High Sorption Capacity Research Articles

Feedstock nitrogen content mediates maximum possible Pb sorption capacity of biochars.

The use of biochar for the adsorption of contaminants from soil and water has received considerable interest due to biochar's high surface area, negative charge, and resistance to degradation. However, a knowledge gap still exists concerning the optimum selection of feedstocks and pyrolysis temperatures to maximise sorption capacity for metals. In this study, biochars were produced from 4 different feedstock materials (hay, wheat straw, coco coir, and pine bark) at 10 pyrolysis temperatures ranging from 300 °C to 750 °C, at 50 °C intervals. Batch sorption experiments were conducted to determine the maximum Pb sorption capacity for each biochar using the Langmuir model. The sorption isotherms fit the Langmuir model well (generally R2 > 0.7). The Langmuir maximum sorption capacity increased with an increase in pyrolysis temperature, according to a sigmoidal relationship. A sigmoidal model was fit to the data to derive the theoretical maximum possible sorption capacity obtainable from a feedstock. We observed a positive correlation between the nitrogen content of the feedstock and the theoretical maximum possible sorption capacity obtainable from the feedstock. This relationship highlights the importance of nitrogen content in feedstock to create biochars with a high Pb sorption capacity. It is possible that cation-π interactions with heterocyclic N structures are the primary mechanism for the sorption of Pb to these biochars, and this warrants further investigation.

Studying the sorption properties of adsorbents obtained on the basis of plant waste

In Uzbekistan theoretical and practical results are being achieved in the creation of adsorbents with a high sorption capacity based on natural resources, in particular plant waste, and their adsorption purification from residues of organic substances that are part of wastewater. The characteristics of the prepared carbon sorbent obtained on the basis of some optimal formulations using small samples of charcoal obtained from activated walnut and almond pods using an iodine composition were studied. The objects of the study were walnut and almond shells. The results of analyses for checking the adsorption activity of coal for iodine and determining the number of moles are presented in the form of a table.

Graphene Oxide Deposited with Transition Metal Chalcogenide for Selective Extraction and Determination of Hg(II): Experimental and Computational Analysis.

A graphene oxide (GO/CdS) nanocomposite was synthesized by an in situ hydrothermal process and studied to develop a micro solid phase extraction procedure. Microscopic and spectroscopic characterizations have confirmed the successful preparation of the GO/CdS composite. The prepared nanocomposite selectively extracts Hg(II) ions from various water samples (tap, river, and groundwater). The intriguing characteristic of GO sheets is to provide exceptional hydrophilicity and Hg(II) accessibility to surface-decorated CdS nanoparticles. The GO/CdS nanocomposite shows excellent extraction of trace Hg(II) in a short interval of time. Computations based on density functional theory (DFT) suggest that energetically favorable multinuclear S-Hg binding leads to rapid adsorption with high sorption capacity at GO/CdS sites. The analytical features of merit suggested that the developed method has a low detection limit (0.07 µg L-1) and shows good accuracy and precision (with RSD 3.5%; N = 5). The developed method was verified by analyzing SRM 1641d (Standard Reference Material) and real samples after spiking to a predetermined amount.

Cellulose Acetate Film Containing Bonechar for Removal of Metribuzin from Contaminated Drinking Water

Bonechar presents high sorption capacity for mobile herbicides retained in soil and water. However, its use in a granulated and/or powder form makes it difficult to remove water. The objective of this study was to produce a cellulose acetate film with bonechar as a viable alternative to remove metribuzin from water. The treatments were composed of 2 and 3 g of bonechar fixed on a cellulose acetate film, pure bonechar, and a control (no bonechar). The sorption and desorption study was carried out in the equilibrium batch mode with five concentrations of metribuzin (0.25, 0.33, 0.5, 1, and 2 mg L−1). The water used in the experiment was potable water. Herbicide analysis was performed by High-Performance Liquid Chromatography (HPLC). The addition of 2 and 3 g of the bonechar fixed on the acetate film sorbed 40% and 60%, respectively, of the metribuzin at the lowest concentrations (0.25, 0.33, and 0.5 mg L−1). For both additions, desorption was low, being 7% and 2.5% at 24 and 120 h, respectively. There are still no reports of the production of cellulose acetate film with bonechar for herbicide removal in water, considered an alternative of easy handling and indicated for water treatment plants.

