Preparation of Silica Gels with High Adsorption Activity for Extraction of Zirconium

Silica gels with a high specific surface area and high adsorption activity ,which have high selectivity and high adsorption capacity for zirconium in acidic high level radioactive liquid waste (HLLW), have been prepared from water-glass and hydrochloric acid through adding surfactants. The surfactant modifies the surface of the primary sol particles, thus suppresses the growth of the primary particle,but accelerates their agglomeration. The action of the surfactant is similar to that of the organic structure-directing agent and makes the sol cluster cross-linkage ring-like network in short order. The specific surface area of the silica gel is 998 m 2/g; the static adsorption capacity and the adsorption distribution coefficient for zirconium in HLLW are 32.6 mg/g and 56.1 mL/g, respectively.

Preparation of organically functionalized silica gel as adsorbent for copper ion adsorption

A novel adsorbent （AMPS-silica） was synthesized by bounding AMPS （2-acrylamido-2-methylpropanesulfonic acid） onto silica surface, which functioned with γ-methacryloxypropyltrimethoxysilane reagent. The adsorbent was characterized by nitrogen adsorption/desorption measurement, thermogravimetric analysis （TGA） and potentiometric titration analysis. The TGA result indicated that the surface modification reactions introduced some organic functional groups onto the surface of silica. The surface area of AMPSsilica was 389.7 m2/g. The adsorbent was examined for copper ion removal in series of batch adsorption experiments. Results showed that the adsorption of Cu2＋ onto AMPS-silica was pH dependent, and the adsorption capacity increased with increasing pH from 2 to 6. The adsorption kinetics showed that Cu^2＋ adsorption was fast and the data fitted well with a pseudo secondorder kinetic model. The adsorption of Cu^2＋ onto AMPS-silica obeyed both Freundlich and Langmuir isotherms, with r^2 = 0.993 and r^2 = 0.984, respectively. The maximum Cu^2＋ adsorption capacity was 19.9 mg/g. The involved mechanism might be the adsorption through metal binding with organic functional groups such as carboxyl, amino and sulfonic groups. Cu^2＋ loaded on AMPS-silica could be desorbed in HNO3 solution, and the adsorption properties remain stable after three adsorption-desorption cycles.

The Adsorption of Pb(II)Using Silica Gel Synthesized from Chemical Bottle Waste:Optimization Using Box-Behnken Design

The adsorption of Pb(II)on silica gel synthesized from chemical glass bottle waste has been studied.The effect of independent variables(adsorbent dose,initial concentration of Pb(II),contact time,and pH)on the Pb(II)removal from water was evaluated and optimized using the Response Surface Methodology(RSM).Under optimized conditions(adsorbent dose:20 mg;contact time:30 min;initial Pb(II)concentration:120 mg.L^(−1);and pH:8),the removal of Pb(II)was 99.77%.The adsorption equilibrium data obtained from the batch experiment were investigated using different isotherm models.The Langmuir isotherm model fits the experimental data.This shows that the surface of the silica gel synthesized from chemical bottles waste was covered by a Pb(II)monolayer.XRF analysis showed that the synthesized silica gel had a SiO_(2) content of 75.63%.Amorphous silica was observed from XRD analysis.SEM-EDX characterization showed that Pb was adsorbed on the silica gel surface.SEM analysis showed that silica gel has irregular particles with a surface area of 297.08 m2.g^(−1) with a pore radius of 15.74 nm calculated from BET analysis.

A comparative study of drying techniques on the morphology of porous silica gels synthesized via sol-gel process

The effect of drying techniques on the microstructure,morphology and pore structure of porous silica gels was studied in the paper.The gels were prepared by using sol-gel process and different drying routes:freeze-drying (FD),low pressure drying (LPD),high temperature drying (HTD) and chemical modification & ambient drying (CMD) techniques.Observation under pore distribution and structural properties showed that CMD technique leads to homogenous mesoporous silica material with specific surface area of 745 m2/g,and the average pore size around 20 nm,while LPD and HTD result in loosely packed particles with non-isotropic aggregation pattern.The specific surface areas of LPD and HTD samples are 419 and 513 m2/g respectively,and the pore size distribution of the samples are observed distributing widely in range of 10-100 nm.Freeze drying method is a new but prospective way to prepare mesoporous silica.The specific area of FD sample is around 500 m2/g.By the comparison for the properties of the gels,this paper wants to induce a further interest in finding a proper method to synthesize the porous silica gels for low price use.

