粒径精确调控的微胶囊催化材料制备及应用

提出基于核材与壳材粒径双调控的微胶囊催化材料制备新思路,通过旋风分级和气力乳化聚合工艺优化,最终实现微胶囊的粒径调控。重点考察了气力乳化工艺参数和核材粒径、核壳材料质量比等对微胶囊平均粒径、粒径分布和包覆率的影响。实验结果表明:当气力乳化的气体流速为1.12 m·s~(-1)时,壳材液滴的融合和乳胶粒的粘并现象均较少,聚合体系可较稳定地保持均质化壳材液滴的尺寸;在保证高包覆率的条件下,核材粒径影响着微胶囊的平均粒径,核材粒径为15.4μm时,制备出的微胶囊平均粒径最小;核壳材料质量比对微胶囊粒径的影响明显,其为1:3.5时,微胶囊材料平均粒径为180μm;亲水亲油平衡值(HLB)对粒径调控能力有限,平均粒径最小时微胶囊包覆率最大。通过对乳化聚合工艺和配方的综合调节,可制得一系列粒径可调范围大,粒径均一,包覆率高的微胶囊材料,应用于烟气脱硝,温度600℃条件下,NO?转化率可达92%。     

硬脂酸改性磁铁矿在含油污水处理中的应用

研究了水溶液中硬脂酸改性后磁铁矿吸附石油的特性,测定了温度、改性剂用量和时间等因素对改性以及吸附的影响,并对吸附后磁铁矿进行了再生。通过对红外图谱、扫描电镜图谱等的分析,对改性及吸附机理进行了探讨。结果表明,硬脂酸改性磁铁矿的最佳改性条件为常温20℃,改性时间45 min,改性剂用量硬脂酸与磁铁矿的质量比为4%,改性过程中伴随着物理和化学变化,硬脂酸在磁铁矿表面形成了双分子层包覆。改性后的磁铁矿表面湿润性降低,改性磁铁矿吸附石油符合Langmu ir型吸附等温线,最大吸附量为749.23 mg/g,最大去除率达93%。对饱和吸附后的改性磁铁矿经再生处理后,石油去除率稳定在85%。     

活性粉末脱硝剂制备及其催化还原NO_x性能

采用熔化分散冷凝法微胶囊技术以蜂蜡为壳材包覆高锰酸钾作为活性添加剂,铵盐、干燥剂、活性添加剂和助燃剂以100∶25∶2∶1的比例混合制备粉末脱硝剂,将其喷入模拟烟气中进行催化还原NO_x实验并确定了最佳反应条件:当模拟烟气流量为4.8 m~3·h~(-1),反应温度600~900℃,氨氮物质的量之比1.15∶1,活性添加剂质量分数1.5%,进口烟气NO浓度为500 mg·m~(-3)时,NO_x转化率最高,可达90%以上。活性粉末催化还原NO_x反应温度窗口宽、NO_x转化率高,投资低,有望适应我国中小型燃煤锅炉脱硝需求。     

包覆型纳米零价铁的制备及其去除水中的活性艳蓝

采用流变相法,以FeSO4.7H2O∶KBH4=1∶2(摩尔比)为固相介质,0.06 g/mL CMC(羧甲基纤维素)水溶液为液相介质,固液比1∶2,反应2 h制备出包覆型纳米零价铁;采用XRD、TEM等手段对合成的纳米零价铁进行表征。探讨不同反应条件对包覆型纳米铁去除活性艳蓝的影响。实验结果表明,初始活性艳蓝(浓度100 mg/L)pH为5,包覆型纳米铁的投加量为6 g/L,反应时间为30 min时,活性艳蓝的去除率可达96%。通过研究机理,其吸附过程符合二级吸附动力学,降解过程符合一级反应动力学。     

KMnO4缓释剂的释放性能及其在垃圾渗滤液处理中的应用

为延长KMnO4在地下水原位修复中的作用时间,通过改变KMnO4与石蜡的分散方式以及KMnO4与石蜡的质量比(P/W),对KMnO4缓释剂的制备过程进行了优化.采用超声与搅拌联用(搅拌速度150 r/min)的分散方式更有利于KMnO4的均匀分布,随着P/W的升高,KMnO4负载量逐渐增大而绝对回收率逐渐减小.静态实验分别研究了缓释剂在8℃、不同pH与DO浓度下的释放性能.结果表明,在8℃环境下,缓释剂仍具有释放性能;缓释剂受pH影响较大而受DO浓度影响较小.利用缓释剂降解垃圾渗滤液中的COD以及对沉淀物进行定量分析.结果表明,缓释剂对COD去除率可高达57.1％,而沉淀量最少仅为投加纯KMnO4的8.5％.     

