Sorption Materials Research Articles

Effects of different modifiers on the sorption and structural properties of biochar derived from wheat stalk.

Nitrobenzene is a widespread contaminant in water. Biochar (BC) is a promising material for removing organic pollutants, but the adsorption capacity of pristine BC is low. Chemical modification is often used to improve the adsorption performance, but information on the sorption of nitrobenzene by modified BC is rare. In this study, BCs pyrolyzed at 300, 500, and 700°C were modified by hydrochloric acid (HCl), sulfuric acid (H2SO4), sodium hydroxide (NaOH), hydrogen peroxide (H2O2), and nitric acid (HNO3), respectively. The properties, nitrobenzene sorption behaviors, and sorption mechanisms of different BCs were analyzed. The results showed that chemical modification decreased the sorption of nitrobenzene on BCs pyrolyzed at 300°C, possibly due to the loss of the partition phase and the increase in polarity after modification. Regarding BCs pyrolyzed at 500 and 700°C, the NaOH and HCl modifications significantly increased the sorption capacity by 19% and 60%, 18%, and 41%, respectively, possibly due to the increase in surface area, available pores, and aromaticity, while HNO3 modification decreased the sorption capacity by 41% and 31%. Two reasons were probably responsible for the decrease: one was the decrease in surface area after HNO3 modification due to the destruction of pore walls and the continuity of holes; the other was the strong repulsion between the nitro groups formed on the surface of BC and the nitro groups of nitrobenzene that drove nitrobenzene molecules away from the surface. A principal component-based comprehensive evaluation of the BC properties, which were significantly correlated with the sorption isotherm parameters, was used to evaluate the nitrobenzene sorption performance of the modified BC. Overall, BC pyrolyzed at 700°C modified with NaOH or HCl were proposed as effective sorption materials for the removal of nitrobenzene in environment, which also provided a chemical modified method of biochar derived from agricultural waste.

Synthesis of Sorption Materials from Low Grade Titanium Raw Materials.

In this paper, a universal technology is proposed for processing low-titanium mineral raw material—apatite-nepheline ore waste, including its treatment with sulfuric or hydrochloric acid in a two-stage mode with a sequential increase in the concentration. This technique allowed us to remove nepheline and apatite in the first stage and achieve a titanium mineral content of TiO2 of more than 30%; in the second stage, we were able to convert the titanium into its precursors—titanyl sulfate monohydrate TiOSO4·H2O and a hybrid rutile-silica composition. The key stage in the sorbent synthesis is the reaction of the precursor with a phosphoric acid solution. The preferred sequence of operations begins with the mechanical activation of the precursor, causing morphological changes in it, and subsequent treatment with phosphoric acid at different concentrations under atmospheric conditions and in an autoclave, accompanied by phase transformations. Conditions for the chemical reactions which regulated the composition and structure of the final product and, accordingly, its sorption activity were found. With the help of XFA, the phase compositions of the sorbents were identified, including the individual crystalline phase α-TiP obtained from TS or the crystalline phase αTi(HPO4)2∙H2O, which is in an amorphous silica matrix obtained from a rutile–silica composition.

