Inexpensive Sorbent Research Articles

Elimination of Arsenic Using Sorbents Derived from Chitosan and Iron Oxides, Applying Factorial Designs

Arsenic is highly toxic, affecting millions of people in many regions of the world. That is why developing economic and efficient technologies is imperative to eliminate it. Sorption techniques are attractive as efficient and inexpensive sorbents can be used. Chitosan is an abundant, naturally occurring, biodegradable, low-cost biopolymer that can be combined with metal oxide to enhance its removability. This work aimed to synthesize a new chitosan–magnetite-based sorbent for arsenic removal. The synthesized sorbent does not present pores, and when using FT-IR, functional groups of the chitosan and the presence of As(V) in the sorbent treated with arsenic were identified. The synthesized magnetite was characterized using XRD spectroscopy. Application of the central composite design model showed that 0.22 g of the sorbent at pH 6.0 could remove 27.6% of As(V). Kinetic data, fitted with the pseudo-first and -second order models, indicated an ion exchange sorption and activation energy of 28.1–31.4 kJ mol−1. The isotherms were fitted with the Langmuir model, indicating favorable monolayer adsorption with high affinity. The sorption energy calculated using Dubinin Radushkevich, 9.60–8.80 kJ mol−1, confirms a sorption mechanism mediated by ion exchange. The thermodynamic parameters of the process were ΔG° (−21.7/−19.7 kJ mol−1), ΔH°(16.7 kJ mol−1) and ΔS°(123.3 J mol−1 K−1).

Isotherms of the Sorption of Fe2+, Fe3+ Ions by Industrial Waste from Aqueous Solutions

The purpose of this work was to study the isotherms of the process of sorption of Fe2+, Fe3+ ions by industrial waste from aqueous solutions.Methods. As a sorbent, technogenic wastes from sugar production (defecation mud of Lgovsky Sugar Plant JSC), leather industry (chrome shavings from the Kursk Tannery OOO Kursk Kozha) and aviation instrumentation enterprises (galvanic sludge from Aviaavtomatika JSC named after V.V. Tarasova"). Fe2+, Fe3+ ions were chosen as sorbates, since the problem of iron removal is especially relevant for the Kursk region, due to the conditions of formation and the peculiarities of the formation of natural and waste waters.As a scientific basis for the study of sorption, thermodynamic approaches are proposed, according to which sorption properties can be estimated by the value of the maximum working value of the transfer of a substance from a solution to the surface of sorbents. The mathematical models of Langmuir and Freindlich were used to describe the sorption isotherms. To determine the residual content of Fe2+, Fe3+ ions, calibration plots of the dependence of optical density on the concentration of Fe2+, Fe3+ ions in aqueous solutions were constructed using the sulfosalicylate photometric method.Results. According to the equations of Freundlich and Langmuir sorption isotherms, the sorption isotherms were processed and analyzed, and the parameters of the process of sorption of Fe2+, Fe3+ ions by production waste from aqueous solutions were determined. The spontaneity of this process is established.Conclusion. The results obtained showed the suitability of production waste as an inexpensive sorbent for the effective removal of Fe2+, Fe3+ ions from aqueous solutions in the range from 0.8636 to 8.636 g/dm3.It has been established that the sorption of Fe2+, Fe3+ ions on production waste occurs in the form of monolayer sorption on the surface, which is homogeneous in sorption affinity and is described by Langmuir isotherms, which is confirmed by a high value of the confidence approximation (R2 = 0.9909-0.9955).In the course of the work, it was found that galvanic sludge and defecation exhibit the greatest sorption capacity.

