Sorbents In Terms Research Articles

Synthesis of Biodegradable Macroporous Poly(l-lactide)/Poly(ε-caprolactone) Blend Using Oil-in-Eutectic-Mixture High-Internal-Phase Emulsions as Template.

We have demonstrated that l-lactide (LLA) forms a eutectic mixture with ε-caprolactone (CL) in a 30:70 mol ratio with a melting point of -19 °C. Taking advantage of the liquid nature and polarity at the LLA-CL eutectic mixture, we have formulated oil-in-eutectic-mixture high-internal-phase emulsions (HIPEs) by stepwise addition of the oil phase (tetradecane) into the continuous phase (mixture of surfactant and LLA-CL eutectic mixture) at room temperature and under stirring. The oil-in-LLA-CL-eutectic-mixture HIPEs were polymerized in the presence of both the organocatalysts 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and methanesulfonic acid (MSA) and the initiator benzyl alcohol (BnOH) at 37 °C and without the addition of any extra reagent or solvent in one single pot. The catalytic selectivities of DBU and MSA for the ring-opening polymerizations of LLA and CL, respectively, allowed the synthesis of macroporous poly(l-lactide)/poly(ε-caprolactone) blend materials. The resulting materials exhibited a macroporous morphology that resembled that of the HIPE internal-phase droplets used as templates. These materials proved effective as oil absorbents for oil/water separation with not only a noticeable performance, similar to that of conventional sorbents in terms of both selectivity and recyclability, but also unprecedented safe disposability, certainly of interest for applications in the cleanup of industrial oily wastewaters and oil spills, thanks to the biodegradable features of both poly(ε-caprolactone) and poly(l-lactide).

Marine residual fuel sorption and desorption kinetics by alkali treated rice husks

An oil absorbent material has been produced from waste biomass with an alkali treatment process. The simple yet effective process is carried out on the agricultural biowaste at 90 °C and ambient pressure. The present manuscript considers the transient behavior of the sorbent during application, in particular the oil sorption and desorption profiles with time. The kinetics data shows that this lignocellulosic sorbent reaches saturation in <2 min of contact with the spilled oily liquid (marine residual fuel). The results showed that the second order kinetic model accurately correlates with the experimental data. The rice-husk product is shown to significantly outperform a commercially available sorbent in terms of uptake capacity (more than 18 g/g by the husk sorbent compared to 10 g/g by Corksorb). However in gravimetric desorption experiments, the as-prepared husk exhibited less favorable behavior than the commercial competitor.

Effect of KI and KOH Impregnations over Activated Carbon on H2S Adsorption Performance at Low and High Temperatures

In the present work, commercial-grade activated carbon was modified by steam activation to improve its surface properties for high temperature desulfurization. The modified sample was also further upgraded by impregnating with KOH and KI to promote the chemisorption with of H2S. The H2S adsorption performance was tested under the temperature range of 30–550°C using the temperature program adsorption technique to understand the effect of adsorption temperature on the material adsorption characteristic. It was found that at ambient temperature, the impregnation of activated carbon with KOH can promote the H2S adsorption capacity of activated carbon, whereas the impregnation with KI does not provide a significant beneficial effect. At high adsorption temperature (upto 550°C), both KOH and KI impregnation considerably improve the H2S adsorption performance of activated carbon in terms of the adsorption capacity and breakthrough time. It was revealed from N2 adsorption, SEM and EDS measurement that the chemical reactions between H2S and alkaline compounds (KOH and KI) are promoted at high temperature. Based on all experimental results, the equilibrium adsorption model using the linear isotherm was developed to predict the adsorption behavior of these sorbents in terms of equilibrium isotherm constant and mass transfer coefficient for later scaling-up process.

Graphene nanoplatelets as a highly efficient solid-phase extraction sorbent for determination of phthalate esters in aqueous solution

Graphene nanoplatelet (GN) as a solid-phase extraction (SPE) sorbent in combination with high performance liquid chromatography has been used for the determination of five phthalate esters (PAEs) in aqueous solution. The operation parameters affecting the extraction efficiency were optimized. Comparative studies showed that GN was superior to other common SPE sorbents in terms of recovery and adsorption capacity. Under optimization conditions, detection limits of 0.09-0.33 ng mL(-1) were achieved for five PAEs and enrichment factors of 402-711 for the analytes were obtained. The proposed method was successfully applied for the determination of PAEs in tap water and drink samples with recoveries ranging from 87.7% to 100.9%.

Encapsulation of ammonium molybdophosphate and zirconium phosphate in alginate matrix for the sorption of rubidium(I)

Ammonium molybdophosphate and Phozir (alone or in combination) have been encapsulated in alginate beads for the synthesis of rubidium sorbents. SEM and SEM–EDX analyses confirm the homogeneity of the sorbents in terms of composition and metal binding. AMP sorbent is less sensitive to pH than Phozir, and optimum pH is close to pH 3 for the binding of Rb(I). The Langmuir equation fitted well sorption isotherms and the maximum sorption capacities were in the range 0.65–0.74mmolRbg−1. The resistance to intraparticle diffusion contributes to control uptake kinetics (effect of particle size) though the presence of solid inorganic particles reduces the impact of drying alginate capsules (preventing the collapse of the porous structure during the drying step). Breakthrough curves demonstrate the potential of these sorbents for the dynamic sorption of Rb(I) while using ammonium chloride (combined to nitric acid) allows recovering Rb(I) from loaded sorbents.

