Protection of mesopore-adsorbed organic matter from enzymatic degradation

Synthetic mesoporous alumina and silica minerals with uniform pore geometries, and their nonporous analogues, were used to test the role of mineral mesopores (2-50 nm diameter) in protecting organic matter from enzymatic degradation in soils and sediments. Dihydroxyphenylalanine (L-DOPA), a model humic compound, was irreversibly sorbed to both mineral types. The surface area-normalized adsorption capacity was greater for the mesoporous minerals relative to their nonporous analogues. The degradation kinetics of free and mineral-sorbed L-DOPA by the enzyme laccase was monitored in a closed cell via oxygen electrode. Relative to freely dissolved L-DOPA, nonporous alumina-sorbed substrate was degraded, on average, 90% more slowly and to a lesser extent (93%), likely due to laccase adsorption to alumina. In contrast, relative to free L-DOPA, degradation of nonporous silica-sorbed L-DOPA was enhanced by 20% on average. In the case of mesoporous alumina and silica-sorbed L-DOPA, the enzyme activity was 3-40 times lower than that observed for externally sorbed substrate (i.e., L-DOPA sorbed to nonporous minerals). These results provide strong evidence to support the viability of the mesopore protection mechanism for sequestration and preservation of sedimentary organic matter and organic contaminants. Nanopore adsorption/desorption phenomena may aid in explaining the slow degradation of organic contaminants in certain soils and sediments and may have implications for environmental remediation and biotechnological applications.     

五乙烯六胺改性介孔材料及其在印染废水处理中的应用

利用五乙烯六胺（PEHA）改性介孔材料SBA-3,利用氨基基团与酸性染料之间的静电吸引力和氢键力作用,提高介孔材料对酸性染料的吸附能力。利用低温N2吸附对SBA-3和SBA-3/PEHA样品进行表征,发现PEHA改性后吸附剂的比表面积、孔容,平均孔径均减少。研究不同吸附条件下PEHA功能化介孔材料SBA-3对酸性染料染色废液的吸附能力,主要包括吸附时间、初始浓度、吸附剂用量、搅拌速度、溶液pH值和吸附温度几个方面。确定最优吸附条件为：吸附时间60min,搅拌速度150rpm,吸附温度为20℃,且初始浓度越大,pH越低,吸附量越大。     

Effect of pore-blocking background compounds on the kinetics of trace organic contaminant desorption from activated carbon

This study examined the effect of pore-blocking (PB) background organic matter, which is known to hinder adsorption kinetics, on the rate of trace contaminant desorption. Adsorption, displaced desorption (DD) and nondisplaced desorption (NDD) kinetic tests were performed using powdered activated carbon (PAC) that was preloaded with natural organic matter (NOM). Since the NOM contained both strongly competing (SC) and PB components, the proposed model separated the contributions of the SC and PB NOM to the overall diffusion coefficient of the target contaminant. By factoring outthe SC NOM contribution, which increases the overall diffusion coefficient it was found that the relationship used to model the effect of PB NOM on adsorption kinetics could also describe desorption kinetics. The results highlighted the substantial influence of competitive SC NOM on the kinetics of adsorption and desorption. SC NOM competition aids contaminant removal by offsetting the undesirable effects of pore blocking on adsorption kinetics. However, for desorption events, PB NOM serves a practical benefit of reducing the rate of release of adsorbed micropollutants, while SC NOM counters that gain by both displacing contaminants and accelerating their diffusion.     