Thermochemical sorption heat storage: Investigate the heat released from activated carbon beads used as porous host matrix for MgSO4 salt

For sustainable and cost-effective thermal management and energy storage, sorption-base thermal storage has received a lot of attention. However, the low sorption capacity of sorbents has long been a barrier to high energy-density sorption-based thermal storage. We present a new promising composite with high heat release and sorption capacity. The use of MgSO4/bead activated carbon composites in thermochemical sorption heat storage has been investigated. Because of the highly developed microporosity and high apparent specific surface area of about 1300 m2/g, bead activated carbon (BAC) is a potential candidate as support for salt/support composites for thermochemical heat storage. Also, the thermal conductivity of BAC has been measured and found to be 0.14 W/mK, which is higher than that of other materials like zeolites or alumina. This high thermal conductivity can influence the water sorption equilibrium, controlling the temperature of the solid, avoiding hot-spots, and thus preventing desorption during the hydration step. In stationary conditions (RH = 60 %, gas flow = 30 mL/min), the water sorption capacity of BAC was 0.138 g/g. This value was 2.32 times higher when the salt was dispersed into the BAC matrix, for the composite 7.6-MgSO4/BAC. A water adsorption capacity, higher than the theoretical value, was observed and attributed to the condensation of water molecules within the porous structure, resulting in a high thermal energy density. The 7.6-MgSO4/BAC composite achieved the highest heat of hydration of 920 J/g. The 10 hydration/dehydration cycles performed (dehydration at 150 °C and hydration at 30 °C with a RH of 60 %) confirmed the composite's excellent stability. This research provides a promising low-carbon pathway for the efficient capture, storage, and utilization of thermal energy.

Modelling atrazine sorption in carbon-rich substrates: a case study

Background The use of carbonaceous materials for environmental remediation is attractive due to low expense and high sorption capacity. However, their efficiency in contaminant removal is affected by substrate composition and sorption mechanism. Objective This study investigated atrazine sorption and desorption in three carbon-rich substrates. Data were evaluated considering isotherm models and sorbent chemical composition. Methods Sorption was performed by the batch equilibrium method with three substrates obtained from pig slurry composting with different proportions (w/w) of charcoal fines [...]

Superhydrophobic polyimide/cattail-derived active carbon composite aerogels for effective oil/water separation

The frequent oil spill accidents have created increasingly environmental and ecological problems. Therefore, the development of effective oil-cleaning materials is of great importance. In this study, we prepared superhydrophobic polyimide/cattail-derived active carbon composite (PI/CAC) aerogels for efficient oil/water separation through a facile approach based on freeze-drying and thermal imidization. The resultant aerogel shows ultralight weight (29.7 mg/cm3), superhydrophobicity (water contact angle = 151.3°), excellent compressibility, and ideal chemical stability, which are conducive to the oil sorption and extrusion at various harsh conditions including acidic, alkaline, and saline solutions, as well as oil-in-water emulsions. Typically, the optimized sample PI/CAC-3 aerogel could achieve saturation within 5–20 s, delivering a high oil sorption capacity of 25.1–71.0 g/g for various oils. When used for continuous oil/water separation, high flux of 4.47 × 104 L m-2 h−1 and separation efficiency of 98.3% were achieved for chloroform/water mixture by gravity-driven separation method. Furthermore, due to the high compressibility, the aerogel can be used for cycling separation through sorption-extrusion process with less than 3% decrease in separation efficiency after 10 cycles. These advantages make it a potential candidate for the treatment of wastewater polluted by various oils and/or organic solvents.

