Development Of Adsorbents Research Articles

Highly efficient adsorption and removal of phthalate esters by polymers of intrinsic microporosity

In recent years, phthalate esters (PAEs) have been found to be endocrine disruptors that pose a serious safety threat to human health. Currently, adsorption is one of the most efficient technologies to remove PAEs, and the development of adsorbent materials that combine high adsorption capacity and short equilibrium time is a challenging problem. In this study, PIM-1, a typical representative of polymers of intrinsic microporosity (PIMs), was prepared through three methods and first used as adsorbents for PAEs removal. PIM-1 prepared under high temperature (HT-PIM-1) exhibited a high capacity of 787mg/g for dibutyl phthalate (DBP), a prevalent PAE in water, which is significantly higher than most reported adsorbents. Furthermore, more than 90.0% of the equilibrium adsorption capacity can be reached within 30mins. In addition, the adsorption of DBP could be inhibited by ethanol due to the enhanced interaction between DBP and ethanol, which could be revealed by molecular simulation. The adsorption mechanism of PAEs on PIM-1 mainly included hydrophobic interactions, π-π interactions, together with the size matching between PAEs and hierarchical pores of PIM-1. This study provides an idea for the application of PIMs for PAEs removal with high adsorption capacity and high efficiency. Environmental ImplicationPhthalate esters (PAEs) are emerging pollutants that pose a significant threat to public health and safety. They have been detected not only in environmental water but also in alcoholic beverages. Adsorption is widely preferred for removing PAEs, and the adsorption of PAEs in alcoholic solutions is a more challenging process compared to pure water. In this study, PIM-1 with o-phenyl groups similar to PAEs were first used as adsorbents for PAEs and demonstrated a remarkable adsorption capacity in both water (787mg/g) and alcoholic solutions (398mg/g) within a short period, surpassing the performance of commercial adsorbents.

Application of the AHP-QFD methodology in the sustainability analysis of a trifunctional adsorbent for inorganic micropollutants from contaminated water

An alternative approach to addressing water pollution is through the development of adsorbent materials. Na-jarosite is a promising material capable of removing simultaneously multiple ions from contaminated water. Employing four Quality Functional Deployment (QFD) matrices alongside the hierarchical analysis process (AHP) methodology, this study aimed to select materials, preparation methods, equipment, and processing conditions of Na-jarosite to remove As(V), Pb(II) and F (-) from contaminated water. The analysis of QFD matrices 1 and 2 identified electrical heating as the optimal method for synthesizing Na-jarosite, exhibiting removal capacities of removal capacity of 65.56 mg g−1 for As(V), 94 mg g−1 for Pb(II) and 2.45 mg g−1 for F(-). Rotating disc granulation was chosen for adsorbent formation, demonstrating environmental viability based on E Factor (0.6 kg of waste) and Eco scale (89) indicators. Further analysis of the QFD 3 matrix allowed the selection of essential equipment, including an electrical heating oven, a rotating disc granulator, and an extended tray for synthesis, granulation, and drying processes, respectively. Additionally, the QFD 4 matrix analysis identified drying the adsorbent at temperatures below 100 °C as a critical parameter for effective adsorbent formation. QFD and AHP analyses findings highlight the potential of Na-jarosite as a trifunctional adsorbent material for addressing water pollution challenges.

Direct Air Capture Technology and Its Application

Direct air capture technology (DAC) is integral to achieving carbon emission targets. This paper briefly analyses the application of DAC technology in indoor CO2 removal and CO2 mineralisation. Thanks to the elevated concentration of CO2 in the air (1000ppm) and the integrated DAC unit and air conditioning unit, the indoor CO2 removal system significantly reduces energy consumption. CO2 mineralisation, combined with DAC technology, offers a safe solution for permanent carbon storage and the possibility of obtaining a valuable end product by selecting the right mineralised feedstock. Future research should continue to focus on the development of adsorbent materials and the integration of CO2 capture with subsequent applications to achieve sustainability.

