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1.
Kevin Thurbide Maher Al-Jabari Mathew Kowalchuk 《Chemical Engineering Communications》2013,200(5):675-683
The supercritical fluid extraction of manganese and iron from solid matrix (wood pulp) is demonstrated experimentally. Supercritical carbon diodixe is used together with lithium bis(trifluoroethyl) dithiocarbonate (FDDC) as the ion-pairing reagent. The metal content of the pulp samples was determined by inductively couple plasma atomic emission spectroscopy (ICP-AES). Optimum conditions were determined to be 30 min each of static and dynamic extraction with 200 atm pressure at 40 °C. Thermomechanical pulp (TMP) extracted under these parameters exhibits an 80% decrease in manganese content, and 91% after a second, sequential extraction. The simultaneous removal of iron was found to be only 6% and supports evidence that it is much more strongly bound to the TMP matrix than manganese. 相似文献
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Ning Duan Changbo Zhou Bing Chen Wenfeng Jiang Baoping Xin 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2011,86(6):832-837
BACKGROUND: Electrolytic manganese residues are the largest and most dangerous waste stream from the electrolytic manganese metal industry, and recovery of Mn from manganese residues is one of the main methods of recycling this waste. Bioleaching of electrolytic manganese residues for Mn extraction was investigated in this study. RESULTS: An extraction efficiency as high as 99.7% was achieved at 1% slag pulp concentration, 2320 mg L?1 extraction concentration and 80% extraction efficiency was attained at 8% slag pulp concentration, indicating the application potential of bioleaching in Mn extraction from manganese residues. CONCLUSION: The extraction of Mn from manganese residues depended exclusively on the non‐contact mechanism. The acidic dissolution of soluble Mn2+ induced by sulfur‐oxidizing bacteria resulted in 91.9% Mn extraction, while the reduction dissolution of insoluble Mn4+ by iron‐oxidizing bacteria caused 5.8% Mn extraction. The combined action of sulfur‐oxidizing bacteria and iron‐oxidizing bacteria assured the maximum Mn extraction. EDS and XRD analysis of bioleaching residues further demonstrated the bioleaching mechanism involved. Copyright © 2011 Society of Chemical Industry 相似文献
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本文叙述了运用盐酸—硝酸—高氯酸组合对竹浆黑液样品进行处理,得到无色溶液,再运用1,10菲罗啉法测定竹浆黑液中铁含量,其平均回收率为98%,相关系数R=0.99948能够应用于竹浆黑液中铁含量的分析。 相似文献
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The effects of alkaline treatment on dissolved carbohydrates in suspensions of Norway spruce thermomechanical pulp (TMP) were studied by agitating 1% consistency TMP suspensions at different pH values (5.4 to 12) for 3 h at 60°, followed by acidification and centrifugation to obtain water samples for analysis. It was found that at pH values above 8, dissolved galactoglucomannans were deacetylated, resulting in their substantial adsorption onto the TMP. Galacturonans began to dissolve from the TMP at pH values greater than 8. The amount of arabinogalactans apparently remained constant throughout the various alkaline treatments. At pH values above 10, arabino-(4-O-methylglucurono)xylans began to dissolve from the TMP. The amount of dissolved and colloidal substances (DCS), measured by TOC, could be substantially decreased by alkaline treatment of filtrate from the 1% consistency suspension, followed by acidification and remixing the filtrate with its original pulp. At 10 m3/t specific water consumption, the TOC of laboratory-prepared circulation water dropped about 20% due to the alkaline treatment. The decrease in TOC was attributed mostly to the adsorption of deacetylated galactoglucomannans. Alkaline treatment of fiber-free mechanical pulp circulation water may be a useful technique to reduce the amount of organic substances circulating in process waters and leaving the pulp or paper mill in the effluent stream. 相似文献