Removal of siloxanes from biogas using acetylated silica gel as adsorbent

Biogas can be used as an alternative energy source for producing heat and electricity;however, volatile methylsiloxanes(VOSiC) present in biogas can severely damage heat exchangers, turbines and gas engines. Consequently, e cient removal of VOSiC from biogas that is used as a biofuel is required. In this work, acetylated silica gel(Ac@SG) was synthesized,via treatment of microporous silica gel(SG) with acetic anhydride as an adsorbent, for removal of VOSiC from biogas,and characterized with XRD, SEM–EDS, N2-BET and FT-IR. This Ac@SG adsorbent exhibited a meso-/microporous structure and hydrophobic surface, indicating it was a more e cient adsorbent for removing hexamethyldisiloxane(L2) and octamethylcyclotetrasiloxane(D4) from biogas samples than conventional SG. It was found that the adsorption capacities of Ac@SG reached 304 mg L2/g for hexamethyldisiloxane and 916 mg D4/g for octamethylcyclotetrasiloxane at lower temperatures in the experimental range, and water had no significant e ect on its absorption e ciency. The used Ac@SG could be easily regenerated by heating it at 110 °C, and the adsorption capacity of recycled Ac@SG for hexamethyldisiloxane and octamethylcyclotetrasiloxane was kept constant in four recycle adsorption experiments.

Effect of Adsorbent/Adsorbate Couple on the Performance of Adsorption Solar Refrigerator

This work presents a contribution to the study of the process of cold production by adsorption from solar energy. In this paper, we discuss a comparative study of the operation of a solar adsorption refrigerator using the silica gel-water couple and the zeolite-water couple through dynamic modeling and simulation. The mathematical model representing the evolution of heat and mass transfer at each component of the adsorption solar refrigerator has been developed. It appears from this study that the evolution of the temperature of the two adsorbents (zeolite and silica gel) is quasi-similar throughout the operating cycle. However, the maximum mass of water vapor adsorbed by the silicagel (0.24 kg/kg) is higher than that adsorbed by the zeolite (0.201 kg/kg). In the same way, the mass of water vapor cycled, obtained with the silicagel-water couple which is 0.14 kg/kg, is higher than that obtained with the zeolite-water couple which is 0.081 kg/kg. Therefore, the amount of cold produced 9.178 MJ and the solar coefficient of performance 0.378 obtained with the solar refrigerator using the silica gel-water couple, are better.

Adsorption of cesium using mesoporous silica gel evenly doped by Prussian blue nanoparticles

In this paper,a novel mesoporous silica gel evenly doped by Prussian blue nanoparticles(PBMSG) was successfully synthesized by using N,N-dimethylamide as template with a large Barrett-Emmett-Teller(BET) surface area of 505 m^(2)/g and an average pore size of 2.9 nm.The static adsorption experiments showed that the equilibration time of PBMSG for Cs^(+) was about 30 min.The adsorption isotherm of PBMSG for Cs^(+) accorded with Langmuir model and the theoretical maximum adsorption capacity was80.0± 2.9 mg/g.When the initial concentration of Cs^(+) was 1.00 mg/L,the adsorption partition coefficient Kd could reach 3.5 × 10^4 mL/g After adsorption,Cs+ could be eluted by dilute hydrochloric acid(pH2) with an efficiency of 89.8%,while no K^(+),Fe^(3+),Fe^(2+) was eluted.PBMSG exhibited good selectivity toward Cs^(+) and Rb^(+).In the presence of high concentration of K^(+),the selective adsorption of PBMSG could change the mass ratio of K^(+),Rb^(+) and Cs^(+) from 96.63:0.83:1.00-1.12:0.73:1.00.The separation of Cs^(+) and Rb^(+) from K^(+) with similar concentration(100 mg/g) was realized by column experiment.This indicated that PBMSG was suitable for rapid recovery of low concentration of rubidium and cesium from complex matrixes,such as wastewater and salt lake brine,etc.

Adsorption of cetyltrimethylammonium bromide at the silica gel/water interface

The adsorption isotherms of cetyltrimethylammonium ion (CTA^+) together with that of the Br^- counterion on silica gel, and the effects of pH and added salts(NaF, NaCl and NaBr)have been systematically determined at 25℃. Electrophoretic mobilities of the silica gel particles have also been measured in the same conditions. The adsorption isotherm of CTA^+ consists of four regions. Region I, at low concentrations of surfactant, the adsorption results primarily from electrostatic force between CTA^+ and the negatively charged silica surface. Region II (first plateau), at medium concentrations, the adsorption is due to both the electrostatic force and the specific attraction (vdW forces) between CTA^+ and the surface. Region III, characterized by an abrupt increase in the slope of the isotherm when the concentration reaches a particular point known as hemimicelle concentration (HMC). The abrupt increase in the adsorption is due to the hydrophobic interaction between hydrocarbon chains. Region IV(second plateau), at or above CMC, the limiting adsorption is reached as the micelle is not adsorbed, Based on this model. the experimental results can be explained reasonably. The results show that the HMC is about half of the CMC. According to the assumption that, each adsorbed CTA^+ ion in the first plateau is an active center for surface aggregation, the average aggregation number of hemimicelle have been calculated.