Bacterial cellulose‐modified castor oil‐based polyurethane sponge for hexavalent chromium removal

AbstractDue to the multiple industrial applications of chromium compounds and their dangerous nature for the environment, the development of adsorbent materials has been investigated. In line with this reality, bacterial cellulose (BC) has become a potential filler in the polymeric matrix due to its ability to remove toxic metals; however, its performance is little explored. This research proposes a new approach for BC as a filler in castor oil‐based polyurethane, obtaining a sponge for Cr(VI) removal. The pure PU and PU + X%BC sponges (X stands for BC content between 5 and 20 wt%) were characterized by Fourier‐transform infrared spectroscopy, scanning electron microscopy, optical microscopy, density, contact angle (CA), and thermogravimetric analysis. Sorption capacity and efficiency were evaluated as a function of the fiber content, with tests performed in function of contact time (2.5 min to 3 h) at 50 mg L−1. The BC fillers of the sponges increased the density and influenced the morphological, chemical structural, thermal, and sorption properties. Thus, the sponge (PU + 20%BC) presented the highest CA (104.4°) and the best sorption capacity and efficiency (4.3 mg g−1 and 43.2%). The sorption mechanism was well‐defined by isotherm models, presenting a maximum adsorption capacity of 23.5 mg g−1 and best fit (R2 = 0.989) with the Freundlich isotherm. The sponge is an efficient material for Cr (VI) removal and provided a promising insight into an adsorption mechanism study.

Progress in preparation of hollow nanomaterials and their application to sample pretreatment

Sample pretreatment technology plays a vital role in the analysis of complex samples and is key to the entire analytical process. Its main purpose is to separate the substance to be measured from the sample matrix or interfering substances in the sample and to achieve a state in which the instrument can be analyzed and detected. Traditional sample pretreatment techniques include liquid-liquid extraction, liquid-solid extraction, precipitation separation, solvent volatilization-rotary evaporation, filtration, and centrifugation. However, the applications of these methods are limited by their low extraction efficiency, complicated operation, long time consumption, unstable recovery, use of large amounts of organic solvents, and large error rates. Several new sample pretreatment techniques, including solid-phase extraction, magnetic solid-phase extraction, solid-phase microextraction, and dispersive solid-phase extraction, have been developed and rapidly applied to various fields to overcome the shortcomings of traditional sample pretreatment methods. However, the development of adsorbent materials with high selectivity and enrichment capability remains a challenge in sample pretreatment technology, in which adsorbents with excellent adsorption performance are crucial. In recent years, various nanomaterials with remarkable properties have been introduced and applied to sample pretreatment, and numerous nano-extraction materials with diverse functions and high selectivity and enrichment capability have been developed. Hollow nanomaterials are nanoparticles with large voids in their solid shells. Owing to their advantageous properties, which include a large effective surface area, abundant internal space, low density, variety of preparation methods, structural and functional tailorability, short mass transmission path, and high carrying capacity, hollow nanomaterials show great application potential in sample pretreatment. The extraction mechanism of these materials is based on the synergistic effects of π-π stacking, electrostatic, hydrogen-bonding, and hydrophobic interactions to achieve the efficient separation and enrichment of the target analytes. Given their noteworthy physicochemical properties, hollow nanomaterials have gained wide attention in various research fields and are considered a research frontier in the field of materials science. Changing the structure or surface properties of the core and shell can lead to various hollow nanomaterials with unique properties. Such changes can create synergy between the physicochemical properties and structural function of the original core-shell material, leading to novel materials with superior performance compared with the starting materials and broad application prospects in sample pretreatment. Nevertheless, only a few hollow nanomaterials with diverse structures and functions are currently used for sample pretreatment, and their adsorption capacity for target analytes is often unsatisfactory. Consequently, enhancing the adsorption selectivity of these materials toward various analytes is the most important step in sample pretreatment. First, hollow nanomaterials with a large specific surface area and suitable pore size can be designed to achieve the specific adsorption of target analytes of varying sizes. The combination of hollow nanomaterials with other materials presenting desirable adsorption properties could also lead to synergistic effects and enhance the performance of composite hollow nanomaterials. In addition, more green methods to prepare hollow nanomaterials with outstanding selectivity can be explored to achieve the superior adsorption of a specific target analyte. Efforts to synthesize hollow nanomaterials have been met with great success, but the available synthesis methods still suffer from complicated steps, high costs, relatively harsh conditions, and the use of highly toxic substances. This paper summarizes the main types of hollow nanomaterials, their synthesis methods, and research progress on sample pretreatment technologies (solid-phase extraction, solid-phase microextraction, magnetic solid-phase extraction, and dispersive solid-phase extraction) and describes the challenges encountered in the synthesis of hollow nanomaterials. The applications and developments of hollow nanomaterials in sample pretreatment are also discussed.

