XAD-2 Resin Research Articles

Removing refractory organic matter from nanofiltration concentrated landfill leachate by electrooxidation combined with electrocoagulation: Characteristics and implication for leachate management

To guide optimization of electrochemical process for landfill leachate concentrate (LLC), systematical experiments were performed on treating LLC with electrooxidation (EO), electrocoagulation (EC) and various combined processes. The results show that EC for 60 min followed by EO for 180 min gave the most satisfactory treatment performance, in which the removal rates of TOC, UV254, COD and CN were 79.00%, 97.30%, 80.32% and 95.0%, respectively. Three fluorescent components were identified in LLC, fulvic acid-like substances (C1), humic-like (C2) substances and long-wave humus (C3) by fluorescence excitation-emission matrix coupled with parallel factor analysis (EEM-PALAFAC). EC effectively remove most of humic-like humus from LLC, and EO could remove fulvic acid (FA) and humic acid (HA) simultaneously and promote the transformation of FA to hydrophilic (HyI). Compared with EC after EO (EO + EC), EO after EC (EC + EO) was more effective in reducing aromaticity and molecular weight, and could remove humus more efficiently. The characteristics of degrading organic matter from LLC were further verified with XAD-8 resin separation technology, which is beneficial to reduce the treatment load of sequent EO. Improving the performance of EC to remove large molecule humic organic matters is vital to comprehensively manage landfill leachate with lower cost.

Adsorption Characteristics and Enrichment of Emodin from Marine-Derived Aspergillus flavipes HN4-13 Extract by Macroporous Resin XAD-16.

Emodin, a hydroxyanthraquinone derivative, has been used as medicine for more than 2000 years due to its extensive pharmacological activities. Large-scale production of emodin has been achieved by optimizing the fermentation conditions of marine-derived Aspergillus flavus HN4-13 in a previous study. However, the fermentation broth contained complex unknown components, which adversely affected the study of emodin. Herein, the conditions for the enrichment of emodin from A. flavipes HN4-13 extract using XAD-16 resin were optimized, and a separation method with high efficiency, simple operation, a low cost, and a large preparative scale was established. The adsorption process of emodin on the XAD-16 resin conformed to pseudo-second-order kinetics and Langmuir models. The optimal conditions for the adsorption process were as follows: An emodin concentration, flow rate, and loading volume of 0.112 mg/mL, 2 BV/h, and 10 BV, respectively. For desorption, 50% ethanol was used to elute impurities and 80% ethanol was used to desorb emodin. After enrichment with XAD-16 resin, the emodin content increased from 1.16% to 11.48%, and the recovery rate was 75.53% after one-step treatment. These results demonstrate the efficiency of the simple adsorption–desorption strategy, using the XAD-16 resin for emodin enrichment.

A voltammetric approach to the quantification of tungsten in environmental waters using a solid bismuth microelectrode

In this paper, a novel eco-friendly solid bismuth microelectrode for direct tungsten quantification by cathodic stripping voltammetry (CSV) is discussed. The novelty of the proposed sensor results from the fact that the used microelectrode (Ø = 25 µm) exhibits perfect long-term persistence. Moreover, on account of spherical diffusion and insensitivity to the presence of oxygen in the solution the analysis could be performed at the point of sampling. The instrumental and chemical factors influencing the sensitivity of the sensor were thoroughly investigated and their most favorable values were selected (pH = 2.88, acetic acid concentration: 0.1 M; activation potential/time: −1.8 V/1 s; accumulation potential/time: −0.5 V/20 s). Under selected conditions, the method exhibits linearity in the range of 1 × 10−8 to 5 × 10−6 M, while the detection boundary was calculated to be 1.3 × 10−9 M. This method has been shown to be highly selective and insensitive to the presence of even 10 mg L−1 of humic substances due to the addition of the adsorptive Amberlite XAD-7 resin to the test solution. In keeping with the outlined procedure, the certified reference materials (SPS-SW1, SPS-WW1, NAAS-5), tap and well water samples were analyzed without any pretreatment and recovery values from 90.4 to 108.5% were obtained.