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为了提高阿希金精矿的生物预氧化效率,研究了3组不同微生物菌群、两步氧化工艺对生物预氧化的强化效果. 结果表明,中度嗜热混合菌为最佳菌群,矿浆浓度提高严重影响菌群生物预氧化效果. 矿浆浓度为2%时,铁、硫脱除率为98.35%和91.90%;矿浆浓度为15%时,铁、硫脱除率下降到50.25%和49.51%. 采用两步氧化法可明显提高中度嗜热混合菌的铁、硫脱除率,降低矿浆浓度的影响. 矿浆浓度为15%时,铁、硫脱除率分别提高到64.93%和65.73%,与常规方法处理10%矿浆结果相当. 相似文献
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以桉木热磨机械浆(TMP浆)为研究对象, 探讨了非硅过氧化氢漂白稳定剂G1、G56替代硅酸钠用于桉木TMP浆漂白的可行性, 并对漂白工艺条件进行了优化。结果表明:桉木TMP浆过氧化氢漂白采用稳定剂G1、G56替代硅酸钠是可行的。在浆浓(质量分数)20%、H2O2用量9.0%(以绝干浆质量计,下同)条件下优化的漂白工艺条件为:G1用量0.5%, G56用量0.5%, NaOH用量5.85%, 温度90 ℃和时间30 min。在此工艺条件下桉木TMP浆单段过氧化氢漂白后, 浆的白度达到77.47% (ISO), 比原浆白度高38.89个百分点, 比2%硅酸钠用量下漂后浆的白度高1.75个百分点, 与2%硅酸钠和2%DTPA同时用作稳定剂的白度(79.88%(ISO))相当。 相似文献
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Abstract The interactions of Optical Brightening Agents (OBA) with High Yield Pulp (HYP) fibers under two methods of OBA addition were evaluated on a softwood TMP and hardwood (aspen) HYP: OBA added to the peroxide bleach liquor (Method A), and OBA added conventionally at the wet end (Method B). The treated pulps were fractionated and OBA retention and efficiency in each fraction were determined. Adding OBA to the bleach liquor gave a higher OBA retention than adding OBA at the wet end; the hardwood HYP had a higher OBA brightening efficiency than the softwood TMP. The results are explained in terms of pulp morphology, lignin content, and process conditions (temperature and contact time). Adding OBA to the mechanical pulp also improved the brightness stability during the light-induced yellowing process. 相似文献
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Previous research efforts on pulp fiber-cement composites have largely concentrated on kraft pulp fiber composites. In this research program, thermomechanical pulp (TMP) fibers were investigated as an economical alternative to kraft pulp fibers as reinforcement in fiber-cement composites. Prior to wet/dry cycling, TMP composites exhibited increased first crack strength, but lower peak strength and lower post-cracking toughness, as compared to unbleached and bleached kraft pulp composites at equivalent fiber volume fractions. It is believed that this behavior can be attributed to the lower tensile strength and shorter fiber length of TMP fibers as compared to kraft fibers. After 25 wet/dry cycles, TMP composites showed losses in first crack (peak) strength and post-cracking toughness. However, TMP composites exhibited a slower progression of degradation during wet/dry cycling than composites containing bleached or unbleached kraft fibers. 相似文献
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《Polymer-Plastics Technology and Engineering》2013,52(5):853-862
Abstract Natural fibers are potentially a high‐performance non‐abrasive reinforcing fiber source. In this study, pulp fibers [including bleached Kraft pulp (BKP) and thermomechanical pulp (TMP)], hemp, flax, and wood flour were used for reinforcing in polypropylene (PP) composite. The results show that pulp fibers, in particular, TMP‐reinforced PP has the highest tensile strength, possibly because pulp fibers were subjected to less severe shortening during compounding, compared to hemp and flax fiber bundles. Maleic‐anhydride grafted PP (MAPP) with high maleic anhydride groups and high molecular weight was more effective in improving strength properties of PP composite as a compatiblizer. Coupled with 10% glass fiber, 40% TMP reinforced PP had a tensile strength of 70 MPa and a specific tensile strength comparable to glass fiber reinforced PP. Thermomechanical pulp was more effective in reinforcing than BKP. X‐ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) were used to aid in the analysis. Polypropylene with high impact strength was also used in compounding to improve the low‐impact strength prevalent in natural fiber‐reinforced PP from injection molding. 相似文献
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Clerg Tchigang Bertille Carine Tchankou Leudeu Csar Kapseu Anaclete Fomethe Michel Parmentier 《European Journal of Lipid Science and Technology》2004,106(9):613-620
