Carbon Cryogel Research Articles

Synthesis and electrochemical performance of low cost nitrogen-doped carbon cryogel composites as supercapacitor electrodes

Developing cost-effective methods for synthesizing Nitrogen-doped carbon cryogels is crucial for advancing supercapacitor technology due to their enhanced electrochemical properties. Nitrogen-doped porous carbon cryogels are synthesized through the freeze-drying method by substituting resorcinol with phenol and using urea/melamine as nitrogen sources. The effect of nitrogen sources on the structure and electrochemical performance is investigated. In the case of carbon cryogel composites samples, using melamine as the nitrogen source (PMF) is more favorable than using urea (PUF), while both nitrogen-doped samples significantly outperform the undoped samples (PF). The PMF sample displays a specific surface area of 1119.00 m2 g−1, and a nitrogen content of 2.19 wt%. In the three-electrode system, the specific capacitance of the PMF sample reaches up to 247.9 F g−1 at a current density of 0.5 A g−1, and its rate performance is 85.52 %. By comparison, the PF sample exhibits specific capacitance and rate performance of 85.4 F g−1 and 33.44 % under the same parameters. The assembled symmetric supercapacitor in a buckle type system also demonstrates exceptional energy density (14.41 Wh kg−1), long-term cycle stability, and a favorable capacitance retention rate (72.2 %). These excellent electrochemical performances can be attributed to the synergistic effects of the hierarchical pore structures and heteroatoms doping.

Nitrogen-Doped Carbon Cryogels as Adsorbents: Efficient Removal of Organophosphate Pesticides from Water and Assessment of Toxicity Reduction

Nitrogen-Doped Carbon Cryogels as Adsorbents: Efficient Removal of Organophosphate Pesticides from Water and Assessment of Toxicity Reduction

Solid-phase extraction of estrogen hormones onto chemically modified carbon cryogel

This study introduces a novel solid-phase extraction (SPE) method utilizing pristine and chemically treated carbon cryogel (CC) as an adsorbent forthe isolation and enrichment of estrogen hormones (estrone, 17?-estradiol, and 17?-ethinylestradiol) from water samples. High recovery values (82-95 %) were obtained after optimizing the SPE technique, which included adsorbent mass and chemical treatment, sample volume and pH, and elution solvent type and volume. The developed analytical method, based on SPE coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS), proves to be selective, efficient, and cost-effective for the determination of selected estrogens. The utilization of self-made cartridges with chemically modified CC produced results comparable to those obtained with commercial cartridges while employing significantly less material. Furthermore, the selectivity of the employed materials contributed to minor matrix effects. The optimized method was successfully applied to analyze estrogen hormones in groundwater, surface water, and wastewater samples, with the results highlighting the importance of monitoring these contaminants in the aquatic environment.

Enhanced microwave conversion of oil palm mesocarp fiber to levulinic acid using H3PW12O40-Nb2O5 functionalized carbon cryogel derived from lignin hydrogel

This study aims to transform a hydrogel functionalized with phosphotungstic acid and niobium oxide into a carbon cryogel, serving as an efficient catalyst for converting oil palm mesocarp fiber to levulinic acid using microwave technology. The lignin-gum hydrogel exhibits desirable properties, including a moderately high swelling ratio (10.3 g/g), water absorption capacity (220 %), robust crosslinking (71.7 % yield), and notable compressive strength (0.8 MPa at 90 % strain). The swollen state of the hydrogel, with an average pore size of 2.5–4.0 μm, enhances microwave energy penetration into the biomass matrix. This work offers an alternative approach to enhance biomass conversion, utilizing lignin-derived cryogel with impressive levulinic acid yield (18.4 %) and conversion efficiency (81 %). Testing the hydrogel properties is crucial for ensuring optimal performance during the upgrade to carbon cryogel.

The Influence of Reduced Graphene Oxide on the Texture and Chemistry of N,S-Doped Porous Carbon. Implications for Electrocatalytic and Energy Storage Applications.

