Sorption of chrysoidine by row cork and cork entrapped in calcium alginate beads

Azo-dyes, molecules characterised by the presence of the azo-group (–NN–), are widely used in textile, leather, rubber, plastic, and food industries. Water-soluble azo-dyes are greatly resistant to biodegradation, and are characterised by a high thermal and photo stability due to their complex structures. The release of these molecules into the environment is of crucial concern due to their toxic, mutagenic and carcinogenic characteristics. Biosorption has been demonstrated an effective method to remove pollutants from wastewaters thus solving ecological tasks, being a low cost process and the sorbent biodegradable. The main requirements of an efficient sorbent are thermal, chemical and mechanical stability, and rapid sorption.In this work, the ability of both row cork and the same sorbent entrapped in a biopolymeric gel of calcium alginate, on the removal of chrysoidine from aqueous solutions was examined.The influence on the sorption of pH, initial dye concentration, and particle size, as well as the efficiency of the entrapment, have been investigated. The maximum sorption was found for cork samples of fine particle size (FC), in both row and entrapped forms, at pH 7; conversely, at pH 4 the difference is significant (0.12 mmol/g for row cork and 0.20 mmol/g for entrapped cork), evoking a cooperation of alginate in binding the positively charged chrysoidine molecule.     

气相色谱-质谱法测定软木塞中2种霉味物质

建立了一种简便、快速的可同时测定软木塞中两种霉味物质(2,4,6-三氯苯甲醚(TCA)和2,4,6-三溴苯甲醚(TBA))的气相色谱-质谱联用(GC-MS)方法。软木塞样品采用甲醇超声萃取,N-丙基乙二胺(PSA)固相萃取柱净化,浓缩后采用GC-MS进行分析,外标法定量。在10～10000 μg/L的质量浓度范围内,TCA和TBA均有较好的线性关系,相关系数(r2)大于0.99。通过对不同种类的软木塞空白样品进行加标回收率试验和精密度试验考察方法的可行性。结果表明TCA和TBA的回收率介于88.4%与97.6%之间,相对标准偏差介于1.02%与4.58%之间。TCA和TBA的检出限分别为12 μg/L和18 μg/L,定量限分别为40 μg/L和50 μg/L。本方法适用于市售瓶装葡萄酒软木塞中TCA和TBA的检测。     

Separation and determination of phenolic compounds by capillary electrophoresis with chemiluminescence detection

A methodology for multi-class pesticide determination at trace level in lanolin is presented. Gel permeation chromatography on a Bio-Beads SX-3 column followed by a dual GC chromatographic determination has been developed. The effluent of the analytical column (50% diphenyl–methyl- or 14% cyanopropyl–phenylpolysiloxane) was split into an electron-capture and a nitrogen–phosphorus detection system. The chromatographic system was optimised for 28 pesticides commonly used to control sheep pests and corresponding to organochlorine, organophosphorus and pyretroid classes. Identification has been carried out by gas chromatography coupled to negative chemical ionization mass spectrometry. Recoveries ranged from 72 to 94% and the detection limits from 20 to 97 ng/g depending on the pesticide class, the RSDs were below 10%. Finally, the developed analytical methodology has been successfully applied to the determination of pesticides in several lanolin samples.     

Influence of Hydronium Ions in Zeolites on Sorption

In the presence of sufficient concentrations of water, stable, hydrated hydronium ions are formed in the pores and at the surface of solid acids such as zeolites. For a medium‐pore zeolite, such as zeolite MFI, hydrated hydronium ions consist of eight water molecules and have an effective volume of 0.24 nm³. In their presence, larger organic molecules can only adsorb in the portions of the pore that are not occupied by hydronium ions. As a consequence, the available pore volume decreases proportionally to the concentration of the hydronium ions. The higher charge density (the increasing ionic strength) that accompanies an increasing concentration of hydronium ions leads to an increase in the activity coefficients of the adsorbed substrates, thus, weakening the interactions between the organic part of the molecules and the zeolite and favoring the interactions with polar groups. The quantitative understanding of these interactions makes it possible to link a collective property such as hydrophilicity and hydrophobicity of zeolites to specific interactions on molecular level.     