NEW SORBENTS BASED ON INDUSTRIAL WASTE FOR WASTEWATER TREATMENT FROM PETROLEUM PRODUCTS

One of the most common types of ecotoxicants are petroleum products - an unidentified group of petroleum hydrocarbons and products of its processing. In this regard, the development of technology for obtaining new highly efficient and inexpensive sorbents for wastewater treatment from petroleum products (including those based on industrial waste) is an urgent problem. In this paper, a method of wastewater treatment from petroleum products using composite sorbents based on waste-tailings of Uchalinsky (SU), Buribaevsky (SB), Sibaysky (SS) mining and processing (GOK), and clay of the Talalaevsky deposit (G) and sodium humates (GN) obtained from the waste of the Tyulgan brown coal. The efficiency plants of purification was investigated using these sorbents of model wastewater contaminated with oil from the Vozeyskoye field of Usinsk Neftegaz LLC and real wastewater from the Ufa refinery of ANC Bashneft. It is shown that the efficiency of purification and the rate of adsorption of model wastewater containing petroleum products (8-50 mg/dm3) increases in a number of sorbents BAU - A < CC + G < SB ++ G < SU + G SU + G + GN (where BAU - A sorbent of comparison, activated carbon) and are maximal for GOK covered with GN. For real wastewater containing petroleum products of the Ufa refinery (3-625 mg/dm3), the adsorption activity increases in the series CC + G < SB ++ G < SU + G. Thus, the most effective sorbents for real and model wastewater containing oil and petroleum products are sorbents based on Uchalinsky GOK waste in a composition with clay (degree of purification 96.1 %), as well as SU modified GN (98.2 %).

Enhanced adsorptive removal of hexavalent chromium in aqueous media using chitosan-modified biochar: Synthesis, sorption mechanism, and reusability

Hexavalent chromium (Cr(VI)) is deemed a priority contaminant owing to its carcinogenicity, teratogenicity, and mutagenicity towards flora and fauna. A novel Chitosan-modified Mimosa pigra biochar (CMPBC) was fabricated and the efficiency of Cr(VI) oxyanion removal in aqueous systems was compared with the pristine biochar. The instrumental characterization of X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR) confirmed the amino modification of MPBC when treated with chitosan. Characteristic features of the Cr(VI) sorptive process by CMPBC and MPBC were examined by performing batch sorption studies. Experimental data suggested that sorption is heavily dependent on pH and the highest adsorption occurred at pH 3.0. The maximum adsorption capacity of CMPBC was 14.6 ± 1.07 mg g−1. It was further noted that the removal efficiency of CMPBC (92%) was considerably greater than that of MPBC (75%) when the solution pH, biochar dose, and initial concentration of Cr(VI) are 3.0, 1.0 g L−1 and 5.0 mg L−1 respectively. The kinetic data were best interpreted by the power function model (R2 = 0.97) suggesting a homogenous chemisorption process. The isotherm data for the removal of Cr(VI) by CMPBC was inferred well by Redlich Peterson (R2 = 0.96) and Temkin (R2 = 0.96) isotherms. Results of sorption-desorption regeneration cycles indicated that the Cr(VI) uptake by CMPBC is not fully reversible. The coexistence of Cr(VI) and Cr(III) on CMPBC was confirmed through the XPS analysis. The electrostatic attractions between cationic surface functionalities and Cr(VI) oxyanions, the partial reductive transformation of Cr(VI) species to Cr(III), as well as complexation of Cr(III) onto CMPBC were identified as the possible mechanisms of mitigation of Cr(VI) by CMPBC. The results and outcomes of this research suggest the possibility of utilizing the CMPBC as an easily available, environmentally sustainable, and inexpensive sorbent to decontaminate Cr(VI) from aqueous media.

Magnetic Ionotropic Hydrogels Based on Carboxymethyl Cellulose for Aqueous Pollution Mitigation

In this work, stabilized ionotropic hydrogels were designed using sodium carboxymethyl cellulose (CMC) and assessed as inexpensive sorbents for hazardous chemicals (e.g., Methylene Blue, MB) from contaminated wastewaters. In order to increase the adsorption capacity of the hydrogelated matrix and facilitate its magnetic separation from aqueous solutions, sodium dodecyl sulfate (SDS) and manganese ferrite (MnFe2O4) were introduced into the polymer framework. The morphological, structural, elemental, and magnetic properties of the adsorbents (in the form of beads) were assessed using scanning electron microscopy (SEM), energy-dispersive X-ray analysis, Fourier-transform infrared spectroscopy (FTIR), and a vibrating-sample magnetometer (VSM). The magnetic beads with the best adsorption performance were subjected to kinetic and isotherm studies. The PFO model best describes the adsorption kinetics. A homogeneous monolayer adsorption system was predicted by the Langmuir isotherm model, registering a maximum adsorption capacity of 234 mg/g at 300 K. The calculated thermodynamic parameter values indicated that the investigated adsorption processes were both spontaneous (ΔG < 0) and exothermic (ΔH < 0). The used sorbent can be recovered after immersion in acetone (93% desorption efficiency) and re-used for MB adsorption. In addition, the molecular docking simulations disclosed aspects of the mechanism of intermolecular interaction between CMC and MB by detailing the contributions of the van der Waals (physical) and Coulomb (electrostatic) forces.

