Carbon Sorbents Research Articles

Simple and Eco-Friendly Route from Agro-Food Waste to Water Pollutants Removal.

The current study reflects the demand to mitigate the environmental issues caused by the waste from the agriculture and food industry. The crops that do not meet the supply chain requirements and waste from their processing are overfilling landfills. The mentioned wastes contain cellulose, which is the most abundant carbon precursor. Therefore, one of the possibilities of returning such waste into the life cycle could be preparing the activated carbon through an eco-friendly and simple route. Herein, the carrot pulp from the waste was used. Techniques such as thermogravimetric analysis (TGA), elemental analysis (EA), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and x-ray diffraction (XRD) were used to investigate the thermal treatment effect during the carbon material preparation. The development of microstructure, phase formation, and chemical composition of prepared material was evaluated. The obtained carbon material was finally tested for water cleaning from a synthetic pollutant such as rhodamine B and phloxine B. An adsorption mechanism was proposed on the base of positron annihilation lifetime spectroscopy (PALS) results and attributed to the responsible interactions. It was shown that a significant carbon sorbent from the organic waste for water purification was obtained.

Antibacterial Activity of Modified Carbon Sorbents, Prospective for Application

The aim of the work is to study the antibacterial and antimycotic properties of carbon sorbents modified with biologically active substances in relation to pathogens of purulent-inflammatory diseases. Material and methods. The activity of modifier solutions and modified samples of carbon sorbents was studied in relation to test strains of opportunistic microorganisms in comparison with the initial sample of carbon sorbent. A suspension with a known content of microbial cells was prepared from test strains of microorganisms; it was incubated in wells with test samples for 48 hours. The survival of microorganisms was determined by quantitative inoculation from each well of the sample and microorganism mixture at regular intervals of incubation on Petri dishes with simple agar nutrient, then the number of viable microbial cells in the test mixture was counted. Results. Studies have shown high antibacterial and antimycotic activity of modified carbon sorbents. The best result in comparison with the initial sample was demonstrated by a carbon sorbent modified with lactic acid oligomers and immobilized lysozyme. Studies have shown the promise of using modified carbon sorbent samples for the application therapy in bacterial infections.

Development, characterization, and testing of a personal passive sampler for measuring inhalation exposure to gaseous elemental mercury

Inhalation of gaseous elemental mercury (GEM) is an occupational exposure concern for workers handling elemental mercury or mercury-containing waste. GEM is also often present near historically mercury-contaminated sites, potentially resulting in low-level, chronic exposure of the wider population. Here we introduce a passive sampler for personal GEM monitoring which combines a radial porous diffusive barrier with an activated carbon sorbent. A total mercury analyzer is used to quantify GEM sorbed to the carbon by thermal decomposition, amalgamation, and atomic absorption spectroscopy. A sampling rate of 0.070 m3/day was determined by calibrating the sampler at low and high concentrations. Deployments lasting 8 h result in limits of quantification well below 200 ng/m3. The sampler has a measurement range of at least four orders of magnitude. Derived air concentrations were not statistically significantly different from those obtained by active air sampling but were more precise than those obtained using a personal pump. If properly stored, the sampler maintains low blank levels in high GEM environments. Affordability, sturdiness, simplicity, and the wide availability of total mercury analyzers make this sampler highly suited for monitoring GEM inhalation exposure, including in developing countries.

Enhanced sorption of perfluorooctane sulfonate and perfluorooctanoate by hydrotalcites

Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) are recalcitrant compounds that are toxic to humans and ecosystems. Hydrotalcite-like compounds have emerged as promising PFOS and PFOA sorbents due to their high anion exchange capacity and high specific surface area. In this study, hydrotalcite (HT) compounds were intercalated with nitrate and carbonate ions (HT-CO 3 and HT-NO 3 ) and their specific surface area and particle aggregate size modified by treatment with acetone (AHT-CO 3 and AHT-NO 3 ). Sorption experiments with AHT-NO 3 indicated that sorption equilibrium was reached faster with PFOS (< 5 min) compared to PFOA (< 20 min), and that sorption capacity for PFOS (1,610.0 mg/g) was substantially higher compared to PFOA (909.0 mg/g). The sorption yields are explained by anion exchange occurring at higher PFOS and PFOA concentrations, along with surface adsorption, and by PFOS having a higher affinity for the HT interlayer. In comparison to AHT-NO 3 , PFOS and PFOA sorption by AHT-CO 3 was slower (equilibration times ≥ 20 min) and the maximum capacities were generally lower, because anion exchange is hindered by the affinity of the carbonate ion for the HT interlayer. As such, surface adsorption dominated across a large PFOS and PFOA concentration range (up to 2,000 mg/L). The presence of non-ionic species (trichloroethylene) did not affect the sorption capacity, while alkaline pH conditions and the presence of other anionic species (dodecyl sulfate) reduced the sorption capacity of AHT compounds towards PFOS and PFOA. Compared to untreated HT compounds, acetone treated HT exhibited improved sorption properties towards PFOA and PFOS removal from groundwater, particularly AHT-CO 3 . Overall, AHT compounds outperform activated carbon sorbents in terms of PFOA and PFOS sorption kinetics and capacities, thus could be promising new sorbents for PFAS removal from contaminated waters. • Acetone-treated hydrotalcites (AHT) show modified physical properties. • Nitrate-intercalated AHT show fast equilibration time (<1 h) towards PFOS and PFOA. • The maximum sorption uptake for PFOS is 1,610 mg/g by nitrate-intercalated AHT. • XPS and other techniques are used to evaluate the sorption mechanism. • Alkaline pH and other anions impact the sorption capacity of PFOS and PFOA by AHT.

Kinetics of organic compound adsorption on carbon sorbents

Adsorption of trichlorethylene from aqueous solutions by activated carbons of various grades was studied previously under static conditions [6]. We carried out a comprehensive study of the trichlorethylene adsorption process in the presence of chloroform by carbon sorbents, including the study of equilibrium, kinetics, and adsorption process dynamics in order to create an adsorption technology for purifying natural waters from organic compounds. The aim of the study was to establish the mass transfer mechanism and obtaining the mass transfer coefficients required for engineering calculations, using various models that describe the kinetics of sorption extraction. The kinetic parameters of sorption process are influenced by various factors, including specific surface area, carbon sorbents’ structure, and conditions for the transfer of adsorbed substance molecules to the grain surface of adsorbent. So, as a result, calculated coefficients of external mass transfer allow us to expect a high rate of the component extraction from the water to be purified by filtering through a a fixed sorbent layer of the AC grades: SCLF-515, AG-WV-1, PPS, Purolat-standard.

Prediction of sorption enhanced steam methane reforming products from machine learning based soft-sensor models

Carbon dioxide-abated hydrogen can be synthesised via various processes, one of which is sorption enhanced steam methane reforming (SE-SMR), which produces separated streams of high purity H2 and CO2. Properties of hydrogen and the sorbent material hinder the ability to rapidly upscale SE-SMR, therefore the use of artificial intelligence models is useful in order to assist scale up. Advantages of a data driven soft-sensor model over thermodynamic simulations, is the ability to obtain real time information dependent on actual process conditions. In this study, two soft sensor models have been developed and used to predict and estimate variables that would otherwise be difficult direct measured. Both artificial neural networks and the random forest models were developed as soft sensor prediction models. They were shown to provide good predictions for gas concentrations in the reformer and regenerator reactors of the SE-SMR process using temperature, pressure, steam to carbon ratio and sorbent to carbon ratio as input process features. Both models were very accurate with high R2 values, all above 98%. However, the random forest model was more precise in the predictions, with consistently higher R2 values and lower mean absolute error (0.002-0.014) compared to the neural network model (0.005-0.024).