ТНЕ INVESTIGATION OF THE INFLUENCE OF FUEL DISTINCTION TEMPERATURE ON ITS MAIN PHYSICO-CHEMICAL INDICATORS

Widespread and indispensable growth of natural adsorbents use is caused by the fact that they, having developed specific surface and good (often specific) bleaching peculiarities, are dozens of times cheaper than artificial adsorbents. It leads to simplification of its usage technology – they often exclude the regeneration stage from the scheme. Chemical and thermal stability of saponite, as well as ion exchange properties, open opportunities for the creation of porous materials based on natural minerals with controlled properties that can replace synthetic analogues, the production of which is associated with high technological costs. The increase in the use of natural adsorbents is based on its specific surface area and good bleaching properties which are ten times cheaper than artificial adsorbents. In this regard, the technology of their application is simplified: the regeneration stage is often excluded from the scheme. Chemical and thermal stability of saponites, as well as ion exchange properties, open up new avenues for the creation of porous materials based on natural minerals with controlled properties that can replace synthetic analogues, the production of which is associated with high technological costs. The expediency of purification of hydrocarbon mixtures using granular saponite to obtain high-octane fuels has been studied. The influence of fuel distillation temperature on its main physicochemical parameters has been studied. The fractional composition of fuel, which is affected by such indicators as: engine warm-up speed, wear of the cylinder-piston group have been investigated. The obtained results of investigations of structural, physic and chemical properties of natural minerals allow to develop theoretical and practical bases of target change of the complex of specific properties that satisfy the basic requirements, which are put forward for sorption materials. The chemical and thermal stability of glauconites, as well as ion-exchange properties, provide opportunities for the production of porous materials based on natural minerals with controlled properties that can replace synthetic analogues associated with high technological costs.

Manufacturing of a Granular Fertilizer Based on Organic Slurry and Hardening Agent

The manufacturing of a granular fertilizer based on organic slurry (OS) and sorptive materials aims to enhance the circular economy. This article describes a technology that was conceived after appraising the chemistry of the anaerobic digestate and wood ash and the synergies of combining both materials. The information available in the literature about similar materials such as cattle slurry and lime was also considered to build a better understanding of the underlying science. The processes and machinery designed were optimized from the points of view of energy and material consumption, cost of storage, transportation and land application. The system was sized to process 1 tonne of OS (97% moisture) in a 10 h batch-shift, consuming 140 kg of wood pellets and 0.55 kW of electricity for the fan blowing preheated air. The results of the market research allowed us to reach the most economically viable routes for the commercialization of granular fertilizers. Based on the financial study, an initial investment of GBP 20,000 is needed to successfully implement the value proposition and business plan. The wide adoption of the composite fertilizer improves the management of the OS and reduces the contamination of air, soil, and water derived from intensive agricultural practices.

Influence of Particle Size Distribution of Wood Waste Pyrolysis Product on Productivity and Purification Efficiency

In this paper, studies were carried out on sorption purification under dynamic conditions of a copper (II) ions model solution with sorption material. Sorption material was obtained by low-temperature pyrolysis from wood wastes. Studies were carried out for fractions with particle sizes less than 0.5 mm, 0.5-1 mm, 1-2 mm, 2 and more mm. Test model solution was a polydisperse system with particle sizes from 145 to 224 nm and 6450 to 8640 nm. Particle size of disperse phase of filtrate after passing through sorption material with particle size of 1-2 mm was in the range from 310 to 412 nm and from 2260 to 3300 nm. Peaks of particle size intensity in the filtrate after passing through the sorbent (fraction 1-2 mm) were shifted downward. This indicates that smaller particles remained in the filtrate after purification. This is confirmed by an increase in the sorption rate of copper ions. As the particle size increases, the filtration rate increases, but the efficiency of removing copper ions decreases. The degree of sorption of copper ions from the model solution with an initial concentration of 1028 mg/dm3 was 96.4% for the fraction of the pyrolysis product with a particle size of 1-2 mm, 91.9% - less than 0.5 mm, 91.1% - 0.5-1 mm, 91.7% - more than 2 mm.

Reducing environmental hazards in the elimination of oil spills through the use of sorption materials based on polyurethane foams containing waste from agricultural and polymer industries

The work is devoted to the development of a sorption material based on elastic polyurethane foam (PUF) containing waste from agricultural and polymer industries. The fillers were fruit shells of buckwheat grains, rice, acacia sawdust, fruit shells, rice straw, walnut shells and ground corn cobs, hardwood sawdust, polymeric waste of expanded polystyrene foam. Oil from the Romashkinskoye field (Tatarstan) was used as a pollutant. The optimal mass ratio of the components of the material A of the PPU component: B of the PPU component: filler = 1: 0.6: 0.16-0.72 (depending on the type of filler) has been determined. The best absorbing capacity of ∼ 13 g / g is possessed by a material based on polyurethane foam and rice straw. Sorption material for cleaning aquatic ecosystems has a high absorbing capacity not only for petroleum products (diesel fuel, industrial oil), but also for products of inorganic origin (vacuum oil). The sorption material is selective and has a higher absorption capacity with respect to oil than to water, the coefficient of selectivity of absorption is 0.4 for an exposure time of 120 min. The possibility of utilization of waste sorption material by the method of thermochemical degradation using a destructive agent based on PPU component A was investigated. The resulting destructate is a homogeneous liquid, easily combined with BND 60/90 bitumen with the formation of a homogeneous polymer-bitumen binder.