Detection of migration of phthalates from agglomerated cork stoppers using HPLC-MS/MS

Agglomerated stoppers are manufactured from natural cork granules and adhesives. Esters, such as phthalates and adipates, are commonly used in adhesives at concentrations of typically 2-5%. Because of this, and regarding consumer safety, it is necessary to ensure that these compounds do not migrate into the beverage where the cork stopper is used. A reversed-phase high performance liquid chromatography method with tandem mass spectrometry detection is developed for the separation of nine phthalates into 12% ethanol, used as simulant of alcoholic beverages. The chromatographic separation was carried out with a Luna C18 (2) HSTcolumn (50 × 3.0 mm, 2.5 μm) with a gradient elution of water/methanol with 0.1% acetic acid at 300 μL min(-1). The method was validated for four selected phthalates: di-butylphthalate, di-isononylphthalate, di-isodecylphthalate, and butyl-benzyl phthalate, with recoveries ranging between 95% and 112% and intralaboratory precision (RSD) between 5 and 14%, depending on the phthalate. The lowest quantification limit, 0.15 mg kg(-1), was achieved for di-butylphthalate. Nevertheless, in all cases, the limits obtained guarantee the method utility if restriction limits set in Commission Regulation No 10/2011 for plastic materials are taken into account.     

Sorption of 2,4-dichlorophenol on modified hydrotalcites

The adsorption of anionic surfactants (sodium dodecyl sulfate (SDS) and sodium bis[2-ethylhexil]sulfosuccinate (AOT)) on hydrotalcite (HT) and the adsorption of 2,4-dichlorophenol (DCP) on HT and its modified forms from aqueous solutions was studied. The modification was carried out by calcinations (heat treatment) and hydrophobization using different anionic surfactants. The anionic surfactant isotherms were of the H-type. It was assumed that first the ion exchange mechanism takes place until approximately the anion exchange capacity of HT is reached and hereafter, the hydrophobic mechanism occurs forming surfactant bilayers. While the DCP adsorption was very poor on HT, significant uptake of DCP took place on calcined HT which was attributed to the simultaneously occurring rehydration and adsorption during the reconstruction of the layered structure. On anionic surfactant-HT complexes (“organo-hydrotalcites”) DCP was considerably adsolubilized in the anionic surfactant layers intercalated in HT. The AOT–HT complex appeared the more effective adsorbents for DCP.     

Tefluthrin Sorption to Mineral Particles: Role of Particle Organic Coatings

Abstract

The sorption of tefluthrin was studied on “pure” clay minerals and those that had been coated with aquatic humic substances over a mass percent carbon range of 0.02 to 2.15. Tefluthrin sorption onto humic-coated minerals was significantly greater than on to the clean minerals and increased with increasing quantities of sorbed humic substances. Humic acid, the most aromatic coating, was the strongest sorbent, followed by fulvic acid, hydrophilic macromolecular acid and natural coatings on estuarine suspended particles. This shows the significant impact of humic coatings on the sorptive capacity of mineral particles. The sorption was linear, also consistent with the operation of a partition process. The partition coefficient normalised to organic carbon (K_oc) after deduction of the contribution from the clean mineral, ranged from 120000 to 770000 and was highest for the most aromatic humic acid fraction.     

Removal of Thiram from Aqueous Solutions

In this study activated carbon was used for the removal of thiram from aqueous solutions. Adsorption experiments were carried out as a function of time, initial thiram concentration and temperature. Equilibrium data fitted well to the Freundlich and Langmuir equilibrium models in the studied concentration range. Adsorption kinetics followed a pseudo second‐order kinetic model rather than pseudo first‐order model. The results from kinetic experiments were used to describe the adsorption mechanism. Both boundary layer and intraparticle diffusion played important role in the adsorption mechanism of thiram. Thermodynamic parameters (ΔG₀, ΔH₀, and ΔS₀) were determined and the adsorption process was found to be an endothermic one. The negative values of ΔG⁰ at different temperatures were indicative of the spontaneity of the adsorption process.     

Sorption behaviour of fluoride on carboxylated cross-linked chitosan beads

Carboxylated cross-linked chitosan beads (CCB) showed a significant defluoridation capacity (DC) of 1385 mgF(-)/kg than the raw chitosan beads (CB) which displayed only 52 mgF(-)/kg. Sorption experiments were performed by varying contact time, pH, presence of co-anions and temperature. The nature and morphology of the sorbent were discussed using FTIR and SEM with EDAX analysis. The stability of the beads in solution was explained in terms of swelling ratio of the beads. The fluoride uptake onto CCB obeys both Freundlich and Langmuir isotherms. Thermodynamic studies revealed that the nature of fluoride sorption is spontaneous and endothermic. Sorption kinetics is mainly controlled by pseudo-second-order and intraparticle diffusion models. 0.1M HCl was identified as the best eluent. The suitability of CCB at field conditions has been tested with field sample collected from a nearby fluoride-endemic area.     

