Properties Of Sorbents Research Articles

Tuning cationic/anionic dyes sorption from aqueous solution onto green algal biomass for biohydrogen production

Global water security and energy demands associated with uncontrollable population growth and rapid industrial progress are one of the utmost serious needs dangerously confronting humanity. On account of waste as a wealth strategy; a multifunctional eco-friendly sorbent (MGAP) from green alga was prepared successfully for remediation of cationic/anionic organic dyes and biohydrogen production. The structural and morphological properties of sorbent were systematically scrutinized by a variety of spectral analyses. The loading capacity of MGAP towards rhodamine B (RhB) and methyl orange (MO) dyes was inclusivity inspected under variable experimental conditions. The adsorption kinetics of both dyes onto MGAP was in good agreement with pseudo-second-order theory, whereas adsorption isotherms could fit well with the Langmuir model, with satisfactory loading capacities of 144.92 and 196.04 mg g−1 for RhB and MO molecules, respectively. Moreover, ultra-sonication treatment admirably decreased the sorption equilibrium time from 180.0 min to 30.0 min. Furthermore, spent sorbent was managed particularly for biohydrogen production with a measured yield of 112.89, 116.59, and 128.17 mL-H2/gVS for MGAP, MGAP-MO, and MGAP-RhB, respectively. Overall, the produced MGAP can potentially be offered up as a promising dye scavenger for wastewater remediation and biohydrogen production, thereby fulfilling waste management and circular economy.

Physical and Chemical Regularities of Phosphorus and Beryllium Recovery by the Sorbents Based on Acrylic Fiber Impregnated by Iron Hydroxide (III)

The paper investigates the physicochemical regularities (kinetics and isotherm) of phosphorus and beryllium recovery by sorbents based on polyacrylonitrile (PAN) fiber and Fe(OH)3 obtained by various methods: PAN or pre-hydrolyzed PAN with precipitation of FeCl3 with ammonia, using ready-made or electrochemically generated Na2FeO4, pre-hydrolyzed PAN treated with an alkaline solution of Na2FeO4, as well as their comparison with granular aluminum oxide. The Langmuir, Freudlich and Dubinin–Radushkevich models show high performance of materials for sorption of stable P and Be used as tracers for the release of 7Be, 32P, and 33P from seawater. The obtained kinetic data are processed using kinetic models of intraparticle diffusion and the pseudo-first-order, pseudo-second-order, and Elovich models. Optimal conditions for obtaining sorbents are established, namely, the effect of NaOH concentration at the stages of preparation on the properties of sorbents based on the PAN fiber and Fe(OH)3 obtained by various methods.

Evaluation of the mechanisms of adsorption of microcystins and nodularin-R onto rice husk-based biochar

• Non-electrostatic and electrostatic interactions govern cyanotoxin adsorption onto RH. • Charge-neutral MC-RR displays high adsorption onto RH at different concentrations. • MC-LR and NOD-R at low concentrations experience attractive interactions with RH surface. • MCs with net negative charge and NOD-R show less adsorption onto RH than MC-RR. • Lateral electrostatic repulsions are more pronounced for MC-LA than for MC-LW and MC-LF. Adsorption mechanisms of individual and collective sorption of microcystins (MCs) and nodularin-R (NOD-R) onto heat-treated rice husk (RH) at neutral pH were evaluated. The functional groups on cyanotoxin standards and RH surface as well as their charge indicate that non-electrostatic and electrostatic interactions are present. Surface area and porosity of RH were determined indicating that MCs and NOD-R can be adsorbed in secondary micropores and mesopores of RH. Positively charged guanidinium ion in arginine-containing MCs and NOD-R created attractive electrostatic forces with the negatively charged RH surface (pH PZC ∼3.3). MCs and NOD-R experience electrostatic repulsion with the surface due to the presence of negatively charged carboxylate groups. MC-RR, even at significantly high toxin concentrations, could be removed by RH as it had a strong attraction to the surface due to two arginines and its neutral charge. Other congeners adsorbed on RH experienced lateral intermolecular repulsion and repulsion with molecules in solution. At low sorbate concentrations, MC-LR and NOD-R had electrostatic attraction to the RH surface and MC-LA, MC-LW, and MC-LF experienced electrostatic repulsion with the surface at all concentrations. Non-electrostatic forces govern the adsorption process of MC-LA, MC-LW, and MC-LF, and electrostatic forces are significant for the adsorption of MC-LR, MC-RR and NOD-R at low concentrations (1-100 ng/mL) as well as the adsorption of MC-RR at high concentrations (1000 ng/mL). The presence of 0.3 M NaCl increases the adsorption of MC-LA and MC-LF proving that those molecules undergo repulsive interactions with RH. The adsorption of MCs and NOD-R onto RH is pH dependent, and it appears to be improved at pH values < pH PZC . Overall, the adsorption of MCs and NOD-R onto RH biochar depends on congener concentration, structure, and charge, and can be modified through optimization of structural properties of RH sorbent and sorption conditions, such as ionic strength and pH.