介孔材料的双功能化修饰及降低卷烟烟气中氰化氢的性能

为开发选择性吸附卷烟烟气中氰化氢的滤嘴添加剂,对水热合成法制备的有序介孔氧化硅材料MCM-41进行了碱性基团和过渡金属离子双功能化修饰,表征了功能化材料的孔结构、孔径分布、孔体积、比表面积以及元素组成等,考察了材料制备条件对吸附氰化氢性能的影响,评价了材料在卷烟滤嘴中的应用效果。结果表明:①采用N-(β-氨乙基)-γ-氨基丙基甲基二甲氧基硅烷(EPDMS)和过渡金属离子修饰后的MCM-41材料,仍保持了二维六方孔道结构以及较高的比表面积与孔体积;②EPDMS用量为4 mL/(g MCM-41)、金属离子为Zn2+时,所制备的MCM-41双功能化材料Zn2+/c-EPDMS/MCM-41的氰化氢吸附性能最好;③将上述条件下制备的Zn2+/c-EPDMS/MCM-41以二元复合滤棒的形式、20 mg/支的添加量应用于卷烟后,主流烟气HCN选择性降低31.2%,卷烟危害性指数(H)下降0.4。所制备的MCM-41双功能化材料Zn2+/c-EPDMS/MCM-41具有良好的氰化氢选择性吸附性能。      

单环刺螠体壁多糖的组成分析及基于MCM-41的吸附富集研究

本文通过胃蛋白酶酶解法提取了单环刺螠体壁多糖,进行了组成分析,并从吸附动力学、吸附热力学的角度,研究了介孔材料MCM-41对多糖的吸附。组成分析结果显示,多糖中总糖含量为（78.82%±1.40%）,蛋白含量为（10.5%±1.07%）,硫酸根含量为（0.52%±0.06%）;单糖组成分析结果显示,多糖主要由葡萄糖、甘露糖、半乳糖和木糖等单糖组成。红外光谱分析结果显示,多糖中含有O-H、C-O-C、C=O、S=O等特征基团,说明单环刺螠体壁多糖中含有糖醛酸组分,且存在硫酸基的取代。利用平均孔径为3.85 nm、孔容1.25 cm3/g的介孔材料MCM-41对单环刺螠体壁多糖进行富集,吸附量达到350 mg/g,吸附动力学符合准二级吸附动力学（pseudo second order adsorption kinetics,PSO）模型,吸附过程由外部扩散和颗粒内扩散控制。Langmuir和Freundlich模型均能够较好拟合吸附热力学,说明MCM-41的吸附过程主要为单分子层并伴随着多分子层的吸附。研究了不同洗脱剂的洗脱效果,发现10% SDS具有相对较强的洗脱能力。单环刺螠体壁多糖在介孔材料上的吸附研究有望为食品产业中含糖物质的富集分离提供指导。     

Solid Phase Extraction of Pb(II) and Cd(II) in Food,Soil, and Water Samples Based on 1-(2-Pyridylazo)-2-Naphthol-Functionalized Organic–Inorganic Mesoporous Material with the aid of Experimental Design Methodology

An effective sorbent of 1-(2-Pyridylazo)-2-naphthol-functionalized mesoporous silica has been prepared to simultaneous separation and preconcentration of lead and cadmium ions in aqueous solution. Structural characterization of 1-(2-Pyridylazo)-2-naphthol-functionalized organic–inorganic hybrid mesoporous materials was conducted by Fourier transform infrared spectroscopy, transmission electron microscopy, N₂ adsorption–desorption measurement, X-ray diffraction, and elemental and thermal analysis, which confirmed the successful grafting of organic moiety on mesoporous silica. The affecting parameters on adsorption and desorption steps were optimized by Box-Behnken design through response surface methodology. Three variables (pH value, sorption time, and amount of the sorbent) were selected as the main factors affecting sorption step, while four variables (type of eluent, eluent volume, eluent concentration, and elution time) were selected for desorption step in the optimization study. The optimized values by this optimization method were 10 mg, 8 min, 6.3, HCl, 1.6 mL, 1.2 mol L^?l HCl, and 10 min, for amount of sorbent, sorption time, pH of solution, type, volume, and concentration of the eluent, and elution time, respectively. Under the optimized conditions, the detection limits of the proposed method for lead and cadmium ions were found to be 0.9 and 0.04 μg L^?1, respectively, while the relative standard deviation (RSD) for five replicate measurements was calculated to be <3 % for both ions. For proving that the proposed method is reliable, a wide range of food, soil, and water samples with different and complex matrixes was used.     