Attempt to Develop an Effective Method for the Separation of Gamma-Decalactone from Biotransformation Medium

Gamma-decalactone (GDL) is a fragrance compound obtained in the process of β-oxidation of ricinoleic acid, which is derived from the hydrolysis of castor oil. The biotechnological method of the synthesis of this lactone has been improved for over two decades, but the vast majority of research results have been based only on determining the concentration of the lactone by chromatographic methods without separating it from the biotransformation medium. In this study, we attempted to separate GDL from the medium in which the lactone was synthesized by Yarrowia lipolytica from castor oil. The effectiveness of liquid–liquid extraction, hydrodistillation, and adsorption on the porous materials (zeolite, vermiculite and resin Amberlite XAD-4) was compared. The influence of the solvent on the efficiency of GDL extraction, the influence of the acidity of the medium on the amount of GDL in the distillate, and the level of lactone adsorption on the above-mentioned adsorbents were compared by calculating the initial adsorption rate. The adsorption isotherm was determined for the most effective adsorbent. Among the five solvents tested, the most effective was diethyl ether, used at the ratio of 1:1. The extraction was characterized by higher efficiency than hydrodistillation; the difference in GDL determinations by these two methods ranged from 12.8 to 22%. The purity of the distillates was much higher than that of the extracts at 88.0 ± 3.4% compared to 53.0 ± 1.8%. The acidification of the biotransformation medium increased the concentration of the lactone in both the reaction mixture and the distillate. GDL was most efficiently adsorbed on Amberlite XAD-4 resin, for which the lactone isotherm adsorption was linear. The amount of lactone adsorbed on Amberlite XAD-4 within 1 h was approx. 80% (2.45 g), of which 1.96 g was then desorbed with ethanol. In the context of industrial applications, adsorption of GDL on Amberlite XAD-4 seems to be the most appropriate method due to material costs, the ease of the process, and low environmental burden.

Development of method for determination and preconcentration of uranium in water samples using XAD-4 resin loaded with Br-PADAP

In the present work, a minicolumn of XAD-4 loaded with 2-(5-bromo-2-pyridylazo)-5-(diethylamino)-phenol (Br-PADAP) is proposed as a preconcentration system for uranium determination in well, tap and mineral water samples by spectrophotometer using arsenazo III as the chromogenic reagent. Initially, a two-level (23) full factorial design was used for the preliminary evaluation of three factors, involving the following variables: sampling flow rate, elution flow rate, and pH. This design has revealed that, for the studied levels, buffer concentration and pH were significant factors. When the experimental conditions established in the optimization step were pH = 8.6, and an elution flow rate of 8.6 mL min−1 using 0.5% m/v ascorbic acid, this system has allowed for the determination of uranium with a detection limit (LOD) (3σ/S) of 0.05 μg L−1 and a quantification limit (LOQ) (10σ/S) of 0.16 μg L−1. The precision expressed as the relative standard deviation (R.S.D.) of 0.8% and 1.9% at 10.0 and 1.0 μg L−1, respectively- and a preconcentration factor of 184.5 for a sample volume of 50.0 mL. Accuracy was confirmed by uranium determination in the standard reference material, NIST SRM 1566b trace element units in Oyster Tissue samples, and spike tests with recuperations ranging from 93.2 to 105%; the procedure were applied for uranium determination in tap water, well water, and drinking water samples collected from Caetité and Cruz das Almas Cities, Bahia, Brazil. Five water samples were analyzed the uranium concentrations varied from 0.50 to 2.07 μg L−1

Arsenic(V) Removal from Water by Resin Impregnated with Cyclodextrin Ligand

More rigorous environmental rules on hazardous metals release require the implementation of diverse methods to remove them from contaminated streams. The adsorption process is the most attractive method for removal of toxic metal ions from different aqueous solutions. In the present study, batch and fixed bed column experiments were carried out to investigate the performance of permethylated β-cyclodextrin impregnated resin for the removal of As(V) ions from aqueous solutions. Sorption of As(V) ions was performed in groups under a variety of pH and metal concentrations. It was noted that removal efficiency was the highest (98%) at pH 6.0, and at an initial As(V) concentration equal to 0.1 mg/L. Sorption model use for experimental data indicates that the removal mechanism of As(V) by the permethylated β-cyclodextrin impregnated resin was the physical sorption. The adsorption capacity of the cyclodextrin ligand immobilized onto Amberlite XAD-4 resin was 19 mg/g. In addition, the impregnated resin was regenerable, thus was able to be used over and over.

