The Potential of Silane Coated Calcium Carbonate on Mechanical Properties of Rigid PVC Composites for Pipe Manufacturing

The inclusion of CaCO3 and kaolin in polyvinyl chloride (PVC) polymer matrices greatly enhances the physical and mechanical properties of the composite. In this study, the effects of kaolin and surface treatment of CaCO3 and kaolin particles on the microstructure and mechanical properties of PVC composites filled with kaolin particles via melt blending method were studied by means of SEM, tensile, Charpy impact testing, and FTIR. Treated and untreated kao-lin particles were dispersed in matrices of PVC resin at different concentrations up to 30 wt percentage. The tensile strength, elastic modulus, strain to failure and morphology of the resulting composites were measured for various filler loadings. Uniform dispersion of the fillers into the matrix proved to be a critical factor. SEM images revealed that small sized particles were more agglomerated than micron-sized particles and the amount of agglomerates increased with increasing particle content. Silane treated Kaolin-CaCO3/PVC composites had superior tensile and impact strengths to untreated kaolin-CaCO3/PVC composites. The Young’s modulus of all composites increased with increasing particle content up to maximum at 10% filler loading followed by gradually decreasing as content increased.

Preparation of Ammonia Adsorbent by Carbonizing and Activating Mixture of Biomass Material and Hygroscopic Salt

We put forward a new and ingenious method for the preparation of a new adsorbent by soaking, carbonizing and activating the mixture of hygroscopic salt and biomass material. The new adsorbent has high porosity, uniform distribution and high content of Ca Cl2, and exhibits high adsorption performance. The ammonia uptake and specific cooling power（SCP） at 5 min adsorption time can reach as high as 0.19 g·g^-1 and 793.9 W·kg^-1, respectively. The concept of utilizing the biomass materials and hygroscopic salts as raw materials for the preparation of adsorbents is of practical interest with respect to the potential quantity of biomass materials around the world, indicating that there would be a new market for biomass materials.Key words： biomass material; adsorption system; ammonia; calcium chloride; activated carbon

Carbonization, Activation and Description of Activated Carbon from Palm Tree Leaves

One of the maximum residences of activated carbon is adsorption capacity, this significance grows every day in a variety of fields. One of its examples is water treatment, processing of potable, all of those residences deliver capacity of activated carbon in smell elimination and flavor in residues of dissolved natural and color. Activated carbon was made from the carbonization of palm tree leave’s stems and activated using calcium chloride, then tested with an increase in reactivity indicated by iodine adsorption test up to 68.6% reactivity increase in commercial sample and 48.7% in palm tree leaves sample. As the methods and precursors of activated carbon are very diverse and result in deferent adsorption properties, the primary test includes: carbonization of palm tree leaves, size reduction and classification of the charcoal produced, applying an iodine test on the non-activated sample, activating another sample with activating agent CaCl2 to comparison between the activated carbon and the non-activated carbon and shows the increasing in the adsorption capacity for elemental iodine in activated carbon.

Experimental Design Technique on Removal of Hydrogen Sulfide using CaO-eggshells Dispersed onto Palm Kernel Shell Activated Carbon：Experiment,Optimization,Equilibrium and Kinetic Studies

This study presents the use of chicken eggshells waste utilizing palm kernel shell based activated carbon（PKSAC） through the modification of their surface to enhance the adsorption capacity of H2S. Response surface methodology technique was used to optimize the process conditions and they were found to be： 500 mg/L for H2S initial concentration, 540 min for contact time and 1 g for adsorbent mass. The impacts of three arrangement factors（calcination temperature of impregnated activated carbon（IAC）, the calcium solution concentration and contact time of calcination） on the H2S removal efficiency and impregnated AC yield were investigated. Both responses IAC yield（IACY, %） and removal efficiency（RE, %） were maximized to optimize the IAC preparation conditions. The optimum preparation conditions for IACY and RE were found as follows： calcination temperature of IAC of 880 ℃, calcium solution concentration of 49.3% and calcination contact time of 57.6 min, which resulted in 35.8% of IACY and 98.2% RE. In addition, the equilibrium and kinetics of the process were investigated. The adsorbent was characterized using TGA, XRD, FTIR, SEM/EDX, and BET. The maximum monolayer adsorption capacity was found to be 543.47 mg/g. The results recommended that the composite of PKSAC and Ca O could be a useful material for H2S containing wastewater treatment.

