微孔分布对凹凸棒石吸附剂吸附油脂色素的影响

凹凸棒石吸附剂属于多孔固体吸附剂,微孔分布在其吸附过程中发挥了重要作用.对不同来源矿物制备吸附剂样品后发现,凹凸棒石吸附剂存在着跨越一定孔径范围的微孔,胁UrICUich吸附等温线研究结果也表明,不同微孔分布的凹凸棒石吸附剂N值和K值具有明显规律性,但其吸附性质相同.吸附剂的微孔与色素类分子直径越接近,其吸附量会越大,在凹凸棒石对油中色素类物质的吸附的过程中,吸附剂对色素类物质的分子筛分作用不是最重要的.     

凹凸棒石在大豆油脱色过程中吸附行为的探讨

本论文在475nm下测定了不同吸附剂对油中色素类物质的吸附情况。通过分析所得的热力学参数,比较了活性碳C1和三种具有不同孔径分布的活性凹凸棒石(C2、C3、C4)四种吸附剂对油脂脱色过程中色素类物质的脱除效果。从理论上探索了凹凸棒石这种新型吸附剂在油脂脱色过程中对油中色素类物质的吸附特性。结果表明,活化的凹凸棒石比活性碳具有更强的去除油中色素类物质的能力。同时通过对四种吸附剂的比表面积及孔隙分布数据的分析比较,说明了吸附剂的的比表面积不能决定吸附剂的吸附效果,吸附剂和吸附质的极性越相近,吸附剂的孔径分布和吸附质的截面大小越相似,越有利于吸附作用的发生。     

凹凸棒石油脂脱色行为及其机理

以凹凸棒石为大豆油脱色吸附剂,通过对其物理特性、脱色热力学和吸附动力学分析,探讨凹凸棒石吸附剂的吸附行为与脱色机理。结果表明,凹凸棒石吸附剂主要为短晶束和单晶形,其孔径集中分布于1.5～10.0?nm的范围内;脱色热力学分析表明,随着脱色温度升高,凹凸棒石的色素吸附能力逐渐增强,但温度不能改变吸附剂对色素类物质的作用方式;吸附动力学分析表明,叶绿素等微量成分在凹凸棒石上的吸附速率较快,正己烷纯溶液体系中吸附速率依次为叶绿素＞亚油酸＞磷脂＞类胡萝卜素,而大豆油体系中吸附速率依次为叶绿素＞类胡萝卜素＞游离脂肪酸＞磷脂。由此可知,凹凸棒石油脂脱色主要通过孔径填充吸附,并伴随有部分氢键吸附和化学吸附。     

Freundlich方程在不同吸附剂的油脂脱色体系中的应用

油脂脱色体系属于稀溶液吸附体系，该体系中的吸附等温式最常用的是Langmuir方程和Freundlich方程，其中Freundlich方程更适合植物油脂脱色体系。作者对植物油脂脱色工艺中常用的3种吸附剂进行了研究，结果表明：在低浓度区时3种吸附剂都符合Freundlich吸附等温方程，K凹〉K膨〉K活，N凹〉N膨〉N活。凹凸棒石的K值和N值均为最大，大孔径范围的孔道和较多的表面酸性点使凹凸棒石不仅具有较强的吸附能力，而且具有较高的吸附强度。     

凹凸棒石脱色过程对油脂体系化学反应影响的研究

研究了凹凸棒石脱色过程对碱炼大豆油体系甘油三酯分解、聚合、过氧化反应的影响,发现油脂脱色体系中同时存在着游离脂肪酸的吸附、生成、反应的平衡关系,凹凸棒石在吸附过程中对氢过氧化物的吸附作用大于催化作用,同时发现凹凸棒石表面酸性点的存在对甘三酯的分解、极性化合物的生成具有明显的催化作用。     

凹凸棒石脱色大豆油的热力学研究

本实验研究了在一定的脱色条件下,大豆油中色素类物质在活化过的凹凸棒石上的吸附平衡热力学特性。实验得出353～383K热力学曲线,计算出这些物质在凹凸棒石上的吸附焓变在-0.0434～-0.0036kJ/mol范围内;吸附Gibbs自由能变在-10.23～11.77kJ/mol之间;熵变在-33.34～27.78J/mol·K范围内。证明活化凹凸棒石对大豆油中色素类物质的吸附反应为放热反应,温度升高和吸附剂添加量的增多有利于吸附作用的进行,在该温度范围内的吸附作用主要是熵趋动的过程。     