Wastewater treatment technology with modified sorbent from the complex of household services

The composition and characteristics of wastewater from the complex of household services and the method of wastewater treatment from the surfactants have been studied. To increase the efficiency of local treatment of the wastewater, a method of neutralization on a carbon sorbent modified with sulfuric acid has been analyzed. Wastewater treatment technology with a high content of organic substances having an increased alkaline reaction is a pretreatment of coal with sulfuric acid solutions, which then serves as a resin charge for filters. The spent resin charge is regenerated with a hydrogen peroxide solution. These results have been obtained using artificially prepared and natural wastewater from the complex of household services and form the basis for the development of wastewater treatment facilities for laundries located in hotels, health centers and recreation facilities. The conclusions on the efficient use of the proposed method are made.

Optimization of Parameters of Synthesis of Carbon Sorbents Modified with Hydroxic Acids

Optimization of Parameters of Synthesis of Carbon Sorbents Modified with Hydroxic Acids

Criteria for the Selection of Synthetic Polymeric Waste as a Raw Material for Producing Carbon Sorbents with Predetermined Properties

The results of studies on the thermal processing of synthetic multi-tonnage polymeric waste (polypropylene, polycarbonate, textolite, PET, organoplastics and tire rubber) with the production of carbon sorbents for technological and environmental purposes are presented. The influence of the nature of the activating agent and the conditions of the process with the production of sorbents with predetermined properties was studied. Analysis of the research results allowed us to establish that the main factors affecting the yield of carbonizate and the formation of a porous structure of carbon sorbents from synthetic polymer waste are the degree of aromaticity and the location of benzene rings in the polymer structure, the proportion of oxygen in the precursor. The criteria for selecting synthetic polymer wastes as raw materials for obtaining carbon sorbents with predetermined properties are established. The results of the research can be used in the development of technologies for obtaining carbon sorbents with predetermined properties from waste synthetic polymers and the selection of technological parameters for processes.

Structural, magnetic and adsorption characteristics of magnetically susceptible carbon sorbents based on natural raw materials

Structural, magnetic and adsorption characteristics of magnetically susceptible carbon sorbents based on natural raw materials

Effect of biochar on the lead mobility in Haplic Chernozem

The determination of mobile Pb compounds in soil is the most important environmental task, due to their sorbtion by plants and migration to other adjacent mediums. The biochar is widely known as an effective for contaminated soil remediation. The aim of the research was to study the effect of biochar remediation on the Pb mobility in soil under model contamination conditions. Haplic Chernozem was artificially contaminated with Pb nitrates at rates of 5 and 10 maximum permissible concentrations (32 mg/kg). Biochar was added in doses of 2.5% and 5% of the soil mass. Loosely bound compounds include exchangeable, complex, and specifically sorbed metal. The largest increase of metal exchangeable forms was observed at a pollution dose of 320 mg/kg (up to 16%). When carbon sorbent was introduced noticeable changes in the content of loosely bound forms occurred. Pb exchangeable forms decreased by 3-10%, complex forms - by 4-13%, specifically sorbed forms- by 4-12%. The highest efficiency of sorbents has been demonstrated by biochar at a dose of 2.5% in the soil contaminated with 160 mg/kg of Pb and at a dose of 5% under contamination of 320 mg/kg of metal.

Mechanisms of copper immobilization in Fluvisol after the carbon sorbent applying

Biochar is widely used sorbent for soil remediation but the mechanism of its effect on immobilization of metals and particular processes of metal transformation are still unclear. We designed an incubation experiment to investigate the impact of wood biochar to copper (Cu) contamination in Calcaric Fluvisols Loamic. The efficiency of biochar implementation for reduction of Cu mobility in soil has been studied using combined method of heavy metal fractioning (Minkina et al., 2013). It was shown that the use of sorbent into polluted soil results in the change of fraction-group composition of metal compounds, fixation of Cu due to reduction of weakly bound forms and increase of the part of residual and metal fractions strongly bound with organic matter. Decrease of pollutant mobility occurs along an increase of the dose of a sorbent. The greater effect was observed after use of biochar in the concentration 2.5 %. Thus, the present study demonstrates the possible remediation of soil contaminated by heavy metals using biochar and provides a particular strategy for remediation of soils contaminated with Cu.