RADIOCARBON DATING ROZHOK I, A MIDDLE PALEOLITHIC OPEN-AIR SITE IN SOUTHERN RUSSIA

ABSTRACTSamples of bone and teeth from the Middle Paleolithic open-air site of Rozhok I, located on the Gulf of Taganrog, were dated by radiocarbon (14C). We obtained 26 accelerator mass spectrometry (AMS) dates on a large sample of nonhuman bone and teeth recovered by N. D. Praslov during 1961–1962 from 5 of the 6 occupation horizons at Rozhok I. Two rigorous pretreatment methods were applied to the samples: ultra-filtration and XAD resin. The 14C ages from the uppermost two layers (Horizons 1 and 2) are infinite with the exception of one age near the limit of the 14C method. By contrast, the dates from Horizon 3 and the two lowermost layers (Horizons 5 and 6) are all finite ages and some are less than 45,000 BP (uncalibrated). While there is evidence of some post-depositional disturbance, there is no evidence of a stratigraphic reversal of the cultural layers. The simplest explanation for the pattern is that bones and teeth in the lower layers have been contaminated by groundwater containing young carbon. We conclude that Rozhok I probably antedates 50,000 cal BP and is beyond the range of 14C dating.

Pollution Characteristics and Risk Assessment of Nitrated Polycyclic Aromatic Hydrocarbons in the Atmosphere of Guangdong-Hong Kong-Macao Greater Bay Area

To investigate the pollution characteristics and sources of nitrated polycyclic aromatic hydrocarbons (NPAHs) in Guangdong-Hong Kong-Macao Greater Bay Area (GBA), 44 ambient air samples were collected using the active sampling method, which were then determined via gas chromatography-triple quadrupole tandem mass spectrometry. The main results showed that filters, polyurethane foam, and XAD-2 resin were the essential materials for sampling NPAHs in ambient air in order to characterize the pollution status accurately. The levels of ρ(Σ18NPAHs) in ambient air at GBA ranged from 162 pg·m-3 to 2094 pg·m-3, and the average levels of ρ(Σ18NPAHs) were (675±430) pg·m-3 in summer and (637±349) pg·m-3 in winter. NPAHs were widely found in the ambient air of GBA and were dominated by 1-nitronaphthalene (220 pg·m-3), 2-nitronaphthalene (146 pg·m-3), 9-nitroanthracene (105 pg·m-3), and 2-nitrofluoranthene (72 pg·m-3). The congener profile characteristics of NPAHs in summer and winter were similar. The gas/particle partitioning characteristics of NPAHs revealed that dicyclic and tricyclic NPAHs tend to occur in the gas phase, and tetracyclic NPAHs tend to be adsorbed in the particle phase. The fraction of NPAHs concentrations in the particulate fraction of their total atmospheric concentrations increased with the increase in their molecular weight. In winter, NPAHs tend to be adsorbed in the particle phase, whereas in summer, NPAHs tend to exist in the gas phase. Based on the ratios of characteristic pollutants, in both the summer and winter season, photochemical reactions were the main source of NPAHs in the atmosphere of GBA and were primarily generated by the reaction of the hydroxyl radical in the daytime. The carcinogenic risk value calculation showed that the current carcinogenic risk of NPAHs in the ambient air of GBA was controllable.