球形纤维素吸附剂对亚甲基蓝的吸附热力学研究

以离子液体(BMIMCl)为反应介质,选用丙烯酸为单体,在均相条件下对纤维素进行接枝改性,后经反相悬浮技术制得球形纤维素吸附剂。通过静态吸附方法研究该吸附剂对阳离子型染料亚甲基蓝的吸附性能,探讨了影响吸附效果的各种因素(溶液pH值,染料初始浓度,吸附时间及温度),并研究了吸附的热力学特征以及吸附剂的再生性能。结果表明,在一定范围内提高pH值,增加染料初始浓度以及延长吸附时间都可以提高吸附效果;吸附剂对亚甲基蓝的吸附符合Langmuir吸附等温式;吸附过程是自发的放热过程;该球形纤维素对亚甲基蓝的吸附具有可循环利用性,再生性能良好。     

凹凸棒石粘土对水溶性染料的吸附脱色研究

研究凹凸棒石粘土对几种水溶性染料的吸附脱色作用,并对其中脱色效果较明显的亚甲基蓝和弱酸艳蓝RAW进行深入探讨.结果表明,凹凸棒石粘土对两种染料的吸附均可在短时间内达到平衡;振荡有利于吸附,而温度、pH值对两种染料的吸附均无显著影响;适当增加染液浓度可以提高凹凸棒石粘土的吸附量,相同条件下凹凸棒石粘土对亚甲基蓝的吸附能力高于弱酸艳蓝RAW.除活性染料外,凹凸棒石粘土对其它染料的脱色性能均优于活性炭.     

改性凹凸棒石处理对啤酒非生物稳定性的影响

研究凹凸棒石的改性条件,以及改性后的凹凸棒石对啤酒中蛋白质的吸附性能,通过单因素试验结合响应面分析,对凹凸棒石的改性和处理条件进行优化,同时测定在不同添加量和不同吸附时间下,经改性凹凸棒石吸附后啤酒的非生物稳定性和泡沬稳定性,以及研究改性凹凸棒石的吸附专一性。结果表明,凹凸棒石在303℃下加热2.54h改性后,对引起啤酒冷混浊的活性蛋白具有很强的亲和力;改性凹凸棒石的添加量为0.875g/L,吸附时间为25min,可使啤酒的SASPL值增加2.0左右,有效提高啤酒的稳定性,并且对啤酒泡沫稳定性无任何不利的影响。     

玉米油中黄曲霉毒素B_1的吸附脱除效果研究

以玉米油中黄曲霉毒素B_1(AFB_1)脱除率为主要考察指标,研究不同吸附剂、吸附剂添加量以及吸附时间、吸附温度对玉米油中AFB_1的脱除效果和最佳脱除条件。结果表明:当吸附剂添加量为油质量的2%时,活性白土、凹凸棒石、WY1活性炭、WY2活性炭及普通活性炭对玉米毛油中AFB_1的脱除率分别为98.04%、97.66%、94.35%、95.72%和75.71%,AFB_1含量由39.28μg/kg分别降至0.77、0.92、2.22、1.68、9.54μg/kg,明显优于GB 2716—2005《食用植物油卫生标准》中规定的AFB_1含量小于等于20μg/kg的限量指标;在玉米油吸附脱色的精炼过程中,选用活性白土或凹凸棒石或WY2活性炭、添加量2%、吸附时间25 min、吸附温度100℃的工艺条件,可将玉米毛油中AFB_1含量降至欧盟要求的小于等于2μg/kg的限量指标;若综合考虑AFB_1脱除、吸附剂成本及油脂损耗,可适当降低吸附剂添加量,当WY1和WY2活性炭添加量为1%时,可将玉米毛油中AFB_1含量分别降至3.07、2.15μg/kg。     

改性凹土对银杏叶总黄酮的静态吸附性能研究

采用改性凹土吸附银杏叶总黄酮,通过对4 种不同改性凹土的筛选,发现壳聚糖改性凹土对银杏叶总黄酮有较大的吸附量,为112.70mg/g;对壳聚糖改性凹土对银杏叶总黄酮的吸附性能进行研究,得到溶液总黄酮质量浓度、pH 值对吸附量的影响趋势曲线、吸附等温线、吸附动力学曲线及吸附速率曲线;以解吸率、总黄酮纯度为指标对洗脱剂进行选择,发现1% 乙酸-70% 乙醇溶液洗脱较好,解吸率为91%,纯度为56%。     

