Synthesis and Characterization of Y-Doped Mesoporous CeO_2 Using A Chemical Precipitation Method

Using cetyltrimethylammonium bromide （CTAB） as the template agent, cerium nitrate as the cerium resource, yttrium nitrate as the yttrium resource, and ammonium carbonate as the precipitating agent, mesoporous CeO2 powders doped with different yttrium contents were successfully synthesized using a chemical precipitation method, under an alkalescent condition. Properties of the obtained samples were characterized and analyzed with X-ray diffraction （XRD）, energy dispersive analysis of X-rays （EDAX）, transmission electron microscopy （TEM）, infrared （IR） absorbance, and the BET method. For the prepared samples with 20% （molar ratio） Y-doped content, a BET specific surface area of 106. 6 m^2 · g^- 1, with an average pore size of3~27 nm were obtained. XRD patterns showed that the doped samples were with a cubic fluorite structure. TEM micrographs revealed that the doped samples showed a spherical morphology with a diameter ranging from 20 to 30 nm and a round pore shape. IR results indicated that the Ce-O-Ce vibration intensity decreased as the Y-doped content increased. N2 adsorption-desorption isotherms showed that the samples possessed typical mesopore characteristics. The average pore size of the samples decreased alter mesoporous CeO2 was doped with yttrium, and the average pore size decreased largely as the Y-doped content increased.

Influence of chemical composition and cold deformation on aging precipitation behavior of high nitrogen austenitic stainless steels

The influence of chemical composition and cold deformation on aging precipitation behavior of 18Cr-16Mn-2Mo-I.IN （HNS-A）, 18Cr-16Mn-I.3N （HNS-B）, 18Cr-18Mn-2Mo-0.96N （HNS-C） and 18Cr-18Mn-2Mo-0.77N （I-INS-D） high nitrogen austenitic stainless steels was investigated. The results show that the ＂nose＂ temperatures and incubation periods of the initial time-temperature-precipitation （TTP） curves of aged HNSs are found to be 850 ℃, 60 s; 850 ℃, 45 s; 850 ℃, 60 s and 900 ℃, 90 s, respectively. Based on the analysis of SAD patterns, the coarse cellular Cr2N precipitate which presents a lamellar structure has a hexagonal structure of a=0.478 nm and c=0.444 nm. The Z phase corresponding to a composition of Fe36Cr^2Mo10, is determined to be a body-centered cubic structure ofa=0.892 nm. The precipitating sensitivity presents no more difference with the nitrogen content increasing from 0.77% to 0.96%, but exhibits so obviously that the cellular precipitates nearly overspread the whole field. The addition of Mo element can restrain the TTP curves moving left and down, which means decreasing the sensitivity of aging precipitation. With increasing the cold deformation, the sensitivity of precipitation increases obviously.

Synthesis of γ-Al_2O_3 nanoparticles by chemical precipitation method

Highly pure active γ-Al2O3 nanoparticles were synthesized from aluminum nitrate and ammonium carbonate with a little surfactant by chemical precipitation method. The factors affecting the synthesis process were studied. The properties of γ-Al2O3 nanoparticles were characterized by DTA, XRD, BET, TEM, laser granularity analysis and impurity content analysis. The results show that the amorphous precursor AI（OH）3 sols are produced by using 0.1 mol/L Al（NO3）3·9H2O and 0.16 mol/L （NH4）2CO3·H2O reaction solutions, according to the volume ratio 1.33, adding 0.024%（volume fraction） surfactant PEG600, and reacting at 40℃, 1000 r/min stirring rate for 15min. Then, after stabilizing for 24 h, the precursors were extracted and filtrated by vacuum, washed thoroughly with deionized water and dehydrated ethanol, dried in vacuum at 80℃ for 8h, final calcined at 800℃ for 1h in the air, and high purity active γ-Al2O3 nanoparticles can be prepared with cubic in crystal system, OH^7-FD3M in space group, about 9 nm in crystal grain size, about 20 nm in particle size and uniform size distribution, 131.35 m^2/g in BET specific surface area, 7 - 11 nm in pore diameter, and not lower than 99.93% in purity.