Fluoride ion removal using amine modified polymeric resin: Batch and column studies

The treatment of water containing pollutants by the solvent impregnated resin was found to be an effective method and caught the attention of the researchers. Here, the study was focused on the separation of fluoride ions from water using Aliquat-336 modified Amberlite XAD-4 resin in batch and continuous mode of operation. Batch studies were conducted to see the impact of resin dosage (2.5–27.5 g/L), pH (2–12), time (0–120 min), temperature (298–323 K), and initial fluoride concentration (1.8–13 mg/L) on the capability of the resin. Freundlich isotherm (R2 = 0.986) and pseudo-second-order model (R2 = 0.999) matched the equilibrium and kinetic data, respectively. Column experiments were designed using the two-level full factorial design considering inlet fluoride concentration (5–10 mg/L), volumetric flow rate (3–5 mL/min), and length of the bed (3–5 cm) as the design variables, and their effect was studied on the breakthrough time, saturation time, and effluent volume. Three regression models were obtained to predict the characteristics of the breakthrough curve with R2 close to one. The Thomas model (R2 = 0.952) best explained the trend of the breakthrough curve. The p-values (p less than 0.05) obtained using MINITAB software indicates that all the prime factors (coF,QandH) affect the breakthrough time.

Determination of multiple organic flame retardants in maricultural water using High-volume/High-throughput Solid-phase extraction followed by liquid/gas chromatography tandem mass spectrometry

A rapid and efficient analytical method is proposed and optimized for the enrichment, extraction and instrument analysis of four typical organic flame retardants (OFRs), including organophosphate esters (OPEs), polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCDs) and dechlorane compounds (Dechloranes) in maricultural waters using High-volume/High-throughput Solid-phase extraction with in-situ ultrasonic technique followed by high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) and gas chromatography tandem mass spectrometry (GC–MS) instrumental detection. The optimized pretreatment conditions were that the analytes were enriched by XAD-2 resins and eluted repeatedly with 50 mL hexane/acetone (1:1, v:v) for 5 min. The results of method validation exhibited that the developed method can be used for quantitative detection of 11 OPEs, 13 PBDEs, 3 HBCDs and 5 Dechloranes in water samples. The method detection limits (MDLs) and limits of quantification (LOQs) are 0.4–26.2 pg/L and 1.5–87.4 pg/L for OPEs, 23.3–35.4 pg/L and 77.5–117.9 pg/L for HBCDs, 0.8–97.4 pg/L and 2.6–324.7 pg/L for PBDEs and 9.3–78.5 pg/L and 31.0–261.8 pg/L for Dechloranes, respectively. The method was successfully applied in lagoon maricultural areas in Hainan province, and the results showed that 4 OFRs were detected in almost all water samples. Total concentrations of 18 water samples were 1.89–39.97 ng/L for OPEs, 0.18–5.40 ng/L for PBDEs, ND-0.24 ng/L for HBCDs and 0.01–1.77 ng/L for Dechloranes, respectively. The optimized analytical method is highly sensitive and efficient with expectation to play an essential role in monitoring the ultra-trace organic pollutants and providing an effective risk assessment in ecological environment.

Rhodamine-B dye removal using aliquat-336 modified amberlite XAD-4 resin in fixed-bed columns in series.

The present work reports studies on the effective removal of Rhodamine-B (RhB) using Aliquat-336 modified Amberlite XAD-4 resin in the fixed-bed columns in series. The effect of flow rate (Q = 2 to 6 mL·min-1), bed height (h = 3.5 to 7 cm) and initial RhB dye concentration (Cin = 10 to 20 mg·L-1) was studied. When a single column was used, 93% RhB dye was removed in 3 h at Q = 2 mL·min-1, Cin = 10 mg·L-1, and h = 7 cm. When three columns in series were used, almost 100% dye was removed until 80 h. The maximum breakthrough time (142 h) and saturation time (244 h) were found by keeping Q = 2 mL·min-1, h = 7 cm of each column and Cin = 10 mg·L-1. Mathematical modeling of the breakthrough curves was done by using Yoon-Nelson, Clark, Wolborska, and pore diffusion models. The Clark model best fitted the experimental data. The possible interaction mechanism between Aliquat-336 and RhB dye was proposed. The column was regenerated in continuous mode using 1 M HCl solution and maintaining a flow rate of 2 mL·min-1.

