天然沸石对食物油脱色工艺的研究

利用天然沸石对压滤大豆油进行了脱色研究。通过沸石的使用量、粒度、脱色时间、脱色温度等条件考察,确定天然沸石用量为8%,脱色温度100℃;脱色时间60 min效果最佳。     

天然沸石在烧结砖中的应用

随着国家“限实”、“禁粘”力度的加大，烧结砖所用的原料开始多样化。我国已在24个省、自治区发现沸石矿（点）370多处，已探明储量9．55亿t，远景储量30～40亿t．并已形成年产325万t以上的生产规模，大量地用于作水泥混合材、混凝土矿物掺合料、饲料添加剂以及其他各种产品。在开采过程中有许多沸石被遗弃。造成资源浪费和环境污染。本文介绍沸石在烧结砖中的应用及其效果。     

Investigations on natural Hungarian zeolite for ammonia removal

Use of natural zeolites deposited at Tokaj mountain, Hungary, for ammonia removal from synthetic and municipal wastewaters was studied. The optimal ion exchange conditions found were as follows: Na-form clinoptilolite, 0.5–1.0 mm in particle size and about 5–7 BV h⁻¹ loading rate. Using synthetic wastewater in the column of 9.5 cm i.d. × 92 cm, about 4.50 mg NH₃-N g⁻¹ clinoptilolite ammonia breakthrough capacity was achieved. For regeneration of the ion exchange bed, 10–20 BV of regenerant were necessary to remove the 98–99%, of ammonia with flow rate of a 5–7 BV h⁻¹.     

Adsorption of basic dyes on granular activated carbon and natural zeolite

The adsorption of basic dyes from aqueous solution onto granular activated carbon and natural zeolite has been studied using an agitated batch adsorber. The influence of agitation, initial dye concentration and adsorbent mass has been studied. The parameters of Langmuir and Freundlich adsorption isotherms have been determined using the adsorption data. Homogeneous diffusion model (solid diffusion) combined with external mass transfer resistance is proposed for the kinetic investigation. The dependence of solid diffusion coefficient on initial concentration and mass adsorbent is represented by the simple empirical equations.     

Applications of natural zeolite to construction and building materials in China

As a main rock mineral, natural zeolite consists of a family of frame-structured alumino-silicate hydrates. This paper presents several research results in China on carrier effect of zeolite, including both an ion-exchange function and an adsorption function, that can be used in the manufacturing of new construction’s products as well as building materials. These products have been successfully applied to overcome some construction difficulties in engineering practice. In the last a few years, two industrial codes (“Technical specifications of application of natural zeolite powder in concrete and mortar (JGJ/T 112-97)” and “Natural zeolite powder used in concrete and mortar (JG/T 3048-1998)”) have been drafted and approved by China Standard Association for construction practice in China. Presently, the annual amount of natural zeolite consumed in the China’s constructions industry is over 30 million tons.     

Ion exchange and hydrolysis of Type A zeolite in natural waters

The ion exchange behavior and hydrolysis rate of the detergent builder Type A zeolite have been studied in a variety of artificial and natural surface water samples. The experiments were conducted at zeolite A and trace metal concentrations characteristic of what could occur in receiving waters. The data indicate that Type A zeolite hydrolyzed extensively in the test waters at rates which were strongly dependent on hydrogen ion concentration. Half lives of 1–2 months were typical for waters at a neutral pH. Also, the extent of trace metal ion exchange was low (< 10%) for the metals Cd, Cu, Ni and Zn. Pb exchange was slightly higher. It is concluded that the use of the zeolite in detergents will result in little effect on the trace metal distribution of surface waters owing to the low degree of ion-exchange by the zeolite and its hydrolysis products.     

一步法合成金红石相TiO_2/沸石

分别以钛酸丁酯为钛源,以天然斜发沸石作为载体,通过一步合成法合成出不同负载率的金红石相TiO2/沸石粉体.其沸石结构未发生明显改变,且比表面积均与活化沸石相近.经实验分析,金红石相TiO2/沸石的性能均优于金红石相TiO2和沸石,且负载率严重影响其晶相的形成.     

A study on the hydration rate of natural zeolite blended cement pastes

Natural zeolite is a type of mineralogical material containing large quantities of reactive SiO₂ and Al₂O_3. It is widely used in the cement industry in China as a cement blending material. Like other pozzolanic materials such as silica fume and fly ash, zeolite contributes to concrete strength mainly through the pozzolanic reaction with Ca(OH)₂, Thus, the pozzolanic reactivity of this type of material in comparison with other pozzolans is of much interest. This paper presents experimental results on the compressive strength, degree of pozzolanic reaction, and porosity of zeolite modified cement pastes. These results are compared with those obtained from similar blended cement pastes prepared with silica fume and fly ash replacements. Based on the experimental results, it can be concluded that natural zeolite is a pozzolanic material, with a reactivity between that of silica fume and fly ash. Generally, in blended cement pastes with a lower water-to-cementitious materials ratio, the natural zeolite contributes more to the strength of the pastes. But in the pastes with a higher water to cementitious ratio and a lower cement replacement level it undergoes a higher degree of reaction.     