Remediation of brownfields contaminated by organic compounds and heavy metals: a bench-scale test of a sulfur/vermiculite sorbent for mercury vapor removal.

In this study, we report for the first time a novel type of sorbent that can be used for mercury adsorption from the air-based off-gasses-vermiculite impregnated with alkali polysulfides and thiosulfates. In contrast to other sorbents, vermiculite exhibits superior thermal stability in air and low adsorption capacity for organic vapors. This allows for a more favorable design of the soil remediation unit-direct coupling of thermal desorber with catalytic oxidizer using air as a carrier gas. In the bench-scale test at 180 °C, the sulfur/vermiculite sorbent exhibited significantly higher efficiency for the adsorption of mercury vapor from the off-gasses than the commercial sulfur/activated carbon sorbent at its highest operating temperature (120 °C). The average mercury concentration in the adsorber off-gas decreased from 1.634 mg/m3for the sulfur/activated carbon to 0.008 mg/m3 achieved with impregnated vermiculite. The total concentration of organic compounds in the soil after thermal desorption was below the detection limit of the employed analytical method.

Study of Thermochemical Transformations of Bast of Birch Bark, Structure and Properties of the Produced Porous Carbon Materials

The porous structure and sorption properties of carbon materials produced by thermochemical activation of the bast of birch bark with potassium hydroxide at 800°C have been studied. The effect of the amount of introduced KOH on the specific surface area of carbon materials obtained from bast was established. The selection of the optimal conditions for the preliminary carbonization of the bast was carried out, providing after thermal activation with KOH the formation of porous carbon materials with a specific surface of up to 2469 m2 g–1, a total pore volume of up to 1.085 cm3 g–1, a micropore volume of up to 0.84 cm3 g–1, and an average size pores less than 2.0 nm. It is shown that preliminary carbonization of bast at 500–580°С and subsequent activation with KOH at 800°С shifts the pore distribution in the resulting carbon materials towards smaller sizes (0.5–1.0 nm). It was found that carbon materials produced from heat-treated birch bast have a sorption activity for benzene, which exceeds the performance of foreign industrial carbon sorbents by 2.4 times and domestic active carbons of SKT-3 and SKT-10 grades by 3.4 times. Pre-carbonization of birch bast increases the yield of porous carbon materials by a factor of 3–4 compared to their yield when using untreated bast.

N-doped mesoporous carbon as a new sorbent for ultrasonic-assisted dispersive micro-solid-phase extraction of 1-naphthol and 2-naphthol, the biomarkers of exposure to naphthalene, from urine samples

This study aimed to optimize a new sample preparation method using N-doped mesoporous carbon sorbent for simultaneous measurement of 1-naphthol and 2-naphthol, the biomarkers of exposure to naphthalene. The samples were analyzed using high-performance liquid chromatography supplied with ultraviolet detector (HPLC-UV). N-doped mesoporous carbon sorbent was obtained via the hard template procedure. The synthesized nanosorbent was then characterized by transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), and elemental analysis (CHN). The effective factors in the extraction of the studied biomarkers were examined by the Box-Behnken (BBD) methodology. Regarding the optimum conditions, the sketched calibration curve for naphthols was linear in the concentration levels of 1–600 µg L-1 for human urine samples. The accuracy and reproducibility of the introduced method were determined using the relative recovery (RR %) and relative standard deviation (RSD %) tests on the fortified urine samples. RR% and RSD% were found to be 97.0–101.2% and 3.1–9.0%, respectively. The calculated method detection limit of the optimized procedure was 0.3 µg L-1 and 0.5 µg L-1 for 1-naphthol and 2-naphthol, respectively.

A Role of Activators for Efficient CO2 Affinity on Polyacrylonitrile-Based Porous Carbon Materials.

