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101.
102.
两亲聚合物对湿法磷酸的助滤性能及机理研究 总被引:1,自引:0,他引:1
以实验室自制单体A、丙烯酰胺(AM)、二甲基二烯丙基氯化铵(DMDAAC)为原料,过硫酸盐氧化还原体系为引发剂,采用水溶液共聚法合成一种用于湿法磷酸助滤的两亲聚合物PADA-10。对所得聚合物的助滤性能进行研究,结果表明:磷酸料浆体系中加入PADA-10后,过滤速度提高了约4.3倍,滤饼水分降低了约10.8%。对PADA-10助滤机理的初步探究结果表明:PADA-10能在一定pH值范围内中和磷石膏表面电荷,使磷石膏微晶絮凝成团,添加PADA-10后滤饼的孔隙率增加;同时,PADA-10能增强磷石膏颗粒的疏水性,使磷酸滤液表面张力降低了5.2 mN/m,磷石膏表面接触角增大了3.4°。 相似文献
103.
Vladimir Plata Darrin Haagenson Ayhan Dağdelen Dennis Wiesenborn Viatcheslav Kafarov 《Journal of the American Oil Chemists' Society》2015,92(6):893-903
Palm oil biodiesel (POB) is characterized by a very high cold soak filtration time (CSFT), which places the acceptability of this biofuel at risk. Therefore, the effect of four adsorbents, namely diatomaceous earth, natural silicate (NS), neutral bleaching earth (NBE), and acid activated bleaching earth (AABE), at two levels of addition (1 and 5 wt%) or two temperatures (25 and 110 °C) on the precipitate content and CSFT of POB was investigated. The impact on total glycerin content, moisture content, and oxidative stability was also examined. All treatments significantly decreased the precipitate content, total glycerin content, and moisture content, but only treatments with NS, NBE, and AABE at 5 wt% and 25 °C achieved acceptable filterability. The OSI value was also decreased; however, it remained above the ASTM limit. Operational conditions of treatment with AABE were further optimized in a two‐factor, five‐level center composite design. The combination of 0.65 wt% AABE and 10 min at 25 °C decreased CSFT to below the ASTM limit. Lower adsorbent concentrations could be effective down to 0.44 wt%, given a corresponding increase in the contact time up to 30 min. 相似文献
104.
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106.
《Urban Water Journal》2013,10(1):33-37
The removal of heavy metals from storm and surface waters by slow sand filtration is described. The importance of speciation as a technique for exploring and improving the mechanisms of removal is identified. Laboratory-scale slow sand filters operating at conventional flow rate and depth were shown to be able to reduce concentrations of selected heavy metals (Cu, Cr, Pb and Cd) found in road runoff, surface water and sewage effluents to drinking water standard. Nitrogen, volatile solids and modified Stover speciation were used to differentiate between the potential mechanisms of removal, i.e. active biomass, organic adsorption and simple adsorption or precipitation on the surface of the sand. The data presented show that adsorption via organic ligands was the predominant mechanism for metal removal at the surface of the filter but chemical adsorption was the more important deeper in the filter. In the lower layers the adsorbed metals were more easily exchanged than the organically bound metals. The precise chemical ligands were not identified and varied from metal to metal. The most important operational factors affecting performance were therefore the concentration of organic matter, filter depth and the flow velocity. 相似文献
107.
Yeast cells were immobilized on calcium alginate beads prepared using different calcium concentrations. The compression properties of the immobilized beads (e.g., softness index and retardation time for compression) were strongly affected by the calcium concentration. The effects of the bead properties on filtration characteristics, such as cake porosity, specific cake filtration resistance, cake compression creeping effect and cake compressibility, were analysed using a dead-end filtration system. The filtration curve of yeast-immobilized beads had an “S” shape, similar to that of soft gel particles. The cake compression behaviour and variation in cake properties were directly reflected on the curve trend. The Voigt in the series model was employed to describe variation in cake porosity with time during a compression. The yeast immobilization increased the bead softness; therefore, the porosity of a cake formed by yeast-immobilized beads was lower than that formed by pure calcium alginate beads. The cakes formed by yeast-immobilized beads possessed a high compressibility of approximately 1.0 and a high softness index of approximately 1.5. The beads prepared using lower calcium concentrations had higher softness, shorter retardation times for compression, higher cake compressibility, lower cake porosity and higher specific cake filtration resistance. The results demonstrated that immobilizing yeast cells on calcium alginate beads is beneficial for retaining higher yeast activity than that of freely suspended yeast. However, the activity levels of yeast immobilized using different calcium concentrations were nearly the same after 3 h. Therefore, using high concentrations of calcium for yeast immobilization is beneficial for improving yeast activity and filtration characteristics. 相似文献
108.