Development of polyfunctional sorbents based on zeolites for wastewater treatment

The article presents technological approaches to solving the problem of involving production waste in the technology of sorption treatment of wastewater by component composition. Zeolites of the Holinsky deposit of Eastern Transbaikalia of the klinoptilolite type were taken as the initial matrix for creating a sorbent. We propose to use chloroanic wastes as an adsorbent of heavy metal ions, as which we propose to consider epichlorohydrin. The analysis of existing technologies for the disposal of organochlorine wastes, as well as known sorption materials, using sulfur as one of the modifier components. As a result of the deposition of a sulfur-containing polymer network on the surface of natural zeolite, not only its hydrophobization occurs. Sulfur atoms appear in its composition, which contributes to an increase in the selective ability to heavy metal ions, while copper ions are sorbed most rapidly. Previously, we proposed a method for modifying natural zeolites with highly organosilicon compounds, which made it possible to effectively neutralize oily wastewater.

New Carbon-Mineral Sorbent Based on Aluminum Oxide, Polydimethylsiloxane, and Single-Wall Carbon Nanotubes: Assessment of the Effect on Erythrocytes In Vitro.

A comparative study of the effect of a sorbent with nanotubes (Al2O3@ WCNT-PDMS) and a carbon-mineral sorbent (Al2O3@C) on the parameters of human erythrocytes was carried out. Using scanning flow cytometry, the morphological and functional parameters of venous blood erythrocytes as well as drainage blood after its perfusion through columns with sorbents were determined. The compared samples Al2O3@SWCNT-PDMS and Al2O3@C are similar by their effect on the morphological and functional parameters of erythrocytes. The maximum membrane extensibility increased to a greatest extent after contact with Al2O3@C, the amount of hemoglobin in erythrocytes decreased to the greatest extent after perfusion through a column with Al2O3@SWCNT-PDMS sorbent. The scanning flow cytometry is promising for assessing the effect on erythrocytes of new sorption materials intended for blood detoxification. Changes in the parameters of erythrocytes of blood collected in a sterile drainage system for subsequent reinfusion were revealed.

Synthesis of amorphous KAlSi3O8 for cesium radionuclide immobilization into solid matrices using spark plasma sintering technique

An effective sorption material for cesium radionuclides immobilization in highly safe and reliable solid-state matrices was proposed. Prepared aluminosilicate (КAlSi3O8) adsorbent had amorphous mesoporous structure and Cs+ ions sorption capacity of ∼3.7 mmol/g. The physical-chemical characteristics of (Cs, К)AlSi3O8 sample saturated with Cs + ions were studied using XRD, FT-IR, SEM-EDX, and DTA-TG methods. Firstly, solid-state aluminosilicate matrices were obtained using spark plasma sintering (SPS) technology with high values of relative density (up to 99.9%), compressive strength (31.3–79.2 MPa), and Vickers microhardness (0.9–5.3 GPa). The sample obtained at 1000 °C had a low value of Cs+ leaching from matrices (RCs within the range of 10-7 g cm-2·day-1) and cesium diffusion coefficient (De 9.07 × 10-14 cm2/s). It was shown that prepared aluminosilicate cesium matrices comply with regulatory requirements of GOST R 50926-96 and ANSI/ANS 16.1.