Selective and reversible surface complexation of aqueous palladium(II) by polycarboxylate (pyromellitic acid) functionalized hybrid aerogel sorbent

The recovery of palladium compounds from aqueous solutions containing other metal salts is a challenging task of environmental technology. One solution is the development of selective sorbents by the appropriate design of surface functionality. For this purpose, a mesoporous, polycarboxylate (pyromellitic acid monoamide) functionalized silica-gelatin aerogel was prepared by the sol-gel method and supercritical drying. It is characterized using low voltage scanning electron microscopy (LV-SEM), N2-sorption porosimetry, small angle neutron scattering (SANS), infrared spectroscopy (FT-IR), solid-state nuclear magnetic resonance spectroscopy (ssNMR) and X-ray photoelectron spectroscopy (XPS). Its aqueous phase Zeta potential was investigated as a function of pH. The aerogel has excellent selectivity for binding Pd(II) around pH = 2.0 in the simultaneous presence of Pt(II), Pt(IV) and six other metal ions with a very high sorption capacity of 369 mg g−1 at pH = 2.3. The quantitative recovery of Pd(II) and the regeneration of the sorbent is possible using 5 mM methionine. The mechanism of binding is the reversible surface complexation of Pd(II) via the O-atoms of the adjacent carboxylate groups of the aerogel, as shown by XPS. This high stability coordination mode accounts for the excellent selectivity of the sorbent, and prevents the reduction of Pd(II).

Insights on macro- and microscopic interactions between Confidor and cyclodextrin-based nanosponges

Imidacloprid is one of the most widely used soluble neonicotinoid insecticide, which is non–volatile and persists in the soil, with hazardous effects on birds, honeybees, and mammals. It is used in both agricultural and veterinary applications, and is found in at least 7% of European topsoils. One of the commercially available formulations is Confidor O–TEQ® that exhibits higher retention, spreading, and penetration capacity being in form of an oil suspension. In this work, porous materials based on cyclodextrin nanosponges (CDNSs) were developed for the efficient removal of imidacloprid. In the synthesis of CDNSs, α– and β–cyclodextrin and two diamine monomers, hexane–1,6–diamine (HDA) and dodecane–1,12–diamine (DDA) were used. It was found that linkers with longer aliphatic chains resulted in CDNSs with higher thermal stability and crosslinking degree. αCD2–HDA and βCD2–HDA showed superior sorption efficiency for Confidor O–TEQ®, as evaluated by kinetic and equilibrium sorption analyses at optimal conditions. To better understand the effects of monomer chain length and type of cyclodextrin, the sorption performance of αCD and βCD, αCD–HDA and βCD–HDA, αCD–DDA and βCD–DDA, dimeric αCD2–HDA and βCD2–HDA, and αCD2–DDA and βCD2–DDA with imidacloprid was also investigated by atomistic molecular dynamics simulations. Relevant contact patterns based on the identification of the stabilizing/destabilizing noncovalent interactions within the CD-based complexes were described in detail. Results suggest that significant modulation of the sorption performance of CDNSs for imidacloprid can be achieved by imposing various features, with direct implications for the rational design of supramolecular materials with high sorption capacity for pesticides.

Screening of Raw and Modified Biochars from Food Processing Wastes for the Removal of Phosphates, Nitrates, and Ammonia from Water

The aim of this work was to compare the performance of biochar from various food processing wastes of different origin for the removal of different nutrients from water. Eggshells (EGS), rice husk (RH), and coffee biochars were pyrolyzed at 400 and 800 °C and were examined for the removal of phosphates, nitrates, and ammonia nitrogen. The raw materials were also modified with magnesium chloride in order to investigate their sorption behavior. The highest sorption capacity (qmax) for phosphates and ammonium was observed with EGS pyrolyzed at 800 °C and was 11.45 mg PO43−-P/g and 11.59 mg NH3-N/g, while the highest nitrates sorption capacity was observed with the magnesium-modified RH pyrolyzed at 800 °C (5.24 mg NO3−-N). The modified EGS biochars pyrolyzed at 800 °C had almost the half the sorption capacity for phosphates and nitrates compared to the unmodified materials. The modification of RH pyrolyzed at 800 °C resulted in higher sorption capacity by 34 and 158% for phosphates and ammonium, respectively. The coffee raw and modified biochars were less efficient in nutrient removal compared to the other materials. The specific surface area values of the biochars examined is not a decisive factor for nutrient sorption. The reaction between magnesium and calcium (for the eggshell samples) ions with phosphates is responsible for the higher sorption efficiency. On the other hand, the presence of magnesium and calcium ions has a detrimental effect on the sorption of NH3-N.