АНАЛИЗ ОСОБЕННОСТЕЙ ОЧИСТКИ МОДЕЛЬНЫХ ВОД ОТ ИОНОВ МЕДИ И НИКЕЛЯ ТЕРМООБРАБОТАННЫМ ЦЕЛЛЮЛОЗОСОДЕРЖАЩИМ МАТЕРИАЛОМ

Adsorption is known as one of the traditional wastewater treatment methods, which is considered effective against heavy metals. At present, plant wastes are often studied as a raw material for inexpensive sorbents obtaining. The article analyzes the effectiveness of a sorption material use obtained by cellulose-containing waste thermal modification in relation to copper and nickel ions. It was established that sorption has a physical character, the maximum sorption capacity for Cu2+ ions was 0.320 mmol/g, for Nu2+ ions 0.342 mmol/g. The processing of the isotherm using the mathematical models of Langmuir and Freindlich indicates the phenomena of multilayer adsorption on a material that has various active sorption centers with unequal energies.

Synthesis, Characterization, and Application of Geopolymer/TiO2 Nanoparticles Composite for Efficient Removal of Cu(II) and Cd(II) Ions from Aqueous Media

The use of fly ash wastes as inexpensive sorbents, mostly for heavy metal cations, is one method of recycling the millions of tons of fly ash waste produced each year. In this paper, a fly ash-based geopolymer was used as an adsorbent for Cu2+ and Cd2+ from an aqueous solution. To improve geopolymer sorption efficiency, fly ash was modified by incorporating titanium oxide (TiO2) nanoparticles that were synthesized hydrothermally and annealed at a temperature of 500 °C. The adsorbents were characterized before and after adsorption by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and scanning electron microscopy (SEM-EDX). Regarding the developed materials, Cu2+ and Cd2+ adsorption equilibria (Langmuir model and Freundlich model) and kinetics (pseudo-first-order and pseudo-second-order model) were investigated. The results show that geopolymer-NanoTiO2 adsorbs heavy metal cations better, which is superior to geopolymer. The maximum experimental adsorption capacity of geopolymer-NanoTiO2 composite for Cu2+ and Cd2+ was 1708.2 mg/g and 706.9 mg/g, respectively. Therefore, geopolymer-NanoTiO2 composite has shown great application prospects in the prevention and control of heavy metal pollution.

Removal of heavy metals from stormwater runoff using granulated drinking water treatment residuals

Stormwater runoff is a significant source of heavy metals, including cadmium (Cd), chromium (Cr), and nickel (Ni), which pose ecological and human health problems. Various filter media have been evaluated for heavy metal removal from stormwater via adsorption, most involving chemical- or energy-intensive processes. Aluminum-based drinking water treatment residuals (WTR), a non-hazardous byproduct of drinking water treatment, are an inexpensive sorbent for heavy metals. However, the low permeability of WTR is a problem and requires mixing with sand and carbon materials to improve flow; but such amendments also reduce its sorption capacity. To overcome this problem, a granulated WTR sorbent was generated using a green technique involving organic materials and a low-energy process. Batch studies showed that WTR granules remove Cd, Cr, and Ni simultaneously. Metal removal was adequately described by pseudo-second-order kinetic models and Langmuir and Freundlich isotherm models. The overall removal performance was Cr > Cd > Ni. The presence of divalent cations in solution negatively affected metal removal; anions had a strong effect on Cd removal. A triple-layer surface complexation model adequately described metal removal. Results demonstrated the strong potential of the WTR granules to emerge as green filter media for the removal of heavy metals from stormwater runoff. • WTR granules are sustainable sorbents that can simultaneously remove Cd, Cr, and Ni. • WTR granules were made from a waste byproduct and organic material with low energy. • The environmental parameters affected the removal of Cd, Cr, and Ni. • Surface complexation model could adequately describe the removal of Cd, Cr, and Ni.