Технологические аспекты использования сорбционного материала на основе листового опада для ликвидации и локализации нефтяных пятен

The paper presents a study of a sorption material based on leaf litter, namely: the effect of the fractional composition on the adsorption capacity in relation to oil and water, as well as the effect of fractions of the sorption material on the technological parameters of water surface purification from oil. The effective technological parameters of oil collection were found: leaf litter, fraction 1-15 mm, formed into cylindrical shapes, contrasting time 90 minutes, with oil film thickness from 0.5 mm to 2.5 mm.

ИСПОЛЬЗОВАНИЕ И СОВЕРШЕНСТВОВАНИЕ СОРБЦИОННОГО МЕТОДА ОЧИСТКИ ДРЕНАЖНОГО СТОКА МЕЛИОРАТИВНЫХ СИСТЕМ

Technologies and methods of directed regulation of the quality composition of drainage runoff in the hydro-reclamation systems of the Non-Chernozem zone of Russia may be different depending on the volume and chemical composition of the runoff and environmental requirements for water quality for reuse and safe disposal. One of the most promising ways to improve the quality of drainage water is sorption treatment of runoff, the effectiveness of which is determined by the design of the sorption-filter unit, the selection of sorption material for the filter based on the flow rate of drainage runoff and the degree of its contamination. The layout, placement and design features of sorption-filter cleaning units are presented, the efficiency indicators of the use of a number of sorbents for cleaning drainage runoff, the main impurities removed and the degree of purification are given. An engineering solution is proposed to increase the efficiency of sorption-filtering facilities by regulating the uniformity of the interaction of drainage water with the entire mass of the sorption-filtering load by equalizing the dynamic pressure of the drainage water flow on the filter material.

Lithium and magnesium separation from brines by hybrid capacitive deionization

Presented work deals with the problem of separating lithium and magnesium from brines. A similar size of ionic radius characterizes the Li+ and Mg2+; hence, separating these elements could be problematic. The hybrid capacitive deionization (HCDI) with lithium‑manganese‑titanium oxides was employed as a potential process for separating lithium and magnesium ions from aqueous solutions. During the investigation, the thermodynamics factors were determined. The enthalpy of activation, the entropy of activation and the Gibbs energy of activation for accumulation Li+ and Mg2+ by Eyring-Polanyi and energy activation by Arrhenius equations were calculated for explanation the separation phenomenon. Next, the HCDI for binary and multicomponent solutions were conducted. The critical role in achieving high βLi/Mg plays the activity coefficient of the initial feed, and the value of a voltage applied in constant voltage electric mode. With the increasing value of brines' activity coefficient, the separation factor βLi/Mg lift when the concentration of lithium ions decreases. HCDI with LMTO material adsorbed lithium ions with βLi/Mg at 2.14 and released Li+ with over 70% efficiency. The proposed HCDI process employed LMTO sorptive material could be considered a potential method for separating lithium and magnesium from lithium sources.

Development of sorption material based on modified alumosilicates with high adsorption ability to hydro sulfur.

The paper considers the possibility of using highly dispersed modified aluminosilicates in the process of extracting hydrogen sulfide from wastewater. The problem of the presence of hydrogen sulfide in natural waters is due to the impossibility of using such waters in human household activities. Water with a high content of hydrogen sulphide has low organoleptic properties, is not suitable for consumption and is highly corrosive. Produced water generated in the process of oil production must also be treated. In the presence of hydrogen sulphide in the produced water, further water injection into the reservoir is highly discouraged, as this can lead to "plugging" of oil-bearing channels. In this regard, the work proposes a method for extracting hydrogen sulfide from natural and waste waters. The work synthesized a new adsorption-coagulation material based on modified aluminosilicates (bentonite clays) using salts of multivalent metals. The possibility of creating a reagent with a different ratio of aluminosilicate matrix: modifier is considered. It was found that the efficiency of the reagent increases with an increase in the pH of the medium. The activity of the reagent in relation to hydrogen sulfide, clarification and removal of oil products was studied. The capacity of the reagents obtained as a result of the modification can reach 32 mg/g in terms of hydrogen sulfide. In the reagent, it is possible to vary the ratio of aluminosilicates and modifiers, which can facilitate the use of the most effective reagent, depending on the conditions. The reagent is capable of extracting not only hydrogen sulfide, but also oil products from the processed aqueous solutions. The reagent binds hydrogen sulfide into insoluble forms, after which the precipitate can be separated from the solution and disposed of.