Electrosorption of phenolic compounds by carbon sheet electrode from zinc chloride functionalized activated carbon from pomegranate husk

The biomass waste from pomegranate husk (PH) was utilized to develop carbon sheet electrode via the chemical and thermal activation approach and the electrode was used to remove 4-chlorophenol (4CP) from the aqueous solution. The effect of solution pH, ionic strength, applied voltage, contact time, and 4CP concentration were investigated to observe the highest 4CP removal efficiency of the biomass derived material at pH 6.0, applied voltage of 1.5 V, ionic strength of 0.85 mM, and contact time of 270 min. The increased applied voltage led to 4CP removal efficiency up to 95.38 ± 4.77 % at 1.5 V with 60 min contact time, nearly-two-times higher than that observed at the open circuit (62.33 ± 3.12 %). The removal efficiency of 4CP sharply decreased from 96.63 ± 1.93 % to 49.34 ± 1.48 % with increasing initial 4CP concentration (50.0–200.0 mg/L). Experimental data were fitted to Freundlich isotherm according to which high sorption capacity of carbon electrode equivalent to 325.85 mg/g at 1.5 V of the applied voltage was observed. The fabricated carbon electrode offered a great potential for the removal of other phenolics from the possible biomass via sorption approach.

Superhydrophobic and superoleophiclic natural rubber latex foam coated by hexadecyltrimethoxysilane modified halloysite nanotube for oil/water separation

In this research, we introduce a facile synthesis of the superhydrophobic natural rubber latex foam (NRLF), sponge-NRLF materials with a high oil-sorption capacity. The superhydrophobic sponge-NRLF was prepared by decorating the halloysite nanotubes (HNTS), which are chemically modified by n-hexadecyltrimethoxysilane (HDTMS) on the surface. The effects of HDTMS@HNTs loading and vulcanization systems towards the superhydrophobic and superhydrophilic properties of the NRLF were investigated. It was found that NRLF vulcanized by conventional vulcanization system (CV) and coated with 6 wt% HDTMS@HNTs showed favorable oil/water selectivity with excellent water repellence with a contact angle of 151°. The modified NRLF showed excellent performance toward gasoline 95 with high sorption capacity, achieving up to 10 times of its own weight for a wide range of oils. Oil sorption capacity tended to decline with respect to increasing HDTMS@HNTs content and oil viscosity due to the reduced porosity and surface area of the modified NRLF. Interestingly, the modified NRLF exhibited excellent durability, as the sorption efficiency remained unchanged after 10 cycles. Moreover, their fire retardant was also improved. • Facile preparation of superhydrophobic and superoleophiclic natural rubber latex foam • Natural rubber latex foam coated by hexadecyltrimethoxysilane modified halloysite nanotube • Oil adsorption capacity and oil-water selectivity of modified natural rubber latex foam

Design and implementation of a new portable hybrid solar atmospheric water-generation system

Abstract During recent years, atmospheric water generation (AWG) has garnered significant attention among researchers as a viable solution to the water-scarcity problem. Generally, AWG requires dehumidification, which includes two main principles of refrigeration and sorption. Among refrigeration methods, thermoelectric coolers are suitable and, among sorption methods, it is best to utilize desiccant materials with high sorption capacity and low heat generation. In the present study, a portable hybrid/integrated solar AWG system was designed and tested under realistic conditions of Babol, Iran (36.5387°N, 52.6765°E) over four typical summer days between 14 and 31 August 2021. Two models (Models A and B) were designed and evaluated. Temperature, relative humidity, solar irradiance and water-production data were recorded to assess the system performance (i.e. the ratio between the generated water and consumed power in ml/W.hour) and economically analyse the system. Based on the results acquired, the maximum water production in the proposed configuration (acquired from Model B) was 2.12 l/m2.day at an average relative humidity and a temperature of 52% and 36°C, respectively. The desired AWG system had a system performance of 0.19 ml/W.hour, annual water production of 774.4 l/m2, production cost of 0.0246 $/l/m2 and a payback period of 1.19 years.

