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31.
通过优化的PVA-H3BO3包埋法制备了抗菌PVA小球,并用新制备的小球填充柱床进行水处理研究. 结果表明:抗菌PVA小球具有良好的杀菌性能,在杀生剂添加量为m(杀生剂)∶m(PVA)3∶2时,杀菌率达到(92±2)%;扫描电子显微镜显示,包埋了杀生剂的抗菌PVA凝胶小球是一种多孔性的球形颗粒,结构较密实,并且包埋效果理想. 随着填充高度的升高、处理液与抗菌材料接触时间(停留时间)的延长、处理液出口端流量的减小, 填充柱的杀菌性能逐渐升高;对于30mm×300mm的填充柱,当填充高度≥20cm, 停留时间≥0.5 h,出口端流量为2.7 mL/s时, 杀菌效果较好. 对于50mm×500mm的填充柱,在填充高度为10 cm,停留时间为0.5 h,出口端流量为2.7 mL/s时,其杀菌率为(93±1)%. 相似文献
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聚乙烯醇降解酶酶解聚乙烯醇最优条件研究 总被引:1,自引:0,他引:1
为了提高聚乙烯醇(PVA)降解酶的催化降解能力,对假单胞菌Pseudomonas.sp XT11-Z90S产生的聚乙烯醇降解酶的降解条件进行了优化.同时,通过单因素实验研究了PVA浓度、温度、缓冲液pH对降解酶活性及PVA降解率的影响.最后,应用响应面分析方法对影响聚乙烯醇降解酶酶活的3个因素进一步优化.结果表明,单因素实验得出的适宜PVA浓度、温度、pH分别为1.0g·L-1、50℃、7.0.响应面分析法得出的最适的降解条件为:PVA浓度0.84g·L-1,温度53.5℃,pH值6.8.在最优条件下,PVA降解酶酶活达到了20.3U.mL-1,比优化前的12.2U.mL-1提高了66.4%.且6h后其降解率达到了52.6%. 相似文献
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The contribution of aliphatic-rich plant biopolymer to sorption of hydrophobic organic compounds is significantly important because of their preservation and accumulation in the soil environment,but sorption mechanism is still not fully understood.In this study, sorption of 1-naphthol by plant cuticular fractions was examined to better understand the contributions of respective fraction.Toward this end,cuticular materials were isolated from the fruits of tomato by chemical method.The tomato cuticle sheet consisted of waxes (6.5 wt%),cuticular monomer (69.5 wt%),and polysaccharide (24.0 wt%).Isotherms of l-naphthol to the cuticular fractions were nonlinear (N value (0.82-0.90)) at the whole tested concentration ranges.The KodKow ratios for bulk cuticle (TC1),dewaxed cuticle (TC2),cutin (TC4),and desugared cuticle (TC5) were larger than unity,suggested that tomato bulk cuticle and cutin are much powerful solption medium.Sorption capability of cutin (TC4) was 2.4 times higher than the nonsaponifiable fraction (TC3).The 1-naphthol interactions with tomato cuticular materials were governed by both hydrophobic-type interactions and polar (H-bonding) interactions. Removal of the wax and polysaccharide materials from the bulk tomato cuticle caused a significant increase in the sorption ability of the cuticular material.There was a linear negative trend between K_(oc) values and the amount of polysaccharides or fraction's polarities ((N O)/C);while a linear positive relationship between K_(oc) values and the content of cutin monomer (linear R~2=0.993) was observed for present in the cuticular fractions.Predominant sorbent of the hydrophobic organic compounds (HOCs) in the plant cuticular fraction was the cutin monomer,contributing to 91.7% of the total sorption of tomato bulk cuticle. 相似文献
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A New Type Synthetic Filter Material for Biofilter: Preparation and its Characteristic Analysis 总被引:1,自引:0,他引:1
In this study, a new type poly(vinyl alcohol)/peat composite bead is prepared and is shown suitable as a filter material for biofiltration. The optimal preparation condition is with the peat size of 16–35 mesh, the ratio of water to peat of 40g water/10 peat and the immersion time in the phosphate solution of 30min. The composite bead prepared by this process is a porous spherical particle with a density of 0.692 g/cm3. It contains phosphor and nitrogen nutrient are 2.91mg P/g dry solid and 3.25mg N/g dry solid, respectively. The diameter of composite bead is between 2.4 and 6.0mm and the average diameter is about 4.0mm. The equilibrium moisture content of the bead from adsorption and holding experiments are 50.5 and 66.8% on a wet basis, respectively, corresponding to the optimal filter material required and is sufficient to sustain biological activity as the bead adsorbs equilibrium moisture. The composite bead has higher moisture holding capacity and the compression strength than the pig manure compost filter material. The composite bead has buffer capacity and could maintain the filter bed at pH = 6.9–7.2 during the operation period. The percentage of removed ethyl acetate could stay at over 99% for 33 days operation while the composite bead adsorbed inorganic nitrate nutrient. 相似文献