Adsorption of phenylalanine from aqueous solution onto active carbon and silica gel

The adsorption isotherms of phenylalanine from aqueous solution on active carbon and silica gel at varying pH,and the influence of inorganic salt upon the ad rption have been studied (at 25℃).The adsorption amount of phcnylalanine on the silica gel is very low due to the strong ad- sorption of water by silica gel.The results on the active carbon show:(1)The adsorption is found to be pH-dependent,within pH 4.1—5.1 it increases with pH,within pH 5.1—11.8 it decreases with pH,at pH 5.1 the adsorption reaches its maximum;(2)The phenylalanine is adsorbed mainly in the form of zwitterion;(3)A certain amount of cations and anions of phenylalanine are also adsorbed with van der Waals interaction;(4)After adding NaCl,the adsorption of phenylalanine increases markedly.

The Numerical Comparison of Heat Transfer in a Coated and Fixed Bed of an Adsorption Chiller

Ecological adsorption technology is becoming a focus of attention by industry due to the utilization of low grade thermal energy sources for cooling production. It can be a promising part of sustainable development concept of the global economy. Therefore, research aiming at improving their performance i.e. Coefficient of Performance(COP) by optimizing the construction of sorption beds with a built in heat exchanger system is crucial. The heat transfer characteristics between the bed of porous media(sorbent) and surface of the heat exchanger system determine the heating power of an adsorption chiller. The HP increase can be obtained by heat transfer intensification due to the increase in the thermal conductivity of the sorbent layer in the vicinity of the heat exchanger's surface. The novel modification of the sorbent layer structure is proposed in the paper in order to improve the heat transfer processes in the heat exchanger boundary layer. The analysis of desorption process conditions in the parametric model of a coated and fixed adsorption bed design is presented in the paper. The computational fluid dynamics(CFD) with conjugate heat transfer analysis is used to determine the crucial input parameters(temperature distribution in the sorbent bed) for further analytical calculations. The commercial code Ansys Fluent was used to perform numerical simulations. The developed computational model consisted of three subdomains representing heating water, heat exchanger material(copper) and sorbent(silica gel). The comparison of a novel coated design and a conventional fixed bed is discussed in the paper. The numerical analysis is based on experimental thermal conductivity measurements of the sorbent layer in different configurations, which were performed using Laser Flash Method.

Silica Gel from Chemical Glass Bottle Waste as Adsorbent for Methylene Blue:Optimization Using BBD

This research focuses on the effective removal of methylene blue dye using silica gel synthesized from chemical glass bottle waste as an environmentally friendly and cost-effective adsorbent.The adsorption process was optimized using Box-Behnken Design(BBD)and Response Surface Methodology(RSM)to investigate the influence of pH(6;8 and 10),contact time(15;30 and 45 min),adsorbent mass(30;50 and 70 mg),and initial concentration(20;50 and 80 mg/L)of the adsorbate on the adsorption efficiency.The BBD was conducted using Google Colaboratory software,which encompassed 27 experiments with randomly assigned combinations.The silica gel synthesized from chemical glass bottle was characterized by XRD,FTIR,SEM-EDX and TEM.The adsorption result was measured by spectrophotometer UV-Vis.The optimized conditions resulted in a remarkable methylene blue removal efficiency of 99.41%.Characterization of the silica gel demonstrated amorphous morphology and prominent absorption bands characteristic of silica.The Langmuir isotherm model best described the adsorption behavior,revealing chemisorption with a monolayer coverage of methylene blue on the adsorbent surface,and a maximum adsorption capacity of 82.02 mg/g.Additionally,the pseudo-second-order kinetics model indicated a chemisorption mechanism during the adsorption process.The findings highlight the potential of silica gel from chemical glass bottle waste as a promising adsorbent for wastewater treatment,offering economic and environmental benefits.Further investigations can explore its scalability,regenerability,and reusability for industrial-scale applications.