Negligible effects of tryptophan on the aflatoxin adsorption of sodium bentonite

The main objective of this study was to determine if the competitive adsorption of tryptophan (Trp) and aflatoxin B₁ (AFB₁) could potentially affect the ability of a sodium bentonite (NaB) to prevent aflatoxicosis in monogastric animals. The adsorption of Trp and AFB₁ on this adsorbent is fast and could be operating on the same time-scale making competition feasible. In vitro competitive adsorption experiments under simulated gastrointestinal conditions were performed. A high affinity of the clay for Trp and NaB was observed. The effect of an excess of KCl to mimic the ionic strength of the physiological conditions were also investigated. A six-times decrease in the Trp surface excess at saturation was observed. A similar behaviour was previously found for AFB₁ adsorption. Taking into account the amount of Trp adsorbed by the clay and the usual adsorbent supplementation level in diets, a decrease in Trp bioavailability is not expected to occur. Tryptophan adsorption isotherms on NaB were ‘S’-shaped and were adjusted by the Frumkin–Fowler–Guggenheim model. The reversibility of the adsorption processes was investigated in order to check a potential decrease in the ability of NaB to protect birds against chronic aflatoxicoses. Adsorption processes were completely reversible for Trp, while almost irreversible for AFB₁. In spite of the high affinity of the NaB for Trp, probably due to the reversible character of Trp adsorption, no changes in the AFB₁ adsorption isotherm were observed when an excess of the amino acid was added to the adsorption medium. As a consequence of the preferential and irreversible AFB₁ adsorption and the reversible weak binding of Trp to the NaB, no changes in the aflatoxin sorption ability of the clay are expected to occur in the gastrointestinal tract of birds.     

Aminated polyacrylonitrile fibers for humic acid adsorption: behaviors and mechanisms

Aminated polyacrylonitrile fibers (APANFs) were prepared by surface modification of polyacrylonitrile fibers (PANFs) with diethylenetriamine in a solution, and the APANFs were studied as an adsorbent for humic acid removal in a series of batch adsorption experiments. The surface modification reaction introduced the amine groups on the surface of the fibers, and the APANFs had a zero point of zeta potentials at pH 8.1, in contrast with pH 3.5 for the PANFs. Adsorption experiments indicated that the APANFs were very effective in removing humic acid from aqueous solutions in the pH range of 2-10, whereas the PANFs did not adsorb humic acid at all under the same conditions. It was found that both electrostatic interaction and surface complexation mechanisms played important roles in humic acid adsorption on the APANFs, although the relative importance of each of the adsorption mechanisms varied with solution pH values. With the advantages of large specific surface areas and enhanced reactive surface properties, the APANFs have great potentials in water treatment for the removal of humic substances and other polarized or electrically charged species.     

失活乳酸菌去除柑橘汁中链格孢霉毒素TeA工艺优化

柑橘果实易受链格孢霉菌等病原微生物的污染产生并积累链格孢霉毒素,其中细交链孢菌酮酸(tenuazonic acid,TeA)是毒性最强的一种链格孢霉毒素,具有潜在的致癌性和细胞毒性,对消费者的健康和安全构成严重威胁。为降低柑橘汁中TeA含量,本研究利用灭活乳酸菌菌体细胞作为吸附剂,主要研究其吸附去除柑橘汁中TeA的工艺条件。首先通过单因素试验分析灭活乳酸菌菌粉添加量、吸附时间、TeA初始质量浓度和pH值对TeA去除率的影响,然后采用响应面法Box-Behnken设计对吸附去除橙汁中TeA工艺条件进行了优化,得到最佳工艺参数为灭活乳酸菌菌粉添加量1.20g/20mL、吸附时间11.43h、TeA初始质量浓度250μg/L、橙汁pH3.15,在此条件下,TeA去除率为86.98%。同时建立了TeA去除率与各影响因素间的二次多项式回归模型,并对该模型进行了验证,结果表明模型拟合程度高,预测效果好。     

Magnetic purification of plasminogen from human plasma by specific lysine affinity

A novel magnetic adsorbent was prepared by covalently binding lysine onto the surface of nanoparticles via a carbodiimide coupling method. The adsorption of plasminogen onto surface-modified magnetic nanoparticles from human plasma was studied in a batch system. Surface modifications of particles were characterized using Fourier-transformed infrared spectra, transmission electron micrography, and ninhydrin assay. The maximum weight ratio of lysine to the superparamagnetic particles was 30 μmol/mg of particles. Effects of pH and temperature on plasminogen adsorption by the magnetic particles were evaluated. Desorption of plasminogen from the magnetic adsorbent was investigated using aminocaproic acid, a lysine analogue. Using a buffer composed by aminocaproic acid or lysine, plasminogen on the magnetic nanoparticles could be eluted. Overall, the results demonstrated that the lysine-coated magnetic adsorbent increased the efficiency and speed of recovery of plasminogen from human plasma.     