Phosphate adsorption on aluminum-impregnated mesoporous silicates: surface structure and behavior of adsorbents

Phosphorus from excess fertilizers and detergents ends up washing into lakes, creeks, and rivers. This overabundance of phosphorus causes excessive aquatic plant and algae growth and depletes the dissolved oxygen supply in the water. In this study, aluminum-impregnated mesoporous adsorbents were tested for their ability to remove phosphate from water. The surface structure of the materials was investigated with X-ray diffraction (XRD), a N2 adsorption-desorption technique, Fourier transform-infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS) to understand the effect of surface properties on the adsorption behavior of phosphate. The mesoporous materials were loaded with Al components by reaction with surface silanol groups. In the adsorption test, the Al-impregnated mesoporous materials showed fast adsorption kinetics as well as high adsorption capacities, compared with activated alumina. The uniform mesopores of the Al-impregnated mesoporous materials caused the diffusion rate in the adsorption process to increase, which in turn caused the fast adsorption kinetics. High phosphate adsorption capacities of the Al-impregnated mesoporous materials were attributed to not only the increase of surface hydroxyl density on Al oxide due to well-dispersed impregnation of Al components but also the decrease in stoichiometry of surface hydroxyl ions to phosphate by the formation of monodentate surface complexes.     

Effect of strongly competing background compounds on the kinetics of trace organic contaminant desorption from activated carbon

Strongly competing (SC) compounds, naturally found in any drinking water source, are known to decrease the adsorption capacity of activated carbon for trace contaminants. While the effect of these substances on the capacity and adsorption kinetics of trace contaminants is fairly well studied, relatively little is known about their impact on desorption kinetics. The purpose of this study was to investigate the relationship between SC matter and trace compound desorption kinetics. A surrogate SC compound, 1,4-dichlorobenzene (p-DCB), was used to displace the preadsorbed target trace contaminant, atrazine, from powdered activated carbon (PAC). The initial concentrations of p-DCB and atrazine were varied to achieve different degrees of competition to atrazine. Atrazine's desorption diffusion coefficient was found to increase with increasing adsorbed concentration of the SC matter, expressed as an equivalent background compound (EBC).The EBC was modeled with atrazine-like adsorption properties, thus representing the portion of p-DCB that competed to occupy atrazine adsorption sites. The increase in atrazine diffusion rate can be explained by a shift from surface diffusion to diffusion through the carbon's pores as the availability of surface sites decreased due to the EBC's competition. The observed desorption kinetic relationship was consistent with the effect of SC competition on adsorption kinetics; further, the effect was consistent for three different types of SC matter. These findings highlight that the impact of SC matter on activated carbon applications could be either detrimental (displacing adsorbed trace contaminants and enhancing their rate of release) or beneficial (offsetting pore constriction effects by enhancing their rate of uptake).     

红曲发酵液中水溶性红曲黄色素的吸附分离

本文考察不同极性大孔树脂、离子交换树脂、活性炭及硅胶等吸附介质对红曲菌深层发酵液中水溶性红曲黄色素的吸附分离性能。结果显示非极性大孔树脂DA201-C效果最好,该吸附过程符合Freundlich方程,吸附动力学符合准一级动力学模型,表明吸附不受单层吸附的限制;液膜扩散是吸附主要限速步骤,扩散速率常数为0.16 min-1。通过静态和动态吸附洗脱条件优化,运用SPSS对数据进行分析,发现静态吸附、解吸料液比为1:2,吸附、解吸时间15 min,解吸液100%乙醇,酸性条件解吸效果较好;动态吸附解吸流速为0.25 BV/min条件下,可得到高回收率（96.99%）、脱盐率（99.44%）和脱糖率（92.52%）的水溶性红曲黄色素,经初步扩大实验显示吸附解吸性能稳定。大孔树脂DA201-C分离纯化发酵液中水溶性红曲黄色素操作简单、快速、放大性能好,具有很好的工业化生产应用价值。     