纳米聚硅酸铝锌絮凝剂的制备及应用

将制备出的聚硅酸铝锌絮凝剂纳米化,在正交实验和单因素优化的基础上,研究了表面活性剂硬脂酸钠的加入量、超声频率、超声时间及投加量对絮凝剂絮凝效果的影响,并且考察了pH、投加量对印染废水的处理效果的影响。结果表明,超声时间对絮凝效果影响最大,超声频率次之,硬脂酸钠含量影响最小。纳米聚硅酸铝锌絮凝剂的最佳制备条件为：表面活性剂硬脂酸钠加入量为0．1％、超声频率为40Hz、超声时间为60min;考虑处理费用,处理印染废水时pH=6～9、投加量为5mL／250mL时效果较好,浊度去除率可达98．5％,色度去除率可达97．4％。     

棕刚玉渣的硬脂酸湿法改性

以棕刚玉渣、硬脂酸为原料,在乙醇体系中进行机械力化学改性研究。分别研究了球磨过程中球料比、球磨时间、转速、硬脂酸用量、浆料浓度等参数对实验样品亲油化度、活化指数的影响。在最佳工艺基础上进行了正交实验,实验结果表明,适宜条件为硬脂酸用量3.5%,球料比4∶1,球磨时间30 min,球磨转速450 r/min,浆料浓度25%时,实验样品的亲油化度和活化指数分别达到46.8%和100%,且完全疏水。     

饮用水源突发性苯胺污染应急处理技术研究

分别从水样浓度、pH、反应时间、药剂投加量以及两者联用时的投加顺序等方面研究了粉末活性炭、高锰酸钾以及两者联合使用时对苯胺的去除效果.结果表明,当污染发生时,高锰酸钾和粉末活性炭联用处理技术是可行的;先投加粉末活性炭再加高锰酸钾处理比先投加高锰酸钾再投加活性炭的去除效果好;当水样pH在中性条件下,粉末活性炭和高锰酸钾联用处理技术的去除效果好;应急处理的反应时间是30 min.     

高锰酸钾降解地下水中PCE的研究

以氯代有机污染物中常见的PCE为目标污染物,以自制高锰酸钾溶液为氧化剂,采用批实验方法,探讨了高锰酸钾降解PCE的反应动力学、影响因素以及反应机理。反应结果表明,高锰酸钾降解PCE的反应符合一级动力学方程,反应活化能E为57.119 kJ/mol,在30℃条件下,反应速率常数为0.0076 min^-1,半衰期为91.20 min。在pH在3～10,离子强度在0～0.1030 mol/L之间变化时,反应速率不受明显影响。     

紫外光协助高锰酸钾降解四环素的研究

高锰酸钾氧化法在实际水处理中得到了一定的应用,但对有机污染物的去除和降解能力相对有限,为此提出了以外加紫外光照射协助高锰酸钾氧化的方法。以四环素作为模型污染物,考察了四环素浓度、高锰酸钾浓度、反应时间、初始pH条件和不同紫外光照射等的影响。结果表明,高锰酸钾能够氧化并去除四环素,紫外光照射明显提高了高锰酸钾对四环素的降解效果,并且254 nm紫外光照射对降解的促进作用远大于365 nm紫外光。在所考察的pH范围内,无论紫外光照射与否,高锰酸钾在酸性条件下的降解效率最高,中性条件较高,碱性条件次之。     

Modification of cloud condensation nucleus activity of organic aerosols by hydroxyl radical heterogeneous oxidation

The modification of cloud condensation nucleus (CCN) activity of saturated organic particles resulting from heterogeneous oxidation by OH radicals was studied. Submicron Bis-2-ethylhexyl sebacate (BES) and stearic acid particles were exposed to OH radicals in a reactor flow tube and CCN activity was monitored. The hygroscopicity parameter, κ, for monodisperse stearic acid and BES particles of 145–150 nm in size increased from <0.008 up to 0.08 as a result of OH exposures equivalent to atmospheric exposure timescales of several days to a week. The oxidation of stearic acid particles led to a 50% reduction in particle volume at high OH exposures, indicating an enhanced degree of volatilization of oxidation products compared to oxidized BES particles, along with possible shape/phase change. Surface tension measurements of water extracts of oxidized BES films showed a significant reduction in surface tension due to oxidation. Köhler calculations modeling the CCN measurements suggest that the surface active oxidation products play an important role.     