Experimental First-Pass Method for Testing and Comparing Sorbent Polymers Used in the Clearance of Iodine Contrast Materials

Background: Sorbents have been shown to adsorb iodinated radiocontrast media. Objective: In this study we describe a simple method to compare various sorbents in terms of capacity to adsorb radiocontrast media. Methods: Iodixanol solution was injected into columns filled with three types of sorbent at filtration velocities of increasing magnitude. Two variables of interest – contrast removal rate and matched iodine retention (MIR) – were calculated to measure the adsorption efficiency and the mass of contrast iodine adsorbed versus sorbent used, respectively. Results: The highest contrast removal and MIR for Porapak Q, CST 401 and Amberlite XAD4 were 41, 38 and 16% (p = 0.22 and 0.0005 for comparisons between Porapak Q-CST 401 and CST 401-Amberlite XAD4) and 0.060, 0.055 and 0.024, respectively (p = 0.18 and 0.0008). Extrapolation to a clinical scenario may suggest that removal of 8 ml iodixanol could be achieved by masses of sorbents of 43, 47 and 107 g, respectively. Conclusion: In this study we set a benchmark for comparing the radiocontrast-adsorbing efficiency of polymer sorbents during first-pass experiments, using a readily available methodology.

Kinetic and structural requirements for a CO2 adsorbent in sorption enhanced catalytic reforming of methane – Part I: Reaction kinetics and sorbent capacity

This paper presents a fundamental model-based analysis for the applicability of integration of a highly active Rh/CeαZr1−αO2 catalyst with two candidate CO2 sorbents for pure H2 production in low temperature sorption-enhanced steam reforming of methane. K-promoted hydrotalcite and lithium zirconate solids are considered in the investigation as CO2 sorbents. The process is analyzed using multi-scale modeling levels of a heterogeneous particle-based model, a heterogeneous bulk-scale model, and a homogenous bulk-scale model. The presence of this active catalyst dictates strict requirements on the sorbent in terms of fast adsorption kinetics for an efficient process performance. The maximum CH4 conversion enhancement is determined to be a strong function of sorption kinetics. This enhancement is not affected by a higher sorbent capacity at slow adsorption kinetics. The process is studied using two fixed bed configurations of an integrated dual function particle and an admixture bed of catalyst/sorbent particles. Optimal operating conditions for the hydrotalcite-based system are identified to provide CH4 conversion of 98% with high H2 purity of 99.8% and low CO2 contamination (<250ppm). The lithium zirconate-based system can provide CH4 conversion and H2 purity of 99.9% at identical conditions. Based on the end application of H2 produced, the process can be tuned to feed gas turbine cycles, fuel cells, or petrochemical plants.

Affinity sorbent based on tryptophyl-threonyl-tyrosine for binding of the immunoglobulins G: Sorption characteristics and aspects of practical application

New chromatographic material based on tryptophil-threonil-tirosine was prepared. This sorbent effectively binds human, sheep, goat and cow immunoglobulins G. New sorbent shows high selectivity for removing immunoglobulins from blood plasma. Effective sorption capacity is 15-25 mg of immunoglobulin G per ml of matrix. Optimal method of covalent attachment ligand to polysaccharide matrix allows achieving high stability of the sorbents in terms of use and storage. This sorbent can be used in medicine and biotechnology.

Solid-phase extraction using molecularly imprinted polymers for selective extraction of a mycotoxin in cereals

The aim of this work was to develop a method for the clean-up of a mycotoxin, i.e. Ochratoxin A (OTA), from cereal extracts employing a new molecularly imprinted polymer (MIP) as selective sorbent for solid-phase extraction (SPE) and to compare with an immunoaffinity column. A first series of experiments was carried out in pure solvents to estimate the potential of the imprinted sorbent in terms of selectivity studying the retention of OTA on the MIP and on a non-imprinted polymer using conventional crushed monolith. The selectivity of the MIP was also checked by its application to wheat extracts. Then, after this feasibility study, two different formats of MIP: crushed monolith and micro-beads were evaluated and compared. Therefore an optimization procedure was applied to the selective extraction from wheat using the MIP beads. The whole procedure was validated by applying it to wheat extract spiked by OTA at different concentration levels and then to a certified contaminated wheat sample. Recoveries close to 100% were obtained. The high selectivity brought by the MIP was compared to the selectivity by an immunoaffinity cartridge for the clean-up of the same wheat sample. The study of capacity of both showed a significant higher capacity of the MIP.

Methane preconcentration in a microtrap using multiwalled carbon nanotubes as sorbents

The GC monitoring of green house gases is a challenging task because the concentration of organic species such as methane are relatively low (ppm to ppb) and their analysis requires some level of preconcentration. Since methane is highly volatile, it is not easily retained on conventional sorbents. In this paper we present multiwalled carbon nanotubes (MWNTs) as an effective sorbent for a microtrap designed for methane preconcentration. Its performance was compared to other commercially available carbon based sorbents, and it was found to be the most effective sorbent in terms of breakthrough volume and enthalpy of adsorption.

Direct and inverse problems in the simulation of gradient ion chromatography

Basic relationships were derived for the kinetic and equilibrium characteristics of gradient ion chromatography. A new version of the IonChrom program was developed to solve direct and inverse problems in the simulation of ion chromatography for various systems with both isocratic and gradient elution conditions. The use of the exploratory inverse problem method for processing data given in the Dionex catalog allowed us to classify Dionex sorbents in terms of selectivity.