Influence of ligand density on antibody binding capacity of cation-exchange adsorbents

Adsorption properties of a set of polymethacrylate-based cation exchangers designed for purification of monoclonal antibodies were investigated. The materials differed significantly in the density of sulphoisobutyl ligand groups. The ligand density had a pronounced effect on the static adsorption capacity of a polyclonal human immunoglobulin G. An optimal ligand density was observed at any pH and NaCl concentration tested when sharp optima were observed at low pH and ionic strength values. This was caused by effective clogging of pore mouth at high ligand densities. An anomalous effect of ionic strength was observed for the adsorbents with the high ligand density when the adsorption capacity increased with the addition of NaCl at low pH.     

Investigation of the factors affecting organic cation adsorption on some silicate minerals

In this study, the effects of some factors on the adsorption of a basic dye (methylene blue) on bentonite and sepiolite samples were studied. These factors are cation (Na(+) and Ca(2+)) saturation of the samples and pH and ionic strength of the dye solution. The adsorption data were found to conform to the Langmuir equation within the concentration range studied and Langmuir constants were determined for each of the samples. The adsorption capacities of the samples were found to increase with cation saturation. Changes in the pH of the dye solution had no significant influence on the adsorption capacity and adsorption capacities were found to decrease with increasing ionic strength. The maximum sorption capacity of methylene blue exceeded the cation exchange capacity of bentonite and sepiolite.     

Adsorption of benzene,toluene, ethylbenzene and p-xylene by NaOCl-oxidized carbon nanotubes

Multiwalled carbon nanotubes (CNTs) were oxidized by sodium hypochlorite (NaOCl) solution and were employed as adsorbents to study their characterizations and adsorption performance of benzene, toluene, ethylbenzene and p-xylene (abbreviated as BTEX) in an aqueous solution. The physicochemical properties of CNTs such as purity, structure and surface nature were greatly improved after oxidation, which significantly enhanced BTEX adsorption capacity. The adsorption capacity of CNT(NaOCl) increased with contact time and initial adsorbate concentration, but changed insignificantly with solution ionic strength and pH. A comparative study on the BTEX adsorption revealed that the CNT(NaOCl) had better BTEX adsorption as compared to CNTs and granular activated carbon. This suggests that the CNT(NaOCl) are efficient BTEX adsorbents and that they possess good potential for BTEX removal in wastewater treatment.     

Selective Recovery of Ammonia Nitrogen from Wastewaters with Transition Metal-Loaded Polymeric Cation Exchange Adsorbents

Extracting valuable products from wastewaters with nitrogen-selective adsorbents can offset energy-intensive ammonia production, rebalance the nitrogen cycle, and incentivize environmental remediation. Separating nitrogen (N) as ammonium from other wastewater cations (e.g., K⁺, Ca²⁺) presents a major challenge to N removal from wastewater and N recovery as high-purity products. High selectivity and capacity were achieved through ligand exchange of ammonia with ammine-complexing transition metals loaded onto polymeric cation exchange resins. Compared to commercial resins, metal–ligand exchange adsorbents exhibited higher ammonia removal capacity (8 mequiv g⁻¹) and selectivity (N/K⁺ equilibrium selectivity of 10.1) in binary equimolar solutions. Considering optimal ammonia concentrations (200–300 mequiv L⁻¹) and pH (9–10) for metal–ligand exchange, hydrolyzed urine was identified as a promising candidate for selective TAN recovery. However, divalent cation exchange increased transition metal elution and reduced ammonia adsorption. Ultimately, metal–ligand exchange adsorbents can advance nitrogen-selective separations from wastewaters.     

The ionic strength effect on microcystin and natural organic matter surrogate adsorption onto PAC