Treatment of Wet FGD Wastewater by a Modified Chemical Precipitation Method Using a Solid Powder Reagent

This research focused on developing a modified chemical precipitation (MCP) method for treating wet flue gas desulfurization (FGD) waste water by adding a solid powder reagent directly. Simulated wet FGD wastewater was treated by MCP method in simulation experiments. Optimization experiments were carried out with the help of response surface methodology (RSM) and central composite design (CCD) to evaluate the effects and the interactions of experimental variables, including reagent dosage, temperature and pH value. The optimal reagent dosage, temperature and pH value were 3018.0 mg/L, 40.5 °C and 5.7, respectively. The RSM was demonstrated as an appropriate approach for the optimization of wet FGD wastewater treatment with the MCP method. A comparative study between the MCP method and the traditional chemical precipitation (TCP) method on raw wet FGD wastewater treatment was conducted. Results indicate that the MCP had less reagent dosage and variety than the TCP method had. Thus, the MCP method had a lower cost. © 2017, Tianjin University and Springer-Verlag Berlin Heidelberg.

Effects of Heating Processing on Microstructure and Magnetic Properties of Mn-Zn Ferrites Prepared via Chemical Co-precipitation

The fine powders of Mn-Zn ferrites with uniform size were prepared via chemical co- precipitation method. X-ray diffraction analysis （XRD）, scanning electron microscopy （SEM）, vibrating sample magnetometer （VSM）, frequency dependence of permeability and metallographical microscope were used to investigate the crystal structure, surface topography and magnetic properties of the powders and the sintering samples. The experimental results demonstrate that the precursor powders have formed a pure phase cubic spinel MnxZn1-xfe2O4 while in the reactor and show definite magnetism, which can solve the difficult issue in washing process effectively. When calcined beneath 450 ℃, the powders have intact crystal form and the crystallite size is less than 20 nm. Comparison tests of sintering temperatures show that 1 300 ℃ is the ideal sintering temperature for Mn-Zn ferrites prepared by using the chemical co-precipitation.

Analysis of chemical composition of precipitation in a typical background site

background precipitation in Lijiang, China was investigated. Results showed that the chemical composition of atmospheric background precipitation mainly comes from fly ash and continental atmospheric transfer, and does not have any obvious correlation with oceanic aerosol, taking Amsterdam in the Pacific Ocean and St. Georges in the Atlantic Ocean and Katherine, Australia as examples for analysing.

Chemical characteristics of precipitation and wet deposition of major ions in Liaozhong County of Liaoning Province,Northeast China

The chemical characteristics of precipitation were analyzed based on the chemical composition of principal ionic within acid rain(from February 2007 to January 2008)of Liaozhong Meteorological Station located in Malong Village in Liaozhong County of Northeast China,meteorological conditions on the corresponding period ground,and variation of several air pollutants concentration.The results indicated that:(1)The precipitation average pH value of all samples was4.76;the frequency of acid rain during the observation period was 70.7%;the frequency was 82.8%in summer and autumn.(2)In the chemical composition of precipitation,the primary anions were SO_4^(2-)and NO_3^-;the primary cations were NH_4^+and Ca^(2+).(3)All concentration of anions was higher in summer and winter,but relatively low in spring and autumn.This showed that the relationship between regional rainfall acidification and pollution was not significant.(4)Rainwater acidity and nearly floor gaseous pollution concentration were different from each other,and pH and NO_x,CO,NO_2 and O_3concentrations showed significant negative correlation,but was not obvious with SO_2 concentration.However,the pH and alkaline pollutants,such as particulate,was positively correlative.

Gas sensitive properties of nanometer materials In_2O_3 synthesized by chemical precipitation

In2O3 nanoparticles were prepared from or with different indium salts by chemical precipitation under the conditions of various pH values. The crystal structure and ceramic microstructure of the samples were characterized by X-ray diffraction （XRD） and transmission electron microscopy （TEM）. The results show that the mean grain size of In2O3 is less than 100 nm, and their particle homogeneity and dispersibility are satisfactory. The gas sensitivity defined as Ra/Rg was detected in a static system. The results show that the sensors made by as-prepared nanoparticles has high sensitivity to many gases such as alcohol, HCHO, NH3 , et al. The response time is less than 20 s and the recovery time is lower than 30 s.