With the aim of contributing to the valorization of the Canarium schweinfurthii Engl. fruit pulp, through the extraction of its oil, we have studied the influence of the Canarium pulp's water content after drying at 45 °C on the yield of extraction using hexane. Furthermore we studied the physicochemical properties of the oil. It was observed that the oil's extraction yield is significantly influenced (p <0.01) by water content of the pulp. Maximum extraction yield (30.6 g fat/100 g) is obtained at a moisture content of 6.3%. The acid, saponification and peroxide values of the oils obtained were significantly influenced (p <0.05) by the humidity. The maximum acid values of 8.88 corresponded to a moisture content of 17.5%. Likewise, the saponification value showed a maximum of 154.1 for humidity content of 43.3% at the beginning of the drying step. The pulp oil's peroxide value initially at 3.7 meqO2/kg increased progressively until attaining 51.0 O2/kg at the end of drying. The iodine value was not influenced by humidity. A moisture content of 7.7% has been determined as the optimal value for optimizing both oil extraction yield and physicochemical property of the oil obtained. 相似文献
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《分离科学与技术》2012,47(15):2305-2312
The effect of bis-2-ethylhexylphosphoric acid (D2EHPA), bis (2,4,4-trimethylpentyl) phosphinic acid (Cyanex 272), and tri-butyl phosphate (TBP) and their mixtures in various proportions for the separation and extraction of zinc and manganese from sulfate solutions were investigated. Experiments were carried out in the pH range of 0.5–5.0 at 25, 40, and 60°C. It was shown that the extraction of zinc and manganese by D2EHPA and/or Cyanex 272 can be increased by the increase in pH and temperature. The synergistic extraction and separation of zinc and manganese with a mixture of D2EHPA and Cyanex 272 was studied and the results showed that mixing the two extractants improved the extraction capacity of the mixture. Increasing the D2EHPA to Cyanex 272 ratio in the organic phase, caused a right shifting of extraction isotherms of manganese and zinc; shifting the manganese curve was more than zinc. The manganese curve had considerable right shifting with 5% D2EHPA and 15% Cyanex 272. TBP did not affect the zinc (Zn) and manganese (Mn) extraction. The stoichiometric coefficients of Zn and Mn were determined with 20% and 5% D2EHPA and 15% Cyanex 272 by applying the slope analysis method. The organic phase was stripped by sulfuric acid. 相似文献
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Debasis Senapati G. Roy Chaudhury P. V. R. Bhaskara Sarma 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1994,59(4):335-339
Acidic nickel-bearing solution containing iron, cobalt, manganese, zinc and copper was processed through a solvent extraction and precipitation technique to obtain a pure nickel sulphate solution. Iron was extracted using 0.2M Cyanex-272 (partially neutralised) as the extractant. Stripping of iron from the loaded organic has also been studied. After iron recovery through solvent extraction the raffinate still contained 0·25 g dm?3 of iron which was quantitatively separated by a lime precipitation technique. During this iron precipitation there was no loss of cobalt and nickel but copper, manganese and zinc were coprecipitated to some extent. From the iron-free nickel sulphate solution the other impurities were extracted using the same extractant (Cyanex-272) in a single stage. The metal ions from the loaded organic were stripped using a 0·5% (v/v) H2SO4 solution in a single stage. The entire operation needs only seven stages: two stages for iron extraction, three stages for iron stripping from the loaded organic, and one stage each for extraction and stripping of other impurities. In the entire operation the loss of nickel was less than 0·5%. 相似文献
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电解锰渣是电解锰生产过程中产生的锰矿石酸浸渣,富含锰、铁等活性组分,理论上可催化氧化SO2实现烟气脱硫,同时脱硫后的电解锰渣可资源化利用,然而目前尚未见电解锰渣矿浆脱硫的研究报道。本文研究了工艺参数对电解锰渣浆液脱除SO2性能的影响,探究了电解锰渣浆液烟气脱硫的过程机制。结果表明:锰渣粒径为200目(<75μm)、锰渣浆液初始浓度5000mg/L、气体流量400mL/min、进口SO2体积分数0.20%、反应温度50℃、反应时间180min的条件下,电解锰渣浆液脱硫率最高可达93.87%。脱硫前后电解锰渣XRD、SEM、XPS表征结果表明,MnO2、MnO、Fe2O3等活性组分参与SO2反应,且浆液中的Mn2+、Fe3+等过渡金属离子液相催化氧化SO2生成H2SO4,实现烟气脱硫。 相似文献