Tan Fırat Eyüboğlu Murat Türkün Necdet Erdilek Mutlu Özcan 《Journal of Adhesion Science and Technology》2016,30(14):1574-1584
This study evaluated the long-term microleakage of access cavities conditioned with phosphoric acid and deproteinizing agents for root-canal-treated teeth using fluid filtration and microscopical analysis. Occlusal surfaces of extracted human mandibular premolars (N = 90) were removed leaving a 4 mm coronal length from the cemento-enamel junction. After root canal treatment, the specimens were randomly divided into four experimental groups (n = 21) and the remaining teeth were used for positive control group (n = 6): SB: 35% H3PO4 + Adper Single Bond 2; SSB: 35% H3PO4 + 5.25% NaOCl + 10% Sodium ascorbate (C6H7NaO6) + Adper Single Bond 2; XP: 35% H3PO4+XP Bond; SXP: 35% H3PO4+5.25% NaOCl + 10% Sodium ascorbate + XP Bond. All cavities were restored with a resin composite (Filtek Z250). After removing the root filling from the apical side, teeth were subjected to fluid filtration test for 1 week, 6 and 12 months followed by ×2500 thermocycling after 1st week and 6th months each. Data were analyzed using one-way ANOVA and Dunnet T3 tests (α = 0.05). SEM analyses were carried out after each microleakage evaluation in two random teeth from all groups. Microleakage values in groups SB and XP presented no significant difference in any of the evaluated period (p > 0.05). Microleakage results of SXP (0.01665) group showed significant difference compared to XP (0.03377) and SB (0.03049) groups after 12 months. SSB group (0.00901) showed significantly less microleakage among all other groups (0.01665–0.03377) (p < 0.05). Prior to endodontic treatment, in access cavities, acid etching with 35% H3PO4 followed by the application of NaOCl and sodium ascorbate completely destroyed the collagen layer, reducing the microleakage and resin–dentin interface degradation up to 12 months. 相似文献
109.
In cake filtration processes with an air-blowing step, cracking is an undesirable phenomenon as it leads to deterioration of the filtration process by highly increasing gas throughput. This leads to higher residual moisture if the pressure difference cannot be maintained and an increase in overall cost. Crack formation can be avoided by compacting the filter cake before desaturation. While this action will make the separation process applicable by highly reducing gas consumption, there are also potential negative effects. Compaction increases filter cake resistance and might therefore slow down desaturation kinetics. Therefore, the authors investigated how the filter cake characteristics governing desaturation change from the nonconsolidated to the consolidated state of the filter cake and compared these findings to the actual dewatering kinetics. The results showed that for the case where cracking could be oppressed, dewatering kinetics of the consolidated cake are actually faster than for the nonconsolidated cake, despite higher resistance of the consolidated cake. Thus, compaction is an appropriate action when dealing with filter cake cracking. 相似文献
110.
通过模拟湿法磷酸实际生产过程中萃取工艺条件,研究了磷酸料浆液固质量比、稀磷酸浓度、料浆温度及真空度对料浆过滤强度的影响。结果表明:液固质量比对料浆的过滤效率无较大影响,稀磷酸浓度、料浆温度和真空度对过滤强度有较大影响,在稀磷酸w(P_2O_5)为24%、料浆温度为80℃时,料浆的过滤强度最大,而真空度可在保证生产能力的条件下选择最大值。 相似文献