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Yan Kong Yuan Zhuang Zhiyong Han Jianwei Yu Baoyou Shi Kun Han Haotian Hao 《环境科学学报(英文版)》2019,31(4):81-91
Hydrogels have attracted large attention in wastewater treatment fields due to their low-cost and good interaction with pollutants, among which novel double network hydrogel is an outstanding class. To expand the application of double network hydrogel in water treatment, in this study, eco-friendly physically cross-linked double network polymer hydrogel beads (DAP) are prepared and studied in depth on the mechanism of Methylene Blue (MB) adsorption; and then the polymer hydrogels are further functionalized by inorganic materials. MB adsorption on DAP favors alkaline condition which is due to the increase of electrostatic attraction and adsorption site, and it reaches equilibrium within 10?hr, which is faster than that of the single network hydrogel beads (SAP). Through thermodynamics study, the process shows to be an exothermic and spontaneous process. The adsorption isotherms are well fitted by Langmuir model, with a maximum monolayer adsorption capacity of 1437.48?mg/g, which is larger than SAP (1255.75?mg/g). After being functionalized with common inorganic materials including activated carbon, Fe3O4 and graphene oxide (GO), the composites show to have larger pore sizes and have obvious increases in adsorption capacity especially the one contains GO. Then the composites contains Fe3O4 are used as heterogeneous Fenton catalyst which shows to have excellent performance in MB degradation. The results indicate the potential of polymer double network to be functionalized in environmental areas. 相似文献
39.
以某化工企业的聚氯乙烯分厂为研究对象,引入美国环境保护署(EPA)推荐的健康风险评价四步法,即危害鉴定、剂量-反应评价、暴露评价和风险表征,对不同作业任务(清釜、看釜、巡检和配料)工人的氯乙烯职业暴露进行健康风险评价。结果表明,从非致癌效应来看,看釜、巡检和配料岗位工人暴露于VC引起肝细胞多态性的HI值均高于安全阈值1,其中看釜工的危害指数最大,引起的不利健康效应最严重。从致癌效应来看,清釜工暴露于VC引起肝血管肉瘤的风险处于可接受水平;而看釜工患肝血管肉瘤的风险值R,达到可接受上限10-4对应的工作年限ED=1.91 a,因此,需要尽可能地采用安全防护措施减少该岗位的职业暴露。巡检和配料岗位的肝血管肉瘤风险达到可接受水平上限10-4时,对应的工作年限分别为4.36 a和9.33 a。由于健康风险评价更侧重长期暴露危害物质对人体健康的影响,即使工作场所满足国标规定的浓度阈值,仍然存在工人长期暴露于低浓度致癌物的风险。 相似文献
40.
Wu-Chung?ChanEmail author Rui-Xiang?Zheng 《Journal of Polymers and the Environment》2005,13(3):267-277
In this study, a Poly(vinyl alcohol)(PVA)/compost composite bead is prepared and is indicated suitable as a filter material for biofiltration. The optimal preparation process is with the compost size of 16–35 mesh, the ratio of water to compost of 40 g/15 g compost, and the immersion time in the phosphate solution of 60 min. The composite bead prepared by this process is a porous spherical particle with a diameter between 2.4 and 6.0 mm and a density of 0.96 g/cm3. It contains 9.43 mg P/g dry solid and 12.1 mg N/g dry solid. The equilibrium moisture content of the composite bead bed from adsorption and holding experiments is 50.5 and 54.6% on a wet basis respectively, which is about 1.74 times higher than that of swine manure compost bed. It corresponds to the optimal filter material required and is sufficient to sustain biological activity as the composite bead adsorbs equilibrium moisture. The bulk compressive strength of the composite bead bed is about 1.15 times larger than that of swine manure compost bed to ensure even distribution of air flow and reduce the head loss as the air flow stream passed through. The pH value of the filter bed could maintain in the 6.9–7.2 range during the operation period due to the composite bead has the phosphate buffer capacity. The percentage of ethyl acetate removal could remain at over 99% for 40 days operation while the composite beads adsorbed inorganic nitrate nutrients. The pressure drop of two kind composite beads and pig manure compost filter beds are 0 and 2 mm H2O, respectively, after operating for 40 days. 相似文献