Amberlite XAD-2 Research Articles

Chromium Speciation Using Flow-injection Preconcentration on Xylenol Orange Functionalized Amberlite XAD-16 and Determination in Industrial Water Samples by Flame Atomic Absorption Spectrometry.

A speciation method for Cr(III) and Cr(VI) by on-line solid-phase extraction using a flow-injection system with FAAS has been proposed. The Cr(III) was selectively retained at pH 5 on the AXAD16-XO chelating resin and was eluted using 0.5 mol L(-1) HNO3. The preconcentration factor and the detection limit (3σ) of 73 and 0.11 μg L(-1), respectively, were obtained for a 120-s preconcentration time. The precision (%RSD) at the 100 μg L(-1) level was 1.08%. The linearity for Cr(III) measurements was up to 600 μg L(-1). The total chromium was determined by reducing Cr(VI) to Cr(III) using hydroxylamine hydrochloride, and the Cr(VI) concentration was obtained by subtraction from the total chromium concentration. The effect of interfering ions was examined towards the selectivity of the proposed system for Cr(III). Spike recovery studies in industrial water samples were carried out using standard Cr(III) and Cr(VI) solutions traceable to NIST. The proposed method was validated using SRM 1643e (Trace Elements in Water) supplied by NIST, USA.

A comparative study for adsorption of carbolic acid by synthetic resins

Carbolic Acid which is called phenol is one of the important starting and/or intermediate materials in various industrial processes. However, its excessive release into environment poses a threat to living organisms, as it is a highly carcinogens and hazardous pollutant even at the very low concentration. Thus removal of phenol from polluted environments is very crucial for sustainable remediation process. We developed a low cost adsorption method for separating phenol from a model aqueous solution. The phenol adsorption was studied using two adsorbents i.e., Amber lite XAD-16 and Amber lite XAD-7 HP with a constant amount of resin 0.1 g at varying aqueous phenol concentrations (50-200 mg L-1) at room temperature. We compared the efficacy of two phenol adsorbents for removing higher phenol concentrations from the media. We investigated equilibrium and kinetics studies of phenol adsorption employing Freundlich, Temkin and Langmuir isotherms. Amberlite XAD-16 performed better than Amberlite XAD-7 HP in terms of phenol removal efficiency that amounted to 95.52%. Pseudo second order model was highly fitted for both of the adsorption systems. The coefficient of determination (R2) with Langmuir isotherm was found to be 0.98 for Amberlite XAD-7 HP. However, Freundlich isotherm showed R2 value of 0.95 for Amberlite XAD-16, indicating that both isotherms could be described for the isotherms on XAD-7 HP and Amberlite XAD-16, respectively.

In vitro effect of seven seaweed extracts on gastrointestinal nematodes

The exploitation of seaweed for animal feed (i.e. protein) and health promoting purposes is becoming more and more important – especially in countries where large amounts of biomass can be produced (e.g. northern countries such as Norway). Many seaweed species contain plant secondary compounds (PSMs) with broad bioactivity and potential animal health and welfare impacts. We report preliminary data on the effect of 7 seaweed extracts on the gastrointestinal nematode species Trichostrongylus colubriformis and Teladorsagia circumcincta which are responsible for considerable morbidity in sheep. For each seaweed species, 50 g of dried and grinded (1 mm) seaweed was extracted with 500 mL of EtOH/H20 (50:50 v/v) for 2h. After elimination of all particulate matter, EtOH was evaporated and the EtOH free extract was mixed with 50 g Amberlite XAD-2 in order to absorb PSMs. After that, the extract was washed again to eliminate NaCl and iodine (present because of marine origin) which both interfere with larval stages (L3) used for in vitro tests. After eluting with 100% EtOH, water was added and the EtOH/H2O extract was subjected to evaporation and lyophilisation. A larval exsheathment test as described by Brunet et. al. (2007) [1] was used for in vitro evaluation of the respective extract efficacies. The test dose (table 1) was calculated considering both the respective extract yield and an estimate of extract concentration available within the rumen of sheep having consumed 25% of dry seaweed within a daily ration. None of the extracts reduced the exsheathment of either T. colubriformis or T. circumcincta (Table 1) significantly.