In this work, we study the influence of reduced graphene oxide (rGO) on the morphology and chemistry of highly porous N,S-doped carbon cryogels. Simultaneously, we propose an easily upscalable route to prepare such carbons by adding graphene oxide (GO) in as-received suspended form to the aqueous solution of the ι-carrageenan and urea precursors. First, 1.25-5 wt% GO was incorporated into the dual-doped polymer matrix. The CO2, CO, and H2O emitted during the thermal treatments resulted in the multifaceted modification of the textural and chemical properties of the porous carbon. This facilitated the formation of micropores through self-activation and resulted in a substantial increase in the apparent surface area (up to 1780 m2/g) and pore volume (up to 1.72 cm3/g). However, adding 5 wt% GO led to overactivation. The incorporated rGO has an ordering effect on the carbon matrix. The evolving oxidative species influence the surface chemistry in a complex way, but sufficient N and S atoms (ca. 4 and >1 at%, respectively) were preserved in addition to the large number of developing defects. Despite the complexity of the textural and chemical changes, rGO increased the electrical conductivity monotonically. In alkaline oxygen reduction reaction (ORR) tests, the sample with 1.25 wt% GO exhibited a 4e- mechanism and reasonable stability, but a higher rGO content gradually compromised the performance of the electrodes. The sample containing 5 wt% GO was the most sensitive under oxidative conditions, but after stabilization it exhibited the highest gravimetric capacitance. In Li-ion battery tests, the coulombic efficiency of all the samples was consistently above 98%, indicating the high potential of these carbons for efficient Li-ion insertion and reinsertion during the charge-discharge process, thereby providing a promising alternative for graphite-based anodes. The cell from the 1.25 wt% GO sample showed an initial discharge capacity of 313 mAh/g, 95.1% capacity retention, and 99.3% coulombic efficiency after 50 charge-discharge cycles.

The Interplay of Brønsted-Lowry and Lewis Acid Sites in Bifunctional Catalyst for the Biomass Conversion to Levulinic Acid

The integration of phosphotungstic acid and niobium oxide forms a bifunctional catalyst that demonstrates an interplay between Brønsted-Lowry and Lewis acid which is able to provide a synergistic effect for the conversion of biomass to LA. This bifunctional acid catalyst shows a higher yield of levulinic acid (LA) (16.4%) as compared to that of sole phosphotungstic acid (10.5%) or niobium oxide (13.2%), presumably caused by a higher selectivity at the tandem steps of the conversion reaction. The bifunctional catalyst was then doped to a lignin-derived carbon cryogel to mitigate the deactivation and leaching of the catalysts. The durability and thermal stability of the carbon cryogel allow the catalyst to recycle up to 3 times while retaining similar performance.

Metal-Organic-Framework-Mediated Fast Self-Assembly 3D Interconnected Lignin-Based Cryogels in Deep Eutectic Solvent for Supercapacitor Applications.

A cost-effective and sustainable method is successfully developed to produce lignin-based cryogels with a mechanically robust 3D interconnected structure. A choline chloride-lactic acid (ChCl-LA)-based deep eutectic solvent (DES) is used as a cosolvent to promote the synthesis of lignin-resorcinol-formaldehyde (LRF) gels that can self-assemble a robust string-bead-like framework. The molar ratio of LA to ChCl in DES has a significant influence on the gelation time and properties of the ensuing gels. Moreover, it is discovered that doping the metal-organic framework (MOF) during the sol-gel process can greatly accelerate the gelation of lignin. It takes a mere 4 h to complete the LRF gelation process at a DES ratio of 1:5 combined with 5% MOF. This study yields LRF carbon cryogels doped with copper that exhibit 3D interconnected bead-like carbon spheres with a prominent micropore of 1.2 nm. A specific capacitance as high as 185 F g-1 can be obtained for the LRF carbon electrode at a current density of 0.5 A g-1, and it has an excellent long-term cycling stability. This study provides a novel method of synthesizing high-lignin-content carbon cryogels with promising potential for application in the field of energy storage devices.

Synthesis of nitrogen doped and nitrogen and sulfur co-doped carbon cryogels and their application for pharmaceuticals removal from water

In this study carbon cryogel, cryogel doped with nitrogen, and both nitrogen and sulfur co-doped carbon cryogels (nominal concentration of nitrogen was in the range 2–10 wt%) were synthesized and used as an adsorbent for the removal of carbamazepine, naproxen, diazepam and diclofenac from water. A batch adsorption kinetics study was performed by determination of contact time influence, the effect of pH, and adsorption isotherms. Structural and morphological analysis showed that there are no changes in turbostratic carbon structure induced by doping/co-doping, but noticeable morphology changes were observed. The presence of both nitrogen and nitrogen/sulfur were confirmed and results showed low content on the surface, especially for sulfur. Obtained high values of the specific surface area for co-doped samples (up to 1530 m2/g) can be caused by sulfur atoms burning or leaving the material during carbonization. The results of the adsorption kinetics study showed that the adsorption of all pharmaceuticals on all tested samples followed the pseudo-second-order kinetic model. The maximum adsorption capacity obtained from the Langmuir isotherm model is higher for doped (91.28–168.92 mg/g) and co-doped (152.97–488.06 mg/g) samples than for pristine sample (59.75–266.28 mg/g). Calculated adsorption energy values from the Dubinin-Radushkevich model indicate that the possible mechanism was physisorption. Desorption tests that were carried out showed satisfactory reusability for all samples. The favorable adsorption characteristics for the co-doped sample with a higher nominal concentration of nitrogen and sulfur qualifies as a potentially good adsorbent for the removal of pharmaceuticals from water.