Carbon nanofibers with gas selective layer containing rich and accessible ultramicropores for methane/nitrogen separation

The adsorption separation and purification of coalbed methane (CH4) has attracted global interest as an important technique for the utilization of unconventional natural gas. The success for this method relies on the development of adsorbent materials that can selectively enrich CH4. Toward this goal, we report a facile in-situ growth method to prepare carbon nanofibers with ultramicroporous gas selective layer as adsorbent for CH4/N2 separation. The thickness of gas selective layer can be precisely tuned from 90 nm to 525 nm. The optimal carbon nanofibers exhibited a high CH4/N2 selectivity of 6.8 with the CH4 uptake reaching 0.97 mmol g−1 as well as two orders of magnitude faster CH4 diffusion kinetics than the commercial activated carbon adsorbent. The high accessibility to the adsorption sites and short diffusion path of the nanofibers facilitate the rapid mass transfer and intensify the dynamic CH4/N2 separation. Pressure swing adsorption simulations indicated the recovery and productivity over the carbon nanofibers with 90 nm-thick gas selective layer increased by 40 % and 20 %, respectively, as compared to the 525 nm-thick counterparts. This work offers a new insight for designing high-performance CH4/N2 adsorbents through suitable combination between rich ultramicropores and short diffusion path.

Development of Adsorbent Materials Using Residue from Coffee Industry and Application in Food dye Adsorption Processes

HIGHLIGHTS The adsorbent activated with H2PO4 removed around 100% of Ponceau 4R dye. The increase in temperature influenced the increase in maximum adsorptive capacity. Langmuir's isotherm was better suited to the experimental data of the Ponceau 4R dye.

Experimental study on silica gel/ethanol adsorption characteristics for low-grade thermal driven adsorption refrigeration systems

• Silica gel/ethanol adsorption pair is promising for EVs and PV/T applications. • Ethanol is highly attracted to silica gel through chemical adsorption. • The silica gel/ethanol presents minor hysteresis owing to condensation. • The theoretical cyclic performance of silica gel/ethanol were calculated 0.97. There has been an increasing interest in adsorption cooling and heat pumps as the most feasible green alternative to the widespread vapor compression technology. Recent developments in adsorption cooling highlighted the need for cost-efficient adsorption pairs of advanced adsorption characteristics. In response, this article experimentally investigates and models silica gel/ethanol pair adsorption characteristics that can utilize low-temperature heat sources, such as those available in the emerging electric vehicles and PV/T systems. The investigated characteristics are the porous structure stability, isosteric heat of adsorption, adsorption diffusion energy, adsorption isotherm, and adsorption kinetic under extended operating conditions 15–55 °C. The results showed the high affinity of silica gel towards ethanol to provide sub-zero cooling. Silica gel showed no structure deterioration during the repetitive adsorption/desorption cycles of net 22 % cyclic ethanol uptake. The chemical adsorption of silica gel/ethanol showed a high level of adsorption/desorption reversibility with minimal hysteresis, which the Langmuir model best simulated. The heat of adsorption was determined to be 4.49 × 10 4 J/mol, which was higher than the diffusion energy of 1.80 × 10 4 J/mol due to the slow physical mobility of ethanol molecules inside silica gel pores. The Elovich kinetic model was the most suitable for simulating the chemical adsorption/desorption processes. The material level cyclic analysis showed the potential of 22 kJ/kg ads cooling effect and 0.97 coefficient of performance by utilizing a 55 °C heat source, widely available in PV/T systems and electric vehicles.