硅胶有效吸脱水特性研究

为了解硅胶在吸脱水过程中水含量分布特征,开展了脱附温度对硅胶吸附量与物相结构的影响,研究了脱附气氛、脱附温度、脱附时间、含水量与脱附次数对硅胶有效残留水的影响,并计算了硅胶在不同脱附条件下的有效吸附水。结果表明,当脱附温度≤130℃时,吸附量无衰减,结构保持稳定。硅胶有效残留水同脱附温度、脱附气氛相关,同脱附前含水量、脱附次数无关。在空气气氛脱附时,最佳脱附条件为130℃,1 h,有效残留水为8.5%~9.1%,当吸附20~150 min时,有效吸附水随吸附时间线性增加,特别当吸附120~150 min时,有效吸附水达到12%~14%。

采出水中核壳型荧光微球浓度的检测方法

聚合物微球调驱是改善水驱效果的主要技术之一。微球在地层中的运移以及能否在采出水中有效检出会直接影响调驱效果。因此,将荧光碳点引入微球调驱剂中,起到示踪的作用。荧光核壳微球调驱剂由含荧光碳点的核心微球溶液和壳层水溶液混合吸附而成。为了降低油水分离后采出水中的杂质对核壳荧光微球有效检出的干扰,首先对荧光微球的浓度与荧光强度进行线性拟合,验证该方法的可行性;然后用硅胶对地层采出水进行吸附,通过对比采出水吸附前后的荧光发射光谱,验证硅胶吸附的实用性;最后用硅胶对采出水配制的荧光微球进行吸附,绘制荧光强度和微球浓度的标准曲线。结果表明,在激发波长为347 nm的条件下,荧光微球的质量浓度与445 nm发射波长处的荧光强度具有良好的线性关系,相关判定系数(R^(2))为0.9870。经硅胶处理后,水驱采出水的荧光发射强度显著降低,硅胶吸附能有效去除采出水中的杂质。在激发波长为347 nm、荧光光谱仪狭缝为10~20 nm、微球质量浓度为1~1200 mg/L时,荧光核壳微球水分散液的质量浓度(x)与462 nm处的荧光发射峰值(y)呈正比线性关系,拟合方程为y=2497.1042+3.1847x,R^(2)为0.9972,置信度较高。荧光强度与核壳微球浓度的线性阶段可满足现场检测要求。该方法可为类似油藏荧光微球含量的定量检测提供借鉴。

硅烷试剂改性硅胶特性及柴油吸附性能研究

选择6种硅烷试剂对B型硅胶进行接枝改性,通过N 2吸附-脱附试验、固体红外光谱分析、热重与质谱联用分析、元素分析和甲苯吸附试验等表征手段探究吸附材料的物理和化学特性,结合静态吸附平衡试验探究吸附材料的柴油吸附性能。结果表明:氨基、巯基和环氧基基团可以和硅胶成功接枝,改性后硅胶的比表面积、总孔体积、最可几孔径和平均孔径均减小,甲苯吸附量与改性硅胶比表面积呈正相关关系。根据改性硅胶中氮元素质量分数的不同计算得出,硅胶改性反应的程度与硅烷试剂的选择有关。静态试验结果表明:6种硅烷试剂中,氨基和环氧基改性硅胶能提高吸附剂对双环芳烃的选择性,同时提高对柴油中含硫化合物的选择性;巯基改性硅胶能降低吸附剂对含硫化合物的选择性;而氨基、巯基和环氧基改性硅胶均能降低吸附剂对单环芳烃的选择性。

银修饰硅胶复合材料对气态碘的捕集及其固化研究

以硅胶为载体,采用水热浸渍法制备银修饰硅胶复合材料,对富碘后的复合材料进行低温玻璃固化处理,以期实现对气态放射性碘的长期安全处置。通过扫描电子显微镜和X射线衍射仪对复合材料的形貌和结构进行表征,考察了浸渍反应温度对银负载量、吸附时间和碘质量浓度对碘吸附量的影响,并对吸附动力学曲线和吸附等温线进行了拟合。结果表明:硝酸银负载在硅胶表面,银负载量达到17.8%;30min内复合材料对气体碘的吸附可达到平衡,吸附行为符合准二级动力学模型,为化学吸附;Langmuir等温吸附模型更适合描述复合材料对气态碘的吸附过程,复合材料吸附碘的过程为单层吸附行为,复合材料对碘的理论最大吸附量为169.5mg/g。固化结果表明,玻璃固化体主要以碘化银(AgI)和碘七氧化五铋(Bi_(5)O_(7)I)形式封存碘,碘元素浸出率为1.436×10^(-6) g/(m^(2)•day)。