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研究以硫铁矿为还原剂,在钛白废酸中湿法还原软锰矿制备硫酸锰的工艺过程。探讨反应温度、反应时间、酸矿比和矿浆浓度等因素对硫酸锰浸出率的影响。实验结果表明:在反应温度为95 ℃、反应时间为2.5 h、硫铁矿与软锰矿(以锰计)的质量比为0.95~1.0、硫酸与软锰矿(以锰计)的质量比为1.30、矿浆质量分数为28%~30%的条件下,硫酸锰的浸出率达到95%以上。通过加入碳酸钙中和浸出溶液使其pH为5~6,以除去溶液中的铁、钛、铝等杂质;加入自制硫化锰以除去溶液中的重金属离子;加入二氟化锰以除去溶液中的钙镁离子等。所得溶液经陈化、过滤、浓缩和结晶后得高纯一水硫酸锰,产品纯度为99%以上。 相似文献
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Extraction and quantification of polyphenols from coffee pulp 总被引:1,自引:0,他引:1
The polyphenol content of coffee pulp extracts was determined using the Folin-Ciocalteau method. The use of polyvynilpirrolidone (PVP) was introduced in order to eliminate interferences. Condensed polyphenols in the extracts were determined by the method of acidified vanillin. Chlorogenic acid and catechin were used as standards for Folin-Ciocalteau and Vanillin methods, respectively, and a calibration curve was constructed for each solvent. The solvents used were methanol, methanol-water (50:50), ammonium hydroxide (3%) and calcium hydroxide (1%), using times of extraction of 10 minutes and 1 hour. No differences were found in the amount of polyphenols extracted by the different solvents at the two extraction times. After 10 minutes, the alkaline solvents NH4OH (3%) and Ca(OH)2 (1%), extracted more polyphenols than the other two solvents. Nevertheless, ammonium hydroxide (3%) was more efficient in extracting condensed polyphenols. The results herein presented suggest that treating coffee pulp with mild alkaline solvents may improve its nutritive value. 相似文献
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为了解汉中地区绿茶中铜、铁、锰、锌、氟的含量,采用微波消解-原子吸收分光光度法及氟离子选择电极法对汉中绿茶中的铜、铁、锰、锌、氟含量进行了测定。结果显示,汉中绿茶中铜、铁、锰、锌、氟的含量范围分别为66.96μg.g-1,482.30μg.g-1,854.57μg.g-1,89.75μg.g-1,48.6μg.g-1。与文献相比,汉中绿茶中铁、锌含量远高于平均值,锰和铜的含量与平均值相当;氟含量略低于绿茶平均氟含量。 相似文献
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Abstract The distribution of anionic groups in fibres, fines, the colloidal fraction, and the dissolved fraction of thermomechanical pulp (TMP) suspensions was determined. The influence of extraction, alkaline treatment, and peroxide bleaching of spruce TMP were also studied. Spruce TMP was extracted with hexane, treated with alkali, or bleached with peroxide. Suspensions were made at pH 5.5 or 8, and fractionated into long fibres, large fines, small fines, a colloidal fraction, and a dissolved fraction. The surface and total charge of the fractions were determined separately by polyelectrolyte titration. To determine the origin of the charges, the contents of fatty acids, resin acids, and acidic units in polysaccharides in the different fractions were determined by gas chromatography. Extraction of TMP with hexane prior to fractionation increased the measured total and surface charge of the fibres. The removal of wood resin probably uncovered some anionic groups on the fibre surface, or improved the penetration of the polymers into the pores of the fibres. The total charge, determined with polybrene titration, of the fines and the colloidal fraction was lower when the resin had been removed, while the surface charge, determined with poly-DADMAC, was not greatly affected. Alkaline treatment of the TMP increased both the total charge and the surface charge of the fibres and fines, mainly because of demethylation of pectins. Alkaline treatment also increased the total and surface charge of the dissolved substances, due to the release of pectic acids into the water phase. Alkaline peroxide bleaching further increased the total and surface charge of fibres and dissolved substances, most likely due to oxidation of lignin. The total charge and the surface charge of the colloidal substances, consisting mainly of wood resin, were only slightly affected by alkaline treatment and peroxide bleaching. The anionic charge in TMP suspensions originated mainly from free uronic acids in the xylans, arabinogalactans, and pectic acids. The contribution from the fatty and resin acids was substantial only for the colloidal fraction. 相似文献