Synthesis of NaY zeolite from a submolten depolymerized perlite:Alkalinity effect and crystallization kinetics

NaY zeolites are synthesized using submolten salt depolymerized natural perlite mineral as the main silica and alumina sources in a 0.94 L stirred crystallizer.Effects of alkalinity ranging from 0.38 to 0.55(n(Na_(2)O)/n(SiO_(2)))on the relative crystallinity,textural properties and crystallization kinetics were investigated.The results show that alkalinity exerts a nonmonotonic influence on the relative crystallinity and textural properties,which exhibit a maximum at the alkalinity of 0.43.The nucleation kinetics are studied by fitting the experimental data of relative crystallinity with the Gualtieri model.It is shown that the nucleation rate constant increases with increasing alkalinity,while the duration period of nucleation decreases with increasing alkalinity.For n(Na_(2)O)/n(SiO_(2))ratios ranging from 0.38 to 0.55,the as-synthesized NaY zeolites exhibit narrower crystal size distributions with the increase in alkalinity.The growth rates determined from the variations of average crystal size with time are 51.09,157.50,46.17 and 24.75 nm·h^(-1),respectively.It is found that the larger average crystal sizes at the alkalinity of 0.38 and 0.43 are attributed to the dominant role of crystal growth over nucleation.Furthermore,the combined action of prominent crystal growth and the longer duration periods of nucleation at the alkalinity of 0.38 and 0.43 results in broader crystal size distributions.The findings demonstrate that control of the properties of NaY zeolite and the crystallization kinetics can be achieved by conducting the crystallization process in an appropriate range of alkalinity of the reaction mixture.

Characteristics and mechanism of Ni^(2+)and Cd^(2+)adsorption by recovered perlite from agar extraction residue

Ni^(2+)and Cd^(2+)in wastewater accumulated through the ecological chain and could jeopardize human health.Adsorption of Ni^(2+)and Cd^(2+)from wastewater using recovered perlite was an important way to solve the problem of resource utilization of solid waste from agar production.Our previous study confirmed that recovered perlite from agar extraction residue had better pore size and specific surface area than commercial perlite.However,the adsorption efficiency and adsorption mechanism of recovered perlite were the main factors limiting its adsorption application.The adsorption process of Ni^(2+)and Cd^(2+)by recovered perlite in aqueous solution was described by the pseudo-second-order kinetic equation,and the relevant adsorption mechanism was mainly chemisorption.Compared with commercial perlite,the adsorption removal rate of Ni^(2+)and Cd^(2+)by enzymatic recovered perlite could reach 92.9%and 89.2%,respectively,and were improved by 12.63%and 13.03%.Langmuir isothermal adsorption model could better describe the isothermal adsorption process of recovered perlite on heavy metal Ni^(2+)and Cd^(2+),and the relevant adsorption mechanism was mainly monolayer adsorption.The X-ray photoelectron spectroscopy(XPS)results indicated that the decrease of Si—O Si^(2+)hydroxyl coordination bond and the increase of C—Si bond might make the binding effect of recovered perlite with heavy metals stronger.The competitive adsorption of Ni^(2+)and Cd^(2+)by recovered perlite was still dominated by chemisorption and monolayer adsorption.This study was expected to provide a theoretical basis and technical support for the removal of Ni^(2+)and Cd^(2+)from wastewater using recovered perlite from seaweed residue.

Study on Sustained-Release Pesticides Blended with Fosthiazate-Stearic Acid/Expanded Perlite

The low utilization rate of pesticides makes the migration of pesticides in water and soil,which brings great harm to the ecosystem.The development of pesticide carriers with good drug loading capacity and release control abil-ity is an effective method to realize effective utilization of pesticides and reduce pesticide losses.In this work,fosthiazate-stearic acid/expanded perlite sustained-release particles were successfully prepared by vacuum impregnation using expanded perlite(EP)as carrier,fosthiazate(FOS)as model pesticide and stearic acid(SA)as hydrophobic matrix.The structure and morphology of the samples were studied by BET,FT-IR,TGA,XRD,DSC and SEM.The effects of different mass ratios of FOS to SA on loading capacity and release rate at 24 h were investigated.The sustained release behavior of FOS-SA/EP at different temperatures and pH values was investigated by static dialysis bag method.The results showed that FOS and SA were adsorbed in EP pores by physical interaction.With the mass ratios of FOS to SA decreasing from 7:3 to 3:7,the 24 h release rate of FOS-SA/EP decreased from 18.77%to 8.05%,and the drug loading decreased from 461.32 to 130.99 mg/g.FOS-SA/EP showed obvious temperature response at 25℃,30℃ and 35℃,the cumulative release rate(CRR)of 200 h were 33.38%,41.50%and 51.17%,respectively.When pH=5,the CRR of FOS was higher than that of pH=7,and the CRR of FOS for 200 h were 49.01%and 30.12%,respectively.At different temperatures and pH=5,the release mechanism of FOS-SA/EP belongs to the Fickian diffusion mechanism;When pH=7,the diffusion mechanism is dominant,and the dissolution mechanism is complementary.