介孔氧化硅/棉复合纤维对染料的吸附性能

为提高对纺织染料废水的吸附处理能力,利用共缩聚合成法和超支化聚合物修饰制备了复合介孔氧化硅纳米颗粒（HMSN）,通过静电自组装法将HMSN 引入阴离子化改性棉纤维表面,制备出了一种基于纤维素纤维以及功能化介孔氧化硅的复合纤维,实现对水溶液中有机染料的高效吸附;对材料表征并对相关吸附性能进行研究。结果表明,介孔氧化硅纳米颗粒呈现虫洞状介孔结构,复合纤维表面被平均粒径约为40 nm的功能化介孔氧化硅纳米颗粒覆盖,形成富含官能基团的复合介孔氧化硅/棉纤维吸附剂,对于水溶液中的染料刚果红有优越的吸附性能,吸附过程在180 min内达到平衡,平衡吸附容量可达195 mg/g。     

多孔硅酸镁的表征及其对糖汁中没食子酸的吸附

本文结合水热合成法和模板法,以氯化镁和硅胶球为前驱体制备多孔硅酸镁,用作糖汁清净剂。运用XRD、FTIR和SEM等多种表征手段对多孔硅酸镁进行了表征。以多孔硅酸镁作为吸附剂,以吸附量为指标,考察了吸附时间、初始浓度对多孔硅酸镁吸附没食子酸性能的影响。由表征结果可知,制备的硅酸镁为孔径为5和22 nm为主的介孔球形多孔硅酸镁;吸附实验结果表明,当没食子酸的初始浓度分别为25、50、75 mg/L时,多孔硅酸镁对没食子酸的吸附过程均可用准二级动力学方程描述(R2分别为0.9965、0.9941、0.9941),附等温曲线符合Freundlich模型(R2=0.9926)。方法可为制糖工艺吸附脱色提供理论研究基础。     

Carbon dioxide capture by functionalized solid amine sorbents with simulated flue gas conditions

A novel solid amine sorbent was prepared using KIT-6-type mesoporous silica modified with tetraethylenepentamine (TEPA). Its adsorption behavior toward CO(2) from simulated flue gases is investigated using an adsorption column. The adsorption capacities at temperatures of 303, 313, 333, 343, and 353 K are 2.10, 2.29, 2.58, 2.85, and 2.71 mmol g(-1), respectively. Experimental adsorption isotherms were obtained, and the average isosteric heat of adsorption was 43.8 kJ/mol. The adsorption capacity increases to 3.2 mmol g(-1) when the relative humidity (RH) of the simulated flue gas reaches 37%. The adsorption capacity is inhibited slightly by the presence of SO(2) at concentrations lower than 300 ppm but is not significantly influenced by NO at concentrations up to 400 ppm. The adsorbent is completely regenerated in 10 min at 393 K and a pressure of 5 KPa, with expected consumption energy of about 1.41 MJ kg(-1) CO(2). The adsorption capacity remains almost the same after 10 cycles of adsorption/regeneration with adsorption conditions of 10 vol % CO(2), 100 ppm SO(2), 200 ppm NO, 100% relative humidity, and a temperature of 393 K. The solid amine sorbent, KIT-6(TEPA), performs excellently for CO(2) capture and its separation from flue gas.     

Synthesis and CO₂ adsorption properties of molecularly imprinted adsorbents

A series of molecularly imprinted adsorbents of CO(2) were developed by molecular self-assembly procedures, using ethanedioic acid, acrylamide, and ethylene glycol dimethacrylate as template, functional monomer, and cross-linker, respectively. Textural properties of these adsorbents were characterized by N(2) adsorption experiment, thermo-gravimetric analysis, and Fourier transform infrared spectroscopy. CO(2) adsorption capacities of adsorbents were investigated by thermo-gravimetric balance under 15% CO(2)/85% Ar atmosphere. Adsorption selectivity of CO(2) was studied by fixed-bed adsorption/desorption experiments. All the adsorbents displayed good thermal stability at 200 °C. Among them, MIP1b, with the higher amine content, exhibited the largest CO(2) capacity, which maintained steady after 50 adsorption-desorption cycles. Although MIP3 showed the highest specific surface, the CO(2) capacity was lower than that of MIP1b. CO(2) adsorption mechanism of molecularly imprinted adsorbents was determined to be physical sorption according to the adsorption enthalpies integrated from the DSC heatflow profiles. The calculated separation factors of CO(2) under 15% CO(2)/85% N(2) atmosphere were above 100 for all adsorbents.     

