Variety Of Sorbents Research Articles

Biogas upgrading through calcium looping: Experimental validation and study of CO2 capture

The calcium looping technology is one of the most promising technologies for capturing and storing CO2. This technology has been evaluated with a variety of sorbents and conditions in previous works, but the inlet CO2-ladden gas has typically been a flue gas from combustion, which typically has a composition of 10–20% CO2 and 80–90% N2. On the other side, the performance of the calcium looping process for CO2 capture of other gases (i.e., biogas or gases resulting from hydrothermal carbonization) remains largely unstudied. In this work, this knowledge gap is assessed through evaluating the performance of the calcium looping process for biogas (synthesized as 40% CO2, 60% CH4) in terms of carbonation conversion. This experimental study investigates the impact of: (1) using an inlet gas composition representative for biogas instead of combustion flue gas; (2) different biogas compositions; (3) the carbonation temperature; (4) the cooling-down and heating-up of the sorbent material between the reactor and ambient temperatures within cycles; (5) the atmosphere composition during calcination; and (6) the solids particle size. The main result obtained is that the overall CO2-capture performance of calcium looping improves when using biogas as inlet CO2-ladden gas, in comparison with combustion flue gas. One main contribution to this improved performance is shown to be the presence of secondary reactions (i.e., dry reforming, methanation). The impact of the CH4 to CO2 ratio tested is not remarkable, showing that the potentialities of the process in this aspect can be adapted to several biogas producing feedstocks.

Zirconium(IV) Metal Organic Frameworks with Highly Selective Sorption for Diclofenac under Batch and Continuous Flow Conditions

Diclofenac (DCF) is among the most effective non-steroidal anti-inflammatory drugs (NSAIDs) and at the same time one of the most consumed drugs worldwide. Since the ever-increasing use of diclofenac poses serious threats to ecosystems, its substantial removal is crucial. To address this issue, a variety of sorbents have been employed. Herein we present the diclofenac removal properties of two metal organic frameworks, namely [Zr6O4(OH)4(NH2BDC)6]·xH2O (MOR-1) and H16[Zr6O16(H2PATP)4]·xH2O (MOR-2). Batch studies revealed fast sorption kinetics for removal of DCF− from water as well as particularly high selectivity for the drug vs. common competitive species. Moreover, the composite MOR-1-alginic acid material was utilized in a sorption column, displaying remarkable removal efficiency towards DCF− anions. Significantly, this is the first time that column sorption data for removal of NSAIDs using MOF-based materials is reported.

Сорбционные характеристики сорбентов для твердофазной экстракции фенольных соединений из экстрактов лекарственных растений

В основе исследований настоящей работы находится твердофазное извлечение фенольных компонентов экстрактов лекарственного растительного сырья различными типами сорбционных материалов. В качестве сорбционных материалов использовали октадецилсиликагель (Strata C18-E), сополимер стирола и дивинилбензола, химически модифицированный N-винилпирролидоном,(Strata X), а также сополимер дивинилбензола и N-винилпирролидона (Oasis HLB). Для каждого из сорбентов получены сорбционные характеристики по отношению к целевым соединениям (объем до проскока, равновесный объем, объем удерживания и др.), а также десорбционные параметры (коэффициент концентрирования и степень извлечения). Показано, что сорбенты на основе октадецилсили-кагеля достаточно эффективны для извлечения группы флавоноидов и их гликозидов, а полимерные материалы - одновременно и флавоноидов, и фенольных кислот. Степени извлечения фенольных кислот и флавоноидов при коэффициенте концентрирования 5 на сорбенте Strata C18-E составили 27-40% и 79-105% соответственно. С применением сорбента Strata X также достигается концентрирова-ние в 5 раз при степенях извлечения 106-107% (для фенольных кислот) и 99-122% (для флавоноидов). На сорбенте Oasis HLB возможно концентрирование в 20 раз фенольных кислот при их степенях извлечения 74-96% и в 32 раза для флавоноидов при степенях извлечения в диапазоне 56-91%.

Measurement techniques for carbon dioxide sorption capacity on various coal samples: critical review

Underground carbon sequestration is proposed as a geologic disposal technique for the long-term storage of CO2 emissions to mitigate climate change and air pollution. Coal bed seams have large CO2 adsorption capacity, long time CO2 trapping and extra enhanced coal-bed methane recovery (CBM). However, CO2 sorption capacity is one of significant steps required to be determined accurately in any feasibility evaluation of carbon sequestration. Hence, in lab scale, there are three methods for CO2 adsorption capacity measurements namely manometric/volumetric, gravimetric and new capsule techniques for gas sorption on variety of sorbents. The manometric and volumetric methods require accurate determination of cell and void volumes and suitable equation of state (EoS). The gravimetric method requires a very accurate sensitive balance and less buoyancy effect and it is the best technique for small amounts (milligrams) of sorbents and the adsorption equilibrium can be mentored. Among all gas adsorption measurement techniques, the newly developed method “capsule method” exhibits the highest CO2 adsorption capacity on Polish coal by 4.08 mmol/g because capsule method that directly measures CO2 uptake of solid coal matrix cylinders, without the application of the equation of state (EoS) for CO2 or volumetric corrections. The main advantage of capsule method is that it is independent of any Equation of State (EoS), and it has no volumetric effects or impurities distort the shape of the gas adsorption isotherm. The disadvantage of capsule method is time-consuming and it is not easy to implement.