Фиторемедиация почв, загрязненных ионами тяжелых металлов, с помощью древесных и кустарниковых растений

The use of woody and shrubby plants with a developed root system and a large biomass in the technology of phytoremediation of soils contaminated with heavy metals is analyzed. Woody plants can be used in the process of phyto-recovery of urban systems as long-term absorbers of heavy metal ions from the soil. The main mechanisms of phytoremediation of contaminated urban areas with the help of trees and shrubs are considered. The sorption capacity of cobalt, manganese and chromium ions by some species of woody and shrubby plants has been studied. The accumulation of heavy metals by seedlings under conditions of soil contamination with cobalt, manganese and chromium ions was studied. The transfer factor of cobalt, manganese and chromium ions was determined for the studied plant species. Species-hyperaccumulators of heavy metals, Gleditsia triacanthos L., Caragána arboréscens L., have been identified, which can be used for phytorestoration of soils of the technogenic region contaminated with cobalt, manganese and chromium ions. Low concentrations of cobalt, manganese and chromium were noted in the seedlings of Quercus robur L. and Robinia pseudoacacia L. in the aerial part, which indicates their ability to exclude heavy metal ions from their aerial parts. It has been established that seedlings of Gleditsia triacanthos L., Caragána arboréscens L., resistant to soil pollution, due to their excellent adaptability, even on degraded and contaminated with heavy metals soil of the experimental plot, have a high level of biomass accumulation without reliable facts of inhibition of growth processes. During the controlled process of phytoremediation carried out in the field, their high sorption capacity was noted, which makes it possible to recommend these species for use in technologies for the restoration of soils contaminated with heavy metal ions.

Mechanistic studies of uranyl interaction with functionalized mesoporous chitosan-superparamagnetic nanocomposites for selective sorption: Characterization and sorption performance

Herein, two hybrid magnetic-chitosan nanocomposite core-shell were synthesized via subsequently heterogeneous nucleation immobilized with alanine/serine functionality for enhanced uranyl ions (UO 2 2+ ) sorption. The physiochemical characteristics of nanocomposites were determined by CHN, FTIR, XRD, BET, pHzpc, TEM, TGA, XPS and VSM studies. The synthesized mesoporous alanine (Ala) and serine (Ser) nanocomposites were found: superparamagnetic with saturation magnetization ( M S : 26.54 and 23.05 emu g -1 for Ala and Ser, respectively), large surface-to-volume ratio for Ser (61.1 m 2 g -1 to 0.41 cm 3 g -1 ), compared to Ala (60.4 m 2 g −1 to 0.36 cm 3 g −1 ), and amine content for Ala and Ser was (2.69 and 2.58 mmol N g -1 with density of ⁓13.42 and ⁓12.73 nm 2- , respectively. The sorption characteristics of uranyl ions were thoroughly examined and compared. At the optimal pH range of 3.5-5.0, Ala and Ser nanocomposites show maximum sorption capacities of 0.498 and 0.609 mmol U/g, respectively in sulfate medium, as well 0.583 and 0.742 mmol U/g in nitrate medium. The Langmuir model suits the sorption process well, and the pseudo-second-order rate equation (PSORE) enables single-layer chemical reactions. Small-size particles afford rapid sorption ⁓50 minutes with half-sorption-time (t 0.5 ) 3.9 and 4.2 min for Ser and Ala nanocomposite, respectively. The sorption is spontaneous, exothermic and regulated by entropy change. The sorption efficiency in various medium types can be arranged according to sorption capacity as follows: nitrate > chlorides >> sulphate medium. According to spectroscopic analyses (FTIR and XPS), the sorption sites are N/O functional groups, which adsorbed UO 2 2+ by anion-exchange, electrostatic attraction and chelation mechanisms. Elution and regeneration are successfully accomplished with using acidified urea solution achieving ⁓92%. Finally, both sorbents were tested and compared for the selectivity of UO 2 2+ from multicomponent simulated waste containing uranyl species. Both sorbents showed high sorption capacity, excellent selectivity, and good recyclability and reusability over multiples sorption cycles. • Alanine and serine efficiently functionalized the magnetic-chitosan nanocomposite core-shell, which were extensively characterized and tested for uranium sorption. • Sorbents have a high sorption capacity, great selectivity, and strong recyclability and reusability through numerous sorption cycles. • Nanocomposites show a high affinity for U(VI) and great selectivity from acidic simulated nuclear effluent. • Interaction mechanisms of nanocomposites with uranyl ions have been elucidated.