Fabrication of small-diameter carbon nanotubes using a coordination polymer with a free-oxygen ligand as a catalyst precursor

Carbon nanotubes (CNTs) that are derived from coordination polymers (CPs) and which have controllable structures have served as a significant class of sorbents in renewable materials. However, it is difficult to achieve efficient conversion of CPs to small-diameter CNTs (SDCNTs) via chemical vapor deposition (CVD). As described herein, we first report the large-scale growth of SDCNTs from a Co-based CP. The oxygen atoms of trimesic acid (BTC) which surround the Co-based CP crystals impede the aggregation of Co nanocatalysts so that they effectively serve as a unique “sieve” which allows the catalyst to promote the formation of SDCNTs during the CVD process. CNTs with a diameter of ∼14 nm evolved from the pristine CP architecture. This strategy is novel and provides a new approach for the large-scale preparation of SDCNTs, and it that may facilitate the development of high performance and inexpensive sorbents as well as photocatalysts for water treatment.

Application of microcrystalline cellulose as an efficient and cheap sorbent for the extraction of metoprolol from plasma and wastewater before HPLC-MS/MS determination.

A dispersive solid-phase extraction method based on a new sorbent has been performed on plasma and wastewater samples to determine metoprolol by high-performance liquid chromatography-tandem mass spectrometry. In this study, the analyte was adsorbed from the samples onto microcrystalline cellulose as a green and efficient sorbent and then eluted for use in the determination step. In the mass spectrometer, the analyte was detected in the positive mode and selectivity of the analysis was increased by sequential mass analysis through multiple reaction monitoring. All of the effective parameters in the extraction of metoprolol from plasma and wastewater were optimized. Under optimal conditions the method was linear in the ranges of 1-1,000 and 0.1-1,000 ng/ml in plasma and wastewater samples, respectively. The detection limits of the method were 0.30 and 0.03 ng/ml in plasma and wastewater samples, respectively. The data showed that the method provides low detection limit, wide linear range, good precision and high extraction recovery. Finally several plasma and wastewater samples were successfully analyzed using the method. The use of a small amount of a green and inexpensive sorbent and a low volume of plasma without the need for further pretreatment steps are the main advantages of the method.

The Use of Inexpensive Sorbents to Remove Dyes from Wastewater - A Review

Dyes are utilized in various industrial applications, and some businesses' effluents include hazardous dyes. Humans, aquatic creatures, and the environment are all harmed by dyes. As a result, adequately treated dyes that manage wastewater must be before being discharged into nearby bodies of water. Adsorption has proven to be high and cost-effective in removing dyes from wastewater. The sorbent material for dye removal from industrial effluent is activated carbon, but its high cost limits massive-scale utilization. The use of cost-effective adsorbents for wastewater discharge dye elimination is discussed and analyzed in this paper. This review underlines and displays a preview of these IASs, including natural, industrial, and made-up materiality/wastes and their utilization in removing dyes. Experiments have shown that various inexpensive non-traditional adsorbents lead to effective dye removal. Accordingly, studies dealing with the search for effective and affordable sources from current resources are becoming increasingly crucial for eliminating dye. The excess desire for functional and affordable processing modes and adsorption significance has led to inexpensive alternative sorbents (IASs). The isotherm analysis and adsorption kinetics indicate that Langmuir / Freundlich, besides the pseudo-second-order model, is the most used pattern for convenient empirical adsorption datum. Low-cost by-products from the agricultural, residential, and industrial sectors have been identified as viable wastewater treatment alternatives. They make it possible to remove contaminants from wastewater while also contributing to waste minimization, recovery, and reuse. This review revealed that some IASs, have ratable adsorption capabilities and rapid kinetics, besides having vastly available.

Activated carbon prepared by co-pyrolysis of waste tobacco straw and waste LDPE mulch film: characterization and application for methylene blue removal.

Efficient and inexpensive sorbents play a key role in removing organic pollutants from water bodies. In this study, a series of high surface area activated carbons (ACs) with excellent adsorption performance was prepared by co-pyrolysis of the waste tobacco straw and the waste low-density polyethylene (LDPE) mulch film. Using the maximum adsorption capacity of methylene blue (MB) as an indicator, the variables such as LDPE content, K2CO3 to raw material ratio, activation time, and activation temperature were optimized. The optimal synthesis conditions were as follows: LDPE content of 40%, K2CO3/raw material ratio of 1 : 2, activation temperature of 900 °C, and activation time of 100 min. The maximum adsorption capacity of MB was up to 849.91 mg g-1. The results of scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), and BET showed that the moderate addition of LDPE was beneficial to the pyrolysis of the waste tobacco straw, bringing about the enrichment of surface groups (-OH, -COOH) and increasing its specific surface area and pore volume (up to 1566.7 m2 g-1 and 0.996 cm3 g-1, respectively). The equilibrium data of MB adsorption by the composite activated carbon (PAC) was consistent with the Langmuir isotherm, while the adsorption kinetics were better described by a pseudo-second-order kinetic model. This work reveals the feasibility of LDPE mulch film and waste tobacco straw as potential and inexpensive precursors for preparing high surface area AC adsorbents.