Soil Chemical Property Changes over Time from Struvite Compared to Other Fertilizer-Phosphorus Sources in Multiple Soils

Studies have shown that phosphorus (P) recovered from wastewater as the mineral struvite [MgNH4PO4·6(H2O)] may be a viable alternative fertilizer-P source. This study aimed to compare the effectiveness of electrochemically precipitated struvite (ECST), reclaimed from synthetic wastewater, to other commercial fertilizer-P sources in cultivated soils from Arkansas [AR;silt loam (SiL) and loam (L)], Missouri (MO;SiL), and Nebraska [NE;SiL and sandy loam (SL)]. A plant-less, moist-soil incubation experiment, including ECST, chemically precipitated struvite (CPST), monoammonium phosphate (MAP), triple superphosphate (TSP), and an unamended control (UC), was conducted to quantify soil pH, nitrate (NO3-N), ammonium (NH4-N), and Mehlich-3 (M3)-P, -Ca, -Mg, and -Fe concentrations at 0.5, 1, 2, 4, and 6 months. All measured soil properties differed (P ·kg-1 for AR-L-TSP after 1 month and NE-SiL-MAP after 6 months, respectively. Soil M3-P ranged from -29.6 mg·kg-1 in the AR-L-UC after 1 month to 429 mg·kg-1 AR-SiL-TSP after 0.5 months. Results showed that, over time, ECST had comparable pH and soil NO3-N, NH4-N, and M3-P, -Ca, -Mg, and -Fe behavior compared to CPST, MAP, and TSP across various soil textures.

沉淀法回收对甲酚模拟废水中酚的研究

用离子沉淀法回收对甲酚模拟废水中的酚,考察了不同的金属离子沉淀剂、沉淀剂加量、温度与pH值对酚去除率的影响。结果表明,最优的沉淀剂为BaCl_(2);对于50 mL、5000 mg/L的对甲酚模拟废水,当温度为25℃,pH值为14,BaCl_(2)溶液加量为18 mL,酚去除率可达52.3%。将收集的酚钡盐沉淀用稀HCl中和,用乙酸丁酯为萃取剂进行萃取,对甲酚的萃取回收率达到99.69%,为高含酚废水的资源化利用提供了思路和方法。

浅谈湿法冶炼锌中上清液净化沉钴方法与应用

本文主要介绍了湿法炼锌硫酸锌溶液中钴的沉淀方法、工艺及生产现状,对传统的沉钴方法及工艺存在的优势、缺陷进行了分析,综述了近几年来沉钴技术上的研究进展及取得的进步,有助于提高企业技术水平及经济效益。

磁分散固相萃取-高效液相色谱法检测人体尿样中天麻素

建立了一种磁分散固相萃取技术结合高效液相色谱法,用于快速检测人体尿液样本中的天麻素。采用化学共沉淀法自组装制备磁性活性炭/大孔树脂三元复合材料(Fe_3O_(4)/AC/MR),并将该材料用作吸附剂,实现尿液样本中天麻素的分离富集。在最佳实验条件下,天麻素浓度与峰面积间呈良好线性关系,线性范围为3.0×10^(-2)~10.0μg·mL^(-1),线性相关系数为0.9994,检出限为5.4μg·L^(-1)。以模拟人体尿液作为实际样品进行加标回收验证,加标回收率为94.87%~106.3%,相对标准偏差(RSD)在2.8%-4.2%之间。本研究建立的方法简便、快速、有效,为生物样本中天麻素的分离提纯提供了新方法。

基于两级强化化学混凝沉淀法的低浓度含氟工业废水深度除氟研究

针对低浓度含氟工业废水处理厂深度除氟至1.5 mg/L的需求,充分利用CaCl_(2)和废水处理厂内PAC、PAM等常规混凝剂及投加设施,考察在废水处理工艺流程的前端与尾端分别采用化学沉淀法除氟、一级/两级化学絮凝沉淀法除氟的效能。结果表明:化学沉淀法不适合处理低浓度含氟废水,投加200 mg/LCaCl_(2)仅能将[F-]由10 mg/L降至6.8 mg/L;一级化学混凝沉淀法采用120 mg/LCaCl_(2)+600 mg/L PAC+3 mg/L PAM组合投加,能将[F-]由10 mg/L降至3.8 mg/L;两级化学混凝沉淀工艺的除氟效率明显优于一级,将120 mg/L CaCl_(2)+600 mg/L PAC+3 mg/L PAM按1:1分两段投加时,能将[F-]由10 mg/L降至1.38 mg/L,可达到深度除氟的目标浓度1.5 mg/L。研究可为含氟工业废水处理项目提供深度除氟工艺设计参考。

