5 research outputs found
Study on Preparation Process of Silica Flatting Agent by Precipitation Method
本文以Na2SiO3•9H2O、H2SO4为基本原料,采用沉淀法路线合成白炭黑消光剂。通过正交实验考察了硅酸钠质量分数、硫酸浓度、表面活性剂添加量、反应温度等制备工艺条件对白炭黑消光剂的比表面积和孔容的影响。实验结果表明:影响(a)比表面积和(b)孔容的因素排序分别是:(a)硫酸浓度>硅酸钠质量分数>反应温度>表面活性剂添加量;(b)反应温度>硫酸浓度>表面活性剂添加量>硅酸钠质量分数。 根据正交实验的分析结果,确定了较优实验区间,分别设计进行了考察白炭黑消光剂比表面积和孔容的单因素实验。并在单因素实验中增加考察了反应pH值、盐析剂添加量、后处理试剂、干燥方式等因素对白炭黑消光剂...Silicas were successfully prepared from aqueous solutions of sodium silicate and sulfuric acid using precipitation method. The aim was to study the effects of various factors in the preparation process on the specific surface area and pore volume by the orthogonal experiments. The factors include temperature, concentration of sulfuric acid, mass fraction of sodium silicate, surfactants. The ...学位:工程硕士院系专业:化学化工学院_化学工程学号:2062010115147
Preparation of agricultural low-cost super water absorbent
概述了合成类吸水树脂在农用上的进展,提出采用低成本且工艺成熟的水溶液法,以丙烯酸(AA)、丙烯酰胺(AM)为基体、接枝可溶性淀粉进行三元单体共聚,经钠基膨润土改性,复合引发剂、复合交联剂制备低成本、易降解的合成类吸水性树脂。经实验改进和工艺条件优化后,树脂吸去离子水倍率可达1 940.9 g/g,吸自来水899.8g/g。采用红外光谱仪、热重分析仪、扫描电镜、X射线衍射仪等分析手段对合成树脂进行了分析表征,证实了产物为淀粉、丙烯酸及丙烯酰胺的共聚物。The utilization status of the synthetic absorbent resin in agricultural applications was summarized.An improved process of three monomer copolymer system was proposed by using an aqueous solution polymerization.These three monomers are soluble starch,acrylic acid and acrylamide,which are modified by sodium bentonite,using a composite initiator and cross-linker.By improving the experiments and optimizing the process conditions,the absorption rate of the synthetic absorbent resins is up to 1 940.9 g/g in deionized water,and 899.8 g/g in tap water.In addition,the structure and performance of the synthetic absorbent resin were characterized by using infrared spectroscopy,thermal gravimetric analysis,scanning electron microscopy and X-ray diffraction,which shows that it is an copolymer of starch,acrylic acid and acrylamide
Optimization of Hydrometallurgical Purification for SiO_2 in the Process of Preparing Solar-grade Silicon
考察了Hf质量分数、H2C2O4质量分数、HnO3质量分数、酸浸时间、粒径、液体质量与固体质量的比值(简称液固比,下同)等因素对混酸法提纯SIO2工艺过程的影响,利用电感耦合等离子体发射光谱仪(ICP-OES)、场发射扫描电子显微镜(SEM)进行表征。结果表明,最佳工艺条件为:W(Hf)=2%、W(H2C2O4)=3%、W(HnO3)=30%、酸浸时间4 H、粒径100~120目、液固比4∶1、酸浸温度30℃。fE、Al、CA、P杂质的去除率分别达到99.99%、14.02%、73.27%、60.00%,经混酸法处理后SIO2中杂质总量的质量分数降至1.465x10-4。As a pre-treatment unit for preparing solar-grade silicon,hydrometallurgical route could remove most metallic impurities in silicon dioxide(SiO2) and raise the yield of the final product.Acid leaching of SiO2 could reduce the cost and energy consumption of industrialized development.Combined with high purity of reducing agent,the successor process of pyrometallurgy can also achieve "continuous casting".Factors such as the mass fraction of leaching agent,time,the particle size of SiO2,and the liquid-solid ratio were investigated,and the samples were characterized by means of ICP-OES,SEM,etc.The optimal reaction conditions were as follows:w(HF)=2%,w(H2C2O4)=3%,w(HNO3)=30%,reaction time 4 h,the average size of SiO2 powder particle 100~120 mesh,the liquid-solid ratio 4∶1,and room temperature 30 ℃.It was found that the final removal rates of impurities of Fe,Al,Ca,P could reach 99.99%,14.02%,73.27%,and 60.00% respectively and the mass fraction of total amount of impurities could be reduced to 1.465×10-4