Behavior of calcium oxalate in sodium aluminate solutions

The stability of calcium oxalate is critical for the removal of sodium oxalate from sodium aluminate solutions.This studyinvestigated the behavior of calcium oxalate in sodium aluminate solution containing sodium carbonate.Results show that calciumoxalate can be converted to tricalcium aluminate hydrate(TCA)and calcium carbonate in sodium aluminate solution and sodiumcarbonate solution,respectively.Elevating temperature,extending residence time,or increasing caustic soda concentration enhancesthe conversion ratio of calcium oxalate in sodium aluminate solution;as a consequence,anti-causticisation occurs.Stability ofcalcium-containing compounds in sodium aluminate solution containing sodium carbonate differs from that in sodium aluminatesolution or sodium carbonate solution.Na2CO3in aluminate solution accelerates the transformation of calcium oxalate;thus,aluminais lost because of4CaO·Al2O3·CO2·11H2O and TCA formation.Calcium carbonate,4CaO·Al2O3·CO2·11H2O and calcium oxalatecan change into TCA in sodium aluminate solution at elevated temperature.Calcium oxalate remains relatively stable in dilutealuminate solution within a short residence time at low temperature.Thus,a novel process for removal of sodium oxalate by limecausticisation was presented and employed in an alumina refinery in China.

Toughness Improvement of Geothermal Well Cement at up to 300^°C: Using Carbon Microfiber

This study aimed at assessing the usefulness of carbon microfiber (CMF) in improving the compressive-toughness of sodium metasilicate-activated calcium aluminate/Class F fly ash foamed cement at hydrothermal temperatures of up to 300°C. When the CMFs came in contact with a pore solution of cement, their surfaces underwent alkali-caused oxidation, leading to the formation of metal (Na, Ca, Al)-complexed carboxylate groups. The extent of this oxidation was enhanced by the temperature increase, corresponding to the incorporation of more oxidation derivatives at higher temperatures. Although micro-probe examinations did not show any defects in the fibers, the enhanced oxidation engendered shrinkage of the interlayer spacing between the C-basal planes in CMFs, and a decline in their thermal stability. On the other hand, the complexed carboxylate groups present on the surfaces of oxidized fibers played a pivotal role in improving the adherence of fibers to the cement matrix. Such fiber/cement interfacial bonds contributed significantly to the excellent bridging effect of fibers, resistance to the cracks development and propagation, and to improvement of the post-crack material ductility. Consequently, the compressive toughness of the 85°-, 200°-, and 300°C-autoclaved foamed cements reinforced with 10 wt% CMF was 2.4-, 2.9-, and 3.1-fold higher than for cement without the reinforcement.

Effect of Alumina Micropowders on Properties of Calcium Hexaluminate

Calcium hexaluminate （ CA6 ） was synthesized by mixing light-weight calcium carbonate and Al2O3 mi- cropowder （calcined α-Al2O3, activated α-Al2O3 or α-Al2O3） according to the stoichimetric ratio of CA6, and reaction sintering at 1 200, 1 300, 1 400 and 1 500 ℃fin 3 h, respectiely. Efcts of the three alu- mina micropowders on the phase composition, micro- structure and properties of CA were investigated. The re- sults show that ： （ 1 ） for the three Al2O3 micropowders, the reaction to generate CA6 in specimens basically com- plete. at about 1 500 ℃ ; CA6 generated in all specimens is planar, bat the array modes are slightly different; （2） the specimel＇s prepared from, calcined α-Al2O3or ρ-Al2O3 shrink almost, while the specimens prepared from activated α-Al2O3 expand ; （ 3 ） the cold crushing strength of the specimen prepared from activated α-Al2O3 is the highest, reaching 42.5 MPa when only CA6 exists （ after firing at 1 500 ℃ ） ; （ 4 ） the specimen prepared from ρ-Al2O3 has the lowest generation temperature of CA6 and the highest apparent porosity, reaching 70. 1% when only CA exists （after firing at 1 500 ℃）; （5） the specimen prepared from calcined α-Al2O3 has the biggest bulk density.