Immobilization of Escherichia coli cells expressing 4-oxalocrotonate tautomerase for improved biotransformation of β-nitrostyrene.

The enzyme 4-oxalocrotonate tautomerase (4-OT) encoded by the xylH gene is a part of the degradation pathway of aromatic compounds in Pseudomonas putida mt-2. 4-OT was described to catalyze Michael-type addition of acetaldehyde to β-nitrostyrene, and the whole cell system based on recombinantly expressed 4-OT has been developed previously. In this study biocatalytic process based on Escherichia coli whole cells expressing 4-OT was significantly improved using immobilization and ex situ product recovery strategies. Whole cell immobilization in alginate beads was applied in biocatalytic production of 4-nitro-3-phenyl-butanal from β-nitrostyrene and acetaldehyde. Immobilized biocatalyst showed wider pH activity range and could tolerate twofold higher initial concentrations of substrate in comparison to the free whole cell biocatalyst. Beads retained their initial activity over 10 consecutive biotransformations of the model reaction and remained suitable for the repetitive use with 85% of the initial activity after two months of storage. Bioprocess was further improved by utilizing Amberlite XAD-2 hydrophobic resin for the product recovery. With this modification, the amount of organic solvent was reduced 40-fold in comparison to previously reported method making this biocatalytic process greener.

An Assessment of a New Synthetic Procedure for Core-shell Polymeric Supports Based on the Amberlite XAD-4 Adsorbent.

In pursuit for new reactive materials designed for synthesis of functional resins, the novel core-shell type polymeric supports with accessible chloromethyl groups were synthesized. The commercial Amberlite XAD-4 adsorbent was impregnated with different mixtures of vinylbenzylchloride and divinylbenzene, that were further polymerized in the structure of the polymer carrier. The syntheses have been evaluated by recording FT-IR spectra, capturing SEM micrographs as well as analyzing the sorption and desorption of nitrogen at 77 K. The amount of the introduced functionalities has been estimated by chlorine content determination. Based on the obtained results, the reactive chloromethyl groups were successfully introduced into XAD-4 structure. Captured SEM micrographs revealed that VBC/DVB copolymer has covered initial polymeric matrix of XAD-4 adsorbent. Based on the results we have determined conditions of the synthesis that allow us to receive that effect.

Determination of copper in industrial water by innovative flow injection flame atomic absorption spectrometry

ABSTRACTAn online flow injection procedure for the preconcentration of copper at µg L−1 levels was developed using a novel chelating resin and flame atomic absorption spectrometry for the analysis of industrial water. Amberlite XAD-2 functionalized with dithizone resin was packed in a minicolumn for flow injection. The pH, sample and eluent flow rates, and eluent concentration were optimized to ensure maximum recovery of Cu(II). The effect of concomittant ions on Cu (II) sorption was also investigated. The limit of detection and enrichment factor for a 180 s preconcentration time were 76 and 0.6 µg L−1, respectively. The resin offered precision of 1.0% for seven successive determinations of 100 µg L−1 Cu(II). The resin was used for more than 300 sorption and desorption cycles without appreciable loss of efficiency. The accuracy of the preconcentration procedure was confirmed by fortified recovery studies in industrial water with NIST certified copper nitrate with recovery exceeding 96%. Validation was performed by the analysis of a standard reference material.