Adsorption of polyhaloalkane vapors by adaptive macrocycle crystals of WreathArene through C-halogen⋯π interactions

Polyhaloalkanes are broadly useful yet environmentally harmful stock chemicals, therefore the development of adsorbent materials with capacity and selectivity for polyhaloalkane vapors is highly desirable. Here we report a novel macrocycle WreathArene, a fluorinated C3-symmetrical [16]-paracyclophane. In the crysalline state, WreathArene features guest-adaptive polymorphism for polyhaloalkanes including chloroform, tribromomethane, 1,1,2-trichloroethane, and 1,2-dibromoethane. Non-covalent C-halogen⋯π interactions are observed in all of these host-guest structures. Based on these properties, the activated WreathArene crystals can be utilized as a selective and recyclable adsorbent for polyhaloalkane vapors with excellent capacity under user-friendly conditions.

Extraction of Tanshinones Rich Extract of Danshen (Salvia Miltiorrhiza Bunge) Root Using Adsorptive (Non-Ionic) Macroporous Resins

Tanshinones are an important lipophilic, bioactive diterpenoid group of danshen roots with many pharmacological activities. In this study, tanshinones rich extract of danshen roots, a typically valuable product of danshen, was prepared through a two-step process of extraction and purification. In which, adsorptive (non-ionic) macroporous resins were exploited in the purification step to remove impurities and enrich tanshinones. The obtained refined extract was red brownish dry powder with the following characteristics: loss on drying of 4.04 ± 0.18%, tanshinone IIA and cryptotanshinone content of 10.55 ± 0.21% and 5.78 ± 0.64%, respectively (the results met the requirements of the Tanshinones monograph in The Chinese Pharmacopoeia 2015). The overall yield of the established extraction process was 2.21 ± 0.12%, calculated by the weight of dry extract.
 Keywords: Tanshinones, danshen, macroporous resins, tanshinone IIA, cryptotanshinone.
 References
 [1] X. Yan, Overview of Modern Research on Danshen, G. Du, J. Zhang, Danshen (Salvia Miltiorrhiza) in Medicine, Springer, Germany, Vol. 2, 2014, pp. 3-17.[2] C. Y. Su, Q. L. Ming, K. Rahman, H. Ting, L. P. Qin, Salvia miltiorrhiza: Traditional Medicinal Uses, Chemistry, and Pharmacology, Chinese Journal of Natural Medicines, Vol. 13, No. 3, 2015, pp. 163-182, https://doi.org/10.1016/S1875-5364(15)30002-9.[3] Y. Cui, B. Bhandary, A. Marahatta, G. H. Lee, B. Li, D. S. Kim, S. W. Chae, H. R. Kim, H. J. Chae, Characterization of Salvia Miltiorrhiza Ethanol Extract as An Anti-osteoporotic Agent, BMC complementary and alternative medicine, Vol. 11, No. 1, 2011, pp. 120-131, https://doi.org/10.1186/1472-6882-11-120.[4] J. Li, H. A. Chase, Development of Adsorptive (Non-ionic) Macroporous Resins and Their Uses in The Purification of Pharmacologically-Active Natural Products From Plant Sources, Natural product reports, Vol. 27, No. 10, 2010, pp. 1493-1510, https://doi.org/10.1039/c0np00015a.[5] Tanshinones, The Chinese Pharmacopoeia, China, 2015, pp. 398-399.[6] G. Tian, T. Zhang, Y. Zhang, Y. Ito, Separation of Tanshinones From Salvia miltiorrhiza Bunge by Multidimensional Counter-Current Chromatography, Journal of Chromatography A, Vol. 945, No. 1-2, 2002, pp. 281-285, https://doi.org/10.1016/S0021-9673(01)01495-9.[7] D. Wu, X. Jiang, S. Wu, Direct Purification of Tanshinones From Salvia miltiorrhiza Bunge by High‐speed Counter‐current Chromatography Without Presaturation of The Two‐phase Solvent Mixture, Journal of Separation Science, Vol. 33, No. 1, 2010, pp. 67-73, https://doi.org/10.1002/jssc.200900491.[8] M. Liu, X. H. Xia, Study on The Chemical Stability of Tanshinone IIA, Zhong Yao Cai, Vol. 33, No. 4, 2010, pp. 606-609, PMID: 20845791 (In Chinese).[9] X. Bi, X. Liu, L. Di, Q. Zu, Improved Oral Bioavailability Using a Solid Self-Microemulsifying Drug Delivery System Containing a Multicomponent Mixture Extracted from Salvia miltiorrhiza, Molecules, Vol. 21, No. 456, 2016, pp. 1-15. https://doi.org/10.3390/molecules21040456.
 