The effectiveness of modified sodium bicarbonate in the purification of exhaust gases from HCl and HF

The effectiveness of gas purification depends on the sorption properties of sorbents. The aim of the research was to determine the ability of sodium sorbents to remove gaseous pollutants such as HCl and HF. The research used baking soda subjected to mechanical and thermal activation, which was introduced into the hot flue gas circuit, similar to the dry flue gas cleaning method used in all kinds of boilers. In almost all cases, mechanical and thermal treatment of baking soda allowed for a significant improvement in the reduction of hydrogen chloride and hydrogen fluoride concentrations in the exhaust gases produced during the combustion of polyethylene terephthalate (PET) bottles. The preparation of sorbents must consider the optimum development of the material's specific surface area, especially during thermal activation, to prevent pores from sintering. In wet and dry flue gas cleaning processes, sodium compounds are used in the power industry. Appropriate preparation of the sorbent allows for improving the effectiveness of reducing the concentration of harmful substances and reducing investment and operating costs. From the point of view of process optimisation, the results obtained will contribute to the identification of optimal operating conditions in dry sorbent injection systems to prevent the pores on the surface of the sorbent from clogging when injected into hot flue gases.

Polymer ligands of taurine – New class of high selective sorbents for exctraction of silver from multicomponent solutions

The systematic study on the properties of the taurine polymer ligand has made it possible to determine the influence of the structure of the sorbents on their selective properties towards silver (I). It has been shown that an increase in the degree of modification of the sulfoethyl groups resulted in an increase in the selectivity of silver(I) sorption from multicomponent solutions onto the materials based on polyallylamine (the values of the KAg/Cu selectivity coefficients for the sorbent with the maximum degree of modification exceeded 103). Sorbents based on polyethyleneimine, unlike other sulfoethylated aminopolymers, are appropriate materials for the group extraction of a number of transition metal ions. The pKa values of amino groups in the composition of sorbents based on poly(N-2-sulfoethyl)ethylenimine and poly(N-2-sulfoethyl)allylamine were determined, and a correlation between the acid-base and selective properties of sorbents was established. A significant effect of the nature of the aminopolymer matrix on the selectivity of sorption was revealed, and recommendations were formulated for the use of N-derivative of taurine polymer ligand in separation and preconcentration processes.

Examining sorption of perfluoroalkyl substances (PFAS) in biochars and other carbon-rich materials.

The use of carbon-rich sorbents to remove and/or immobilize perfluoroalkyl substances (PFAS) in contaminated environmental scenarios is attracting increasing interest. The identification of key sorbent properties responsible for PFAS sorption and the development of models that can predict the distribution coefficients (Kd) for PFAS sorption in these materials are crucial in the screening of candidate materials for environmental remediation. In this study, sorption kinetics, sorption isotherms, and the effects of pH, calcium concentration and dissolved organic carbon (DOC) content on PFAS sorption were evaluated in four representative carbon-rich materials: two biochars with contrasting properties, a compost, and charcoal fines rejected by the metallurgical industry. Subsequently, the sorption of seven PFAS with numbers of fluorinated carbons ranging from 4 to 11 was evaluated in a total of ten carbon-rich materials, including activated carbons, so as to build up a Kd prediction model. The sorption of PFAS increased with greater fluorinated chain length, suggesting that hydrophobic interactions play a major role in sorption and electrostatic interactions a minor one. These results were confirmed by a principal component analysis, which revealed that the CORG/O molar ratio and the specific surface area of the material were the two main sorbent properties affecting PFAS sorption. Furthermore, the DOC content in solution had a negative effect on PFAS sorption. Using this information, a simple Kd prediction model applicable to a wide range of materials and PFAS was developed, using only a few easily-derived physicochemical properties of sorbent (CORG/O molar ratio and SSA) and PFAS (number of CF2), and was externally validated with data gathered from the literature.