Acetone-butanol-ethanol (ABE) fermentation using the root hydrolysate after extraction of forskolin from Coleus forskohlii

The biomass obtained after the extraction of forskolin from the roots of Coleus forskohlii was evaluated as a substrate for the production of acetone-butanol-ethanol (ABE). The spent biomass constituting more than 90% of the raw material showed 50–70% carbohydrates with starch and cellulose being the major constituents. This study was undertaken to optimize enzymatic hydrolysis of C. forskohlii roots for maximum release of fermentable sugars and subsequent fermentation to ABE. The root biomass was hydrolyzed using the Stargen® 002 and Accellerase® 1500. Cocktail of both enzymes (16U Stargen® 002 and 60 FPU Accellerase® 1500) could produce 41.2 g/l of total reducing sugars (glucose equivalent to 32.33 g/l). The production of ABE was optimized in a batch fermentation using Clostridium acetobutylicum NCIM 2877. The maximum ABE production using the root hydrolysates was 0.55 g/l. Pretreatment with lime and Amberlite XAD-4 increased the production of total solvent to 5.33 g/l.

Characterization of vitamin B12 in Dunaliella salina.

Vitamin B12 is one of nature's complex metabolite which is industrially produced using certain bacteria. Algae could be an alternative source of vitamin B12 and in this study, vitamin B12 from a halotolerant green alga, Dunaliella salina V-101 was purified and characterized. The extract of Dunaliella was purified by passing through Amberlite XAD-2 and EASI-extract vitamin B12 immunoaffinity column. The total vitamin B12 content in purified sample fractions was 42±2μg/100g dry weight as determined by the chemiluminescence method which was almost close to 49±2μg/100g dry weight as estimated by microbiological method. Further quantification of total vitamin B12 using gold nanoparticle (AUNPs) based aptamer showed 40±0.8/100g dry weight. There was a good correlation among all the methods of quantification. Adenosylcobalamin, a form of vitamin B12 which is a cofactor for methylmalonyl CoA mutase was identified by HPLC. Upon quantification, Dunaliella was found to contain 34±4μg of adenosylcobalamin for 100g dry biomass. Authenticity of adenosylcobalmin was confirmed by tandem mass spectrometry (MS/MS), selected ion recording (SIR) and multiple reaction monitoring (MRM) studies.

Augmenting the adsorption of palladium from spent catalyst using a thiazole ligand tethered on an amine functionalized polymeric resin

Palladium is an industrially important precious metal and its recovery is of utmost significance in miscellaneous applications. Polystyrene divinylbenzene resins are known for their high surface area and porosity to effectively capture metal ions after suitable modification. In this work, we report the anchoring of 2-mercaptobenzothiazole onto the amine functionalized Amberlite XAD-1180 resin for the effective adsorption of palladium. The macroreticular resin serves as a good host to welcome palladium (guest) and the proof of concept was established comprehensively using FT-IR, SEM, EDX and optical imaging analysis. The Langmuir adsorption capacity of the functionalized resin for Pd2+ acquired through the linear isotherm model was found to be 50.00mgg−1. Kinetics of the adsorption process synchronized well with the pseudo-second order model and furthermore the exergonic and endothermic nature of the adsorption process was quantified through the negative free energy and positive enthalpy values. Regeneration of the resin surface was done using thiourea and the method was tested in recovering palladium from a spent catalyst containing 5% Pd on activated carbon.

Localization of free and bound aromatic compounds among skin, juice and pulp fractions some grape varieties

The localization and distribution of free and glycosidically-bound aroma compounds among the skin, pulp and juice of three red grape varieties ( Vitis vinifera L. var. Monastrell, Cabernet Sauvignon and Tempranillo) have been studied. An Amberlite XAD-2 column was utilized to separate and extract the free aroma compounds and the glycosidically-bound aromatic compounds. A commercial enzymatic preparation (Pectinol C) was used to release the bound aroma compounds. Gas chromatography and gas chromatography-mass spectrometry were used for the analysis of the compounds. The results showed that the major compounds in these varieties were alcohols and aldehydes, the skin being the fraction with the largest quantities of aromatic compounds. After the enzymatic hydrolysis. the analysis of the liberated compounds showed that they were mainly alcohols and monoterpenes. Two monoterpenes that did not appear as free aroma compounds could he found.