Extraction desulphurization of fuels using ZIF-8-based porous liquid

Porous ionic liquids (PILs), coupling the permanent porosity of porous solids with the good solubility and liquid fluidity of ionic liquids, have been successfully synthesized and offer great opportunities in the development of adsorption and separation. In this study, series of zeolitic imidazolate framework-8 based PILs (ZIF-8-PILs) are constructed and used for extractive desulfurization of fuels. Effects of extraction time, temperature, mass ratio of PILs to model oil and initial sulfur concentration on desulfurization are investigated. ZIF-8-based N-butylpyridinium bis(trifluoromethanesulfonyl)imide PILs (ZIF-8/[Bpy][NTf2]) exhibits encouragingly high performance with the removal efficiencies of thiophene (TH) and benzothiophene (BT) of 72.41% and 80.87% under optimum extraction conditions. After extraction, PILs can be facilely recovered and reused with steady removal efficiencies. The stable liquid porous structure of ZIF-8-PILs plays a dominant role for the excellent extractive desulfurization performance, and the synergistic effects of electrostatic interaction, hydrogen bonding and π-complexation interaction among ILs, ZIF-8 and sulfur compounds are also closely relevant to the high removal efficiency. The results of this work show that PILs are a new and promising extractant for fuel extraction desulfurization process.

Aminosilane-grafted bismuth-alumina adsorbents: Role of amine loading and bismuth content in iodine immobilization from aqueous solutions

Development of adsorbent materials that can efficiently remove radioactive species, in particular, iodine from aqueous waste streams is of great importance to prevent the discharge of these highly toxic chemicals into waterways, while providing a means for a safe disposal of nuclear wastes. In this study, we present a detailed investigation of the performance of a series of bismuth-loaded alumina adsorbents (Bi/Al) grafted with three different aminosilanes including 3-Aminopropyl-triethoxysilane (APS), N-methylaminopropyl-trimethoxysilane (MAPS), and 3-N,N-dimethylaminopropyl-trimeth-oxysilane (DMAPS), in the removal of iodine from aqueous solutions. Specifically, we studied the effects of bismuth loading, amine type and content, as well as iodine concentration and capture temperature to determine the best performing material and removal conditions for iodine immobilization from caustic scrubber solutions. Our results indicated that amine grafting can enhance the iodine removal performance of Bi-Al, with DMAPS giving rise to highest capacity. It was also found that iodine capture over amine-grafted Bi/Al changes dramatically with amine content. Among the materials investigated, Bi5/Al-DMAPS with an amine content of 60 wt% exhibited the highest iodine capture capacity of 215.7 mg/g at 50 °C. Moreover, amine grafting improved the retention of adsorbed iodine species within the adsorbent over time with no degree of leaching after 24 h, unlike Bi/Al2O3 analogue.

Computational Evaluation of the Diffusion Mechanisms for C8 Aromatics in Porous Organic Cages

The development of adsorption and membrane-based separation technologies toward more energy and cost-efficient processes is a significant engineering problem facing the world today. An example of a process in need of improvement is the separation of C8 aromatics to recover para-xylene, which is the precursor to the widely used monomer terephthalic acid. Molecular simulations were used to investigate whether the separation of C8 aromatics can be carried out by the porous organic cages CC3 and CC13, both of which have been previously used in the fabrication of amorphous thin-film membranes. Metadynamics simulations showed significant differences in the energetic barriers to the diffusion of different C8 aromatics through the porous cages, especially for CC3. These differences imply that meta-xylene and ortho-xylene will take significantly longer to enter or leave the cages. Therefore, it may be possible to use membranes composed of these materials to separate ortho- and meta-xylene from para-xylene by size ...