TiO2-based photocatalytic degradation of 2-chlorophenol adsorbed on hydrophobic clay

The combination of adsorption and heterogeneous photocatalysis has been investigated as a promising technology for the removal of organic water pollutants. A laboratory study of the removal and decomposition of 2-chlorophenol (2-CP) as a toxic organic pollutant was carried out under various conditions with an organophilized clay mineral (hexadecylpyridinium chloride-modified montmorillonite; HDPM) as adsorbent and Degussa P25 TiO2 as photocatalyst. Three different oxidation processes leading to the degradation of 2-CP were compared: direct photolysis, heterogeneous photocatalysis in a TiO2 suspension, and the decomposition of substrate adsorbed on HDPM in the presence of TiO2. Both the degradation of 2-CP and the formation of intermediates were analyzed by HPLC, the total organic carbon content and the total organic and inorganic chloride contents were measured to monitor the mineralization process, and X-ray diffraction and thermoanalytical measurements were made to characterize the hydrophobic clay adsorbent. The heterogeneous photocatalytic degradation of dissolved (2-CP/UV/TiO2) and desorbed 2-CP (2-CP/HDPM/UV/TiO2) appeared to be equally efficient, whereas direct photolysis of 2-CP was far less efficient in the oxidative destruction. HDPM proved to be a suitable adsorbent, capable of adsorbing toxic organics from water. It was demonstrated that the adsorbent (at relatively high concentration) did not decrease the rate of mineralization of 2-CP. The results confirmed that the adsorbent retains its structure and composition during the mineralization process, and thus it can be reused without regeneration. The combination of adsorption and heterogeneous photocatalysis studied may be an efficient and economical means of accumulating, removing, and oxidizing organic water contaminants, and its application is in accordance with the growing environmental demands.     

改性酒糟对亚甲基蓝的吸附性能及动力学研究

选取废弃酒糟进行超声波辅助酸处理,以得到可吸附亚甲基蓝的生物质吸附剂。考察不同条件下改性酒糟对吸附亚甲基蓝的影响,并采用二次回归正交旋转对影响显著的因素进行优化。结果表明,亚甲基蓝初始质量浓度500 mg/L、吸附时间200 min、改性酒糟加入量0.6 g（50 mg/L）时有最大去除率98.85%。采用吸附等温式和吸附动力模型分析,表明该过程主要由化学速率控制的多位点物理化学混合吸附且饱和吸附量为126.01 mg/g。扫描电镜（SEM）、BET比表面仪和傅里叶红外光谱（FTIR）分析可知改性酒糟表面疏松多孔且孔径较大利于吸附,在吸附过程中羟基、羧基起主要作用。改性酒糟的吸附效果极显著优于其他材料（P＜0.01）,循环再生后该吸附剂仍具有较好的吸附性能。     

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。     

琥珀酸和乳酸在树脂HBCT-8上的吸附平衡

模拟移动床色谱分离琥珀酸和乳酸的前提是确定它们在合适的固定相上的吸附平衡参数。树脂HBCT-8可以将琥珀酸和乳酸很好的分离,文中用迎头法在30～50℃的温度内进行了琥珀酸和乳酸在该树脂上的单组份吸附平衡试验,酸的浓度为0～10 g/L。试验结果表明:琥珀酸和乳酸在该树脂上的吸附符合朗格缪尔和双朗格缪尔模型,并且2种酸在树脂HBCT-8上的吸附均为放热的,这种效应被表达在模型方程中,由此产生的温度依赖型模型方程在试验温度内可以准确的预测琥珀酸和乳酸的吸附平衡数据。     

Molecular characterization of high affinity, high capacity clays for the equilibrium sorption of ergotamine

Ergot alkaloids (mycotoxins) produced by Claviceps and Neotyphodium species of fungi may contaminate animal feedstuffs and result in disease in livestock. In this study, diverse phyllosilicate clays and other adsorbent materials, differing in chemical and structural characteristics, were tested for their ability to sorb ergotamine, a prevalent ergot mycotoxin, from acidic solution. Results indicated minimal binding to those sorbents possessing low surface area, cation exchange capacity and inaccessible interlayer regions. Cetyl pyridinium-exchanged montmorillonite (organoclay) exhibited decreased propensity for ergotamine in acidic solution as compared with the unexchanged hydrophilic parent clay. The highest ergotamine sorption was observed with cation exchanged montmorillonite clays; whereas, when collapsed, these same clays sorbed very little ligand. Based on initial binding experiments, calcium and sodium montmorillonite clays were prioritized for further characterization, including: capacity, affinity, and heat (enthalpy) of adsorption. Computer models of energy-minimized ergotamine isomers and clay were used to illustrate possible mechanisms of ergot alkaloid sorption at interlayer sites. Additional studies are warranted to assess the stability of ergot alkaloid/clay complexes under alkaline conditions to further understand the mechanism of adsorption.