This work aims to contribute to a better understanding of the ionic strength effect on microcystin and natural organic matter (NOM) surrogate adsorption by analyzing the importance of adsorbate molecular size, and surface concentration. Adsorption kinetics and/or isotherms were performed on PAC Norit SA-UF for four microcystin variants (MC-LR, MC-LY, MC-LW, MC-LF), and three NOM surrogates (salicylic acid (SA), tannic acid (TA), Aldrich humic acid (AHA)) at different solution ionic strengths. Results showed that the ionic strength effect depends upon the adsorbate surface concentration, cation charge (mono or divalent), and adsorbate molecular size. Potassium seemed not to affect the MC-LR adsorption, while calcium enhanced MC-LR kinetics and adsorption capacity. K+ and, particularly, Ca2+ improved the adsorption kinetics of the other microcystin variants. For identical surface concentration and ionic strength, the impact of K+ and Ca2+ on NOM surrogates depended on the adsorbate molecular size: K+ effect was only observed for AHA, whereas Ca2+ caused no effect on SA adsorption, slightly enhanced TA adsorption, and greatly enhanced AHA adsorption. MC-LR isotherms with two salt concentrations (KCl or CaCl2) indicated that, for the studied range of equilibrium surface concentration (5.3-18.7 mg/g), an enhanced adsorption regime prevails, and no transition regime was observed.     

辛巴蓝F-3GA修饰的啤酒废酵母菌亲和吸附溶菌酶

利用j嗪染料辛巴蓝F-3GA修饰经戊二醛交联的啤酒废酵母菌,得到一种新型染料亲和吸附剂.辛巴蓝F-3GA的固载量为161.1 mg/g.以溶菌酶为研究对象,考察吸附时间、酶初始浓度、pH值、离子强度等因素对吸附率的影响.结果表明:当pH=7.0时,其对溶菌酶有较高的吸附量(229.1 mg/g),吸附性能明显优于未接枝...     

Adsorptive removal of tannin from aqueous solutions by cationic surfactant-modified bentonite clay

The removal of tannin from aqueous media by cationic surfactant-modified bentonite clay was studied in a batch system. The surfactant used was hexadecyltrimethylammonium chloride. Adsorbent characterizations were investigated using X-ray diffraction, infrared spectroscopy, surface area analysis, and potentiometric titration. The effects of pH, contact time, initial solute concentration, adsorbent dose, ionic strength, and temperature on the adsorption of tannin onto modified clay were investigated. The adsorbent exhibited higher tannin removal efficiency (>99.0%) from an initial concentration of 10.0 micromol/L at pH 3.0. Adsorption capacity decreased from 90.1 to 51.8% with an increase in temperature from 10 to 40 degrees C at an initial concentration of 25.0 micromol/L. The adsorption process was found to follow pseudo-first-order kinetics. Film diffusion was found to be the rate-limiting step. Tannin adsorption was found to decrease with increase in ionic strength. The tannin equilibrium adsorption data were fitted to Langmuir and Freundlich isotherm models, the former being found to provide the best fit of the experimental data. The maximum monolayer adsorption capacity for tannin was 69.80 micromol/g at 30 degrees C. Comparison of adsorption capacity of the modified clay with reported adsorbents in the literature was also presented. Adsorbed tannin on modified clay can be recovered by treatment with 0.1 M NaOH solution. Regeneration experiments were tried for four cycles and results indicate a capacity loss of <10.0%. From the results it can be concluded that the surfactant-modified clay could be a good adsorbent for treating tannin-contaminated waters.     

Cadmium ion adsorption on different carbon adsorbents from aqueous solutions. Effect of surface chemistry, pore texture, ionic strength, and dissolved natural organic matter

Adsorption of Cd(II) species at pH = 5 was studied on three carbon adsorbents: granular activated carbon, activated carbon fiber, and activated carbon cloth. As-received and oxidized adsorbents were used. Cd(II) adsorption greatly increased after oxidation due to the introduction of carboxyl groups. The use of a buffer solution to control the pH introduced some changes in the surface chemistry of carbons through the adsorption of one of the compounds used, biphthalate anions. The increase in ionic strength reduced Cd(II) uptake on both as-received and oxidized carbons due to a screening of the electrostatic attractions between the Cd(II) positive species and the negative surface charge, which in the case of as-received carbons derived from the biphthalate anions adsorbed and in the oxidized ones from the carboxyl groups. Tannic acid was used as a model compound for natural organic matter. Its adsorption was greatly reduced after oxidation, and most of the carbon adsorbents preadsorbed with tannic acid showed an increase in Cd(II) uptake. In the case of competitive adsorption between Cd(II) species and tannic acid molecules, there was a decrease in Cd(II) uptake on the as-received carbon whereas the contrary occurred with the oxidized carbons. These results illustrate the great importance of carbon surface chemistry in this competitive adsorption process. Finally, under all experimental conditions used, when the adsorption capacity of carbons was compared under the same conditions it increased in the following order: granular activated carbon < activated carbon fiber < activated carbon cloth.     