Morphological and functional aspects of zeolite filled siloxane composite foams

ABSTRACTOne of the main objectives of the recent research and development activities on adsorption heat pumps is the improvement of the volume‐specific power while maintaining a reasonable thermodynamic efficiency. In this sense, a potentially effective approach is the development of adsorbent materials with high zeolite/support mass ratio such as zeolites‐based foam adsorbent composites. In this work, the influence of the morphological aspects on adsorption performances of innovative SAPO‐34 silicone composite foams has been investigated by varying zeolite filler content. The composite foam evidenced a mixed open/closed‐cell structure, depending on zeolite amount. At low zeolite content (20%), a mainly open cell structure was obtained, while at large zeolite content foams (up to 70 wt %), a mainly closed‐cell structure was obtained. Adsorption tests evidenced that SAPO‐34 zeolite foams have a high adsorption efficiency when compared with pure zeolite highlighting the active behavior of siloxane matrix during water vapor diffusion. Based on the morphological and physical properties of the foam, a simplified model for vapor diffusion flow process in composite foams was proposed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45683.

Particle Adsorption on Hydrogel Surfaces in Aqueous Media due to van der Waals Attraction

Particle adhesion onto hydrogels has recently attracted considerable attention because of the potential biomedical applications of the resultant materials. A variety of interactions have been taken advantage of for adsorption, including electrostatic forces, hydrophobic interactions and hydrogen bonding. In this study, we report significant adsorption of submicron-sized silica particles onto hydrogel surfaces in water, purely by van der Waals (vdW) attraction. The vdW forces enabled strong adhesions between dielectric materials in air. However, because the Hamaker constant decreases in water typically by a factor of approximately 1/100, it is not clear whether vdW attraction is the major driving force in aqueous settings. We investigated the adsorption of silica particles (diameter = 25–600 nm) on poly(acrylamide) and poly(dimethylacrylamide) gels using optical microscopy, under conditions where chemical and electrostatic adsorption is negligible. The quantity of adsorbed particles decreased on decreasing the Hamaker constant by varying the refractive indices of the particles and medium (ethyleneglycol/water), indicating that the adsorption is because of the vdW forces. The adsorption isotherm was discussed based on the adhesive contact model in consideration of the deformation of the gel surface. The present findings will advance the elucidation and development of adsorption in various types of soft materials.

Development of adsorption and electrosorption techniques for removal of organic and inorganic pollutants from wastewater using novel magnetite/porous graphene-based nanocomposites

Abstract Herein, we report a new synthesis route for generating porous on graphene with a scalable and controllable size of micron to submicron through the successive insertion of potassium atoms into interlayers of graphite at low temperature. Comprehensive studies such as physico-chemical analysis confirm that the as-obtained porous graphene has few layers with fewer defects. Further, the magnetically separable magnetite (Fe 3 O 4 )/porous graphene nanocomposites were synthesized through a facile, cost-effective hydrothermal process. The as-prepared nanocomposites were characterized by different analytical techniques. In the nanocomposites, superparamagnetic Fe 3 O 4 nanoparticles with an average size of 30 nm nanoparticles uniformly dispersed on the porous graphene sheets, and they acted as mutual spacers in the nanocomposites to avoid aggregation of the magnetic nanoparticles and restacking of the porous graphene layers. In addition, Fe 3 O 4 /porous graphene nanocomposites possessed high adsorption capacities of dyes and heavy weight metal ions from wastewater. An organic dye methyl violet was used as an adsorbate for investigating the adsorption characteristics of the Fe 3 O 4 /porous graphene nanocomposites. Fe 3 O 4 /porous graphene exhibited rapid adsorption (5 min), high adsorption capacity (Q o -460 mg/g), easy separation and reuse owing to the high specific surface area with porous nature of graphene and high magnetic property of Fe 3 O 4 nanoparticles. Also, the nanocomposite used as an ultrahigh performance of novel capacitive deionization electrodes (CDI) for removal of Pb 2+ and Cu 2+ ions at constant applied potential 1.2 V and constant flow rate 4 ml/min. The results indicate that the Fe 3 O 4 /graphene nanocomposites exhibit an ultrahigh electrosorption for Pb 2+ , Cu 2+ and Cd 2+ ions. The progress made so far will guide further development of graphene based nanostructures with porous and exploration of such porous nanomaterials in environmental remediation toward removal of organic and inorganic contaminants.