Preparation of Lightweight Alumina-silica Castables by Replacing Closed-cell Perlite Aggregates with Coal Gangue Ceramsites

Lightweight alumina-silica castables were prepared using closed-cell perlite(2-4 mm),open-cell perlite(4-6 mm)and coal gangue ceramsites(2-5 mm)as aggregates,floating beads(0.3-0.5 mm),sinking beads(0.6-0.8 mm),silica micropowder,α-Al_(2)O_(3) micropowder,zirconia and zircon micropowder as fines,and Secar 71 cement(calcium aluminate cement)as the binder.The effects of the coal gangue ceramsites addition(0,6%,12%,18%and 24%,by mass)on the properties of the as-prepared lightweight alumina-silica castables were investigated.The results show that:(1)the addition of coal gangue ceramsites can reduce the sintering shrinkage of the specimens and help to improve the strength and thermal shock resistance;(2)the samples with the addition of coal gangue ceramsites can produce pores in the matrix of the sintered samples,which provides enough space for the growth of CA6 complex solid solution and expands the irregular lamellar structure;(3)with the addition of coal gangue ceramsites increasing,the linear shrinkage of the samples heat treated at 1000 or 1200℃firstly reduces and then increases,the bulk density increases and the apparent porosity decreases;the cold compression strength and the thermal shock resistance of the specimens heat treated at 1200℃firstly increase and then decrease.Thus,the optimal addition of coal gangue ceramsites is 18%.

Preparation and hygrothermal performance of composite phase change material wallboard with humidity control based on expanded perlite/diatomite/paraffin

Phase change material(PCM)can reduce the indoor temperature fluctuation and humidity control material can adjust relative humidity used in buildings.In this study,a kind of composite phase change material particles(CPCMPs)were prepared by vacuum impregnation method with expanded perlite(EP)as supporting material and paraffin as phase change material.Thus,a PCM plate was fabricated by mould pressing method with CPCMPs and then composite phase change humidity control wallboard(CPCHCW)was prepared by spraying the diatom mud on the surface of PCM plate.The composition,thermophysical properties and microstructure were characterized using X-ray diffraction instrument(XRD),differential scanning calorimeter(DSC)and scanning electron microscope(SEM).Additionally,the hygrothermal performance of CPCHCW was characterized by temperature and humidity collaborative test.The results can be summarized as follows:(1)CPCMPs have suitable phase change parameters with melting/freezing point of 18.23°C/29.42°C and higher latent heat of 54.66 J/g/55.63 J/g;(2)the diatom mud can control the humidity of confined space with a certain volume;(3)the combination of diatom mud and PCM plate in CPCHCW can effectively adjust the indoor temperature and humidity.The above conclusions indicate the potential of CPCHCW in the application of building energy efficiency.

Hydration Heat Effect of Cement Pastes Modified with Hydroxypropyl Methyl Cellulose Ether and Expanded Perlite

Hydration heat effect of cement pastes and mechanism of hydroxypropyl methyl cellulose ether （HPMC） and expanded perlite in cement pastes were studied by means of hydration exothermic rate, hydration heat amount, FTIR and TG-DTG. The results show that HPMC can significantly delay the hydration induction period and acceleration period of cement pastes. As mixing amount increased, hydration induction period of cement pastes enlarged and accelerated period gradually went back. At the same time, the amount of hydration heat gradually decreased. Expanded perlite had worse delay effects and less change of hydration heat amount of cement pastes than HPMC. HPMC changed the structure of C-S-H during cement hydration. The more amount of HPMC, the more obvious effect. However, EXP had little influence on the structure of C-S-H. At the same age, the content of Ca （OH）2 in cement pastes gradually decreased as the mixing amount increase of HPMC and expanded perlite, and had better delay effect than that single-doped with HPMC or expanded perlite when HPMC and expanded nerlite were both dooed in cement pastes.