Superoleophilic oil-adsorbing membranes based on porous and nonporous fluorinated polyimides for the rapid remediation of oil spills

• Electrospun nanofibrous mats of fluorinated porous and nonporous 6FDA-based polyimides as oil sorbents. • Fine-tuning the oil-sorption performance by tuning the polymer porosity and functional groups. • The nanofibrous sorbents of fluorinated polyimides exhibited superoleophilicity. • A high crude oil-sorption capacity of 83 g g −1 was achieved by the electrospun nanofibrous mats. • Excellent sorption capacity was maintained for up to five cycles. Oil spills present significant environmental hazards that threaten the marine ecosystem and human life. To rapidly clean up oil spills and prevent ecological disasters, various oil sorbents have been developed. Here, highly effective hydrophobic nanofibrous sorbents were developed through the electrospinning of four different 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA)-based polyimides with Brunauer–Emmett–Teller surface areas of 46 and 530 m 2 g −1 . Uniform nanofibers with wrinkled surfaces and mean diameters of 250–860 nm were produced. Cross-sectional images revealed the presence of pores within the fibers, attributable to the unsteady evaporation of solvent molecules from the jet. Water contact-angle (WCA) measurements demonstrated the hydrophobic nature of the nanofibers, whose WCAs were in the range of 130°–147°. Oil-sorption experiments revealed the high performance of the nanofibrous sorbents. The sorbent produced from 6FDA–3,5-diaminobenzoic acid exhibited the highest adsorption capacities for crude oil (61 g g −1 ) and diesel (109 g g −1 ). In contrast, the highest gasoline-adsorption capacity was observed for the sorbent produced from 6FDA–3,5-diamino-2,4,6-trimethylbenzene benzoic acid (6FDA–TrMCA) (41 g g −1 ). Using polymer blends, the sorption capacities of the resulting sorbents were enhanced up to 83 and 42 g g −1 for crude oil and gasoline, respectively; however, the diesel-sorption capacity decreased to 71 g g −1 . The nanofibrous sorbents could be recovered mechanically through squeezing and reused multiple times, while maintaining higher than 80% of their initial sorption capacities. These hydrophobic polyimide nanofibrous sorbents with high oil-adsorption rates and sorption capacities exhibit significant potential for application in oil-spill remediation.

Chemical Composition of Industrial Wood Waste and the Possibility of its Management

Organic wood waste (sawdust, shavings, pieces of wood and bark), is widely used as a secondary raw material and, after composting, for soil fertilisation and substrate production in agriculture, horticulture, forestry, urban landscaping and rehabilitation of degraded land. However, problematic to process is wood waste that is very dirty with soil. They have limited calorific value and cannot be used in the R10 recovery process of land treatment benefiting agriculture or improving the environment. However, the morphological composition of these wastes indicates that they have good properties and can be used for agricultural use and for the reclamation of degraded land. The research involved wood waste with the code 03 01 99 (other unspecified waste from wood processing and the production of panels and furniture) generated during the preparation of deciduous tree logs for the veneer production process, and ashes from the burning of wood waste generated in the veneer production factory. The aim of the study was to assess the chemical composition of these wastes and the possibility of their agricultural use. In the samples of wood waste and ashes there was determined: pH; chlorines content; conductivity; hydrolytic acidity; content of micro and macroelements and heavy metals. The morphological composition of the waste is dominated by sawdust, with a smaller share of shavings, bark and earth parts, and a small addition of pieces of wood of various sizes. It is rich in easily bioavailble as well as total macroelements and is not contaminated with heavy metals. Analyzed wood waste has deacidifying properties, high sorption and buffering capacity. Studies have shown that the wood waste produced at the veneer factory, can be used as an organic fertiliser, a component of other organic fertilisers, for soil mulching, horticultural substrate and soil and land reclamation.The ash obtained from burning wood is strongly alkaline and rich in alkaline cations, mainly Ca, Mg and K. It is not contaminated with heavy metals. The ash can be used for soil deacidification and fertilization, especially for soil reclamation. The waste from the heap can be used as an organic fertilizer, a component of other organic fertilizers, for mulching soils and as a gardening substrate. However, the possibilities for non-agricultural (e.g.: for the production of pallet, particle board) use are limited due to the high proportion of earthy parts.