Development of adsorption and solidification process for decontamination of Cs-contaminated radioactive water in Fukushima through silica-based AMP hybrid adsorbent

Abstract Developing highly efficient cesium (Cs) adsorbent and a stable solidification method for Cs is vital for the advancement of the decontamination system for Fukushima Daiichi Nuclear Power Plant. A novel porous silica loaded with ammonium molybdophosphate (AMP/SiO 2 ) was prepared through impregnation/precipitation/freeze-drying method. The composite with 32.4 wt% AMP loading amount had superior large 254.2 A pore width and 72.2 m 2 /g surface area. The 137 Cs removal efficiency in actual seawater was 97.1% within 30 min, indicating that AMP/SiO 2 effectively treated contaminant water with low-level concentration of Cs even in the presence of highly concentrated competing ions. The AMP/SiO 2 adsorption of 137 Cs in seawater conformed well with Redlich-Peterson model. The ion exchange ratio of Cs + and NH 4 + in AMP was estimated to be 71% from the equivalent of Cs 2 NH 4 MP. Pyrogenetic AMP/SiO 2 -adsorbed Cs (Cs-AMP/SiO 2 ) was decomposed above 400 °C sintering temperature, and Cs immobilization (%) decreased from 100% to 40% after sintering at 1200 °C; porous silica support matrix had no immobility for Cs. In contrast, adding natural mordenite (NM) can depress the volatilization of Cs, resulting to the steady immobilization ratio of Cs at nearly 100% for the sintered products. The crystal phase immobilizing Cs was identified as Cs 4 Al 4 Si 20 O 48 through X-ray diffractometry. The Cs leachability from the sintered products was less than 0.1% even at 90 °C in distilled water and 0.1 M sodium chloride.

High-Throughput Screening of Metal–Organic Frameworks for CO2 Capture in the Presence of Water

Competitive coadsorption of water is a major problem in the deployment of adsorption-based CO2 capture. Water molecules may compete for adsorption sites, reducing the capacity of the material, and dehumidification prior to separating CO2 from N2 increases process complexity and cost. The development of adsorbent materials that can selectively adsorb CO2 in the presence of water would be a major step forward in the deployment of CO2 capture materials in practice. In this study, large-scale computational screening was carried out to search for metal-organic frameworks (MOFs) with high selectivity toward CO2 over H2O. Calculating framework charges for thousands of MOFs is a significant challenge, so initial screening used a fast, but approximate, charge calculation method. On the basis of the initial screening, 15 MOFs were selected, and Monte Carlo simulations were carried out to compute the adsorption isotherms for these MOFs using more accurate framework charges calculated by density functional theory. A detailed investigation was performed on the effect of using different methods for calculating partial charges, and it was found that electrostatic interactions contribute the majority of the adsorption energy of H2O in the selected MOFs.

Kinetics of Hg and Pb Removal in Aqueous Solution Using Coal Fly Ash Adsorbent

Water pollution caused by heavy metals is a serious problem to environment. Hg and Pb are heavy metals having high toxicity level. Heavy metals treatment is necessary before releasing them to environment. The use of adsorption method is interesting because of its relatively simple operation. The development of adsorption is oriented to the use of industrial waste such as coal fly ash. The objective of this research is to investigate the kinetics aspect of Hg and Pb adsorption using coal fly ash. A series of a Hg and Pb adsorption experiment using coal fly ash with time variation was carried out. The results were plotted to pseudo first order kinetic and pseudo second order kinetic model. The conclusion obtained was that Hg and Pb adsorption kinetics followed pseudo second order kinetic model

Development of Adsorbent Material from Tamarind-Seed Testa for Reactive Dye Adsorption

In this research, the adsorbent material was developed from the agricultural waste, tamarind-seed testa. The adsorption of 6 different reactive dyes viz. Procion Red H-E7B, Procion Yellow H-E4R, Procion Navy H-ER, Remazol Brilliant Red F3B gran, Remazol Yellow 3BS-A 150% and Remazol Black B 133%, on the adsorbent prepared from tamarind-seed testa was investigated. The chemical composition analysis showed that the major components in the tamarind-seed testa were lignin and carbohydrates (cellulose and hemicellulose). When the bleached tamarind-seed testa was used as an adsorbent, it was found to efficiently adsorb the reactive dyes at pH 2 without any assisting mechanical agitation. The reactive dye exhibiting ultimate adsorption on the adsorbent was Procion Navy H-ER (66.3 mg/g). A high rate of dye adsorbed capacity was noticed in the first hour and the equilibrium adsorption was reached within 3 hours.