Study on Kinetics of Hydrometallurgical Purification Unit for Quartz
为了提高湿法提纯石英的浸出效率并提供理论依据,从动力学角度研究了酸浸提纯石英工艺中除Al的浸出过程并建立动力学模型.在W(Hf)=2%、W(H2C2O4)=3%、W(HnO3)=30%,液固比4∶1,搅拌转速150r/MIn,粒径100~120目的实验条件下,通过常用的液固相化学反应动力学模型的比较并结合宏观现象,得到描述浸出过程的经验方程,湿法提纯石英过程浸出Al的动力学模型为基于界面反应模型的微粒模型.杂质Al的去除率X(Al)对反应时间T的关系式为1-[1-X(Al)]1/3=k2″T,浸出过程频率因子A=58 204.04S-1,反应表观活化能为E=44.588 1kJ/MOl,属于化学反应控制.提高温度和酸液浓度、降低石英颗粒的半径,均可提高Al的浸出速率和浸出率.In order to improve the leaching efficiency of Aluminum(Al) from the quartz and provide its theoretical base,the leaching process was analyzed.On the basis of previous experiments,the dissolved rate of Al from quartz with hydrometallurgical purification unit was studied on the condition of w(HF)=2%,w(H2C2O4)=3%,w(HNO3)=30%,the liquid-solid ratio 4∶1,stirring speed 150 r/min and quartz powder 100--120 mesh.By means of comparison between several common liquid-solid phase chemical reaction kinetics models,an empirical equation for leaching process was established.The leaching process of Al could be simulated with a corpuscular model which is based on the interface reaction model [1-(1-X(Al)]1/3=k2″t with the frequency factor of 58 204.04 s-1 and the apparent activation energy of 44.588 1 kJ/mol.The overall leaching rate appears to be controlled by the chemical-reaction.The leaching rate and speed can be increased by enhancing the temperature and acid concentration and reducing the particle size
Study of Preparation of Silica with High Specific Surface Area Using Precipitation Method
以nA2SIO3·9H2O、H2SO4为原料,沉淀法路线合成高比表面积SIO2.实验考察了反应温度、H2SO4溶液浓度、nA2SIO3溶液浓度、反应终点PH值、表面活性剂添加量、后处理试剂、干燥方式等因素对SIO2比表面积的影响.采用bET低温液氮吸附比表面分析仪、热重分析仪、场发射扫描电镜、激光粒度分析仪、傅里叶变换红外光谱仪等分析仪器对SIO2样品进行表征.结果表明,在C(H2SO4)=1.5MOl/l、W(nA2SIO3)=6.3%、反应温度T=60℃、PH值为5,用正丁醇置换水等实验条件下,可制得SIO2粉末比表面积为841M2/g,相较于一般沉淀SIO2300~400M2/g的比表面积有明显提高.Silica with high specific surface area was successfully prepared from sodium silicate solution and sulfuric acid using precipitation method.The aim was to study the effects of various factors in the preparation process,which include temperature,concentration of sulfuric acid,mass fraction of sodium silicate,pH of the reaction system,surfactants,post-processing reagent and the drying method.The silica samples prepared in different conditions were characterized by BET,thermogravimetric analysis(TG),scanning electron microscope(SEM),laser particle size analyzer(LDSA) and Fourier transform infrared(FT-IR).Optimum condition was established for carrying out the precipitation process of silica.The specific surface area of silica can reach up to 841 m2/g with the optimum condition of c(H2SO4)=1.5 mol/L,w(Na2SiO3)=6.3%,t =60 ℃,pH 5.The specific surface area is improved remarkably compared with the regular value of 300-400 m2/g using precipitation method.福建省科技计划项目(2010H6024