以硅藻土为原料的玻璃配合料的水热处理

以硅藻土为原料,对 Na_2O-CaO-Al_2O_3-B_2O_3-SiO_2玻璃配合料进行了不同时间、温度下的水热处理,用 X 射线衍射、差热分析、红外光谱等分析了水热处理产物。结果表明,在水热处理过程中生成了硅酸盐或硼酸盐化合物,这是降低熔制温度和缩短熔制时间的主要原因,将水热处理过的玻璃配合料熔制成玻璃,测定其结构、密度、膨胀系数、弹性模量、电阻率;还同未经水热处理的玻璃配合料和一般化学试剂为原料熔制玻璃,测量玻璃的结构、性能以作比较。结果表明,前者电阻率降低,膨胀系数上升,密度、弹性模量增加,转变温度、软化温度提高。     

硅藻土处理低浓度含氟地下水的实验研究

饮水中氟化物的含量对人体的健康有重大影响,饮水中最佳的氟含量是介于0.5～1.0 mg/L之间.利用静态实验,研究了硅藻土对天津市某地区含氟浓度为4.22 mg/L的地下水中氟离子的吸附能力以及pH值、硅藻土投加量、聚合氯化铝投加量、搅拌时间、初始氟浓度对除氟效果的影响.结果表明:硅藻土在原水pH值为6,硅藻土投加量为3.0 g/L,搅拌15 min时达到最佳氟吸附效果,去除率达到97.18%.减少硅藻土投加量可提高其吸附量,最大可以达到1.78 mg/g,此时氟的平衡浓度为0.662 mg/L,证明了硅藻土在饮水除氟上有巨大的应用潜力.     

TiO2-xNx／硅藻土复合光催化剂的制备及其可见光催化活性

以尿素为氮源,硅藻土为载体,用溶胶-凝胶法合成了硅藻土负载氮掺杂纳米TiO2复合光催化剂。采用XRD,UV-vis对样品进行了表征;以罗丹明B为降解对象,考察了罗丹明B初始浓度、催化剂投加量、溶液初始pH值对降解率的影响,同时考察了样品在太阳光下的光催化活性。结果表明,掺氮Ti02450oc焙烧2h后为锐钛矿型,N掺杂使催化剂的吸收边红移至550nm左右,诱发TiO2可见光催化活性;当催化剂用量为2g／L,溶液初始pH值为6．5时,初始浓度为10mg／L的罗丹明B在氙灯光照45min后降解率为100％,太阳光照160min后降解率为97．4％。     

SCIENTIFIC BASES FOR PREPARATICN OF DIATOMITE AND PERLITE FLTER-AID

According to the filtration mechanism andfiltration formula, it is considered that thesurface area, bulk density and grain size distri-bution of filter-aid are the main factors affectingthe filtration rate. On the basis of analysing phy-sical and chemical properties of diatomite and per-lite, the scientific bases for preparation of filteraid are discussed. It is possible that the complexfilter aid, which is made up of low grade diatomiteand perlite, is favourable to build-up a fine"steely-bridged structure" for the filter cake, andits filtration performance of beer could be improvedas good as that of commercial filter-aid made fromhigh grade diatomite. The above points have beendemonstrated by the results of laboratorial andindustrial experiments of beer filtration.     

Preparation of a novel type of flame retardant diatomite and its application in silicone rubber composites

A novel strategy was used for preparation of flame retardant based on biomass debris to improve the flame retardant property of silicone rubber (SR). [(6-oxido-6H-dibenz[c,e][1,2]oxaphosphorin-6-yl)methyl]butanedioic acid (DDP) was used to modify diatomite by esterification method, and DDP@diatomite was obtained. The structure and morphology of this novel additive was identified using Fourier transform infrared spectroscopy (FTIR), Brunner-Emmet-Teller (BET) measurements, and X-ray photoelectron spectroscopy (XPS) together with scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS) techniques. Thermogravimetric (TG) analysis was performed to evaluate the thermal degradation behaviors of diatomite and DDP@diatomite. This novel additive was applied into silicone rubber (SR) composites. Combustion parameters, including heat release rate (HRR), total heat release (THR), smoke production rate (SPR), carbon monoxide (CO), peak smoke production rate (PSPR), peak carbon monoxide (PCO) and vertical burning time, were characterized by cone calorimeter and vertical burning tests. Results indicated that this flame retardant can reduce fire risk and toxicity effectively. TG and X-ray diffraction (XRD) patterns of SR and its composites were also investigated. The inexpensive property of modified diatomite could also expand its fire safe applications.     

