir sorption isotherm. In contrast, the sorption isotherm involving unwashed P. aeruginosa showed a different isotherm profile and did not attain equilibrium in the range of metal concentrations investigated; the amount of Co2+ uptake increased with increasing initial metal concentration but never reached adsorption equilibrium, most likely due to bacterial production of extracellular polymeric substances (EPS). The biosorption results utilizing unwashed P. aeruginosa were best described by a Freundlich isotherm. The level of metal adsorption in low pH was significantly small due to competition between the cation and H+ ions for binding sites distributed on cell surfaces, while the increase in pH favored metal sorption because of the elevated quantities of negatively charged surface functional groups. The sorption of Co2+ was strongly influenced by the presence of competing cations in the solution. Trivalent Cr3+ added to the solution was preferentially adsorbed onto the cells relative to Co2+ and Ni2+. The results may be attributed to the higher adsorption affinity of Cr3+ in comparison to either Co2+ or Ni2+. The affinity order (Cr3+ > Co2+ » Ni2+) was maintained over a pH range up to 5.3 in a mixture solution.
Authors: Yong Wei Song, Da Yong Shan, En Hou Han
Abstract: Magnesium alloys are considered as “difficult to plate” metal. The pretreatment processes play a key role for plating. The pretreatments of alkaline cleaning, chromic acid etching and hydrofluoric acid activating were carried out and the microstructures investigated by SEM and EDAX in detail. The hydrofluoric acid activating time of 8 minutes was determined by Potential-Time curve. The experimental results showed that the alkaline cleaning moved the grease and oils off the substrate surface, but there was no apparent surface morphology change. The chromic acid etching was a very critical step, and the optimum etching time of 1 minute was chosen; the eutectic α was severely etched, and the chromic compounds were mainly formed on the surface. During the hydrofluoric acid activating, the white activating product of magnesium fluoride was preferentially generated on the β–phase, and obvious morphology change has been observed on the alloy substrate surface.
Authors: Yong Chen, Xin Long Zhang, Ji Lai Lu, Wei Jing Liu, Yong Tu
Abstract: The research on accelerated seeded precipitation pre-treatment for the improvement of secondary RO membrane was investigated. The influences of seed type, initial pH and seed dosage on accelerated seeded precipitation were studied. SEM images for the secondary RO membrane were also discussed.
Authors: Jian Hong Bai, Shu Ling Cui
Abstract: Combining the application of tea saponin in short pre-treatment of cotton fabric, the chemical reaction characteristics and mechanism of one-bath process were discussed. The impact of various parameters on the one bath process with tea saponin was analysed, and the optimum process prescription was obtained: tea saponin 40 g/L, penetrating agent JFC 5 g/L, scouring agent YS198 6 g /L and hydrogen peroxide stabilizing agent GJ-101 4 g/L. By tea saponin qualitative analysis, the action mechanism of tea saponin in one bath pretreatment was proposed.
Authors: Peng Luo, Chuan Min Yang
Abstract: Wheat straw is one of the most abundant and cheap lignocellulosic waste materials in the world. Nowadays, field burning is the major practice for removing wheat straw due to lack of effective utilization, but it increases the air pollution and consequently affects public health. Wheat straw is an attractive lignocellulosic raw material for binderless particleboard production. In this study, steam explosion was adopted as pretreatment method for wheat straw. The pretreated wheat straw was used to produce binderless particleboard panels. The influence of both pretreatment temperature and residence time on chemical composition of wheat straw, and modulus of rupture, internal bond and water absorption of panel boards was investigated. The results showed that defiberation of wheat straw raw material occurred during steam explosion pretreatment. The modulus of rupture and internal bond increased while water absorption of panels decreased as pretreatment severity increased. The optimum pretreatment condition, with 19.8 MPa of modulus of rupture, 0.2572 MPa internal bond and 61.5% of water absorption of panels, occurred under 170°C temperature and 10 minute residence time.
Authors: Kun Chen, Long Jun Xu, Jun Yi
Abstract: Lignocellulose biomass is a kind of rich reserve in china, and it is a renewable bio-resource. Researches on the bioconversion of lignocellulose (lignocellulosic biomass) to ethanol have been hot spot in recent years. The key technologies of producing fuel alcohol by aspects of lignocellulosic raw materials, pretreatment technology, fermentation process, enzymatic hydrolysis and fermentation of strains as well as the removal of fermentation inhibitors have been reviewed. It is pointed out that the improvement of fermentation strains, exploitation of double function saccharomyces cerevisiae (glucose and xylose fermenting) to ethanol, will be the direction and focus in future researches.
Authors: R. Winarko, M. Zaki Mubarok, I.N. Rizki, Siti Khodijah Chaerun
Abstract: The ability of an iron-sulfur-oxidizing mixotrophic bacterium to treat two types of sulfide-rich carbonaceous refractory gold concentrates from Sulawesi and Sumatra in Indonesia was studied in comparison with an acidophilic chemolithotrophic bacterium Acidithiobacillus ferrooxidans. Over the course of the biooxidation experiments, the pH of the solution tended to rise (pH>5) due to the high content of acid-consuming minerals such as carbonates in both concentrates. Ferric ions were frequently observed to precipitate due to high solution pH. The BIOXskc employed in this study was able to increase the gold extraction from low sulfidic carbonaceous refractory gold concentrates by ~15% higher than that by using At. ferrooxidans. It was also capable of treating carbonaceous matters which causes preg-robbing effect and retaining iron in ionic form due presumably to the production of extracellular polymeric substances (EPS) under high solution pH. Nevertheless, BIOXskc also reduced the gold extraction yield of high sulfidic gold concentrates because of passivation effect. It is suggested that the precipitation of iron and sulfur on the surface of sulfide minerals during biooxidation may prevent cyanide ion contact with gold.
Authors: Zhen Liu, Lei Ming Lu
Abstract: In this study we used 1-allyl-3-methyl imidazole formate ([Amim][HCOO]) as ionic liquid to pre-treat the cellulose and determined the rate of polymerization and enzymatic hydrolysis. The results showed that pretreatment with ([Amim][HCOO]) significantly decreased the cellulose polymerization. As the pretreatment temperature went up, the enzymatic hydrolysis rate was first increased and then decreased. The maximal enzymatic hydrolysis rate was achieved when the pretreatment temperature was 90°C. Under the ultrasonic condition, the initial rate of enzymatic hydrolysis for the ionic liquid-treated cellulose was up to 11.10 gL-1h-1, which was 33% increase compared to the untreated cellulose. Scanning Electronic Microscopy (SEM) and Fourier Transform Infrared-Raman Spectroscop (FT-IR) analysis showed that ionic liquid- treated cellulose started to depolymerize. In addition, the crystallinity of the cellulose was significantly decreased after pretreatment with ionic liquid.
Authors: Guo Jun Han, Li Jun Qu, Xiao Qing Guo
Abstract: The main objective of this paper was to investigate a low cost pretreatment method, namely microwave-assisted extraction(MAE) pretreatment, which could be applied to hemp degumming with low environmental impact. Degumming index, contrast of different pretreatment methods, transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and single fiber tensile testing were used to characterise the effect of pretreatment on hemp fibers. In this paper, the results of degumming effect were given comparing MAE pretreatment with acid pretreatment for hemp degumming. It was found that the MAE pretreatment could remove non-cellulosic compounds from hemp bundles effectively with very short period of time. Meanwhile, seen from SEM micrographs, the fibers pretreated by MAE were cleaner than that of fibers pretreated by acid. These results suggested that MAE pretreatment was higher efficiency and more environmental friendly than traditional pretreatment methods.
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