Thermodynamic study on phosphorus removal from tungstate solution via magnesium salt precipitation method

The thermodynamic equilibrium diagrams of Mg2＋- 3-4PO - ＋4NH -H2O system at 298 K were established based on the thermodynamic calculation. From the diagram, the thermodynamic conditions for removing phosphorus from the tungstate solution by magnesium salt precipitation were obtained. The results show that when the concentration of total magnesium increases from 0.01 mol/L to 1.0 mol/L, the optimal pH for the phosphorus removal by magnesium phosphate decreases from 9.8 to 8.8. The residual concentration of total phosphorus almost keeps the level of 4.0×10-6 mol/L in the system. MgHPO4, Mg3（PO4）2 and the mixture of Mg3（PO4）2 and Mg（OH）2 are stabilized in these system, respectively. However, increasing the total concentration of magnesium has little effect on phosphorus removal by magnesium ammonium phosphate, while it is helpful for phosphorus removal by increasing the total ammonia concentration. The calculated results demonstrate that the residual concentration of total phosphorus can decrease to 5.0×10-7 mol/L as the total concentration of ammonia reaches 5.0 mol/L and the optimal pH value is 9-10. Finally, verification experiments were conducted with home-made ammonium tungstate solution containing 50 g/L WO3 and 13 g/L P. The results show that when the dosage of MgCl2 is 1.1 times of the theoretical amount, the optimum pH for removing phosphorus is 9.5, which matches with the results of the theoretical calculation exactly.

沈阳市大气降水污染与沉降特征的城郊差异

为了解沈阳地区大气降水污染与沉降特征的城郊差异,对2018~2022年沈阳市铁西区站点(城市)和苏家屯站点(郊区)降水样品的电导率、pH值和各种水溶性离子浓度及其沉降量进行了研究.结果表明,观测期间两站点平均pH值分别为7.12(6.09~8.36)和7.11(5.88~8.19),均呈碱性,无酸性降水.城郊站点的降水电导率和总水溶性离子平均浓度差异不大,2018~2022年期间整体呈现下降趋势.沈阳两站点的相对酸度(FA)均值为0.0004,(Ca^(2+)+NH_(4)^(+))/(SO_(4)^(2-)+NO_(3)^(-))均值分别达到了1.57和1.61,表明碱性离子的中和能力较强.大气降水中NO_(3)^(-)/SO_(4)^(2-)的比值介于0.41~0.58,SO_(4)^(2-)-S湿沉降量分别是NO_(3)^(-)-N和NH_(4)^(+)-N沉降量的1.14倍~2.20倍,表明沈阳大气降水主要以硫沉降为主.城市站的无机氮沉降量总体上高于郊区站,其中NH_(4)^(+)-N平均沉降量分别是NO_(3)^(-)-N的1.74和1.78倍,说明沈阳市大气降水中的无机氮以还原态氮占主导,这主要与汽车尾气、城市绿地养护、人体排泄物以及郊区频繁的农业活动相关.

退役锂电池回收废液制备磷酸锂工艺研究

鉴于锂电池报废量大、锂含量高,探讨从退役锂电池回收废液中利用锂资源。根据溶液高钠含锂、碱含量高的特性,采用磷酸钠沉淀法回收锂,系统研究了反应过程中各工艺参数对磷酸锂回收率、纯度及粒度的影响。结果表明反应温度为102℃,磷酸钠1.1倍理论用量,磷酸钠浓度350 g·L^(-1),加料速率5 mL·min-1,搅拌速率500 r·min-1,冷水洗1 L时,磷酸锂收率能达到92.63%,纯度(质量分数,下同)达到98.81%,产品达到彩色荧光粉用磷酸锂行业标准二级要求。该工艺能广泛应用于各种高钠含锂溶液,特别是从锂浓度较低的溶液中回收锂资源,不仅解决了退役锂电池废液排放问题,还为锂资源提取提供了新途径。