硅藻土含量和粒径对聚丙烯/硅藻土复合材料口模膨胀行为的影响

应用熔体流动速率仪测定了3种粒径硅藻土填充聚丙烯复合材料的口模膨胀比,考察了硅藻土含量和粒径对复合材料口模膨胀行为的影响。结果表明:当载荷和温度一定时,复合材料的口模膨胀比随着硅藻土体积分数的增加而非线性减小,随着硅藻土粒径的增加而非线性提高,两者之间成二次函数关系。     

硅藻土陶粒的研究

本文介绍了我国以中低品位硅藻土研制硅藻土陶粒的概况,涉及原料、制陶工艺产品性能。实际应用等诸多方面的问题。     

The fabrication of magnetic recyclable nitrogen modified titanium dioxide/strontium ferrite/diatomite heterojunction nanocomposite for enhanced visible-light-driven photodegradation of tetracycline

Powdery photocatalyst has long been studied in various aspects, yet its low recovery in suspension system is still the bottleneck which hinders its practical application. An alternative method to overcome this shortcoming is to develop magnetic recyclable ferrite-based hybrid photocatalyst. In this work, we prepared nitrogen modified titania/strontium ferrite/diatomite (N-TSD) ternary hybrid via sol-gel method. The physicochemical properties of various hybrid catalysts were characterized and studied, and their photocatalytic properties were evaluated via the degradation of antibiotic tetracycline (TC) under visible light. The formation of heterojunction between N modified TiO₂ and strontium ferrite hindered the recombination of photo-induced charge carriers and improved the photocatalytic activity. The photodegradation rate of TC was accelerated by the high adsorption ability of diatomite, due to the adsorption and degradation synergistic effect between catalysts and substrate diatomite. Based on the degradation results, the optimal N dopant amount, as well as optimal catalyst dosage was determined. The ternary N-TSD composite could simply be recovered from TC solution via an external magnet, and the repetition tests indicated no obvious decrease of photoactivity, even after 5 turns. This nanocomposite was considered appropriate to be applied in wastewater remediation process, thanks to its high photocatalytic efficiency under visible light irradiation, as well as its good reusability and stability.     

硅藻土在城市污水处理中的应用研究

采用硅藻土对污水处理厂进水进行混凝处理,尝试将硅藻土混凝和微滤分离膜处理技术相结合对污水进行处理。试验结果表明,硅藻土用于城市污水处理,效果显著。当硅藻土用量为300mg/L时,结合微滤分离膜系统,能够满足生活杂用和市政杂用所需水质要求。应用环境扫描电镜表征硅藻土混凝前后的组分和表观特征,初步提出了硅藻土的污水处理机理为吸附、混凝和中和三个协同作用。     

Low-temperature catalytic synthesis of SiC nanopowder from liquid phenolic resin and diatomite

ABSTRACT

3C–SiC nanopowder was catalytically synthesised at 1400°C for 3?h in argon using industrial diatomite powder and phenolic resin as raw materials, and cobalt nitrate as a catalyst precursor. Phase composition and microstructure of product samples were characterised using X-ray diffraction analysis, scanning electronic microscopy and transmission electronic microscopy. The effects of temperature, catalyst content and reaction time on the formation of SiC were examined. The results indicated that (1) phase pure 3C–SiC can be synthesised at 1400°C for 3?h using 1.0?wt-% Co catalyst; (2) if no catalyst was used, only little 3C–SiC was formed under the identical firing condition; (3) as-prepared 3C–SiC nanoparticles had irregular shapes with overall sizes of 30–300?nm. Density functional theory calculations further reveal that the Co catalyst assisted Si–O bond breaking and thus the SiC formation.