Physicochemical Characterization of Cherry Pits-Derived Biochar.

Although the suitability of some biochars for contaminants’ sorption separation has been established, not all potential feedstocks have been explored and characterized. Here, we physicochemically characterized cherry pit biochar (CPB) pyrolyzed from cherry pit biomass (CP) at 500 °C, and we assessed their As and Hg sorption efficiencies in aqueous solutions in comparison to activated carbon (AC). The basic physicochemical and material characterization of the studied adsorbents was carried out using pH, electrical conductivity (EC), cation exchange capacity (CEC), concentration of surface functional groups (Boehm titration), and surface area (SA) analysis; elemental C, H, N analysis; and Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDX). AsO43− anions and Hg2+ cations were selected as model contaminants used to test the sorption properties of the sorption materials. Characterization analyses confirmed a ninefold increase in SA in the case of CPB. The total C concentration increased by 26%, while decreases in the total H and N concentrations were observed. The values of carbonate and ash contents decreased by about half due to pyrolysis processes. The concentrations of surface functional groups of the analyzed biochar obtained by Boehm titration confirmed a decrease in carboxyl and lactone groups, while an increase in phenolic functional groups was observed. Changes in the morphology and surface functionality of the pyrolyzed material were confirmed by SEM–EDX and FTIR analyses. In sorption experiments, we found that the CPB showed better results in the sorption separation of Hg2+ than in the sorption separation of AsO43−. The sorption efficiency for the model cation increased in the order CP < CPB < AC and, for the model anion, it increased in the order CPB < CP < AC.

ДОСЛІДЖЕННЯ СОРБЦІЙНИХ ВЛАСТИВОСТЕЙ ВОЛОКНИСТИХ МАТЕРІАЛІВ, МОДИФІКОВАНИХ ГЛИНИСТИМИ МІНЕРАЛАМИ

Abstract. The paper presents the results of determining the sorption properties of nonwoven materials modified with clay minerals, obtained on the basis of fibrous waste, in relation to the methylene blue indicator to determine the possibility of using the created materials in the purification of light industry wastewater from dyes and heavy metal ions.Purpose. Determination of kinetic regularities of sorption (by methylene blue) of fibrous nonwoven materials modified with different types and amounts of clay adsorbents.Methodology. Nonwovens obtained from elastic fibrous waste of the textile industry were used as a basis in the work. They consisted of Lycra 162 C (PU) complex fibers and Nylon 6.6 f20 / 1 (PA-6.6) fibers in a ratio of 70/30 wt. %. For bonding the nonwoven material, adhesive bicomponent fibers Acebon 4/51 black (4 den) (BVCh) (20 wt%) were added to the initial composition. To enhance the sorption capacity of the PU / PA / BV 80/20 fabric, powders of montmorillonite clay (clay grade PBA-18) and palygorskite (clay grade PP-5) type were introduced in an amount of up to 40% by weight of the nonwoven material. Evaluation of the sorption properties of modified fibrous materials with different clay adsorbents was performed by determining the change in the optical density of MS solutions of a given concentration.Scientific novelty. It was found that fibrous materials modified by the studied samples of montmorillonite and paligorskite clays show high absorption capacity relative to the methylene blue dye due to its multilayer sorption. After 24 hours of processing, the degree of absorption is 70% when using clay brand PBA-18 in the amount of 40% by weight of the fibrous material, which is higher than when using clay brand PP-5 (45%) under the same conditions.Practical value. Sorption materials modified with clay minerals can be further used to treat wastewater from light and chemical industries from heavy metal ions.