Sol-Gel Technique—A Versatile Tool for Adsorbent Preparation

Preparation of samples for analysis, first of all isolation and/or enrichment of analytes, is becoming a key stage of each analytical procedure including determination of trace components. Effectiveness of this stage, i.e., analyte enrichment, removal of interferents and change of the original sample matrix, depends both on the chosen extraction technique and utilized materials and reagents. Though liquid-liquid extraction is still widely used in analytical practice, it seems that solid phase extraction (SPE) techniques are gaining the dominating position. In these techniques, solid sorbents and pseudo-liquid materials are used as the analytes retaining media. Although a variety of sorbents and stationary phases usable in analytical procedures is known, due to an even larger assortment of analytes present in samples differing in matrix composition, the need for search for new types of sorbents exists. In this field, the sol-gel technique offers good opportunities of producing new sorption materials. Using this technique, one can obtain fit-for-purpose materials. Although sol-gel technique had been known for many years, its first applications in analytical chemistry were described in early 1990s. Since then, an increasing number of papers discussing the preparation of new sorbents using this technique and their applications is a proof positive of great opportunities offered by the technique.

Systematic Investigation of the Sorption Properties of Tenax TA, Chromosorb 106, Porapak N, and Carbopak F

A variety of sorbents is available for the sampling of airborne organic pollutants. However, choosing the right sorbent for a certain analytical target is still a challenge. Here we present a systematic sorption study for a diverse set of up to 200 compounds at temperatures between 40 and 250 degrees C for four frequently used sorbents: Tenax TA, Chromosorb 106, Porapak N, and Carbopack F. The experimental data are used to calibrate a polyparameter linear free energy relationship (pp-LFER) for each sorbent which allows one to predict the safe sample volume and the complete sample elution volume of chemicals not tested here at any desirable temperature.

Modification and Evaluation of Non‐Polar Sorbents for Solid‐Phase Extraction

Modification of packings for solid‐phase extraction through high‐frequency low‐temperature plasma treatment is a new method to obtain a wide variety of sorbents. This method is still in the process of investigation and application. In this study, several commercial sorbents have been modified in high‐frequency low‐temperature plasma with the mixed hydrogen/benzene system. The solvation parameter model is used to characterize the sorption properties of commercially available and plasma treated sorbents for solid‐phase extraction. Chromatographic test mixtures from the literature were used to probe hydrophobicity, free silanol interactions and shape selectivity of the sorbents. The physical and retention properties of the plasma treated sorbents indicate their suitability to be used in solid‐phase extraction. Some suggestions concerning the possible practical application of the newly obtained sorbents have been made.

Determination of Non-Steroidal Anti-Inflammatory Drugs in Natural Waters Using Off-Line and On-Line SPE Followed by LC Coupled with DAD-MS

Two different procedures for simultaneous determination of six NSAIDs (diflunisal, diclofenac, fenoprofen, ibuprofen, naproxen and tolmetin) in environmental waters are described. Final analysis of target compounds is performed by reversed-phase liquid chromatography – diode array detection and mass spectrometry (HPLC-DAD and LC-MS), whereas sample preparation is based on solid-phase extraction (SPE). A variety of sorbents and their respective advantages and disadvantages are discussed. For the off-line SPE of NSAIDs from water samples, a LiChrolut RP-18 was selected out of all investigated sorbents. In case of on-line coupling of SPE with chromatographic system LiChrosphere RP-18 was selected as the best one in terms of recovery of NSAIDs evaluated, RSD and availability. The applicability of the method was also evaluated. Method detection limits were in the range of 0.7−94 ng L−1. Recoveries ranged from 96 to 109% and relative standard deviations were lower than 5%. The procedures were shown to be linear over a wide range of concentration, exhibited satisfactory repeatability and accuracy, and reached limits of detection in the low ng L−1 range. No breakthrough volume was observed neither for off-line SPE (in the studied range of 100, 200, 300, 500, 700, 1000 and 2000 mL of tap water sample) nor for on-line SPE (in the wide range of 10 mL, 20 mL, 30 mL, 50 mL, 70 mL, 100 mL and 200 mL of tap water sample).

Efficiency of membrane-sorption integrated processes

The paper presents the characteristics of membrane-sorption integrated process, which comprise sorption of the solute with membrane separation of the sorbent. The main advantage of this separation method is the high efficiency and lower costs of the process comparing with classical sorption in fixed beds. The variety of sorbents and binding materials in form of very fine particles may be applied in this system. This increases the specific surface of the sorbent and consequently rise the uptake of the sorbate and enhances kinetics. Moreover, the high intensity of the process may be achieved due to synergetic effects of sorbent concentrating at membrane vicinity. The best results may be accomplished when flux is maintained below critical value and when the permeate flux is fully synchronized with the sorption kinetics and rate of sorbent renewal on membrane surface. Sorbent’s “residence time” at membrane surface may be controlled by various means such as backflushing, cross-flow, reverse flow, pulsations, gas sparking, etc. The experimental results on membrane biosorption of heavy metals fully support this idea. The mathematical model enables to attain the optimum process conditions. A new factor, i.e. biosorption efficiency has been introduced as a criterion to evaluate the process performance, which comprised yield and selectivity of separation simultaneously.