Exploring nicotine adsorption performance of commercial XAD-4 resin: Experimental design, isotherm, kinetic modelling and regeneration

Due to tobacco smoking and production, nicotine has been widely found in natural water environment which causes serious effects on living organisms. Herein, the nicotine adsorption over commercial polystyrene resin (XAD-4) was systematically studied via experimental design technique. Response surface methodology was applied in order to analyse the effect of different factors including pH, adsorbent dosage, and initial concentration. The solution pH predominantly affected the nicotine removal and the increase in pH significantly increased the nicotine adsorption ascribed to the electrostatic attraction and Lewis’s acid-base interactions. According to the Box-Behnken design, the maximum nicotine removal of 85.06% was observed at an initial concentration of 5.8 mg/L, pH 8.8 and adsorbent dosage of 1.6 g/L. The pseudo-second order kinetic model displayed the highest correlation coefficient (R2 = 0.993) while the Langmuir-Freundlich isotherm model fitted best to the experimental data (R2 = 0.980; χ2 = 0.064) with a maximum adsorption capacity of 5.949 mg/g. The resin could be easily regenerated by methanol or methanol/amin solutions which further enabled its repeatedly usage until six cycles. The commercial XAD-4 resin can be considered as a sustainable strategy to eliminate the emerging toxic contaminant of nicotine.

In vitro antioxidant activity and antidiabetic effect of fractionated potato protein hydrolysate via ultrafiltration and adsorption chromatography

Potato processing effluents represent a potential source of valuable proteins for the production of bioactive peptides. In this study, potato protein was hydrolyzed with Alcalase and fractionated using ultrafiltration (10, 2 kDa molecular weight cut off) and adsorption chromatography (adsorbent resin XAD-16 column). Potato protein hydrolysates (PHM and PHC), membrane fractions PHR1 (>10 kDa), PHR2 (2–10 kDa) and PHR3 (<2 kDa) and column fractions PF1 (hydrophilic) and PF2 (hydrophobic) were investigated for antioxidant activity, α-glucosidase and α-amylase inhibition. In addition, α-amylase kinetic inhibition, fluorescence quenching and surface hydrophobicity were evaluated. PF2 fraction showed the best antioxidant activity with the highest ABTS•+ scavenging activity, Fe2+ chelating and DPPH• scavenging activity. PHR1 was the most active against α-amylase whereas α-glucosidase activity was weak for all samples. Fluorescence quenching results of α-amylase showed higher red shift after interaction with PHR1 than PF2. Higher quenching constant for PHR1 demonstrated higher affinity and interaction between this fraction and the enzyme than PF2. Enzyme kinetic studies revealed that PHR1 and PF2 fractions reduced α-amylase activity through uncompetitive and mixed inhibition, respectively. These results demonstrate higher antioxidant activity for hydrophobic fraction and higher α-amylase inhibitory activity for high molecular weight fraction of the potato hydrolysates.

Preconcentrations of Zn(II) and Hg(II) in Environmental and Food Samples by SPE on B. licheniformis Loaded Amberlite XAD-4.

In this work, the separations and preconcentrations of Zn(II) and Hg(II) ions on Bacillus lichenifoemis loaded onto Amberlite XAD-4 resin by solid-phase extraction has been performed. The biosorbent was characterized by using FT-IR, SEM, and EDX. pH, sample flow rate, eluent type and concentration, amount of B. licheniformis and XAD-4 resin, sample volume, and possible interfering ions effect were investigated in detailsas experimental variables in the SPE procedure. Limit of detection values for Zn(II) and Hg(II) were detected as 0.03 and 0.06ngmL-1, respectively. 0.2-15ngmL-1 linear range values were achieved for Zn(II) and Hg(II), respectively. Relative standard deviation values were found to be lowerthan 5%. For validation of the procedure, the certified standard reference materials (CWW-TM-D, EU-L-2, NCS ZC73O14, NCS ZC73350) were analyzed. The concentrations of Zn(II) and Hg(II) in water and food samples were measured by ICP-OES. Consequently, it can be inferred that the immobilized B. licheniformis microcolumn has ideal selectivity for Zn(II) and Hg(II) biosorption.