Fabrication, property characterization and thermal performance of composite phase change material plates based on tetradecanol-myristic acid binary eutectic mixture/expanded perlite and expanded vermiculite for building application

A binary eutectic mixture composed of tetradecanol(TD)and myristic acid(MA)was maximally absorbed into the microstructures of expanded perlite(EP)and expanded vermiculite(EVMT),respectively,through a self-made vacuum adsorption roller to prepare phase change material(PCM)particle(PCP).Then EP and EVMT-based composite PCM plates were respectively fabricated through a mold pressing method.The thermal property,chemical stability,microstructure and durability were characterized by differential scanning calorimeter(DSC),Fourier transform infrared spectroscope(FT-IR),scanning electron microscope(SEM)and thermal cycling tests,respectively.The results show that both PCPs have high latent heats with 110 J/g for EP-based PCP and more than 130 J/g for EVMT-based PCP,compact microstructure without PCM leakage,stable chemical property and good durability.The research results have proved the feasibility for the vacuum adsorption roller used in the composite PCM fabrication.Results of thermal storage performance experiment indicate that the fabricated PCM plates have better thermal inertia than common building materials,and the thermal storage performance of PCM plates has nonlinearly changed with outside air velocity and temperature increase.Therefore,PCM plates show a significant potential for the practical application of building thermal storage.

Experimental and mathematical modeling of Cr(Ⅵ) removal using nano-magnetic Fe3O4-coated perlite from the liquid phase

Modification of perlite using nano-magnetic iron oxide was implemented to produce nano-magneticFe3O4-coated perlite composite(Fe3O4/Perlite).The prepared composite was characterized using Scanning Electron Microscopy,Fourier-Transform Infrared spectroscopy and Powder X-ray Fluorescence.The potentiality of both perlite and Fe3O4/Perlite composite to eliminate Cr(VI)from the environmentally relevant water was investigated.The influence of main factors which could affect the adsorption was studied including;pH of medium,shaking time and Cr(VI)ions concentration.The experimental outcome demonstrated that the modification of perlite by nano-magnetic Fe3O4 showed a significantly enhanced Cr(VI)removal efficiency relative to that of unmodified perlite.From the kinetic studies,the experimental data fitted well with the pseudo-second-order model.Moreover,it proposes that Langmuir isotherm is more adequate than the Freundlich isotherm for both perlite and modified perlite.The results recommended that Fe3O4/Perlite composite had a great potential as an economic and efficient adsorbent of Cr(VI)from contaminated water,which has huge application potential.

USE OF INDUSTRIAL WASTE OF PERLITE IN BUILDING MATERIALS INDUSTRY

We have observed the components, structure and properties of perlite ore. Through a series of ex- periments, it has been proved that the perlite has higher pozzolanic activity and maybe used as addi- tion of cement in manufacturing pozzolanic cement. The paper also proposes the way to increase the early strength of this kind of cement and utilize it to make many kinds of silicate concrete products.

SCIENTIFIC BASES FOR PREPARATICN OF DIATOMITE AND PERLITE FLTER-AID

According to the filtration mechanism and filtration formula, it is considered that the surface area, bulk density and grain size distri- bution of filter-aid are the main factors affecting the filtration rate. On the basis of analysing phy- sical and chemical properties of diatomite and per- lite, the scientific bases for preparation of filter aid are discussed. It is possible that the complex filter aid, which is made up of low grade diatomite and perlite, is favourable to build-up a fine 'steely-bridged structure' for the filter cake, and its filtration performance of beer could be improved as good as that of commercial filter-aid made from high grade diatomite. The above points have been demonstrated by the results of laboratorial and industrial experiments of beer filtration.

Water-affinity of Perlite Products and Its Anti-water Mechanism after Being Modified

The structure modification and its mechanism have been studied when perlite products changed from water-affinity state to anti-water state. The structure of fused perlite and its surface physicochemical properties have also been studied. The modification of perlite products has provided the products with anti-water property, which not only enhanced the quality of thermal insulating function, reduced the lost of heat energy, but also made the products water-proof These modified perlite products are used as ideal thermal insulating layers for the thermodynamic equipment and heat transporting conducts.