A new 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) precursor isolated from Riesling grape products: Partial structure elucidation and possible reaction mechanism

A heteroside, which produces 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) by acid hydrolysis, was isolated from Riesling grapes by retention on Amberlite XAD-2 resin, followed by preparative TLC and HPLC techniques. It was partially identified by NMR spectroscopic procedures. The presence of a megastigm-4-en-9-one structure with an enol-ether function in the C 4 position and a OH/OR function in the C 6 position was ascertained. The sugar part should be constituted of two or three glucose moieties with the same NMR characteristics. The linkage of these moieties to the megastigmane structure in the C 4 position and possibly also in the C 6 position remains to be determined. The isolated conjugated form produced only a TDN-d 4 isomer when reacted at 50 degrees C in D 2 O at different acid pH values. A possible reaction mechanism was proposed, considering the kinetics of TDN-d(4) formation during the hydrolysis of the raw glycosidic fraction from two differently aged Riesling wines at pH 2, and comparing it with the kinetics of TDN formation as well. The latter may correspond to the mechanism proposed by WINTERHALTER (1991). Thus, the presence of at least two different TDN precursors in grape products at different concentrations was proved.

Metal complexes of the nanosized ligand N-benzoyl-N′-(p-amino phenyl) thiourea: Synthesis, characterization, antimicrobial activity and the metal uptake capacity of its ligating resin

The new nanosized N-benzoyl-N′-(p-amino phenyl) thiourea ligand H2L was synthesized by nanoprecipitation method. The [Cu (H2L)2 Cl]·2H2O, [Zn (H2L)2(OAc)2], [Cd (H2L)2Cl2] and [Hg (H2L)2Cl2] complexes were synthesized and characterized by various physicochemical methods. Results revealed that the ligand act as hypodentate and bonded to the metal ion via the sulfur atom forming mononuclear non-electrolyte diamagnetic complex. Magnetic moment results indicated a reduction of Cu (II) to Cu (I) during the coordination process. Thermal studies demonstrated variable stabilities of the complexes and [Zn (H2L)2(OAc)2] exhibited the highest thermal stability while [Hg (H2L)2Cl2] was volatile. The prepared compounds were screened against different pathogenic microorganisms. The ligand performed high antibacterial activity against certain bacterial strain compared to its complexes, and the standard bacteriocide in use. The ligand was successfully immobilized on modified Amberlite XAD-16 forming the hypodentate ligating resin PS-SO2-H2L. The new resin was characterized and the extent of metal adsorption reached maximum at pH 6.0 for Cu (II), Cd (II) and Ag (I), with an adsorption amount of 4.3, 4.0 and 3.7 mmol g−1 respectively. The nanosized H2L represents a new category of promising adsorbent that would have a practical impact on biological and water treatment applications.

Optimization of Remazol Brilliant Blue R dye removal by novel biosorbent P. eryngii immobilized on Amberlite XAD-4 using response surface methodology

This study investigates preparation of biosorbent Pleurotus eryngii immobilized on Amberlite XAD-4 and the optimal conditions for removal of Remazol Brilliant Blue R (RBBR) reactive dye from synthetic aqueous solutions. The process was optimized using the response surface methodology (RSM) developed by the application of the quadratic model associated with the central composite design. For this purpose, RSM was employed to determine the effects of operational parameters on this material as effective and available adsorbent. The investigated variables were dye initial concentration (10–60 mg L−1), solution pH (2–9), adsorbent dosage (0.1–0.5 g), and temperature (20–45°C). The significant factors on each experimental design response were identified from the analysis of variance (ANOVA). The RSM indicated that optimum conditions of initial dye concentration, pH, adsorbent dosage, and temperature for maximum RBBR removal (98%) were achieved as 36.3 mg L−1, 2.0, 0.304 g, and 38.7°C, respectively. The results showed that this biosorbent was an appropriate adsorbent for the removal of RBBR from aqueous solutions.