Перспективы использования листостебельной биомассы Тростника южного для очистки водных объектов

The article is devoted to the actual environmental problem of cleaning water bodies. The authors studied the properties of new sorbents obtained from crushed leafy biomass of the southern reed (Phragmites australis) and their use in the pollution of water bodies by accidental oil spills and oil products. Information about the most common cellulose-containing sorbents used to clean up oil spills is given. The prospects of using sorbents based on crushed and carbonized leafy biomass of southern reed (Phragmites australis) for cleaning water bodies are shown. Keywords: PLANT RAW MATERIALS, CELLULOSE-CONTAINING SORBENTS, LEAF BIOMASS, OIL CAPACITY, ADSORPTION ACTIVITY, WATER POLLUTION, ENVIRONMENTAL CONSEQUENCES, SOUTHERN REED (PHRAGMITES AUSTRALIS)

Influence of Spirulina Platensis in the composition of feed on the content of heavy metals in rabbit meat

An important area for the further development of animal husbandry is to provide humanity with environmentally friendly food. One way to reduce the content of heavy metals in livestock products in general and meat in particular is to feed some feed products that have sorbent properties. For this purpose, a scientific and economic experiment was conducted to study the effect of feeding compound feeds containing 0.5–2% Spirulina platensis to rabbits raised for meat. The experimental period of the research lasted from the 60th to the 120th day of life of young rabbits and ended with a control slaughter. During this period, the live weight of the rabbits, their safety and the amount of feed consumed were monitored. During the control slaughter, the chemical composition of the longest back muscle was studied, as well as the content of Lead and Cadmium. According to the results ofthe experiment it was found that the introduction of compound feed rabbits Spirulina platensis in doses of 0.5–2.0% helps to improve their growth, reduce the content of Cadmium and Lead in meat, reduce the fat content in it and increase the proportion of dry matter and protein. It should be noted that the highest productivity of rabbits was achieved at a feed content of 1.5% of Spirulina platensis, ahead of control counterparts by 7.8% (P&lt;0.01). Instead, the lowest concentration of heavy metals in meat was recorded at the content of 2.0% of the specified feed: Cadmium by 34.1% (P&lt;0.01), and Lead – by 25.9% (P&lt;0.001) less than the control indexes. As for the chemical composition of meat, the highest protein and the lowest fat in it was recorded at 1.5% Spirulina platensis in the feed. Compared to control animals, rabbit meat in this group contained 1.2% more protein and 0.7% (P&lt;0.01) less fat. Thus, 1.5% of Spirulina platensis in the feed for rabbits raised for meat can be considered the optimal proportion. Key words: rabbits, Spirulina platensis, live weight gain, productivity, Cadmium, Lead, meat.

Synthesis and sorption properties of organo-mineral sorbents based on poly(styrene-b-4-vinylpyridine) copolymer

New organo-mineral composites SiO2/poly(styrene-b-4-vinylpyridine) were obtained by adsorption of block- copolymers poly(styrene-b-4-vinylpyridine) with molar ratios of styrene (St) and 4-vinylpyridie (4-VP) St:4-VP = 1:4 and St:4-VP = 1:5 from THF solution onto silica gel surface. Block-copolymers were synthesized by controlled radical polymerization of styrene with RAFT agent and further copolymerization with 4-vinylpyridine. Also blok-copolymer with thiol end-group was obtained and has been employed for preparation of the composite. Composition of the block-copolymers and surface morphology of composites obtained were determined using 1H NMR and FT-IR spectroscopy, differential scanning calorimetry, thermogravimetric analysis and scanning electron microscopy. It was established that sorption capacity of the organo-mineral composites toward Pb(ІІ), Fe(ІІІ) and Cu(ІІ) ions is in 2–4 times higher in comparison with parent silica gel.