Dry Mix Slag—High-Calcium Fly Ash Binder. Part One: Hydration and Mechanical Properties

High-calcium fly ash (HCFA)—a residue of high-temperature coal combustion at thermal power plants, in combination with sodium carbonate presents an effective hardening activator of ground granulated blast-furnace slag (GGBFS). Substitution of 10% - 30% of GGBFS by HCFA and premixing of 1% - 3% Na2CO3 to this dry binary binder was discovered to give mortar compression strength of 10 - 30 to 30 - 45 MPa at 7 and 28 days when moist cured at ambient temperature. High-calcium fly ash produced from low-temperature combustion of fuel, like in circulating fluidized bed technology, reacts with water readily and is itself a good hardening activator for GGBFS, so introduction of Na2CO3 into such mix has no noticeable effect on the mortar strength. However, low-temperature HCFA has higher water demand, and the strength of mortar is compromised by this factor. As of today, our research is still ongoing, and we expect to publish more data on different aspects of durability of proposed GGBFS-HCFA binder later.

碳酸钙晶须对碱矿渣胶凝材料的减缩增强作用

针对碱矿渣胶凝材料易收缩开裂等问题,采用一种新型微米级纤维——碳酸钙晶须对碱矿渣胶凝材料进行减缩增强,研究了碳酸钙晶须掺量对碱矿渣胶凝材料流变性能、抗压强度和干燥收缩的影响,并探究其显微增强机理.结果表明:微米级碳酸钙晶须的掺入对碱矿渣胶凝材料流动性影响较小,当碳酸钙晶须掺量为3%时,其新拌浆体塑性黏度为12.33 Pa·s,较未掺碳酸钙晶须的对照组仅增长14.48%,其硬化浆体28 d抗压强度可达105.8 MPa;碱矿渣胶凝材料的干燥收缩率随着碳酸钙晶须掺量的增加而降低,当碳酸钙晶须掺量为5%时,其28 d干燥收缩率仅有0.87%,较未掺碳酸钙晶须的对照组降低32.56%;碳酸钙晶须与基体紧密结合,在基体受力破坏时分散其所受应力,提升了碱矿渣胶凝材料的力学性能;碳酸钙晶须在体系内部的桥接作用能够有效延缓碱矿渣胶凝材料微裂纹的形成与扩展,在一定程度上遏制了宏观裂纹的发展.

氧化钙-碳酸钠复合激发矿渣砂浆的自收缩机制

为探究氧化钙和碳酸钠复合激发矿渣对碱激发水泥自收缩的影响机制,采用氧化钙和碳酸钠(摩尔比1∶1)为复合激发剂制备碱矿渣砂浆(AM),研究复合激发剂Na_(2)O质量分数(CaO和Na_(2)CO_(3)反应生成的Na_(2)O质量与矿渣质量比,为2.5%、4.5%、6.5%和8.5%)对AM自收缩的影响;通过XRD、TG-DTG、MIP和NMR分析其水化产物与微观结构。结果表明:随着Na_(2)O质量分数的增加,激发剂反应耗水量增加,孔结构细化,孔隙压力增大;Al^(3+)对C-(A)-S-H中Si^(4+)的取代量增多导致Na^(+)的吸附量增多,C-(A)-S-H滑移增大;水化程度提高,水化产物数量增多,AM的自收缩增大。Na_(2)O质量分数为6.5%的AM为最优组,其力学性能高于普通硅酸盐水泥砂浆(OM),但由于较低的晶体含量和致密的孔结构,其自收缩大于OM。

活性氧化钙绿色低碳制备国内外发展现状及展望

石灰行业碳排放量巨大,是建材行业第二大碳排放产业,绿色低碳转型刻不容缓。本文总结了高品质石灰(活性氧化钙)绿色低碳制备国内外技术现状,展望了未来发展趋势和研究热点,强调了工艺和装备的关键性,提出了加强技术创新、智能化手段应用、碳捕集利用等建议,以推动石灰行业迈向更环保、高效的未来。