Emerging microporous HOF materials to address global energy challenges

Madhab C. Das is currently an Associate Professor of Chemistry at IIT Kharagpur. He received his BS (2002) from Midnapore College, MS (2004) in Chemistry from Vidyasagar University and PhD in Supramolecular Chemistry from IIT Kanpur (2009). Then, he worked with Professors Banglin Chen at the University of Texas at San Antonio, George K.H. Shimizu at University of Calgary, and Hiroshi Kitagawa at Kyoto University as postdoctoral fellow (2009–2013) before joining IIT Kharagpur as Assistant Professor in 2013. His work is focused on functional porous materials for gas sorption, separation, and proton conduction. Shyam Chand Pal received his BSc (2015) in Chemistry from Burdwan University (Suri Vidyasagar College) and MSc (2017) in Chemistry from IIT Kharagpur. He is currently pursuing his PhD under the supervision of Dr. Madhab C. Das at IIT Kharagpur. His research interest focuses on metal–organic framework and hydrogen bonded organic framework materials for proton conduction and gas adsorption/separations applications. Banglin Chen received his BS (1985) and MS (1988) degrees from Zhejiang University in China, and his PhD (2000) from the National University of Singapore. He worked with Professors Omar M. Yaghi at University of Michigan, Stephen Lee at Cornell University, and Andrew W. Maverick at Louisiana State University as a postdoctoral fellow during 2000–2003 before joining the University of Texas-Pan American in 2003. He moved to the University of Texas at San Antonio in August 2009 and was promoted to be a professor in August 2011, working on multifunctional metal–organic framework and hydrogen-bonded organic framework materials. Madhab C. Das is currently an Associate Professor of Chemistry at IIT Kharagpur. He received his BS (2002) from Midnapore College, MS (2004) in Chemistry from Vidyasagar University and PhD in Supramolecular Chemistry from IIT Kanpur (2009). Then, he worked with Professors Banglin Chen at the University of Texas at San Antonio, George K.H. Shimizu at University of Calgary, and Hiroshi Kitagawa at Kyoto University as postdoctoral fellow (2009–2013) before joining IIT Kharagpur as Assistant Professor in 2013. His work is focused on functional porous materials for gas sorption, separation, and proton conduction. Shyam Chand Pal received his BSc (2015) in Chemistry from Burdwan University (Suri Vidyasagar College) and MSc (2017) in Chemistry from IIT Kharagpur. He is currently pursuing his PhD under the supervision of Dr. Madhab C. Das at IIT Kharagpur. His research interest focuses on metal–organic framework and hydrogen bonded organic framework materials for proton conduction and gas adsorption/separations applications. Banglin Chen received his BS (1985) and MS (1988) degrees from Zhejiang University in China, and his PhD (2000) from the National University of Singapore. He worked with Professors Omar M. Yaghi at University of Michigan, Stephen Lee at Cornell University, and Andrew W. Maverick at Louisiana State University as a postdoctoral fellow during 2000–2003 before joining the University of Texas-Pan American in 2003. He moved to the University of Texas at San Antonio in August 2009 and was promoted to be a professor in August 2011, working on multifunctional metal–organic framework and hydrogen-bonded organic framework materials.

CHEMICAL TRANSFORMATIONS OF DUST OF BAG FILTERS OF THE REINFORCED CONCRETE PLANT IN AQUEOUS SOLUTIONS

Nickel and copper compounds are among the most dangerous environmental pollutants and their removal from wastewater is an important task. To extract them from aqueous media, traditional methods are used, such as ion exchange, reagent purification, membrane filtration, and adsorption. Recently, for the purification of aqueous media from heavy metal ions, it is increasingly proposed to use waste from various industries, for example, slag, sludge, ash, dust, etc. The paper considered the possibility of wastewater treatment from Cu2+and Ni2+ions using dust from bagfilters in the production of reinforced concrete products as reagents.It was determined that bag filter dust has a fine structure and contains a significant amount of silicates of various composi-tions.The paper describes the chemical transformations that occur in the aquatic media when dust from the bag filters of the reinforced concrete plant is added to it. Some reagents, coagulants, sorp-tion materials that can be used to purify wastewater from heavy metal ions are given. The values of the solubility products of the formed compounds -copper hydroxide, nickel hydroxide, hydrox-omeric carbonate are indicated. The results of granulometric, X-ray phase and chemical analyzes of bag filter dust are presented. According to the studies, the efficiency of purification of the model solution from heavy metal ions in this case is at least 99.3%.