Water Sorption by Polyheteroarylenes.

The sorption–diffusion characteristics of rigid-chain glassy polymers based on polyheteroarylenes (PHAs) have been studied in a wide interval of relative humidity and temperatures of thermal treatment of the polymer sorbents. Experimental data on water vapor sorption for polynaphthoyleneimidobenzimidazole (PNIB) and its copolymers with different chemical nature have been obtained. Water diffusion coefficients have been calculated, and parameters of their concentration and temperature dependences have been determined. It was found that water molecules sorbed by PNIB and its copolymers are strongly bounded. Water mobile and cluster states depend on the structure of macromolecules and thermal prehistory of polymer sorbents. It is shown that the translational coefficients of water diffusion for all PHAs are in the range from 10−9 to 10−8 cm2/s. The diffusion coefficients also increase slightly with temperature increasing, and their general dependence on temperature is satisfactorily described by the Arrhenius equation. The average activation energy of water diffusion varies from 24.3 to 25.9 kJ/mol. The hydrate numbers of rigid-chain PHAs functional groups have been determined. The above-mentioned results allow us to predict the sorption properties of heterocyclic macromolecular sorbents with complex chain architecture.

Sorption-photometric definition of thorium (IV) in clays

A simple and selective method for sorption-photometric determination of thorium (IV) micro amounts in clay using a new chelating sorbent, a copolymer of maleic anhydride with styrene modified with N1,N1,N2-triphenylguanidine, is proposed. The sorbent is white substance, insoluble in water, acids, weak alkalis and organic solvents. Sorbents were first ground in an agate mortar and sieved through a sieve (0.14 mm). The effect of pH of the medium, the ionic strength of the solution, contact time of the phases, concentration of thorium (IV) in the solution and on the sorption was studied under static conditions. Thorium concentration was determined by the photometric method using 2,2’,3,4-tetrahydroxy-3’-sulfo-5’-chloro-benzene. The concentration of thorium (IV) was calculated using a calibration curve, the results were processed statistically. The full static sorption capacity of the resulting sorbent on K+ ion was 13 mmol/g. An emphasis was also made on the study of the effect of the kinetic properties of sorbents on the sorption process. The maximum degree of thorium extraction by the sorbent was achieved from the solutions with pH 4. The time dependence of sorption was also studied. The results of the study showed that the sorption equilibrium is achieved after 2.5 h of contact of the sorbent with the metal. The sorption of thorium increases with an increase in the thorium concentration in the solution and attains maximum at a concentration of 8 × 10–3 M (pH 4, = 8 × 10–3 M, Vgen = 20 ml, mabsorbed = 0.05 g, sorption capacity = 348 mg/g). The degree of thorium (IV) extraction in optimal conditions exceeds 95%. It is shown that the main micro- and macro-components of clay do not affect the results of the determination of thorium. The developed technique was applied to determine thorium in a clay sample from the Shemakhi region of Azerbaijan. The correctness of the obtained results was confirmed by the spike test.

New boron selective sorbents for sorption – membrane hybrid system

The synthesis and properties of core-shell sorbents dedicated to the removal of borates from aqueous solutions were described. By modification of polymer matrices with vinylbenzyl chloride followed by its derivatization with N-methyl glucamine a new kind of sorbents were obtained. The testing of boron sorption reviled that the process efficiency was related to the pore diameter and the content of ligand in the sorbent. The best material for use in a hybrid system, where boron is absorbed by fine particles and removed in microfiltration, was Poropak Q with a specific surface area of 300 m2/g.