BIOCARBON FROM DIFFERENT BIOMASS PRECURSORS

Thermochemical conversion of lignocellulosic biomass is considered as a good opportunity to obtain liquid raw materials for biofuels and biochemicals. During this pyrolysis process a solid product, biocarbon, is obtained. Nowadays there is a growing interest in biocarbon, due to the potential benefits of its application in soil as a stimulant and CO2 trap. The physicochemical and porous properties of biocarbon are suitable for development of effective and inexpensive sorbents for the removal of contaminants from water. Biocarbon has promising sorption properties for various pollutants in water, including polycyclic aromatic hydrocarbons and heavy metals. Banana and orange peels, as well as cocoa flakes, were used as precursors. The carbonization was carried out at temperatures from 500 ° C to 900 ° C. Some of the samples were subjected to physical and chemical activation. The obtained carbon adsorbents are characterized by adsorption of iodine, BET, etc. It is planned to study the possibilities for the successful application of the obtained carbon materials as adsorbents for water and air purification, catalysts, hydrogen depots, etc.

Facile fabrication of porous waste-derived carbon-polyethylene terephthalate composite sorbent for separation of free and emulsified oil from water

Containment of oil spills in aquatic bodies and treatment of oily wastewater are necessary to mitigate oil pollution. Synthetic oil sorbents are commonly used for managing oil spills and while they are effective, their usage introduces a considerable amount of non-biodegradable plastic into the environment. In an effort to develop an inexpensive sorbent by reutilizing solid wastes for a sustainable future, this study investigates the fabrication of a composite oil sorbent from used polyethylene terephthalate bottles and waste carbonaceous residue from the gasification of oil refinery bottoms via an energy efficient phase inversion method. The composite sorbent demonstrated oil sorption capacity of ∼ 8 g/g, which is comparable to some commercially available adsorbents, and excellent retention capacity for mineral, paraffin and crude oils of different viscosities. Furthermore, the composite is able to remove oil from mineral or paraffin oil-in-water emulsions by sorption, with an efficacy of > 99.7 %, indicating its promising application in the treatment of industrial oily wastewater. Cost analysis shows that this waste-derived composite can be produced commercially at a competitive price.

Combining dispersive solid phase extraction using an inexpensive sorbent with dispersive liquid–liquid microextraction for the efficient extraction of some plasticisers from plastic-packed liquids

ABSTRACT The aim of this study is the extraction and determination of di(2-ethylhexyl) adipate and three phthalate esters including di-iso-butyl phthalate, di-n-butyl-phthalate, and di-(2-ethylhexyl) phthalate in several samples which were packed in plastic packages (orange and pineapple juices, three brands of mineral water, and two injectable pharmaceutical solutions). In this work, stearic acid coated calcium carbonate is used as a sorbent in dispersive solid phase extraction followed by dispersive liquid-liquid microextraction. The procedure initiates with the adsorption of the analytes onto the adsorbent. Then, the analytes are removed from the adsorbent by employing an elution solvent. After eluting the adsorbed analytes, the elution solvent is mixed with a few microlitres of a proper extraction solvent. Then, the obtained mixture is rapidly injected into deionised water during the microextraction procedure to attain higher concentrations of the target analytes. Ultimately, an aliquot of the sedimented organic phase is isolated from the aqueous phase by centrifuging and injected into gas chromatography–flame ionisation detector. Under optimal extraction conditions, the limits of detection and quantification were in the ranges of 0.15–0.40 and 0.50–1.33 µg L−1, respectively. Relative standard deviations were less than or equal to 5% for both intra- (n = 6) and inter-day (n = 4) precisions at a concentration of 50 µg L−1 of each analyte. Additionally, sufficiently high values of extraction recoveries and enrichment factors were obtained in the ranges of 53–89% and 266–446, respectively. Abbreviations: DLLME: Dispersive liquid–liquid microextraction; DSPE: Dispersive solid-phase extraction; EF: Enrichment factor; ER: Extraction recovery; FID: Flame ionisation detector; GC: Gas chromatography; LOD: Limit of detection; LOQ: Limit of quantification; MS: Mass spectrometry; RSD: Relative standard deviation