稻壳基硅胶/石墨烯复合材料的制备及有机气体吸附性能

利用价廉、可再生的稻壳为原料,经热解、水热处理得到脱硅溶液,在酸性环境下加入氧化石墨烯分散液制得稻壳基硅胶/石墨烯复合材料(GRHS)。利用扫描电子显微镜、微孔物理吸附分析仪表征了产物结构,重点研究了GRHS对水蒸气、正己烷的吸附性能及其循环吸附稳定性。结果表明,GRHS的平均孔径为2.87 nm,比表面积为723.22 m^(2)/g;GRHS与未复合的稻壳基硅胶相比,表面有更多纳米级的粒子堆积,并形成了二氧化硅的三维网状结构;20℃时,GRHS对水蒸气的静态饱和吸附量为0.097 g/g,远小于稻壳基硅胶(0.226 g/g)的吸附量,GRHS对正己烷的静态饱和吸附量为0.332 g/g,大于稻壳基硅胶(0.217 g/g)的吸附量;GRHS的循环吸附稳定性较好,第7次吸附时,对正己烷的吸附量较第1次仅减少了0.023 g/g,对水蒸气的吸附量较第1次仅增加了0.012 g/g,有利于提高其应用于挥发性有机化合物回收时的使用寿命。

用多孔硅胶从高含氟放射性废水中吸附铀

试验研究多孔硅胶对高含氟溶液中UO_(2)^(2+)的静态和动态吸附行为,探索硅胶吸附除铀技术在高含氟放射性废水处理中应用的可行性,并验证各吸附条件的影响。当溶液中ρ(F^(-))达到100 g/L时,多孔硅胶对UO_(2)^(2+)的静态吸附容量(以干硅胶计)为31~33 mg/g,高含氟环境对多孔硅胶吸附UO_(2)^(2+)的影响较小,且多孔硅胶对UO_(2)^(2+)与F^(-)有较高的选择性。通过静态吸附试验可知,多孔硅胶在pH为8~9的环境中,对UO_(2)^(2+)的吸附效果最佳。动态吸附试验表明,当进料pH为9时,硅胶吸附柱的工作容量约为20倍柱体积。使用1 mol/L HNO_(3)解吸液可将吸附UO_(2)^(2+)硅胶柱中的部分UO_(2)^(2+)洗脱,解吸液容量约为10倍柱体积。硅胶柱用1 mol/L HNO_(3)解吸后复用5~6次,UO_(2)^(2+)的穿透曲线位置基本一致。

巯基化多孔二氧化硅的制备及其亚甲基蓝吸附性能

以氨水为催化剂,正硅酸四乙酯(TEOS)为前驱体,十六烷基三甲基溴化铵(CTAB)为致孔剂,采用溶胶-凝胶法制备多孔二氧化硅,并使用γ-巯丙基三甲氧基硅烷(KH590)对其进行改性,对改性前后的多孔二氧化硅进行表征和亚甲基蓝吸附性能测试。结果表明,所制备的多孔二氧化硅粒径均在40~80 nm,孔径在2.25~4.39 nm之间,具有较大的比表面积,最大为379.4m^(2)/g,且分散性良好。红外光谱分析表明KH590成功对多孔二氧化硅进行了改性,改性后的多孔二氧化硅疏水性能提高。相较于未改性的多孔二氧化硅,KH590改性后的多孔二氧化硅对亚甲基蓝的吸附性能更好。

氨气报警器检定中标准气体的使用

研究了氨气报警器检定中标准气体的使用。结合实际工作经验,论述了标准气体中不同稀释气体、不同气体管路、传感器保护罩透气性对检定结果的影响。采用氮中氨气体标准物质和空气中氨气体标准物质进行了对比试验,结果表明不同稀释气体对使用过一段时间的氨气报警器的示值存在较大影响;采用聚四氟乙烯管和硅胶管两种气体管路进行了对比试验,结果表明硅胶管对氨气具有较强的吸附性,不适用于氨气报警器检定。

硅胶吸附法制备红花总黄色素抗凝血作用的实验研究

目的 观察硅胶吸附法制得的红花总黄色素 (简称SY1)抗凝血及抑制血栓形成的作用。方法 以比浊法测定家兔洗涤血小板聚集作用 ;观察家兔血浆凝血酶原时间 (PT)与血浆复钙时间 (RT) ;以小鼠尾尖出血时间试验观察SY1灌胃对出血时间的影响 ,并进行小鼠急性毒性试验。结果 SY1抑制家兔血小板聚集 ,延长家兔血浆PT与RT的作用均呈现体外浓度依赖性 ;小鼠灌胃SY1延长尾尖出血时间呈现明显的剂量依赖性 ;小鼠腹腔注射LD50 =(7.5 4± 0 .2 4 ) g·kg-1。结论 SY1具抗血栓作用 ,抑制血小板聚集及抗凝为其重要机制 。