Olive mill wastewater valorisation through phenolic compounds adsorption in a continuous flow column

A continuous-flow adsorption/desorption process for the recovery of phenolic compounds (PCs) from olive mill wastewaters (OMWs) was developed in a 0.53m packed column, using a previously selected resin (Amberlite XAD16) and an actual OMW. The main goals of the study were (i) to evaluate the PC adsorption/desorption performances of XAD16 by means of adsorption isotherms and adsorption/desorption breakthrough tests, and (ii) to develop a reliable model of the process. A combination of centrifugation and microfiltration resulted necessary to attain a high suspended solid removal (98.5%) and thus avoid clogging of the packed bed. The quality of two packing procedures was evaluated by means of frontal analysis tests. XAD16 performed well in terms of both adsorption yield at 20% breakthrough (87–88%) and PC/COD selectivity (PC/COD adsorption constant=7–9). The desorption solvent (acidified ethanol) was effectively regenerated by vacuum distillation. The adsorption breakthrough curves were successfully simulated with a 1-D convection/dispersion model with mass-transfer (R2=0.95–0.99; kLa=0.8–2.5·10−3 1/s), whereas an equilibrium adsorption model with dispersion failed to predict the experimental data. In the perspective of a process scale-up, the simulation of the best-performing operational condition was used to evaluate the process performances for different column lengths (0.5–10m). A precise and automated HPLC method for total PC measurement was developed and compared to the traditional Folin–Ciocalteu methodology. Further research is needed to optimize the desorption step, to scale up the process and to evaluate the long-term resin performances.

Comparison of preconcentration and determination methods of a textile dye by spectrophotometry: cloud point extraction and solid-phase extraction

This study deals with the preconcentration, determination, and removal of Lanaset Blue 2R textile dye from aqueous medium by two different methods. For this purpose, cloud point extraction (CPE) and solid phase extraction (SPE) methods were optimized. Amberlite XAD-1180 resin was used as adsorbent for SPE while Tergitol NP-7 non-ionic surfactant was used as surfactant rich phase for CPE. The common optimization steps were determined as initial solution pH, linear dynamic range, sample volume, equilibrium time and limits of detections were characterized for both SPE and CPE techniques while specific optimization steps such as temperature and surfactant concentration were also determined for CPE. The results showed that the CPE and SPE of dye were quantitative at pH 6. Detection limits were 21-μg L−1 for CPE and 9-μg L−1 for SPE. The enrichment factors were 40 and 10 for SPE and CPE, respectively. The real sample analysis was successfully performed with both techniques. The strengths and weaknesses of the methods were highlighted.

Changes in the Physicochemical Characteristics, Free and Bound Aroma Compounds in the Raspberry Juice during Storage

The changes in the physicochemical characteristics of raspberry juice during storage were studied. Free aroma compounds during storage were analyzed by solid-phase microextraction/gas chromatography–mass spectrometry. Bound fractions were isolated and extracted with methanol and Amberlite XAD-2 resin and then hydrolyzed by almond β-glucosidase. The content of the ascorbic acid was reduced by 47 and 31% in fresh and processed juice after 20 days of storage, respectively. A total of 23 free aroma compounds were identified in the raspberry juice. Only 12, 10, 9 and 10 free aroma compounds were found in this juice after 5, 10, 15 and 20 days of storage, with total contents of 1,614, 696, 806 and 1,103 μg/L. C13-norisoprenoids were the predominant compounds during storage. In total, 14 bound aroma compounds were found in this juice. Benzoic acid was the most abundant benzene compound. Most of the bound fractions were missed during storage. Practical Applications Aroma attribute is one of the most important factors to the quality of the fruit juice. It changed seriously during hot processing or storage. The main reason was that the aroma compounds in the juice were transferred, degraded or evaporated. Nevertheless, glycosidically bound aroma compounds might be released during processing or storage. The findings of this research revealed that most of the physicochemical characteristics remained stable during storage, except ascorbic acid. The free and bound aroma compounds of the raspberry juice changed a lot during storage. Most of these compounds decreased or were missed during hot processing and storage. The information gained from this research could be further applied in the raspberry and food industry to improve the quality of the juice during processing and storage.