The Impact of Time-Integrating Active or Passive Sampling Methods on Bioanalytical Water Quality Risk Assessment

Since traditional chemical analytical methods only consider a minor fraction of substances present in the water cycle, biological effect monitoring (BEM) is required for a more reliable assessment of the chemical status. BEM integrates the effects of all micropollutants that may trigger adverse outcome pathways. For reliable risk assessment it is important that substances are efficiently recovered from the water matrix by the environmental sampling and extraction methods. The present study compares the performance of five time-integrated sampling and extraction methods for large effluent volumes at three wastewater treatment plants (WWTPs). Both chemical and bioassay data are evaluated to select the best suited method for bioanalytical monitoring. Large volumes of WWTP effluents, collected for three weeks by flow-proportional active sampling, were extracted with XAD resins and large-volume solid-phase extraction (SPE). Simultaneously, three types of passive samplers (silicon rubber, POCIS and Speedisk) were deployed in the effluent channels. Clear differences were observed between both chemical and bioanalytical profiles for the five time-integrated sampling/extraction methods. Higher levels of extracted chemicals did not always lead to higher responses in the bioassays. If the total amount of extracted substances reflects the overall bioactivity, this may be since both agonistic and antagonistic compounds are extracted more efficiently. The best of the investigated active sampling methods seems to be SPE, that concentrated more compounds and at higher concentrations than XAD. The results obtained with passive samplers are highly dependent on estimations of average extracted water volumes, which are difficult to predict for complex environmental mixtures. POCIS seems to be the most efficient passive sampler for concentration of polar organic micropollutants. The preference between SPE and POCIS depends on the application. Since differences in sampling and extraction will affect the assessments of environmental risks, effect-based trigger values need to be adjusted for each method.

Measurement of soot mass and PAHs during the pyrolysis of C2[sbnd]C4 alcohols at high temperatures

Particulate matter (PM) is emitted from a range of combustion sources, can vary greatly in properties, and is able to penetrate deep into the human lungs, conveying carcinogenic PAHs present on the particle surface. Alcohol based biofuels have been shown to potentially reduce PM emissions when displacing fossil fuels. To improve understanding of the influence of fuel bound oxygen on and the relative toxicity of PM, this paper investigates quantitatively the soot mass and PAHs produced from the pyrolysis of ethanol, 1-propanol, 2-propanol,1-butanol, and 2-butanol in a laminar flow reactor. The pyrolysis of alcohol fuels and collection of soot-bound and gas-phase PAH was carried out between 1323 and 1623 K at a fixed carbon atom concentration in nitrogen. Accelerated solvent extraction (ASE) was used to extract soot bound PAH and gaseous species captured on XAD resin, with speciation and quantification of PAHs undertaken using GCMS. Of the primary alcohols, the highest and lowest masses of soot were observed for 1-butanol and ethanol respectively, while secondary alcohols generated more soot mass than corresponding primary alcohols. An effect of hydroxyl group position on the total PAH distribution in the gas and particulate-bound phases was observed within the temperature range of 1323 to 1423 K. At 1323 K, 1-propanol produced approximately three times more particle phase (PP) PAH concentration than 2-propanol. Amongst the fuels tested, 1-propanol produced the highest level of carcinogenic PAHs at 1323 K, while for all C3 and C4 fuels the toxicity equivalence factor decreased with increasing pyrolysis temperature.

Waste-to-energy: biobutanol production from cellulosic residue of sweet potato by Clostridia acetobutylicum

Biobutanol has been emerging as a renewable replacement to overcome fossil fuel limit due to its attractive qualities. The waste resources utilization is an economically feasible and eco-friendly way to produce biobutanol. In this work, the potential of butanol fermentation with sweet potato residue (SPR) obtained from ethanol fermentation was evaluated. To assist sugar release for butanol production by Clostridia acetobutylicum, a pretreatment approach with dilute sulfuric acid was established via response surface methodology. The maximum butanol concentration of 3.77 g/L was obtained at the optimal conditions of pretreatment at 1% (v/v) dilute sulfuric acid, and 115℃ for 30 min. Detoxifying the hydrolysate with XAD-4 resin significantly enhanced butanol fermentation performance, while adding nutritional supplements had no significant influence. The stability of the fermentation process was verified by the 2 L-scale of fermentation, resulting in 7.96 g/L of butanol, 13.42 g/L h of Acetone-Butanol-Ethanol (ABE), and 0.34 g/g of ABE yield, respectively. This study demonstrates a bio-refinery strategy of conversion from waste biomass to energy, confirms the feasibility of utilizing the cost saving SPR as feedstock to produce butanol through fermentation, and provides a novel approach for minimization of environmental pollution.