Transport of N-CD and Pre-Sorbed Pb in Saturated Porous Media

Carbon dots (CDs) are a new type of nanomaterials of the carbon family with unique characteristics, such as their small size (e.g., <10 nm), high water solubility, low toxicity, and high metal affinity. Modification of CDs by Nitrogen functional groups (N-CDs) enhances their metal adsorption capacity. This study investigated the influences of pH (4, 6, and 9), ionic strength (1, 50, and 100 mM), and cation valency (Na⁺ and Ca²⁺) on the competitive adsorption of Pb to quartz and N-CD surfaces, the transport and retention of N-CDs in saturated porous media, and the capacity of N-CDs to mobilize pre-adsorbed Pb in quartz columns. Pb adsorption was higher on N-CDs than on quartz surfaces and decreased with increases in ionic strength (IS) and divalent cations (Ca²⁺) concentration. N-CD mobility in quartz columns was highest at pH of 9- and 1-mM monovalent cations (Na⁺) and decreased with decreases in pH and increases in ionic strength and ion valency. N-CDs mobilized pre-adsorbed Pb from quartz due to the higher adsorption affinity of Pb to N-CD than to quartz surfaces. These findings provide valuable insights into the transport, retention, and risk assessment of lead in the presence of carbon-based engineered nanoparticles.     

树脂填充聚醚砜纤维吸附剂对牛血清蛋白吸附性能的研究

重点研究树脂填充聚醚砜(PES)纤维吸附剂与模型蛋白质牛血清蛋白(BSA)之间的吸附与脱附行为.结果表明,蛋白质BSA在树脂填充PES纤维吸附剂中的平衡吸附过程较好地符合朗格缪尔吸附模型,树脂Lewatit CNP80ws填充PES吸附剂的最大吸附容量约为139mg BSA/g吸附剂.表面具有开孔结构的树脂填充PES纤维吸附剂的吸附速率较快,在不同结构纤维吸附剂中BSA的扩散系数在1·82×10-14~8·7×10-14m2/s范围内变化.另外,考察了BSA溶液的pH与洗脱剂等因素对吸附剂吸附与脱附性能的影响,研究结果对蛋白质的实际分离纯化具有重要的参考价值.     

Physical and chemical properties of PAN-derived electrospun activated carbon nanofibers and their potential for use as an adsorbent for toxic industrial chemicals

A recently developed carbon material, electrospun Activated Carbon nanoFiber (ACnF), exhibits strong potential for use as an adsorbent for toxic industrial chemicals (TICs). As-prepared ACnF contains as much as 9.6?wt% nitrogen, creating a basic surface that enhances acid-gas adsorption. ACnF shows 4–20 times greater HCN adsorption capacities and 2–5 times greater SO₂ adsorption capacities in dry nitrogen, compared to commercially available activated carbon fiber cloth (ACFC) and Calgon BPL? granular activated carbon, which are considered here as reference adsorbents. ACnF has 50?% of the micropore volume (0.30?cm³/g) of these reference adsorbents, which limits its adsorption capacity at high concentrations for volatile organic compounds (>500?ppm_v). However, at low concentrations (<500?ppm_v), ACnF has a similar capacity to ACFC and about three times the VOC adsorption capacity of Calgon BPL?. ACnF’s small fiber diameters (0.2–1.5?μm) allow for higher mass transfer coefficients, resulting in adsorption kinetics nearly twice as fast as ACFC and eight times as fast as Calgon BPL?. ACnF drawbacks include hydrophilicity and reduced structural strength. The rapid adsorption kinetics and high capacity for acidic TICs warrant further investigation of ACnF as an adsorbent in respiratory protection and indoor air quality applications.     

Adsorption behavior of uranium on polyvinyl alcohol-g-amidoxime: Physicochemical properties, kinetic and thermodynamic aspects

Amidoxime-based adsorbents are widely studied as the main adsorbent in the recovery of uranium from seawater.However,the adsorption rate and loading capacity of such adsorbents should be further improved due to the economic viability consideration.In this paper,polyvinyl alcohol functionalized with amidoxime(PVA-g-AO)has been prepared as a new adsorbent for uranium(Ⅵ)adsorption from aqueous solution.The physicochemical properties of PVA-g-AO were investigated using infrared spectroscopy(IR),scanning electron microscope(SEM),X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).Results showed that the ligand monomers were successfully grafted onto the matrixes.The XRD and XPS analysis showed that uranium was adsorbed in metal ionic form rather than in crystal form.Uranyl(U(Ⅵ))adsorption properties onto PVA-g-AO were evaluated.The adsorption of U(Ⅵ)by PVA-g-AO was fast,with an equilibrium time of less than 50 min.Additionally the maximum adsorption capacity reached 42.84 mg/g at pH 4.0.     