硬脂酸改性纳米碳酸钙表面研究

为了改善纳米碳酸钙(nano-CaCO_(3))在基体中的分散情况,采用硬脂酸对nano-CaCO_(3)表面进行改性,通过改变硬脂酸用量、反应温度、反应时间、浆料质量浓度,测定反应前后nano-Ca CO_(3)的活化度和吸油值,进而确定最佳反应条件。结果表明:硬脂酸可以改性nano-Ca CO_(3),其最好的改性条件为硬脂酸质量分数4%,浆料质量浓度90g·L^(-1),反应温度为60~80℃,反应时间为50~60min。红外光谱显示硬脂酸与nano-CaCO_(3)之间形成了牢固的化学键,扫描电镜观察到用硬脂酸处理过的nano-CaCO_(3)可减少在基体中团聚,有助于其在基体中分散。

Decreased bioavailability of aminomethylphosphonic acid(AMPA)in genetically modified corn with activated carbon or calcium montmorillonite clay inclusion in soil

The widespread use of pesticides has resulted in detectable residues throughout the environment,sometimes at concentrations well above regulatory limits.Therefore,the development of safe,effective,field-practical,and economically feasible strategies to mitigate the effects of pesticides is warranted.Glyphosate is an organophosphorus herbicide that is degraded to aminomethylphosphonic acid(AMPA),a toxic and persistent metabolite that can accumulate in soil and sediment and translocate to plants.In this study,we investigated the binding efficacy of activated carbon(AC)and calcium montmorillonite(CM)clay to decrease AMPA bioavailability from soil and AMPA translocation to plants.Adsorption isotherms and thermodynamic studies on AC and CM were conducted and showed tight binding(enthalpy values>-20 k J/mol)for AMPA with high capacities(0.25 mol/kg and 0.38 mol/kg,respectively),based on derivations from the Langmuir model.A hydra assay was utilized to indicate toxicity of AMPA and the inclusion of 1%AC and CM both resulted in 90%protection of the hydra(**p≤0.01).Further studies in glyphosate-contaminated soil showed that AC and CM significantly reduced AMPA bioavailability by 53%and 44%,respectively.Results in genetically modified(GM)corn showed a conversion of glyphosate to AMPA in roots and sprouts over a 10-day exposure duration.Inclusion of AC and CM reduced AMPA residues in roots and sprouts by 47%-61%.These studies collectively indicate that AC and CM are effective sorbents for AMPA and could be used to reduce AMPA bioavailability from soil and AMPA residues in GM corn plants.

密闭机械活化浸出电石渣制备高纯钙溶液

电石渣是工业生产过程产生的碱性危废,利用于CO_(2)固化,将有助于“碳达峰、碳中和”目标早日实现。在碱性环境中,用氯化铵浸出剂可选择性浸出Ca,使电石渣中的Ca与其他杂质分离开来,从而制备高纯度含钙溶液,之后将所得富钙液与CO_(2)反应制备高纯碳酸钙,从而实现固废资源化。以氯化铵为浸出剂,球磨机为浸出反应设备,采用密闭机械活化手段进行处理,探究了浸出剂用量、机械搅拌转速、反应时间和液固比等工艺参数对电石渣中Ca浸出率的影响。结果表明,在氯化铵用量为理论用量的1.1倍、球磨机转速500 r/min、反应时间10 min和液固比4∶1最佳反应条件下,Ca浸出率可达到89.76%,滤液Ca浓度高达79.4 g/L。相较于常规浸出,采用密闭机械活化手段可提高Ca浸出率3个百分点,且可大幅度降低氨气挥发,保证良好操作环境。