A composite thermal insulator based on xonotlite and perlite

A low cost thermal insulating material can be produced by compounding anactive xonotlite slurry, fired-perlite, HOMO PAN fibers and glass fibers. The maximum servicetemperature of the product is 800 deg C; linear shrinkage after 800 deg C X 16 h firing is 0.9percent; the cold crushing strength is 1.56 MPa; the flexural strength at ambient temperature is0.81 MPa; the thermal conductivity at ambient temperature (25 deg C) is 0.056 and 0.128 W/(m centredot K) at 800 deg C. The production cost of such a composite is only 1/3 of that of the normalxonotlite thermal insulators. It can substitute the normal xonotlite thermal insulators on mostoccasions with a similar cost to that of normal perlite products.

Sorption Kinetics and Capacity of Composite Materials Made up of Polymeric Fabric and Expanded Perlite for Oil in Water

The oil sorption capacity of composite materials made up of different polymeric fabrics (namely acrylic fabric (AF), polypropylene nonwoven (PP), and silk stocking (SS) as composite out-packing materials) and expanded perlite (EP) was evaluated for oil removal from the water. The effects of sorbent dosage, desorption time, oil amount in the water, and contact time on composite materials sorption were investigated. The results showed that the optimum quantity of EP was between 0.5 g and 1.0 g for 25 cm2 polymeric fabrics bags. Oil removal efficiency for 6 L/m2 of oil amount in the water was 52%-72%, 44%-63%, and 37%-48% for AF, PP, and SS composite materials, respectively. Oil/water selectivity analysis of different composite materials showed that AF composite material had a very high degree of hydrophobicity and oil sorption capacity of approximately 10.17 g/g. Both oil sorption kinetics and equilibrium studies were carried out, and the equilibrium process of composite materials was described well by the Langmuir isotherm, and the oil sorption kinetics of composite materials showed good correlation coefficients for the pseudo-second order kinetic model. Intra-particle diffusion studies showed that oil sorption mechanism was controlled by the three processes, involving in external liquid membrane diffusion, surface sorption, and intra-particle diffusion.

Light Panels Based on Expanded Perlite, Application as Adsorbers and Insulator against Rapid Evaporation in Subsaharien Countries

Our project concentrates on manufacture of light panels based on available natural materials (expanded perlite, sawdust and refuse of wood, vegetable coal.) mixed with a natural resin not toxic (resin of the pine). The manufacturing process permits to carry out panel’s low thickness and in various colors which give an aesthetic aspect for waste water treatment plants while preventing the emanation of the nauseous odors coming from the anaerobic metabolism of the organic matter present in the liquid effluents. Panels are also a suitable solution against rapid evaporation of stored rain fed water into lakes and dams. The particularities of these panels are especially: Lower density than water’s one, provide big capacity of adsorption for the organic gas matter, composite material acts like filter in which organic gases are photo oxidized with dioxide titanium involved in the composite material and these composite materials are insulators of basins against solar heating and consequently fast evaporation.

Alkali-Silica Reactivity and Strength of Mortars with Expanded Slate, Expanded Glass or Perlite

Lightweight aggregates are increasingly used in concrete construction. They reduce concrete selfweight furnishing a structural advantage. In contrast, the mechanical properties and durability of lightweight concrete can become the governing factor on lightweight aggregate replacement ratios. Alkali-Silica Reactison (ASR) and compressive strength of mortar samples with expanded slate, expanded glass or perlite, covering the spectrum of internal porosity and weight of lightweight aggregates, were evaluated. Scanning electron microscopy was utilized to evaluate the contribution of the aggregates’ porosity and chemical composition in inhibiting ASR. Perlite, owing to its highly porous microstructure and lower matter excelled in ASR expansion while chemical composition and denser microstructure of the heavier expanded slate resulted in more signified late ASR expansion and higher compressive strength. An attempt in visual inspection of ASR attack of alkali metal ions on silica-rich expanded glass using an ultra-accelerated exposure to sodium hydroxide solution was made.