负载型氨基酸离子液体的制备及其对二氧化碳的吸附性能

采用浸渍蒸发法将四甲基铵甘氨酸([N1111][Gly])和四甲基铵赖氨酸([N1111][Lys])两种离子液体分别负载到硅胶(SG)表面,利用EA、TGA、BET和FT-IR等技术对所得到的吸附剂进行表征,考察了离子液体种类、离子液体负载量和温度等条件对其CO_2吸附性能的影响。结果表明,离子液体成功负载到硅胶表面,所制得的负载型氨基酸离子液体对二氧化碳具有良好的吸附性能。在所考察的温度范围(303.15-323.15 K)内,温度越高,平衡吸附量越小;在负载量为10%-60%,随着负载量的增加,平衡吸附量先增加后减小。对于[N1111][Gly]/SG,当负载量为22.4%(质量分数)、吸附温度为30℃、压力为0.1 M Pa时,二氧化碳的平衡吸附量可达到41 mg/g(相对于1 mol AAILs吸附0.62 mol CO_2),而且,吸附20 min即可达到平衡吸附量的90%。吸附剂在循环使用六次之后,其结构与性能均保持良好。     

微波辅助细菌纤维素酯的制备及对Pb(Ⅱ)的高效去除

以细菌纤维素(BC)为原料,通过微波辅助酯化改性的方法制得了两种改性细菌纤维素,细菌纤维素黄原酸酯(XMBC)和细菌纤维素硫酸酯(SMBC)。对所制备的样品进行X射线衍射(XRD)、扫描电镜-电子能谱(SEM-EDS)、傅里叶变换红外(FT-IR)光谱和BET比表面积分析,通过续批式实验考察其对Pb(Ⅱ)的去除效果。研究了pH值、反应时间、温度、污染物初始浓度、离子强度对其吸附能力的影响以及材料再生性能。结果表明,改性细菌纤维素的比表面积和孔容均有上升,其对Pb(Ⅱ)的吸附量随反应温度和离子强度的增加而降低,最优pH值为5.0。巯基的引入增强了细菌纤维素对Pb(Ⅱ)的吸附能力,改性后的吸附剂显示出比原始BC更优异的吸附性能,其中XMBC和SMBC的最大吸附量分别为144.93和126.58 mg·g^-1,该吸附过程符合准二级速率方程和Langmuir等温吸附模型。材料对Pb(Ⅱ)的吸附是自发的放热过程,且吸附剂易于再生和重复回收。因此, SMBC和XMBC作为从水中富集分离重金属的新型材料具有及大应用前景。     

Influence of the ionic form of a cation-exchange adsorbent on chromatographic separation of galactooligosaccharides

Separation performance of sodium, lithium, potassium and hydrogen ionic forms of a commercial cation exchanger, Diaion UBK 530, based on a styrene-divinylbenzene copolymer resin support was studied. The adsorbents were applied to the separation of galactooligosaccharides from their mixture with lactose, glucose and galactose. Separation performance of the hydrogen ionic form of the adsorbent was superior to that of other adsorbent forms. A much higher yield of galactooligosaccharides of the requested purity was achieved for this adsorbent form owing to its better kinetic properties. Adsorption properties of individual adsorbents were discussed in relation to possible adsorption mechanisms.     

Inverse GC Investigation of the Adsorption of Thiophenic Compounds on Zeolites

Inverse gas chromatography (IGC) has been used to examine the adsorption of organo-sulfur compounds on various zeolites. Results obtained were used to explain the behaviour of these materials as adsorbents for ultra-deep desulfurisation of fuels. The model compounds chosen were thiophene and 2,5-dimethylthiophene, with zeolite adsorbents NaX, HX, NaY and HY. Zeolite NaY showed the largest adsorption capacity. Adsorption isotherms in the gas phase are not representative of saturation adsorption in the liquid phase. However, the heat of adsorption and the specific interaction parameter were found to be well correlated to the strength and the selectivity of adsorption in the liquid phase by the different zeolites. The main conclusion of this work is that IGC is a useful tool for preliminary comparison of different adsorbents for the removal of sulfur compounds from fuels.     