改性介孔材料对贝类副产物中重金属离子的脱除性能

为研究改性介孔材料对贝类副产物中重金属离子的脱除性能,对SBA-15介孔材料分别嫁接2-巯基噻唑啉、2-巯基苯并噻唑、吡咯烷二硫代氨基甲酸铵三种不同基团,得到三种材料分别记作MT-SBA-15、MBT-SBA-15、APDC-SBA-15,然后对材料孔结构进行表征,采用三种材料吸附铅(Pb)、铬(Cr)、镉(Cd)、铜(Cu)标准溶液,考察脱除pH、脱除时间、金属离子加标浓度对脱除能力的影响,最后用APDC-SBA-15脱除贝类副产物中重金属离子,考察重金属脱除率以及营养损失率。结果表明,三种材料都具有较大的比表面积和孔容。三种材料对重金属最优脱除pH为6.0,吸附平衡时间均为30 min;当金属离子浓度为1200 mg/L时,三种材料对金属离子吸附量最大,其中APDC-SBA-15的吸附量最高,对Pb、Cr、Cd、Cu吸附量分别为223.6、240.0、259.8、259.0 mg/g。APDC-SBA-15对菲律宾蛤仔蒸煮液中Pb的脱除率为100.00%,总糖损失率为7.32%;对菲律宾蛤仔蒸煮液多糖中Pb脱除率为84.50%,总糖损失率为2.57%;对牡蛎多肽中Pb、Cr的脱除率分别为62.20%和100.00%,对可溶性蛋白质的损失率为14.62%。综上,APDC-SBA-15可以高效脱除贝类副产物中的重金属,对蛋白质、总糖等营养成分的损失率较低。     

Cu-BTC-SiO_2材料的制备及其对亚甲基蓝的吸附性能

利用原位合成法,将Cu-BTC负载到介孔/大孔二氧化硅孔道中,获得介孔Cu-BTC-SiO_2材料.研究在不同温度、亚甲基蓝浓度、pH值下Cu-BTC-SiO_2对亚甲基蓝吸附效果的影响,并对其吸附动力学及其吸附热力学数据进行分析.结果表明,该样品对亚甲基蓝的吸附符合Langmuir吸附等温模型和准一级动力学模型,其最佳条件为反应温度25℃,染料质量浓度为5mg/L,pH值为5.热力学研究发现,在25~45℃内,亚甲基蓝在Cu-BTC-SiO_2上的吸附行为是放热过程而且是自发进行的.     

Controlled release of allyl isothiocyanate from brown algae Laminaria japonica and mesoporous silica MCM-41 for inhibiting food-borne bacteria

Allyl isothiocyanate (AITC), a naturally occurring antimicrobial compound, is an effective inhibitor of various pathogens, but its use in the food industry is limited by its volatility and pungency. The objective of this study was to overcome the volatility of AITC using dried Laminaria japonica and mesoporous silica MCM-41 as its carrier. AITC-loaded L. japonica (raw and deoiled) powder and silica MCM-41 was achieved via vapor adsorption. The study of AITC adsorption and desorption was determined by monitoring sample weight changing with time. AITC presence in L. japonica and MCM-41 samples was confirmed by FTIR spectroscopy. Antimicrobial tests were made against 4 microorganisms: Bacillus cereus, Staphylococcus aureus, Escherichia coli, and Salmonella Typhimurium. Controlled release and antimicrobial activity from MCM-41 was always superior to those from raw and deoiled L. japonica.     