铝掺杂氧化锌纳米粉末制备及其对PET的抗静电改性

采用化学共沉淀法制备了不同含量的Al单元掺杂氧化锌(AZO)纳米粉体,并将自制的纳米AZO粉末用于聚对苯二甲酸乙二酯(PET)制备,以提高PET的抗静电性能。利用X射线行射、扫描电子显微镜、热重分析、表面电阻测试仪等测试手段,探究了Al单元掺杂对AZO粉体结构、形貌及电性能的影响。在PET制备过程中加入AZO,探究AZO对PET抗静电性能的影响。结果表明:所制备的AZO纳米粉体为结晶度良好的六方纤锌矿结构。Al掺杂浓度影响AZO粉体形貌、晶体结构及电性能。随着Al掺杂浓度的增加,粉体的结晶质量降低,电性能先变好后变差,粉体尺寸变大,出现团聚、结块现象。适度的Al掺杂可使AZO电阻率达到最低,改善AZO的导电性能。在Al掺杂浓度为2%时,AZO纳米粉体的电性能最佳,电阻率为5.3×10^(4)Ω/m^(2)。使用制备的AZO纳米粉末作为导电填料能有效改善PET的抗静电性能,降低PET/AZO复合材料的表面电阻率,使材料由绝缘体转变为静电耗散体,抗静电性能增强。AZO填充量在0.005%时复合材料的表面电阻率最低,为1.16×10^(10)Ω/m^(2)。

高含蜡原油聚烯烃降凝防蜡剂的合成及性能评价

以丙烯酸十八酯(ODA)、十八烯(ODE)和苯乙烯(SM)为单体合成三元共聚物P(ODA-co-ODE-co-SM),以其为主剂合成了聚烯烃降凝防蜡剂POOS,对三元共聚物的合成条件进行了优化,并对加剂前后原油流变性、析蜡特性、微观形态以及降凝防蜡效果进行了评价。结果表明,三元共聚物最优的合成工艺条件为n(ODA)∶n(ODE)∶n(SM)=5∶3∶2、引发剂过氧化苯甲酰含量(以丙烯酸十八酯、十八烯和苯乙烯总质量为基准,下同)为5‰、反应温度70℃、反应时间8h。当POOS质量浓度为200mg/L时,原油流变性与未加POOS原油相比变化明显,15℃下加剂前后屈服应力为50.30和2.95 Pa,屈服应力降幅为94%,析蜡温度由31.33℃降至24.94℃,凝点由25℃降至15℃,加剂后冷指测试防蜡率为88.00%,环道测试防蜡率为83.70%,蜡晶形态由针状转变为圆状结晶,加剂后蜡晶析出分布不均匀,多个微小蜡晶聚集析出形成单个聚集体,POOS的加入有效改善了蜡晶分散形态,抑制网状结构形成,显著改善了原油低温流动效果。

硫酸亚铁废液的综合回收利用

在工业生产中每年都会产生大量的硫酸亚铁废液,其中钢铁深加工过程的产出量最大。硫酸亚铁废液中含有硫酸,pH值较低,且含有铁、钴、镍、铝、铬等金属离子,直接排放不仅浪费其中的金属资源,还会对土壤和水体造成严重污染。综合回收硫酸亚铁废液对企业具有巨大的经济效益,对社会具有一定的环境效益。目前主要的处理方法有中和处理法、化学沉淀法、结晶析出法、溶剂萃取法、微生物法等。针对不同生产过程产生的硫酸亚铁废液应采用相应的处理办法。由于中和处理法产生大量金属污泥、结晶析出法的产品市场需求低、溶剂萃取法处理能力低、微生物法处理周期长,化学沉淀法是目前主要采用的回收方法。化学沉淀法操作简单、无需高性能设备,但试验影响因素多,产品性质波动大。硫酸亚铁废液回收产品主要被应用于颜料行业、水处理行业、磁性材料行业等。多数产品仅利用了废液的铁元素,而硫酸和硫元素并未得到回收利用,如何对废液进行综合回收是一个研究重点。由于硫酸亚铁废液中杂质元素含量较多,对其进行提纯具有很大的难度,所需生产成本也较高,因此如何直接利用废液也是未来研究的主要方向。