Novel Extractant Impregnated Resin for Thorium Preconcentration from Different Environmental Samples: Column and Batch Study

A developed method based upon impregnation of Isonitroso-4-methyl-2-pentanone (HIMP) as extractant on Amberlite XAD-4 for Th4+ enrichment and spectrophotometric determination in a variety of samples were reported. This Extractant Impregnated Resin (EIR) sorbent is characterized by Fourier Transforms-Infrared Spectrometer (FT-IR), Field Emission-Scanning Electron Microscope (FE-SEM), and Brunauer-Emmett-Teller (BET) analysis. The EIR packed in column was studied for various parameters to optimize sorption desorption condition for Th4+. Sorption of Th4+ from aqueous solution onto EIR was studied and equilibrium isotherms, kinetics were determined. These investigations facilitate its determination in different real samples. The developed method was validated by analyzing lake sediment standard reference material (IAEA-SL-1).

Mango Peel as Source of Antioxidants and Pectin: Microwave Assisted Extraction

In this study, we evaluated the microwave-assisted extraction of pectin and polyphenols from mango (Mangifera indica) peels var. Ataulfo using several extraction conditions (time and temperature). Under best extraction conditions, an extract was prepared from dehydrated and pulverized mango peels and fractionated by liquid chromatography on Amberlite XAD-16, until obtain an polyphenols-rich ethanolic fraction which was evaporated to recover the total polyphenols as fine powder. Chemical and antioxidant properties were measured. The dry peels represent only 2.66 % of the fresh mango, however this extraction method was shown to significantly act upon yield of pectin (3.88–10.43 % dry weight). Also, this material is an important source of polyphenols (11.66 mg g−1 dry peels) with higher antioxidant capacity (70.31, 91.46 and 86.46 % of inhibition to DPPH, ABTS and Lipid oxidation inhibition, respectively) at 75 ppm. Based in our findings a good recovery yield was obtained. Fine characteristics of the pectin and polyphenols make them an important biomaterial that can be exploited and used in food, pharmaceutical and other industries.

Rapid isolation of malvidin 3-glucoside from red wine by high speed countercurrent chromatography (HSCCC)

Rapid isolation of malvidin 3-glucoside from red wine was achieved by High Speed Countercurrent Chromatography (HSCCC). Red wine pigments were cleaned-up on an Amberlite XAD-7 column prior to separation by HSCCC. Separation of the anthocyanin isolate yielded 65 mg of pure malvidin 3-glucoside per liter red wine in a single run. Purity and identity of the isolated compound was checked by HPLC-DAD, ESI-MS/MS and 1 H-NMR. The method can be applied to red wine as well as grape skin extracts.

Study of highly porous polymers for H2 fuel storage using positron annihilation lifetime spectroscopy

Positron annihilation lifetime spectroscopy (PALS) was applied to study the porosity of four highly porous polymers: Amberlite XAD 4, Amberlite XAD 16, Haysep S and Hypersol-Macronet MN 200, all of which have been evaluated for H2 fuel storage. PALS revealed two types of pores, with average sizes around 2.0 Å and 6.0 Å. It was also determined that the smaller pores have a larger adsorption potential, while the larger pores constitute most of the fractional free volume. At low temperature (77 K), large pores trap most H2 molecules in the condensed gas state, rather than adsorb H2 molecules on their internal wall, as characterized by the Brunauer–Emmett–Teller (BET) method. In addition, it was found that 1) the fractional free volume (fv) of large pores, 2) the uniformity of large pores, and 3) the relative percentage of small pores are all key factors in storing H2 molecules at a low temperature. Ultimately, the PALS technique, one of the most powerful tools in characterizing micropores at the Å scale, can provide more informational (e.g. pore size, number, distribution) and accurate (e.g. fractional free volume rather than specific surface area) knowledge on the porosity of materials potentially used for H2 fuel storage in the future.