Status of biodiesel production using heterogeneous alkaline catalysts

This paper describes biodiesel production using heterogeneous alkaline catalysts instead of the conventional homogenous alkaline catalysts, such as NaOH, KOH or sodium methoxide, for the methanolysis reaction, in the search for more profitable and sustainable alternatives regarding biodiesel production. The heterogeneous catalytic process has many differences from that currently used in industrial homogeneous processes. The main advantage is that it requires lower investment costs, as there is no need for separation steps such as methanol/catalyst, biodiesel/catalyst and glycerine/catalyst. This paper also describes experimental work towards the development of new heterogeneous alkaline catalysts able to produce biodiesel from vegetable oils. The research has resulted in the selection of CaO and CaO modified with alkaline and alkaline earth metal catalysts. They show very good catalytic performances with high activity and stability. In fact, biodiesel (FAME) yields higher than 94% were observed in several consecutive reaction batches without expensive intermediate reactivation procedures. Therefore, those catalysts appear to be suitable for biodiesel production.     

小粒晶ZSM-5分子筛的合成及其影响因素研究

小晶粒ZSM-5分子筛与微米ZSM-5分子筛相比,具有较大的外表面积和较高的晶内扩散速率,在提高催化剂的利用率和选择性、增强大分子的转化能力、减少深度反应以及降低结焦失活等方面表现出优越的性能.采用两种不同的模板剂,探索ZSM-5分子筛的制备参数,合成出小晶粒的ZSM-5分子筛并通过XR、SEM及激光粒度分析法对其进行表征,并考察了ZSM-5分子筛合成及晶粒大小的影响因素.结果表明:较为合适的合成条件为晶化时间96 h.晶化温度170℃、碱度0.13、n(NaCl)/n (Al2O3)=15、CTAB用量0.5CMC、晶化方式为搅拌晶化,在上述条件下合成的ZSM-5分子筛的晶粒大小为400～900 nn.     

地聚合物注浆在三级公路上的应用

沥青路面地聚合物注浆的方法具有可缩短老路维修和加固的施工期、提早开放交通等优点,是一种较好的公路加固和维修技术,特别是对公路刚性基层的板底脱空现象有显著效果。通过上海川南奉公路的案例,阐述地聚合物注浆的方法在三级公路养护工程中的加固应用。通过后期测试数据表明此方法的良好效果,不仅能解决刚性基层板底脱空部位的病害现象,提高道路的抗弯强度和抗变形能力,改善路用性能,延长道路的使用寿命,而且缩短工期,降低工程造价,能实现道路的经济效益、社会效益和环境效益。     

粉煤灰合成沸石的研究与应用现状

对当前粉煤灰合成沸石在传统水热合成沸石的基础上的改进和发展研究进行了分析总结,同时对粉煤灰合成沸石产品的应用研究等情况作了阐述,指出其具有良好的市场应用前景。     

硅粉偏高岭土基地聚合物微观结构分析

采用硅粉、偏高岭土和碱激发剂制得硅粉-偏高岭土基地聚合物.应用X射线衍射、扫描电镜-能谱、红外光谱和核磁共振等技术分析硅粉-偏高岭土基地聚合物的化学组成与微观结构,揭示硅粉-偏高岭土基地聚合物具有独特耐久性的原因.结果表明:硅粉-偏高岭土基地聚合物为无定形的碱金属铝硅酸盐胶体,Si/Al摩尔比较高,与硅酸盐水泥水化产物完全不同.加入碱激发剂发生化学反应后,偏高岭土和硅粉中对应于Si-O-Si键非对称伸缩振动的谱带吸收强度减弱,同时向低频率方向移动,铝氧四面体取代Si-O-Si链上部分硅氧四面体.硅粉-偏高岭土基地聚合物中的铝氧四面体和硅氧四面体相互键接构成空间三维网络状结构,从而使其具有优良的耐久性.     

Effects of natural zeolite and sulfate ions on the mechanical properties and microstructure of plastic concrete

One of the strategic materials used in earth-fill embankment dams and in modifying and preventing groundwater flow is plastic concrete (PlC). PlC is comprised of aggregates, water, cement, and bentonite. Natural zeolite (NZ) is a relatively abundant mineral resource and in this research, the microstructure, unconfined strength, triaxial behavior, and permeability of PlC made with 0%, 10%, 15%, 20%, and 25% replacement of cement by NZ were studied. Specimens of PIC-NZ were subjected to confined conditions and three different confining pressures of 200, 350, and 500 kPa were used to investigate their mechanical behavior and permeability. To study the effect of sulfate ions on the properties of PlC-NZ specimens, the specimens were cured in one of two different environments: normal condition and in the presence of sulfate ions. Results showed that increasing the zeolite content decreases the unconfined strength, elastic modulus, and peak strength of PlC-NZ specimens at the early ages of curing. However, at the later ages, increasing the zeolite content increases unconfined strength as well as the peak strength and elastic modulus. Specimens cured in the presence of sulfate ions indicated lower permeability, higher unconfined strength, elastic modulus, and peak strength due to having lower porosity.     