Optimization of preparation conditions for activated carbon from palm oil fronds using response surface methodology on removal of pesticides from aqueous solution

Palm oil fronds were used to prepare activated carbon using the physiochemical activation method, which consisted of potassium hydroxide (KOH) treatment and carbon dioxide (CO₂) gasification. The effects of variable parameters activation temperature, activation time and chemical impregnation ratios (KOH: char by weight) on the preparation of the activated carbon and for the removal of pesticides: bentazon, carbofuran and 2,4-Dichlorophenoxyacetic acid (2,4-D) were investigated. Based on the central composite design (CCD), two factor interaction (2FI) and quadratic models were respectively employed to correlate the effect of variable parameters on the preparation of activated carbon used for the removal of pesticides with carbon yield. From the analysis of variance (ANOVA), the most influential factor on each experimental design response was identified. The optimum conditions for preparing the activated carbon from oil palm fronds were found as follows: activation temperature of 750 °C, activation time of 2 h and chemical impregnation ratio of 2.38. The percentage error between predicted and experimental results for the removal of bentazon, carbofuran and 2,4-D were 8.2, 1.3 and 9.2%, respectively and for the yield of the palm oil frond activated carbon was 5.6.     

Sorption of copper by suspended particulate matter

The sorption of copper by suspended particulate matter from river water was investigated as a function of pH and solids concentration. Water was collected from the Delaware River and particulate matter was concentrated using Tangential-Flow Filtration (TFF). The adsorption of copper increased with increasing pH until pH 9.0. A decrease in copper adsorption was found for higher pH values. The adsorption of copper was greater for the samples with added copper than for the suspension for which no metal was added. An increase of copper adsorption proportional to particulate matter concentration was also observed. At both pH 6.0 and 7.0, there was a decrease in the adsorption of copper with increasing copper concentration.     

两性淀粉螯合剂吸附性能的研究

采用玉米或红薯淀粉，经环氧氯丙烷交联、醚化剂阴、阳离子化，制得两性淀粉。研究了离子化的方式 、条件与产品螯合容量的关，制得了向种络合容量相当高的两性淀粉，并研究了它们的使用条件及反复利用的可能性能，试验表明两性淀粉螯合剂是一种高效的污水处理剂。     

Sorption on eggshell waste—A review on ultrastructure,biomineralization and other applications

The structure, adsorption behavior and applications of eggshell waste materials have been reviewed. The ultrastructure of eggshell particles has been discussed to understand the pore structure as well as the surface geometry of the materials leading to its multifarious applicability. Besides, the ultrastructure studies give full information regarding the chemical constituents of egghell particles as well as eggshell membranes. The process of biomineralization in living organisms, their consequent effect of controlling the formation of inorganic–organic composites propelling their application in biomimetic designing of advanced composites with optimized novel properties leading to advances in materials design have been discussed. Utilization of eggshell waste materials for the removal of organic dyes and heavy inorganic ions has been reviewed with suitable models for understanding their adsorption quality and capacity. The applications of these materials in various fields of research have been extensively discussed.     

Two-resistance mass transfer model for the adsorption of the pesticide deltamethrin using acid treated oil shale ash

Adsorption characteristics of the pesticides Deltamethrin were studied in aqueous solutions using acid treated Oil Shale Ash (ATOSA) in a series of batch adsorption experiments. The maximum loading capacity of the adsorbent and the rate of adsorption were found to increase with increasing the pesticide initial concentration, mixing speed and were found to decrease with temperature and particle size. Langmuir as well as Freundlich isotherm models fit the adsorption data with R ²>0.97 in all cases. The maximum adsorption capacity for Deltamethrin was 11.4 mg/g. The two-resistance mass transfer model based on the film resistance and homogeneous solid phase diffusion was used to fit the experimental data. A computer program has been developed to estimate the theoretical concentration-time dependent curves and to compare them with the experimental curves by means of the best-fit approach. The model predicts that the external mass transfer coefficient K was affected by varying the initial pesticide concentration, the agitation speed and temperature whereas the diffusion coefficient D was affected by the initial pesticide concentration, and temperature.     