Self-activated, urea modified microporous carbon cryogels for high-performance CO2 capture and separation

Conventionally, porous carbons were synthesized using corrosive chemical activating agents. On contrary, we designed a single-step synthesis method for the preparation of a series of self-activated heteroatom (N)-doped carbon cryogels from potassium hydrogen phthalate (KHP) and urea at various temperatures (700–1000 °C), in the absence of any activating agent. To highlight the effectiveness of N-doping in porosity generation and CO2 adsorption/separation, a comparative analysis was drawn with a series of undoped carbon cryogels. Notably, the N-doped cryogels exhibit a highly porous structure with remarkable specific surface area (SSA; 2084 m2 g−1), micropore volume (1.1806 cm3 g−1), well-defined pore size distribution, and abundant narrow micropores (<1.04 nm). Additionally, a considerable mechanical strength (compressive strength = 0.621 MPa and compressive modulus = 8.86 MPa) was also observed. Moreover, the porous cryogel endowed with sufficient pyrrolic nitrogen content (≈51.4 at %) lead to high CO2 adsorption (280.57 mg/g at 273 K and 171.31 mg/g at 298 K at 1 bar) and an excellent ideal adsorbed solution theory (IAST)-based CO2/N2 selectivity (≈115) at 273 K, surpassing the CO2 adsorption/separation performance of previously reported N-doped carbons and resorcinol-based carbon gels. Furthermore, the moderate heat of adsorption (36.109 kJ mol−1) and stable cyclic behavior of CO2 adsorption-desorption under flue gas conditions (i.e., 15% CO2/85% N2) unveils the physisorption nature of adsorption which governs the energy-effective regeneration process. Summarizing, the present work demonstrates the successful fabrication of highly porous carbon cryogels as efficient CO2 adsorbents, thereby opening new synthetic avenues for self-activating porous carbon formation.

Controlled preparation of nitrogen-doped hierarchical carbon cryogels derived from Phenolic-Based resin and their CO2 adsorption properties

Nitrogen-doped hierarchical carbon cryogels with good monolithic structure are synthesized from phenol (P), melamine (M), and formaldehyde (F) by sol-gel, freeze-drying, and carbonization process with different molar ratios of F/(P + M). The synthesized cryogels have the characteristics of cost-effective and abundant hierarchical pores. The pore structures, chemical properties, and CO2 adsorption performance of the prepared carbon cryogels are investigated. The results reveal that the PF carbon cryogel without N doping shows poor porosity characteristics, which leads to lower CO2 adsorption performance. For the N-doped PMF carbon cryogels, with the increase in the molar ratio of F/(P + M), the specific surface area and micropore volume decreases from 1160.6 to 874.1 m2/g and from 0.47 to 0.35 cm3/g, respectively, indicating that a lower formaldehyde content is conducive to the formation of more micropores and higher specific surface area. The carbon cryogel PMF2.0 (F/(P + M) = 2.0) exhibits a CO2 adsorption capacity as high as 5.79 mmol/g, and it also has a high CO2/N2 adsorption selectivity (13.43) and isosteric adsorption heat (33.06 kJ/mol). Thus, the PMF carbon cryogel exhibits immense potential as an adsorbent for CO2 capture, and its excellent performance is attributed to the synergistic effect of N doping and abundant micropores with appropriate size.

CO2 adsorption by cryogels produced from poultry litter wastes

Poultry litter waste (PLW) is the main by-product generated by the Brazilian poultry industry. A sustainable approach for reusing this waste is the production of biochar to be further used aiming CO2 adsorption. In this work, biochars were produced by varying the N2 flow along the pyrolysis process of 150 (PLW-150) and 1000 (PLW-1000) mL min-1. PLW and biochars were characterized for their morphology, porosity, specific surface area, and CO2 adsorption capacity. From the biochars, carbon cryogels (CC) were produced aiming their use as CO2 adsorbents. The results of the cryogel adsorption test showed a CO2 adsorption capacity of 13.1±2.9 and 33.8±3.3 mg g-1 for the CC-PLW.150 and CC-PLW.1000 cryogels, respectively. Therefore, reusing this residue for cryogels production and its use in the CO2 adsorption signifies an attractive perspective to minimize the environmental damage caused by CO2 emissions.