Controlled-release formulations of cyromazine-lignin matrix coated with ethylcellulose

An encapsulation system was developed and designed to give long-lasting effectiveness of the insect growth regulator cyromazine. Cyromazine was incorporated in lignin-poly (ethylene glycol) (PE) controlled-release formulations by means of a melting process. The basic formulation [lignin (65%)–PE (20%)–cyromazine (15%)] was coated in a Wurster-type fluidized-bed equipment using two different amounts of ethylcellulose. That of the highest one was modified by the addition of a plasticizer, dibutyl sebacate (DBS). The effect on cyromazine release rate caused by the incorporation of ethylcellulose and DBS in lignin-PE formulation was studied by immersion of the granules in water under static conditions. Using an empirical equation, the time taken for 50% of the active ingredient to be released into water (T₅₀) was calculated. From the analysis of the T₅₀ values, the influence of ethylcellulose appears clearly defined, observing a delay in release rate of cyromazine with respect to the basic lignin-PE formulation. In addition, the granules coated with ethylcellulose and the plasticizer lead the slowest release rate into water. The release of cyromazine into water is controlled by a diffusion mechanism. The thickness and permeability of the coating film are the most important factors that affect cyromazine release.     

Controlled-release formulations of cyromazine-lignin matrix coated with ethylcellulose

An encapsulation system was developed and designed to give long-lasting effectiveness of the insect growth regulator cyromazine. Cyromazine was incorporated in lignin-poly (ethylene glycol) (PE) controlled-release formulations by means of a melting process. The basic formulation [lignin (65%)-PE (20%)-cyromazine (15%)] was coated in a Wurster-type fluidized-bed equipment using two different amounts of ethylcellulose. That of the highest one was modified by the addition of a plasticizer, dibutyl sebacate (DBS). The effect on cyromazine release rate caused by the incorporation of ethylcellulose and DBS in lignin-PE formulation was studied by immersion of the granules in water under static conditions. Using an empirical equation, the time taken for 50% of the active ingredient to be released into water (T(50)) was calculated. From the analysis of the T(50) values, the influence of ethylcellulose appears clearly defined, observing a delay in release rate of cyromazine with respect to the basic lignin-PE formulation. In addition, the granules coated with ethylcellulose and the plasticizer lead the slowest release rate into water. The release of cyromazine into water is controlled by a diffusion mechanism. The thickness and permeability of the coating film are the most important factors that affect cyromazine release.     

新型复合预氧化技术控制副产物的试验研究

臭氧被广泛应用于饮用水预氧化工艺中,但是成本较高,而且会生成臭氧化副产物,如可同化有机碳(AOC)、溴酸盐和甲醛.因此,提出臭氧/高锰酸钾复合预氧化技术,并对照预臭氧化技术,进行了消毒副产物前质及臭氧化副产物控制的小试试验研究.结果表明,与预臭氧化(1.5 mg/L臭氧)相比,复合预氧化(0.6 mg/L臭氧 0.4 mg/L高锰酸钾)能促进混凝沉淀对消毒副产物前质的去除,总去除率与单独预臭氧化的去除率相当.而且又能降低AOC生成量,并促进混凝沉淀对AOC的去除,合计AOC去除率达43%左右.此外,对溴酸盐和甲醛生成量也有明显去除效果,比单独预臭氧化降低了78.4%和21.2%.     

Modifying sorbents in controlled release formulations to prevent herbicides pollution

The herbicides chloridazon and metribuzin, identified as groundwater pollutants, were incorporated in alginate-based granules to obtain controlled release properties. In this research the effect of incorporation of sorbents such as bentonite, anthracite and activated carbon in alginate basic formulation were not only studied on encapsulation efficiency but also on the release rate of herbicides which was studied using water release kinetic tests. In addition, sorption studies of herbicides with bentonite, anthracite and activated carbon were made. The kinetic experiments of chloridazon and metribuzin release in water have shown that the release rate is higher in metribuzin systems than in those prepared with chloridazon, which has lower water solubility. Besides, it can be deduced that the use of sorbents reduces the release rate of the chloridazon and metribuzin in comparison to the technical product and to the alginate formulation without sorbents. The highest decrease in release rate corresponds to the formulations prepared with activated carbon as a sorbent. The water uptake, permeability, and time taken for 50% of the active ingredient to be released into water, T(50), were calculated to compare the formulations. On the basis of a parameter of an empirical equation used to fit the herbicide release data, the release of chloridazon and metribuzin from the various formulations into water is controlled by a diffusion mechanism. Sorption capacity of the sorbents for chloridazon and metribuzin, ranging from 0.53mgkg(-1) for the metribuzin sorption on bentonite to 2.03x10(5)mgkg(-1) for the sorption of chloridazon on the activated carbon, was the most important factor modulating the herbicide release.     