吸附剂对选矿废水中丁基黄药的吸附性能研究

为高效解决选矿废水残余浮选药剂浓度高的问题,将活性炭和钙基膨润土分别作为吸附剂,系统探究了吸附剂用量、吸附时间、反应温度、溶液初始pH值等因素对废水中丁基黄药吸附性能的影响。试验结果表明:活性炭对丁基黄药的吸附量和去除率最大值分别为6.55mg/g和98.32%,而钙基膨润土对丁基黄药的吸附量和去除率最大值分别为2.73 mg/g和40.95%。通过X射线衍射(XRD)和傅里叶红外光谱(FTIR)对吸附材料吸附前后的结构变化进行对比表明,活性炭和钙基膨润土对丁基黄药的去除机制主要为物理吸附。

关中农田土壤有机质和碳酸钙空间变异特征及其机理分析

为了研究人为活动对于农田土壤有机质含量和碳酸钙空间变异性的作用与影响,在陕西杨凌杜寨村研究了农田土壤有机质和碳酸钙空间变异性,并对其变异机理进行了分析。试验表明：表层0-10 cm和底层20-40 cm土壤有机质平均值分别20.64 g/kg和10.81 g/kg,变异系数为0.087和0.013,均属弱变异程度;亚表层10-20cm土壤有机质平均值为16.96 g/kg,变异系数为0.130,属中等变异程度;碳酸钙均属弱变异程度。经过对土壤特性空间分布等值线图的分析得出：在水平方向上,土壤有机质和碳酸钙均具有相同的变异规律,距离村庄越近土壤有机质和碳酸钙含量越高,以村庄为圆心土壤有机质和碳酸钙含量呈同心圆式的空间变异特征。

活性轻质和重质碳酸钙添加在软质PVC中的效果比较

采用活性轻质碳酸钙和活性重质碳酸钙填充软质聚氯乙烯(PVC),考察了两种填料在不同添加比例下对PVC材料流变性能和力学性能的影响。结果表明,添加活性轻质碳酸钙的PVC材料的加工性能优于添加活性重质碳酸钙的PVC复合材料,并且前者比后者在性价比和降低生产成本方面更具有优势。

土壤中游离碳酸钙对土壤pH及酶活性的影响

游离碳酸钙是我国北方石灰性土壤的重要组成物质,密切影响着土壤的物理、化学、生物学性质以及土壤的环境学效应,但是将游离碳酸钙作为土壤重要组成物质而探讨其对土壤生物学特性尤其是对土壤酶活性的影响研究较少。通过研究探讨碳酸钙与土壤pH值之间的定量关系以及碳酸钙含量对土壤酶活性的影响,为进一步研究游离碳酸钙对土壤生物学性质及土壤环境效应的影响提供理论参考。采用实验室模拟培养及分析测试的方法进行试验。结果表明:土壤pH随游离碳酸钙含量的增加而增加,趋近于达到该试验条件下的最大值(pH=8.19),但并非呈直线相关,而是呈非线性相关关系。中性磷酸酶活性和转化酶随碳酸钙浓度的增加而降低,其最大降低幅度分别为0.402个活性单位和3.16个活性单位。碳酸钙含量与土壤pH值之间呈非线性相关关系。碳酸钙对土壤中性磷酸酶和转化酶活性产生极显著的抑制作用,对脲酶活性呈现低含量促进而高含量抑制的作用,而对过氧化氢酶则产生极显著的促进作用。

钙催化活化制备活性炭的研究进展

介绍了采用钙催化物理活化制备活性炭的机理,对水蒸气和二氧化碳在钙催化物理活化中所起到的作用进行了介绍并进行了比较。随后介绍了钙催化剂的热力学和分散性的研究,以及物理活化制备活性炭的应用。

纳米级和特型活性碳酸钙的制备

详细介绍了三种液相法合成纳米碳酸钙的反应系统 :Ca(OH) 2 H2 O CO2 反应系统、Ca2 + H2 O CO2 -3反应系统、Ca2 + R CO2 -3 反应系统 (R为有机介质 )以及每种反应系统的特点 ,综述了利用添加剂控制碳酸钙形状 ,制备链状、立方状、纺锤状、球形、片状等 5种微粉碳酸钙的工艺条件及方法 ,并对碳酸钙的表面活性化处理进行了系统的研究。