Sorption properties of Zr-CaMg and Ti-Ca-Mg phosphates in relation to Sr(II) ions

The synthesis of Zr-Ca-Mg and Ti-Ca-Mg phosphates of different composition was carried out and their sorption properties to Sr(II) ions were studied. The effect of pH of aqueous solutions, as well as of background electrolytes NaCl, CaCl2 , the seawater solution on the sorption-selective properties of phosphate sorbents was studied. The sorption isotherms and kinetic regularities of the Sr(II) ion removal were studied, the mathematical modeling of the experimental data using various models was carried out. It was found that Ti-containing sorbents had the greatest selectivity to Sr(II) ions. The maximum sorption capacity for the Ti-2 sample reached 196.5 mg/g (2.2 mmol/g). Samples of Zr-Ca-Mg and Ti-Ca-Mg phosphates had a high sorption capacity in the 0.1 M NaCl solution and in seawater. The sorption kinetics for all sorbents with a high degree of confidence (R2 ≥ 0.99) was described by a pseudo-second-order equation, due to the chemical interaction during the Sr(II) ions sorption. The study of the phase composition of sorption products indicated the ion exchange and chemisorption mechanism of the Sr(II) ions sorption.

Sorption of copper(II) ions from aqueous solution by activated carbon BAU-A and coal sorbent MIU-S. The relationship between the structure of sorbents and their sorption properties.

The sorption of copper(II) ions in a wide range of pH by two Russian carbon sorbents BAU-A and MIU-S was studied. Sorbents varied in structure, surface area, pH of the point of zero charge (pHZPC), and graphitization degree. The sorption studies were conducted in batch mode. The removal of copper(II) ions from a solution at pH 4, 5, 6, and 6.7 is described by the classical adsorption isotherms of Freundlich, Langmuir, and Dubinin-Radushkevich. With an increase in pH from 4 to 6.7, the sorption capacity of sorbents increases, from 0.910 to 7.163 mg/g for BAU-A, and from 0.265 to 3.307 mg/g for MIU-S. The relationship between the degree of crystallinity and the sorption properties of sorbents has been established.

Sorbent Properties of Orange Peel-Based Biochar for Different Pollutants in Water

Efficient and reasonable utilization of waste biomass resources can not only avoid serious waste of material resources, but also solve the problem of environmental pollution. Therefore, the development of efficient and environmentally friendly waste biomass carbonization technology has important practical significance. Here, the activated carbon from orange peel (OAC) is prepared by potassium hydroxide (KOH) activation combined with high-temperature carbonization. The adsorption effects of OAC on three different pollutant aqueous solutions, methylene blue (MB), tetracycline (TC), and fluorescein sodium (NaFL), are examined. The OAC absorbent has excellent adsorption capacity for MB, TC, and NaFL pollutants of 10 mg L−1, with adsorption rates of 99.17%, 73.5%, and 94.24%, respectively. This study provides a new idea for turning waste biomass into treasure and eliminating the hidden danger of environmental pollution.

The use of polyvinylpyrrolidone for tamponade of the nasal cavity in patients with epistaxis

Gauze tamponade of the nasal cavity is one of the most common and affordable ways to stop nosebleeds. To prevent local fibrinolysis, polyvinylpyrrolidone (PVP) powder, which has the properties of a local sorbent, was used. The study involved 2 groups of patients: group 1 included 38 patients who underwent tamponade of the nasal cavity after surgery, group 2 included 52 p patients with spontaneous epistaxis on the background of arterial hypertension. PVP was applied to tampons and also insufflated into the nasal cavity after their removal. The degree of nasal mucosa damage was estimated by the change in mucociliary transport, determined by the saccharin test. There was a decrease in the severity of reactive edema after tamponade and in the frequency of recurrent epistaxis. These effects are explained by the modifying effect of PVP on fibrin thrombus and an increase in the aggregation properties of erythrocytes.

Improvement of performance and function in respiratory protection equipment using nanomaterials.