Wastewater Treatment for Heavy Metals and Dyes Using Low-Cost Biosorbents: A Review

The pollution of industrial wastewater with heavy metals and dyes is a highly important environmental problem, because of the propagation of the pollution and because of its unfavourable consequences. Sustainable wastewater treatment is one of the foremost challenges of this century. Various waste materials characterized by lignocellulose composition are low cost, non-conventional adsorbent for biosorptive removal of heavy metal ions from aqueous solutions. Recent studies point to the potential of use of low-cost materials (zeolites, carrot residue and green tea waste) as effective sorbents for the removal of Cd2+ from aqueous solution. The use of bentonite to the treatment of wastewater containing reactive dyes in aqueous solutions requires the modification of the hydrophilic surface by inorganic cations with organic cations exchange. The use of bentonite as an inexpensive sorbent for the removal of Remazol Brilliant Blue R (RBBR) from synthetic aqueous solutions has been also presented in recent studies. The influence of some parameters such as: pH, initial dye concentration, sorbent dose on sorption kinetics for dye removal has been reviewed in this paper.&#x0D;

Efficient sorption performance of carbon-diatomaceous silica compounds towards phenol

Phenol removal as organic pollutant model has been studied on new composite adsorbents prepared from carbon and natural diatomaceous silica mixtures in different proportions (KCp1, KCp2, and KCp3 with 10, 20, and 30% of carbonaceous matter, respectively). SEM observations clearly showed the porous aspect evolution when mixing carbon with the macroporous diatomite skeleton, further proved by TEM images that revealed a co-existence of two distinct pore sizes. FTIR and XRD characterization mainly demonstrated the disappearance of calcium carbonate species as consequence of the undertaken treatments in presence of carbon. N2 sorption analysis at 77 K confirmed the obtaining of more developed textural properties with enhanced BET surfaces, and the creation of narrower porosity. The best area was obtained for KCp3 (336 m2/g) as compared to the starting carbon and diatomite surfaces (118 and 8 m2/g, respectively). The influence of several parameters such as contact time, temperature, pH, and initial concentration on the performance of the resultant materials in terms of phenol adsorption was investigated. The pH ≤ 8 favored the phenol removal, whereas the temperature did not have a great impact in the selected range (30-60°C). The sorption isotherms followed well the Freundlich and, more accurately, Langmuir models with the highest adsorption capacity recorded for KCp3 (98.5 mg.g−1). A fast kinetic was revealed whose data best fitted with the pseudo-second-order model with a correlation factors values of R2=0.996, 0.999, and 0.992 for KCp1, KCp2, and KCp3 respectively. More than 50% of the maximum adsorption ratio was achieved in half the time needed for saturation. The new composites offer promising prospects as inexpensive sorbents for use with competitive capacities in the industrial water treatment.

Assessment of commercial porous polyethylene frit for extraction of polycyclic aromatic hydrocarbons from water.

Exploring commercial and inexpensive sorbents for extraction of organic pollutants is still an active area of research. Ultrahigh molecular weight polyethylene sieve plate (UMPESP) is a commercially available, low-cost, and porous frit, which has been widely used in solid-phase extraction cartridges to fix the filling materials. In this work, UMPESP was investigated for the extraction of polycyclic aromatic hydrocarbons (PAHs) from water samples. The desorption and sorption efficiencies of UMPESP were first evaluated and compared with two previously reported sorbents, low-density polyethylene plastic pellet (LDPEP) and silicone rod (SR). The comparative results showed that quantitative desorption of analytes from UMPESP, which could be easily achieved with 2 × 1.5mL n-hexane, was more effective than that of LDPEP (>6 × 1.5mL n-hexane) and comparable to that of SR. Additionally, shorter equilibrium time was rendered by UMPESP (shaking for 120min) compared with SR (>480min), due to the porous structure and larger surface area of the former. Different parameters that affect the extraction efficiency, including organic modifier, ionic strength, and pH value, were then studied. The optimized method coupled with gas chromatography-mass spectrometry afforded good linearity in a concentration range of 10-5000ngL-1 (except acenaphthene in the range of 25-5000ngL-1) with coefficients of determination ranging from 0.9957 to 0.9995 and relative standard deviations below 13.8%. The limits of detection and quantification were 0.04-3.35ngL-1 and 0.13-11.16ngL-1, respectively. Finally, the method was successfully applied to determine PAHs in real water samples, and the results showed no statistically significant difference with the concentrations derived from liquid-liquid extraction.