Cadmium and lead adsorption and desorption by coffee waste-derived biochars

Biochar derived from coffee waste has been reported as a promising material for heavy metal sorption. However, if the intended use is environmental remediation, knowing the extent to which desorption may occur is critical. Thus, the objective of this work was to evaluate the efficiency of spent coffee ground (SCG) and coffee parchment (CP) biochars pyrolyzed at 700 °C under laboratory conditions, in the sorption of Cd and Pb from aqueous solutions, in a pH range from 2 to 10, and their retention after an induced desorption process with a 2.9 pH acetic acid solution. Both biochars were alkaline, and the initial pH of the solution had a large effect on the sorption capacity of SCG but a small effect on the sorption capacity of CP. The Pb sorption capacity was higher for CP (18.6 mg·g–1) than for SCG (11.4 mg·g–1), while both biochars had low Cd retention capacities (1.18 mg·g–1). Coffee parchment also showed the highest Pb retention (30% to 87%), while for Cd there was no difference between CP and SCG biochars. Our results showed that metal precipitation was the main mechanism for metal immobilization and CP biochar proved to be more reliable than SCG, mainly for Pb, due to its higher sorption capacity and lower metal release by desorption than SCG. These characteristics are particularly important for the use of biochar in environmental remediation. Besides that, the biochar production represents an eco-friendly destination for these feedstocks, contributing to the circular economy.

Vibrational mode analysis of hydrogen-bonded organic frameworks (HOFs): synchrotron infrared studies.

Hydrogen-bonded organic frameworks (HOFs) are a promising class of porous crystalline materials for gas sorption and gas separation technologies that can be constructed under mild synthetic conditions. In forming three-dimensional networks of flexible hydrogen bonds between donor/acceptor subunits, these materials have displayed high stability at elevated temperature and under vacuum. Although the structural properties of HOFs are commonly characterized by diffraction techniques, new complimentary methods to elucidate phase behaviour and host-guest interactions at the molecular level are sought, particularly those that can be applied under changing physical conditions or solvent environment. To this end, this study has applied synchrotron far-IR and mid-IR spectroscopy to probe the properties of two known and one new HOF system assembled from tetrahedral amidinium and carboxylate building blocks. All three frameworks produce feature-rich and resolved infrared profiles from 30 to 4000 cm-1 that provide information on hydrogen-bonded water solvent networks and the HOF channel topography via lattice and torsional bands. Comparison of experimental peaks to frequencies and atomic displacements (eigenvectors) predicted by high-level periodic DFT calculations have allowed for the assignment of vibrational modes associated with the aforementioned physicochemical properties. Now compiled, the specific vibrational modes identified as common to charge-assisted hydrogen-bonding motifs, as well as low frequency lattice and torsional bands attributed to HOF pore morphology and water-of-hydration networks, can act as diagnostic features in future spectroscopic investigations of HOF properties, such as those toward the design and tuning of host-guest properties for targeted applications.

Removal of Cd2+ metal ions from aqueous solutions by Na-alginate-containing composite biosorbent.

This research is related to the effect of alginate-containing composite biosorbent on the sorption capacity of heavy metal Cd2+ ions. The study aims to determine the character and optimization of the sorption of Na-alginate-containing composite biosorbent on the sorption of heavy metal Cd2+ metal ions in an aqueous solution. Optimum conditions of parameters such as biosorbent amount, pH value effect, concentration effect, contact time, and temperature that affect the sorption of Cd2+ ions were determined. Langmuir, Freundlich, D-R isotherms were applied to the obtained data, and it was noted that the sorption Cd2+ ions are better explained with Freundlich and D-R models. The thermodynamic parameters (ΔGo, ΔHo, ΔSo) for Cd2+ sorption onto composite biosorbent were also determined given from the temperature dependence. The results suggested that composite biosorbent is suitable as a sorbent material for recovery and sorption of metal ions from aqueous solutions.