Nanotechnology has become one of key areas for the current development and research. Nanotechnology focuses on matter at the nanoscale and is capable of using different approaches to produce nanomaterials, structures, devices, and systems. One of the concerns that have to be addressed is the adverse effects of exposure to pathogens and pollutants in different workplaces and environments. Respiratory protective equipment (RPE) is one of the personal protective equipment (PPE) utilized to reduce the risk of exposure to environmental or occupational respiratory hazards. Thus, various studies have been conducted for improving the functional properties of sorbents or filters in different kinds of RPE. Different categories of nanomaterials have been reported as effective agents for achieving this goal. The application of these nanomaterials in mask layers or respirators’ cartridge could significantly increase the filtration efficiency, breathing comfort, and antibacterial/antiviral properties of the masks and respirators. The present study aimed to comprehensively review the nanomaterials used in different types of face RPE with emphasis on various properties of the utilized nanomaterials. The study also aimed to show an applied perspective for future research on this important subject.Graphical abstract

Nitrogen-doped porous carbons from polyacrylonitrile fiber as effective CO2 adsorbents

In this report, nitrogen-doped porous carbons were synthesized from polyacrylonitrile fiber by a facile two-step synthesis process i.e. carbonization followed by KOH activation. Activation temperature and KOH/carbon ratio are two parameters to tune the porosity and surface chemical properties of sorbents. The as-obtained sorbents were carefully characterized. Special attention was paid concerning the change of sorbents’ morphology with respect to synthesis conditions. Under the activation temperatures of this study, the sorbents can still retain their fibrous structure when the KOH/carbon mass ratio is 1. Further increasing the KOH amount will destroy the original morphology of polyacrylonitrile fiber. CO2 adsorption performance tests show that a sorbent retaining the fibrous shape possesses the highest CO2 uptake of 3.95 mmol/g at 25°C and 1 bar. Comprehensive investigation found that the mutual effect of narrow microporosity and doped N content govern the CO2 adsorption capacity of these adsorbents. Furthermore, these polyacrylonitrile fiber-derived carbons present multiple outstanding CO2 capture properties such as excellent recyclability, high CO2/N2 selectivity, fast adsorption kinetics, suitable heat of adsorption, and good dynamic adsorption capacity. Hence, nitrogen-doped porous carbons with fibrous structure are promising in CO2 capture.

CO2 Sorption and Regeneration Properties of K2CO3/Al2O3-Based Sorbent at High Pressure and Moderate Temperature

In this study, the CO2 sorption mechanisms and regeneration properties of alumina-based sorbent using K2CO3 loading under high-pressure and moderate temperature conditions were examined. To investigate the mechanism of CO2 sorption, a zirconium-based sorbent was compared with an alumina-based sorbent. The CO2 capture capacities of the PAI10, 20, 30, and 40 were 32.3, 63.0, 95.4, and 124.5 mg CO2/g sorbent, respectively. To investigate the CO2 sorption mechanism of an alumina-based sorbent, we performed XRD, TG/DTG, and FTIR analyses after CO2 sorption in the presence of 10 vol% CO2 and H2O each at 200 °C and 20 atm. For PAI10–40 sorbents, KHCO3 and KAl(CO3)(OH)2 phases were observed by TG/DTG and FTIR analysis. For PAI-x sorbents, it was confirmed that the captured CO2 is desorbed completely at a temperature below 400 °C at 20 atm.

Fundamental thermodynamic properties of sorbents for atmospheric water capture

The thermodynamic properties of various sorbents, namely carbon-based sorbents, silica gel and metal–organic frameworks (MOFs) were assessed and compared based on their adsorption isotherms at 25, 30 and 35 °C. The isotherms were measured in a custom-made and calibrated environmental chamber using a gravimetric method. Gibbs free energy demonstrated the spontaneity of the adsorption process and the hygroscopicity variation of the sorbents depending on their surface chemistry. The carbon-based sorbent, nanoporous sponges (NPS), and one of the MOFs, Cr-MIL-101, had lower sorbent-adsorbate interactions and thus had integral enthalpies converging rapidly to the heat of vaporization of pure water. As such, these samples would release less heat during an adsorption step with partial filling of the sorbent. Integral entropy showed that, for most of the environmental conditions, adsorbed water molecules had an entropy equivalent to pure water for most of the sorbent materials, except for silica gel, due to its higher energy sites and higher water-sorbent interactions. NPS and Cr-MIL-101 were shown to be entropically advantageous for the recovery/removal of water. Enthalpy and entropy can provide insight to select favorable conditions to perform adsorption–desorption cycles in a practical water capture system.