Auto-Continuous Synthesis of Robust and Hydrophobic Silica Aerogel Microspheres from Low-Cost Aqueous Sodium Silicate for Fast Dynamic Organics Removal.

An efficient auto-continuous globing process was developed with a self-built apparatus to synthesize pure silica aerogel microspheres (PSAMs) using sodium silicate as a precursor and water as a solvent. A hydrophobic silica aerogel microsphere (HSAM) was obtained by methyl grafting. A reinforced silica aerogel microsphere (RSAM) was prepared by polymer cross-linking on the framework of the silica gel. The pH value of the reaction system and the temperature of the coagulating bath were critical to form perfect SAMs with a diameter of 3.0 ± 0.2 mm. The grafted methyl groups are thermally stable up to 400 °C. Polymer cross-linking increased the strength significantly, owing to the polymer coating on the framework of silica aerogel. The pore volumes of HSAM (6.44 cm3/g) and RSAM (3.17 cm3/g) were much higher than their state-of-the-art counterparts. Their specific surface areas were also at a high level. The HSAM and RSAM showed high organic sorption capacities, i.e., 17.9 g/g of pump oil, 11.8 g/g of hexane, and 22.2 mg/g of 10 mg/L methyl orange. The novel preparation method was facile, cost-effective, safe, and eco-friendly, and the resulting SAM sorbents were exceptional in capacity, dynamics, regenerability, and stability.

Radiolabeled nanoporous hydroxyapatite microspheres: An advanced material for potential use in radiation synovectomy

The design and fabrication of porous and biocompatible inorganic materials having high adsorption capacity for therapeutic radioisotopes can trigger development of ‘next-generation’ radiopharmaceuticals for use in clinical nuclear medicine. In this study, nanoporous hydroxyapaptite (HA) microspheres of 1–10 μm diameter were synthesized by sol-gel technique followed by spray drying. The synthesized microparticles exhibited remarkably high sorption capacity for 90Y (141 ± 5 mg Y/mg) and 166Ho (262 ± 3 mg Ho/mg), which enabled the use of low specific activity radioisotopes produced in medium flux research reactors. Sorption of 90Y and 166Ho in nanoporous HA followed Langmuir-Freundlich adsorption isotherm and pseudo second order kinetics, indicating that the process was chemisorption. A chelator-free radiolabeling technique was developed for loading clinically relevant doses of radioisotopes such as 90Y and 166Ho in the HA matrix for use in treatment of arthritis. As a proof of concept, 90Y labeled formulation was administered in a patient with painful arthritis of knee joint. Selective localization of the radiolabeled agent in the synovial cavity was demonstrated by SPECT/CT imaging which demonstrated its potential for use in radiation synovectomy.

Total organic carbon content as an index to estimate the sorption capacity of micro- and nano-plastics for hydrophobic organic contaminants

The worldwide existing micro- and nano-plastics (MNPs) showed high sorption capacity for hydrophobic organic contaminants (HOCs), and thus leading to change of the environmental behaviors and fates of HOCs. However, there is a lack of general index for evaluating the sorption capacity of MNPs for HOCs. Herein, we investigated the sorption of chlorobenzene, naphthalene and phenanthrene to 10 MNPs of different polymer types with and without UV-aging, respectively. It was found that the sorption was well fitted by Freundlich isotherm model with coefficients R2 in the range of 0.892–1.00, and aging of most MNPs resulted in decreased sorption capacity for naphthalene and phenanthrene but slightly increased sorption capacity for chlorobenzene. More importantly, for the 8 MNPs commonly present in the environment and with measured total organic carbon (TOC) covering the range of 23.0–91.9%, the logarithm sorption constant (logKd) values of the studied HOCs positively correlated with TOC contents of MNPs, with a good determination coefficient (R2) of 0.923 for naphthalene, 0.694 for chlorobenzene, and 0.565 for phenanthrene. Our study demonstrated that the TOC content of MNPs is a good index for estimating the contribution of total MNPs to the sorption of nonpolar HOCs in the environmental media.