Disinfection Byproduct Recovery during Extraction and Concentration in Preparation for Chemical Analyses or Toxicity Assays.

Over 700 disinfection byproducts (DBPs) have been identified, but they account for only ∼30% of total organic halogen (TOX). Extracting disinfected water is necessary to assess the overall toxicity of both known and unknown DBPs. Commonly used DBP extraction methods include liquid-liquid extraction (LLE) and solid-phase extraction (SPE), which may use either XAD resins or other polymeric sorbents. With few exceptions, DBP recoveries have not been quantified. We compared recoveries by LLE, XAD resins, and a mixture of Phenomenex Sepra SPE sorbents (hereafter SPE) for (semi-)volatile DBPs and nonvolatile model compounds at the 1-L scale. We scaled up the three methods to extract DBPs in 10 L of chlorinated creek waters. For (semi-)volatile DBPs, XAD resulted in lower recoveries than LLE and SPE at both 1- and 10-L scales. At the 10-L scale, recovery of certain trihalomethanes and trihalogenated haloacetic acids by XAD was negligible, while recovery of other (semi-)volatile DBPs extracted by XAD (<30%) was lower than by SPE or LLE (30-60%). TOX recovery at the 10-L scale was generally similar by the three extraction methods. The low TOX recovery (<30%) indicates that the toxicity assessed by bioassays predominantly reflects the contribution of the nonvolatile, hydrophobic fraction of DBPs.

Effective removal of methyl orange dye using aliquat 336 impregnated Amberlite XAD-2 resin

Methyl orange (MO) dye was removed using Amberlite XAD-2 resin modified by wet impregnation method with Aliquat-336. The modified resin was characterized by FTIR, FE-SEM, SEM with EDX, and pH of zero charge. Experimental parameters such as time, initial dye concentration, pH, temperature, resin dose and presence of NaCl salt affecting the adsorption rate were studied. 2 g.L −1 of resin was found to be optimum for 20 mg.L −1 MO dye. A maximum of 40.93 mg dye was removed per gram of resin. Langmuir, Freundlich, and Temkin isotherms were used to predict the equilibrium points at four temperatures. Pseudo-second-order fitted the kinetic data ( R 2 = 0.982). The resin could be reused for five successive cycles effectively. Also, the prepared resin was used for the removal of a cationic dye, rhodamine-B and an industrial dye, Pink S8EB.

Extraction chromatography based separation of zirconium(IV) from simulated high-level liquid waste using N,N-di-octyl-2-hydroxyacetamide impregnated amberlite XAD-7 resin

Selective separation of zirconium(IV), from the simulated high-level liquid waste solution containing uranium(VI) and trivalent lanthanides, during reprocessing of fast reactor metal fuel was studied by extraction chromatography using N,N-di-octyl-2-hydroxyacetamide (DOHyA) impregnated on to Amberlite XAD-7 resin. The extraction behavior of Zr(IV), Nd(III) and U(VI) with varying concentrations of nitric acid was explored using a solvent impregnated resin with different compositions of DOHyA in XAD-7 [10, 20, 30, 40 and 50 (w/w) %]. The resin exhibited faster kinetics with more than 99 % recovery of Zr(IV) and with an apparent Langmuir adsorption capacity of ∼54 mg.g−1of Zr(IV) on to the resin phase. Quantitative (> 99%) and selective extraction of Zr(IV) with minimum loading of other trivalents and uranium was observed during column chromatography. Results of the study showed that Zr(IV) can be selectively separated in presence of trivalent lanthanides and U(VI).