基于带鱼骨的多孔羟基磷酸钙的制备及其对柴油的吸附动力学性能

为提高带鱼骨的利用率,以带鱼骨为原料,将其制备成多孔羟基磷酸钙,以期增加带鱼骨的附加值。带鱼鱼骨经过脱肉处理、粉碎后进行高温煅烧,分别对过筛目数、温度、时间进行单因素实验,通过比表面积测试,确定多孔羟基磷酸钙的最佳制备条件,并对其进行扫描电子显微镜检测、X射线衍射分析、红外光谱分析、紫外光谱分析等一系列表征,最后探讨了该多孔羟基磷酸钙对柴油的吸附性能。结果表明:带鱼骨的多孔羟基磷酸钙制备的最佳工艺为:煅烧温度800 ℃,时间为4 h,过500目筛。所制得的羟基磷酸钙孔穴疏松细密、比表面积增大,达到463.63 m2·g-1,平均孔径分布为1.1~9.5 nm,属于介孔材料,其结构主要为六方晶系结构。吸附动力学实验表明,该多孔羟基磷酸钙对柴油具有良好的吸附性能,该吸附过程符合准二级动力学模型,平衡吸附量为69.93 mg·g-1,初始吸附速率38.656 mg·(g·min-1)-1。     

CO_2固体吸附剂研究述评

由于介孔材料具有比表面积大和空隙较多等优点,被广泛地应用于对空气中或工业废气中的CO2的吸附.活性炭、沸石、硅胶等传统的吸附剂具有制备方法简单、制造工艺成熟、成本低廉等优点,是吸附空气中CO2的首选材料,但较强的吸湿性使其不能用于高湿度的吸附环境等,而通过对传统的介孔材料进行表面改性,接枝胺类等碱性物质,将单纯的物理吸附转变为物理吸附和化学吸附共同作用的吸附方式,在改善吸附剂适应环境能力的同时也能增加吸附量.开发具有最佳结构且物理及化学性能稳定的功能复合吸附剂将是该领域的研究热点和主要方向.     

大孔树脂对柠檬苦素的动态吸脱附性能

研究了大孔吸附树脂Y7对橙汁中柠檬苦素动态吸附和解吸过程,系统分析了柠檬苦素在Y7树脂上动态动力学及影响动态吸附曲线和解吸曲线的因素,确定了树脂对橙汁脱苦的最佳工艺参数,这些参数包括柱操作流速、温度、上柱果汁中柠檬苦素浓度以及洗脱液浓度。结果表明:树脂吸附最佳工艺参数为,流速1·0mL/min、温度30℃和上柱橙汁中柠檬苦素浓度21·1μg/mL;树脂解吸最佳工艺参数为,流速0·75mL/min、洗脱温度20℃和洗脱液为80%乙醇水溶液。     

Effect of grain size on uranium(VI) surface complexation kinetics and adsorption additivity

The contribution of variable grain sizes to uranium adsorption/desorption was studied using a sediment from the US DOE Hanford site. The sediment was wet sieved into four size fractions: coarse sand (1-2 mm), medium sand (0.2-1 mm), fine sand (0.053-0.2 mm), and clay/silt fraction (<0.053 mm). For each size fraction and their composite (sediment), batch and flow-cell experiments were performed to determine uranium adsorption isotherms and kinetic uranium adsorption and subsequent desorption. The results showed that uranium adsorption isotherms and adsorption/desorption kinetics were size specific, reflecting the effects of size-specific adsorption site concentration and kinetic rate constants. The larger-size fraction had a larger mass percentage in the sediment but with a smaller adsorption site concentration and generally a slower uranium adsorption/desorption rate. The same equilibrium surface complexation reaction and reaction constant could describe uranium adsorption isotherms for all size fractions and the composite after accounting for the effect of adsorption site concentration. Mass-weighted, linear additivity was observed for both uranium adsorption isotherms and adsorption/desorption kinetics in the composite. One important implication of this study is that grain-size distribution may be used to estimate uranium adsorption site and adsorption/desorption kinetic rates in heterogeneous sediments from a common location.