Sampling Submicrometer Particles Suspended in Near Sonic and Supersonic Free Jets

This paper is concerned with sampling submicrometer particles in perisonic flows. The study employed a high volume (30-45 L/min) condensation aerosol generator to produce stearic acid particles having a mean diameter of 0.8μm and a geometric standard deviation of 1.28. The aerosol was diluted with dry air and accelerated to Mach 0.6, 0.8, 1.26, or 1.47 through a flow nozzle. Aerosol mass concentrations were determined using a small bore probe in the jet and by a large bore probe sampling isokinetically upstream of the jet nozzle. The results of both samples were compared to compute the sampling error associated with I ho high spood jot sample. The mass of stearic acid colloctod on polycarbonate mombrono flltors was determined by gravimoirlc and chromalogrophlc mothods. Studies at Mach 0.8 with four sampling probes having Inlet wall to bore area ratios ranging from 3.8 to 0.28 (a knife edge) demonstrated that probe wall thickness effects are not significant when the sample is extracted isokinetically. Subisokinetic experiments using the knife edged probe showed relative errors of 124 ± 12% when sampling at 2 0% of the isokinetic condition. The subisokinetic results are compared favorably with the extended empirical results of other authors. For the supersonic cases it is shown that the subsonic velocity downstream of the sampling probe bow shock can be used in estimating the sampling error.     

Transport characteristics of gas phase ozone in unsaturated porous media for in-situ chemical oxidation

Encapsulation technology is being investigated as a method for controlling pH in situ at contaminated groundwater sites where pH may limit remediation of organic contaminants. This study examined the effectiveness of using KH2PO4 buffer encapsulated in a pH-sensitive coating to neutralize pH in laboratory sand columns (1.5-1) under a simulated groundwater flow rate and characterized the pattern of capsule release in the flow-through system. Denitrification was used in the columns to increase the pH of the pore water. Each of three columns was equipped with three miniature mesh wells to allow contact of the buffer with column pore water, but capsules (15 g) were inserted into only one column (amended). The two other columns served as amendment (no buffer) and abiotic (no denitrification) controls. Oxidation-reduction potential, dissolved organic and inorganic carbon, NH4+, NO3- +NO2-, PO(4)3-, and pH were measured in the influent, two side ports, and effluent of the columns over time. Near complete conversion of 80 mg N/1 of nitrate and 152 mg/l of ethanol per day resulted in a mean pH increase from 6.2 to 8.2 in the amendment control column. The amended column maintained the target pH of 7.0 +/- 0.2 for 4 weeks until the capsules began to be depleted, after which time the pH slowly started to increase. The capsules exhibited pulses of buffer release, and were effectively dissolved after 7.5 weeks of operation. Base-neutralizing capacity contributed by the encapsulated buffer over the entire study period, calculated as cation equivalents, was 120 mM compared to 8 mM without buffer. This study demonstrates the potential for this technology to mediate pH changes and provides the framework for future studies in the laboratory and in the field, in which pH is controlled in order to enhance organic contaminant remediation by pH-sensitive systems.     

负载壳聚糖膨润土的制备及其吸附性能的影响

以天然膨润土和壳聚糖为原料,制得一种新型水处理剂——负载壳聚糖膨润土,研究了制备条件对酸性大红印染废水处理效果的影响。实验表明,当壳聚糖的浓度为30 g/L、膨润土质量与壳聚糖溶液体积之比为0.7、浸泡时间80 min、微烘时间15 min时,壳聚糖改性膨润土对酸性大红印染废水的脱色率可达97%。对改性土进行比表面积测定、电镜扫描及X-射线衍射等结构特性分析,证明壳聚糖的引入改变了膨润土在水中的分散状态,增强了其对污染物的吸附和离子交换能力。     

Development of controlled release formulations of azadirachtin-A employing poly(ethylene glycol) based amphiphilic copolymers

Controlled release (CR) formulations of azadirachtin-A, a bioactive constituent derived from the seed of Azadirachta indica A. Juss (Meliaceae), have been prepared using commercially available polyvinyl chloride, polyethylene glycol (PEG) and laboratory synthesized poly ethylene glycol–based amphiphilic copolymers. Copolymers of polyethylene glycol and various dimethyl esters, which self assemble into nano micellar aggregates in aqueous media, have been synthesized. The kinetics of azadirachtin-A, release in water from the different formulations was studied. Release from the commercial polyethylene glycol (PEG) formulation was faster than the other CR formulations. The rate of release of encapsulated azadirachtin-A from nano micellar aggregates is reduced by increasing the molecular weight of PEG. The diffusion exponent (n value) of azadirachtin-A, in water ranged from 0.47 to 1.18 in the tested formulations. The release was diffusion controlled with a half release time (t_1/2) of 3.05 to 42.80 days in water from different matrices. The results suggest that depending upon the polymer matrix used, the application rate of azadirachtin-A can be optimized to achieve insect control at the desired level and period.