Herein, we investigated polyacrylonitrile (PAN)-based porous activated carbon sorbents as an efficient candidate for CO2 capture. In this research, an easy and an economical method of chemical activation and carbonization was used to generate activated PAN precursor (PAN-C) adsorbents. The influence of various activators including NaOH, KOH, K2CO3, and KNO3 on the textural features of PAN-C and their CO2 adsorption performance under different temperatures was examined. Among the investigated adsorbents, PANC-NaOH and PANC-KOH exhibited high specific surface areas (2,012 and 3,072 m2 g−1), with high microporosity (0.82 and 1.15 cm3 g−1) and large amounts of carbon and nitrogen moieties. The PAN-C activated with NaOH and KOH showed maximum CO2 uptakes of 257 and 246 mg g−1 at 273 K and 163 and 155 mg g−1 at 298 K, 1 bar, respectively, which was much higher as compared to the inactivated PAN-C precursor (8.9 mg g−1 at 273 K and 1 bar). The heat of adsorption (Qst) was in the range 10.81–39.26 kJ mol−1, indicating the physisorption nature of the CO2 adsorption process. The PAN-C-based activated adsorbents demonstrated good regeneration ability over repeated adsorption cycles. The current study offers a facile two-step fabrication method to generate efficient activated porous carbon materials from inexpensive and readily available PAN for use as CO2 adsorbents in environmental applications.

Research of absorbing properties of carbon sorbents for purification of aquatic environment from oil products

The article presents the results of the study of structural-sorption performance and absorption properties of both raw materials and carbon sorbents obtained in the carbonization process, in terms of their ability to absorb petroleum products from water and contribute to the preservation of environmental infrastructure. Under the proposed mode of carbonization received hydrophobic sorbents. The analysis of the obtained results shows that carbon materials based on pine sawdust, obtained at a temperature of 300 °C for 8-10 minutes, have the best buoyancy – 97-100%. This can be explained by the fact that in the process of carbonization of cellulose-containing raw materials the last of the components of plant tissues decomposes lignin (active decomposition of lignin occurs in the temperature range 280-325 °C). As a result of research it is established that in the process of low-temperature one-stage carbonization of vegetable raw materials unauthorized hydrophobization of the sorbent surface is carried out. For fast and efficient collection of oil and oil products, the sorbent must have the maximum sorption rate, which will reduce the absorption time of pollutants. The highest sorption rate is shown by a mixture of pine sawdust carbonate: expanded graphite (50:50) and carbon material based on pine sawdust, which can be explained by the developed porous structure and surface chemistry of the materials.

Sorption of Interleukins 12 and 23 Using the Developed Magnetocontrollable Ustekinumab-Based Sorbent.

The aim of the study was to assess the sorption capacity of Ustekinumab, a drug based on interleukins 12 (IL-12) and 23 (IL-23), when using it with a magnetocontrollable sorbent.Materials and Methods.To reduce the concentration of proinflammatory cytokines (IL-12, IL-23), the blood of patients with psoriatic arthritis was passed through magnetocontrollable polyacrylamide granules (MPG) of spherical shape with the particle size of 10–100 μm, obtained by emulsion polymerization. Perfusion was performed through a 10 ml column equipped with an electromagnet, into which MPG with immobilized antibodies to IL-12 and IL-23 was added. Ustekinumab, a commercial drug with concentration of monoclonal antibodies equaling 0.2 mg per 1 ml of saline was used as the source of antibodies to these interleukins. The specific sorption capacity of MPG was determined using a column filled with the granules in a volume of 0.2 ml and inducing their subsequent interaction with 1 ml of IL-12 and IL-23 solutions with increasing concentrations.The heparinized blood of 10 patients with psoriatic arthritis of various degrees of activity, who had no parenteral administration of IL-12/IL-23 inhibitors (Ustekinumab) for 12 months, was subjected to in vitro treatment. The blood of 10 healthy donors was used as the control; the perfusion procedure was similar.Results.Digital parameters were measured for each sample before and after the interaction between the sorbent and blood plasma. There was a significant decrease in cytokines from the baseline — by 99.8% (in donors) and by 99.9% (in patients). When using a carbon sorbent, their concentration decreases by 92.6% from the baseline. As a result of sorption, blood cell counts did not change reliably, which is an additional positive aspect of this procedure.Conclusion.The maximum possible decrease in the level of cytokines has great practical importance, since they play a leading role in the pathogenesis of psoriatic arthritis. The use of a synthesized Ustekinumab-based sorbent is a highly effective way of removing them simultaneously from blood plasma.