多壁碳纳米管对稀土元素的吸附性能

研究了改性多壁碳纳米管(MWCNTs)对稀土元素的吸附。 采用硝酸、次氯酸钠、过氧化氢、高锰酸钾4种方法对MWCNTs进行改性,考察了改性MWCNTs对稀土元素的吸附能力。 采用紫外-可见分光光度法测定稀土元素的浓度,比较了未处理和不同方法处理的MWCNTs对稀土元素的吸附能力。实验结果表明,NaClO改性的MWCNTs对稀土元素的吸附能力最强。以稀土元素钐(Sm)、钆(Gd)、镱(Yb)为代表,研究了NaClO改性MWCNTs对稀土元素的吸附性能。 考察了溶液pH值、离子强度、吸附剂用量、温度等因素对吸附性能的影响。当溶液pH值在2~7范围内,NaClO改性的MWCNTs对Sm、Gd、Yb的吸附随pH值增大而增强。 当离子强度和MWCNTs的用量增大时,对稀土元素的吸附能力降低。3种元素在NaClO改性的MWCNTs上的吸附均为放热过程,其反应焓变ΔH分别为：-6.44、-5.63和8.31 kJ/mol。吸附等温线符合Langmuir和Freundlich等温吸附方程。     

基于废弃固定化酶再利用的高容量强阳离子交换树脂及其对溶菌酶的吸附性能

采用表面引发-原子转移自由基聚合( SI-ATRP)技术,以废弃的固定化酶为基质、4-乙烯基苯磺酸钠为单体,30℃聚合3 h,制备了一种新型强阳离子交换树脂。采用傅里叶变换红外光谱( FT-IR)对合成的强阳离子交换树脂进行表征。以溶菌酶为模型蛋白,考察了溶菌酶初始浓度、离子强度、有机溶剂浓度、吸附时间及温度对吸附容量的影响。结果表明,强阳离子交换树脂对溶菌酶的吸附是一个放热的过程。在室温下对溶菌酶的最大吸附量可达240 mg/g,在30 min内快速达到吸附平衡,比文献报道的阳离子交换树脂具有更好的吸附性能。 Langmuir吸附模型与准二级动力学方程可以较好地对吸附过程进行拟合。     

Factors affecting drug adsorption on beta zeolites

The adsorption behaviour of three commonly used drugs, namely ketoprofen, hydrochlorothiazide and atenolol, from diluted aqueous solutions on beta zeolites with different SiO₂/Al₂O₃ ratio (i.e. 25, 38 and 360) was investigated by changing the ionic strength and the pH, before and after thermal treatment of the adsorbents. The selective adsorption of drugs was confirmed by thermogravimetry and X‐ray diffraction. The adsorption capacity of beta zeolites was strongly dependent on both the solution pH and the alumina content of the adsorbent. Such a remarkable difference was interpreted as a function of the interactions between drug molecules and zeolite surface functional groups. Atenolol was readily adsorbed on the less hydrophobic zeolite, under pH conditions in which electrostatic interactions were predominant. On the other hand, ketoprofen adsorption was mainly driven by hydrophobic interactions. For undissociated molecules the adsorption capability increased with the increase of hydrophobicity.     

Adsorption Studies of Nonionic Surfactants onto Polyvinyltoluene Microlatexes in Aqueous Medium

Negatively charged polyvinyltoluene (PVT) microlatexes of various dimensions were prepared by polymerization of the corresponding vinyltoluene-in-water microemulsion precursors containing sodium dodecyl sulfate and n-pentanol. PVT microlatexes were used as adsorbents for adsorption of nonionic surfactants such as Tween 80, Tween 20, and Triton X-100. The extents of adsorption were known from the differences in the diffusion coefficient of the PVT microlatexes containing a solubilized suitable electro active probe. The surface excess (Gamma), equilibrium constant of adsorption (K(ads)), molecular cross-sectional surface area (sigma), intercalation ratio (kappa), etc., were determined for sodium dodecyl sulfate composition variation and ionic strength effects. A surface reconstruction model was proposed to rationalize the results. Copyright 2000 Academic Press.