偏高岭土矿渣基地聚合物缓凝剂的性能研究

以自主研发的缓凝剂BCH对偏高岭土-矿渣基地聚合物浆体凝结时间进行调节;利用反应热分析、化学结合水量测定和微观形貌观察等方法对BCH的缓凝效果进行验证.结果表明:缓凝剂BCH能有效延缓地聚合物浆体的反应速率,且对其硬化体抗压强度有一定增强作用.当BCH掺量为5.0%(质量分数)时,缓凝效果最佳,地聚合物浆体20℃和80℃的初凝时间分别比未掺BCH的增加了20.4倍和13.7倍;80℃养护3d和28d的地聚合物硬化体抗压强度分别比未掺BCH的提高了12.28%和5.80%;在20℃和50℃下碱激发反应放热峰出现时间较未掺BCH的明显延迟,放热峰强度显著降低;80℃时碱激发反应主要发生在4.0～6.0h时间段,较未掺BCH的反应时间段(0.2～1.0h)滞后;80℃碱激发反应1.0h后,反应产物浆体不凝结,产物颗粒表面覆盖黏附物,而未掺BCH的碱激发反应产物为连续致密的硬化体.     

硅灰-氧化铝地质聚合物的力学性能

采用正交试验对硅灰-氧化铝地质聚合物进行了力学性能试验研究.结果表明:影响硅灰-氧化铝地质聚合物强度的因素依次为碱激发剂浓度、硅铝比(n(SiO_2)/n(Al_2O_3))、碱激发剂种类.配制硅灰-氧化铝地质聚合物的碱激发剂为KOH,其最佳浓度为3.0mol/L,硅铝比为4.当KOH浓度为3.6mol/L,硅铝比为4时,硅灰-氧化铝地质聚合物的抗折强度可达7.17MPa,抗压强度可达17.15MPa.     

铜对地聚合物化学结构的影响

借助X射线衍射(XRD)、扫描电镜能谱(SEM EDS)、红外光谱(FTIR)、核磁共振（NMR）等技术,研究了铜对地聚合物化学结构的影响.地聚合物由硅粉、偏高岭土、氢氧化钾和水制得,铜以硝酸盐的形式加入.结果表明：加入的铜影响到地聚合物化学结构中Al—O—Si键和Si—O—Si 键的周围气氛,使其振动频率发生微小变化,也影响到Al和Si原子核周围的电子密度,使27Al NMR和29Si NMR特征峰发生微小偏移,但加入的铜没有改变地聚合物中化学键振动模式,也没有引起硅氧四面体、铝氧四面体结构单元和两者之间键接方式的变化.     

纤维导电性对地聚合物压敏行为的影响

采用碳纤维和玄武岩纤维改性地聚合物,分析了纤维掺量对其流动性、力学性能、电阻率及压敏行为的影响规律,揭示了纤维导电性能对地聚合物压敏性能的影响机制.结果表明：碳纤维对地聚合物流动性的影响大于玄武岩纤维;当碳纤维掺量升高时,地聚合物电阻率明显下降,且可分为缓降、突降和平缓阶段;随着碳纤维掺量的升高,地聚合物压敏性能先增强后减弱;当碳纤维体积分数为0.4%时,地聚合物压敏性能最优;玄武岩纤维对地聚合物压敏性能具有削弱作用.     

地聚物固化软黏土的力学特征及机理分析

采用无侧限抗压强度(UCS)试验、X射线衍射(XRD)和扫描电子显微镜(SEM),研究了地聚物对软黏土的固化和UCS提升效果,分析了地聚物碱激发剂模数、掺量对软黏土固化效果和UCS提升的影响,并探讨了其固化机理.结果表明:碱激发剂模数为1.2时,地聚物固化软黏土的UCS得到大幅提高,最大值为4.37MPa;碱激发剂掺量的增加对地聚物固化软黏土的早期强度提升影响显著,但对14、28d强度影响较小,当掺量超过5.0%时,强度提升效能降低;地聚物固化软黏土中同时生成了水化硅铝酸钠(N-A-S-H)、水化硅酸钙(C-S-H)、碳酸钙晶体和莫来石晶体,土颗粒间的孔隙得到填充,凝胶的胶结作用提高了土体的整体性.基于试验数据给出了28d龄期内地聚物固化软黏土强度提升的评价公式.     

土工聚合物作为反滤层在水库库坝中的应用

土工聚合物作为岩土工程领域中的一种新型建筑材料,由于其突出的力学、水理及高抗腐蚀等优越性在岩土工程中得到广泛应用。文章通过对砂卵石反滤层排水体和土工聚合物反滤层排水体两种方案进行技术和经济比较,选用了土工聚合物滤层排水体措施对病危水库库坝进行加固处理,取得了显著的经济、技术效果。