Stabilization of heavy metals in sediments: A bioavailability-based assessment of carbon adsorbent efficacy using diffusive gradients in thin films

This study investigated the effectiveness of carbon adsorbents as remediation material for sediments contaminated with heavy metals and the feasibility of utilizing diffusive gradients in thin films (DGT) as a biomimetic tool to estimate the accumulation of heavy metals in Venerupis philippinaram (Manila clam). The results showed that carbon materials had significant inhibitory effects (14.0–53.0%) on the enrichment of heavy metals in organisms and the order of increasing overall inhibitory effect was: charcoal, peat, activated carbon, and biochar. There were significant correlations (P < 0.0001) between the four heavy metals accumulated in Venerupis philippinaram and those accumulated in DGT devices after 28 days in the laboratory. Observed concentrations of heavy metals enriched in DGT (5.4–42.0%) were less than accumulations in Venerupis philippinaram. The results of in situ DGT applications showed significant correlations between the amount accumulated in DGT and the acid-soluble portion in sediments for both Cu and Pb, with positive linear correlations and R-squares of 0.97 and 0.92, respectively. These results supported the notion that a DGT device can be used as a biomimetic tool that predicts and monitors the accumulation of heavy metals in aquaculture ponds. Future studies should focus on improving the stabilization of heavy metals in sediments using different types of carbon sorbents, as well as minimizing simulation deviations using DGT.

Single-Laboratory Validation of a Multi-residue Method for Simultaneous Analysis of Multi-class Pesticides in Turmeric by Liquid Chromatography Tandem Mass Spectrometry.

For years, turmeric has been used in several cuisines worldwide because of its proven health benefits. However, as its cultivation often involves applications of polar and semi-polar pesticides, their residues might cause health hazards to consumers. The dearth of a validated LC-MS/MS method for the residue analysis of these pesticides in turmeric has warranted the present study. The aim was to develop and validate a multi-residue method for simultaneous determination of multi-class pesticides in turmeric (both rhizome and powder) by LC-MS/MS. Both the rhizome and powder samples (1 kg) were soaked in water for 30 min, followed by homogenization. Each homogenate (2 g) was mixed with 10 mL water, and extracted with acetonitrile (10 mL) in the presence of acetic acid and NaCl. The extract was cleaned by using dispersive solid phase extraction (dSPE) with graphitized carbon (5 mg/mL) sorbent. The cleaned extract was measured by LC-MS/MS with a runtime of 20 min. The method was validated on 211 multi-class pesticides. The method performance was satisfactory at 10 ng/g and higher levels, in compliance with the SANTE/12682/2019 guidelines. The dSPE cleanup was effective in minimizing the matrix effects. The use of matrix-matched calibrations specific for turmeric powder and rhizome corrected all recoveries within the satisfactory range of 70-120%. The precision -RSDs were <20% for all test pesticides. The Horwitz ratio and measurement uncertainty results were satisfactory as well. As the method was convenient, selective, accurate, and repeatable, it is recommended for regulatory and commercial testing purposes. For the first time, this study reports a validated LC-MS/MS method for the multi-residue analysis of pesticides in turmeric. The method provided a high throughput analysis of multi-class pesticides in turmeric rhizome and powder matrices with satisfactory selectivity, sensitivity, accuracy, and precision. The method performance satisfied the requirements of the SANTE/12682/2019 guidelines, and the method sensitivity complied with the EU-MRL requirements.