Sorption and permeation behaviour of metal thiocyanate complexes on cellulose acetate polymers

Various metal thiocyanate complexes in aqueous solution were sorbed on solid cellulose acetate polymers. The sorption selectivity increased in the order Zn(2+) > Fe(3+) > Cu(2+) > Co(2+) > Ni(2+). The sorption behaviour followed a Langmuir-type adsorption isotherm, and the maximum adsorption capacity was 6.1 x 10(-5) mole of complex per g of polymer under optimum conditions. The zinc species sorbed appear to be NH(4)Zn(H(2)O)(SCN)(3) or (NH(4))(2)Zn(SCN)(4) according to analysis of the sorption equilibrium. The ion-association species formed by the complex zinc anion and the ammonium ion was supposed to be sorbed (or "extracted") onto the polymer matrix. As an application of sorption of metal complexes, a new hyperfiltration process was proposed for selective separation of metal ions. Thus, a mixture of metal thiocyanate complexes was hyperfiltered through cellulose acetate membranes. Permeation of certain metal complexes was preferred, and the selectivity was found to be similar to the sorption selectivity. These findings lead to a generalized idea that hyperfiltration separation of ionic species, particularly anionic metal complexes, can be attained by using polymer membranes which selectively adsorb or extract such ionic species as ion-association complexes onto the polymer matrix.     

Development of a high‐throughput method based on thin‐film microextraction using a 96‐well plate system with a cork coating for the extraction of emerging contaminants in river water samples

In this study, a new method was developed in which a biosorbent material is used as the extractor phase in conjunction with a recently described sample preparation technique called thin‐film microextraction and a 96‐well plate system. The method was applied for the determination of emerging contaminants, such as 3‐(4‐methylbenzylidene) camphor, ethylparaben, triclocarban, and bisphenol A in water samples. The separation and detection of the analytes were performed by high‐performance liquid chromatography with diode array detection. These contaminants are considered hazardous to human health and other living beings. Thus, the development of an analytical method to determine these compounds is of great interest. The extraction parameters were evaluated using multivariate and univariate optimization techniques. The optimum conditions for the method were 3 h of extraction time, 20 min of desorption with 300 μL of acetonitrile and methanol (50:50, v/v), and the addition of 5% w/v sodium chloride to the sample. The analytical figures of merit showed good results with linear correlation coefficients higher than 0.99, relative recoveries of 72–125%, interday precision (n = 3) of 4–18%, and intraday precision (n = 9) of 1–21%. The limit of detection was 0.3–5.5 μg/L, and the limit of quantification was 0.8–15 μg/L.     

Sorption behaviour of some chlorophenols in lake aquatic humic matter

The sorption behaviour of 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP), 2,3,4,5-tetrachlorophenol (2,3,4,5-TeCP) and pentachlorophenol (PCP) with an aquatic humic sorbent (HS) was examined in their single and mixed solutions at different acidities (pH 3, 5.5 and 7). The binding capacities and equilibrium coefficients (K(OC)) obtained were fairly close to the literature values but still underline HS's structural and steric influence on the sorption. The most acidic carboxylic (COOH) groups of the HS structure have unquestionably an essential role in the sorption. The amounts of different chlorophenols bound onto the constant quantity of the aquatic HS were in reality very low demonstrating that the amount of the dissolved organic carbon (DOC) in the environment plays a greater role than the value of K(OC). The ability of the aqueous phase to force chlorophenols to associate with the HS becomes at more neutral acidities weaker and weaker and other binding mechanisms become favoured in comparison to hydrogen or hydrophobic bonds. Sorption isotherms were constructed from sorption data, and conformity to a linear model, non-linear Freundlich equation and Langmuir equation was checked.     

Chromatographic behaviour of aromatic compounds on gel filtration Media

Summary Highly cross-linked gels utilized as gel filtration media exhibit adsorption effects towards aromatic or apolar compounds. The adsorption is linearly dependent on salt concentration. We investigated the effect of various salts spanning the Hofmeister series on the adsorption of three model compounds, Adenosine 5′-phosphate, ε-dinitrophenyllysine and tryptophan. It was found that salts exhibiting marked salting-out properties, such as potassium phosphate and sodium sulfate, were the most effective in enhancing the adsorption were the most effective in enhancing the adsorption of the aromatic molecules onto the gel. On the contrary, in the presence of salts with marked salting-in properties, such as Kl or KSCN, the linear dependence of elution parameters for the same compounds was negatively correlated and adsorption decreased with salt concentration. However, a number of salts of intermediate character in the Hofmeister series, such as NaCl or NH₄Cl, did not affect the elution behaviour of the chosen model compounds. The different effects observed are probably due to differential hydration of the molecules in the presence of the salts and to the consequent different hydrodynamic behaviour of the solute when interacting with the hydration layers of the gel matrix.     

Sorption behaviour of some actinides on silica gel from mineral acids and alcoholic solutions

Sorption of Th, Pa, U, Np and Pu on silica gel from HNO₃, HCl and HCl−ROH solutions was investigated. Equilibrium studies indicated sorption behaviour to vary greatly with the acid used. In mixtures of HCl with different alcohols, distribution coefficints were found to depend on alcohol percentage as well as on acidity. Results were discussed and conditions for possible separations were indicated.