Investigation of the Conditions for Preconcentration of Cadmium Ions by Solid Phase Extraction Method Using Modified Juglans regia L. Shells.

Juglans regia L. shells as agricultural waste can be considered as alternative sorbents to minimize the problems associated with heavy metal pollution. In this study, J. regia shells (JRS) and JRS modified with hydrazine hydrate (JRS-HH) were used as sorbents and compared for the preconcentration of Cd(II) ions from aqueous solution. For the characterization of sorbents, scanning electron microscopy and energy dispersive X-ray (SEM/EDX) analysis and Fourier transform infrared (FTIR) spectroscopy were used. For preconcentration, the solid phase extraction (SPE) technique was used. Preconcentration studies were performed by column method and pH, eluent type and concentration, sample volume, flow rate, and interfering ions effect were studied to determine the optimum column parameters. The limit of detection (LOD) of the sorbents (JRS and JRS-HH) are 0.31 and 0.18 µg/L, respectively. According to the Langmuir isotherm model for both sorbents, for JRS KL = 0.030 L/mg, R2 = 0.992, 0.016 L/mg, and for JRS-HH KL = 0.016 L/mg, R2 = 0.998 and maximum adsorption capacities of the sorbents were found to be as 29.6 and 65.7 mg/g, respectively. The mean recoveries and RSD values at a 95% confidence level (N = 6) for Cd(II) were 100.9% and 3.42, and 100.6% and 3.79, for the JRS and JRS-HH sorbents, respectively. Using this method good results were obtained when compared with those in the literature and the proposed method was successfully applied to the analysis of the certificated reference material (NIST 1640). JRS are an effective and inexpensive sorbent for the preconcentration of metal ions when modified. Thus, low-cost agricultural wastes are both recovered and have an economic value.

МОДИФИЦИРОВАННЫЕ ПОЛИЭТИЛЕНПОЛИАМИНОМ ИЭПОКСИДНОЙ СМОЛОЙ ЦЕОЛИТЫ ДЛЯ ИЗВЛЕЧЕНИЯ ИОНОВ СВИНЦА ИЗ СТОЧНЫХ ВОД

Актуальность. Создание эффективных и недорогих сорбентов широкого профиля, одним из актуальных направлений которого является дизайн сорбентов для очистки вод различного назначения, постоянно востребовано в науке и производстве. Новые ионообменные сорбенты позволяют решать сразу две связанные задачи: очистка технической воды предприятий и регулирование содержания токсикантов в окружающей среде. Модифицирование ионообменников приводит к улучшению сорбционных и кинетических характеристик, особенно перспективны природные высокопроницаемые сетчатые полиэлектролиты с большой скоростью поглощения ионов крупных размеров. Модифицирование этих минералов поверхностным слоем сополимеров с эпоксидными группами, полученными при отверждении смеси полиэтиленполиамина и эпоксидной смолы, позволяет получить новые дешевые сорбционные материалы для очистки воды от тяжелых металлов, преимущественно катионов свинца Pb2+. Исследование обусловлено необходимостью очистки сточных вод металлургических предприятий от катионов Pb2+, которые относятся к токсичным веществам, проявляющим мутагенные, канцерогенные свойства, кроме того, встроенные в биогенные формы ионы обладают свойством локально накапливаться в природных объектах, тем самым являясь сильным экотоксикантом. Цель: определить сорбционные свойства природного цеолита и его модифицированной формы по отношению к иону Pb2+ и оптимизировать условия сорбции. Объекты: Шанханайский природный цеолит и его модифицированные полиэтиленполиамином (ПЭПА) и эпоксидной смолой (ЭД-20) формы. Методы: спектрофотометрия. Результаты. Получены модифицированные полиэтиленполиамином и эпоксидной смолой сорбенты на основе Шанханайского природного цеолита. Установлены оптимальные условия рН сорбции ионов Pb2+ в статических условиях. При использовании модифицированного природного цеолита в диапазоне рН 7–9 извлечение ионов свинца происходит на 90 % по сравнению с исходным цеолитом.Модифицированный природный цеолит может быть использован в качестве сорбционного материала для очистки промышленных и сточных вод.