膨胀珍珠岩调控固化淤泥物理-力学性能的方法

疏浚淤泥含水率高导致干化和固化成本过高。充分利用膨胀珍珠岩(expanded perlite,简称EP)的多孔吸水性,局部分离淤泥中的自由水,使其变为不均匀分布,营造泥-水分离的固化环境。试验发现,掺入EP可以有效提高固化淤泥的无侧限抗压强度(unconfined compressive strength,简称UCS),但其掺入方式影响固化强度的增长速率和孔隙分布特征。焖料方式最有利于提升固化效果,即把EP先掺入到淤泥中,混合24 h后再加水泥固化;养护28 d时,焖料试样的强度是直接固化试样(EP掺入后直接加水泥固化)强度的1.56倍,是仅掺入水泥固化试样强度的2.15倍,说明EP营造的局部泥-水分离环境可有效提高固化淤泥的强度。同时,水化热试验结果表明,EP促进了水泥水化作用。EP-淤泥固化土的孔隙分布曲线和表观形貌照片显示,虽然掺入EP引入了气孔,但也为水化产物提供了生长空间,使得淤泥和EP界面形成嵌入式胶结,共同构成固化土骨架。EP调控淤泥含水率属于物理方法,方便快捷,并且EP是高硅轻骨料,与淤泥相容性好,兼具环境友好性。

多巴胺包覆珍珠岩对抑制甲烷爆炸的试验研究

通过自行搭建的试验平台,以9.5%的甲烷为爆炸性气体,研究了不同质量的珍珠岩、多巴胺包覆珍珠岩以及SiO_(2)粉体对火焰传播形状、甲烷爆炸压力以及火焰传播速度的影响。采用热重分析、粒径分析、XRD分析以及扫描电镜对包覆前后珍珠岩粉体的热稳定性以及表面微观情况进行了分析,并对比分析改性珍珠岩的抑爆机理。各种数据对比表明,3种粉体均具备抑制甲烷爆炸的作用,其中多巴胺包覆的珍珠岩效果最为明显,喷撒320 mg工况下最大爆炸压力最小,较纯甲烷下降了62.3%,360 mg火焰的最大传播速度最小,下降了42.6%。多巴胺包覆珍珠岩粉体的加入阻碍了火焰的传播,通过化学和物理抑爆中断甲烷爆炸的链式反应,从而达到甲烷抑爆的效果。

改性TiO_(2)/膨胀珍珠岩光催化剂对赤潮微藻的抑制

米氏凯伦藻是引发赤潮的经典赤潮微藻,会造成水体环境污染甚至是水中动植物死亡。将膨胀珍珠岩(EP)作为漂浮性载体,采用水热合成法、简易包衣法和海藻酸钠固定法3种方法合成的漂浮性光催化剂,并探究3种方法合成的漂浮性光催化剂对于米氏凯伦藻的抑藻作用。结果表明,水热合成法制备的漂浮式光催化剂对于米氏凯伦藻的抑藻作用最为有效,实验进行4 h后藻类去除率达到80%以上;漂浮式光催化剂作用1 h后米氏凯伦藻体内叶绿素a含量和可溶性蛋白质含量急剧下降,表明米氏凯伦藻的光合系统受到破坏,藻细胞失去了能量来源,而蛋白质含量的降低也使得藻细胞的代谢活力下降。该研究为光催化技术应用于赤潮治理提供了一定的理论依据。

模拟高原环境下敏化方式对乳化炸药爆轰性能的影响研究

为研究高原环境对不同敏化方式乳化炸药的影响程度,选取3种典型的敏化材料制备乳化炸药样品,模拟并对比分析了高原环境(-20℃、约0.05 MPa)储存后乳化炸药的微观结构和爆轰性能变化。结果表明:低温低压下的高原环境主要从加剧破坏乳化体系稳定性与热点分布两方面影响炸药的性能,在该环境下化学敏化炸药相较于物理敏化炸药的析晶程度较低,但热点变化较大,导致爆轰性能下降;物理敏化中,膨胀珍珠岩炸药晶体的生长方式更加复杂,因此更易破乳析晶,储存稳定性与爆轰性能均有明显降低;相对而言,树脂微球炸药在低温低压下的析晶程度与爆轰性能均较稳定。综合上述结果,树脂微球乳化炸药具有更好的高原适应性。

建筑用膨胀珍珠岩的资源特性及研究现状分析

对国内外建筑用膨胀珍珠岩的相关产品标准进行梳理,对膨胀珍珠岩的化学成分、微观结构及亲水机理进行分析,指出保持膨胀珍珠岩优异绝热性能的关键是改变其表层的亲水官能团及微孔结构,总结有机硅憎水剂喷涂、聚合物包覆、SiO2气凝胶填充等膨胀珍珠岩改性方法的机理及研究现状,为相关技术人员生产或使用膨胀珍珠岩提供参考。