Carbon Cryogel Preparation via Urea-furfural Gel Synthesis as an Adsorbent for CO2 Capture Application

Carbon Cryogel Preparation via Urea-furfural Gel Synthesis as an Adsorbent for CO2 Capture Application

Carbon cryogel preparation and characterization

The carbon cryogels (CCs) show significant potential for application in a wide variety of applications, from absorbents and catalysts to supercapacitors and fuel cells, due to their high specific surface area, multimodal pore-size distribution, electrical conductivity, and thermo-mechanical stability. In the present study, the CC material was prepared by a sol-gel process from resorcinol with formaldehyde and heat treatment in an inert atmosphere. The Brunauer Emmett Teller (BET) measurements, X-ray diffraction (XRD), Raman spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), differential thermal analysis with thermogravimetric measurements (DTA-TG), scanning electron microscopy (SEM), and small-angle X-ray scattering (SAXS) analysis, as complementary techniques, were used to characterize the obtained CC. It was found that the obtained CC is a porous amorphous material with high open porosity (≈82.5%) and complex porous structure organization. Using the small-angle neutron scattering (SANS) with the contrast variation technique and the adsorption of deuterated water by carbon cryogel it was possible to separately study the structure of open and closed pores, as well as to estimate both the volume fraction of closed pores (φclose pore ≈ 1%) and the total porosity (φtotal ≈ 83.5%) of the obtained CC.

Glucose-derived bio-fuel additive via ethanolysis catalyzed by zinc modified sulfonated carbon

The transformation of biomass derivative components such as glucose to levulinate esters via direct conversion in alcohol with acid catalyst has attracted great attention. In this study, the sulfonate urea-furfural carbon cryogel doped with zinc (UFCS-Zn) has been applied as an acid catalyst for the glucose ethanolysis reaction. Initially, the carbon cryogel was prepared via a mixing process of urea and furfural in an acidic medium followed by freeze-drying and calcination steps. Then, the urea-furfural carbon cryogel (UFC) was sulfonated before modification with zinc via impregnation of zinc (II) nitrate to provide the Bronsted and Lewis acid catalyst which is required for reaction conversion. The effects of reaction parameters on the ethanolysis of glucose have been conducted to determine the selected condition in obtaining high ethyl levulinate yield. The parameters studied include the glucose feed (0.2 to 0.5 g), catalyst loading (0.15 to 1.2 g), and reaction temperature (140 to 190 °C). The catalyst was characterized using TGA-DTG, FTIR, and SEM-EDX techniques to study the surface chemistry and thermal stability. The glucose ethanolysis reaction with UFCS-Zn catalyst has provided maximum ethyl levulinate yield of 27.4 mol% at selected condition of 180 °C, 6 h, 0.8 g (1:2) of catalyst and 0.4 g of glucose. Based on characterization of UFCS-Zn, the presence of sulfonate group and Zn element on the catalyst through the sulfonation and impregnation steps have been verified. This result has been confirmed through the detection of SO3H functional group and Zn-O bonding from the FTIR, and elements of S, O, and Zn from the EDX. High thermal stability of the UFCS-Zn (via TGA-DTG curves) allows the catalyst to assist the reaction at setting temperature without degradation in mass during the reaction. The UFCS-Zn catalyst has drafted its potential as catalyst for further conversion of biomass components.

Adsorption of estrone, 17β-estradiol, and 17α-ethinylestradiol from water onto modified multi-walled carbon nanotubes, carbon cryogel, and carbonized hydrothermal carbon.

Carbon materials of different structural and textural properties (multi-walled carbon nanotubes, carbon cryogel, and carbonized hydrothermal carbon) were used as adsorbents for the removal of estrone, 17β-estradiol, and 17α-ethinylestradiol from aqueous solutions. Chemical modification and/or activation were applied to alter surface characteristics and to increase the adsorption and desorption efficiency of carbon materials. Surfaces of treated and untreated carbon materials were characterized through the examination of the textural properties, the nature of surface functional groups, and surface acidity. It was found that the adsorption capacity of tested carbon materials is not directly proportional to the specific surface area and the content of surface oxygen groups. However, a high ratio of surface mesoporosity affected the adsorption process most prominently, by increasing adsorption capacity and the rate of the adsorption process. Adsorption of estrone, 17β-estradiol, and 17α-ethinylestradiol followed pseudo-second-order kinetic model, while the equilibrium adsorption data were best fitted with the Langmuir isotherm model. Calculated mean adsorption energy values, along with the thermodynamic parameters, indicated that removal of selected hormones was dominated by the physisorption mechanism. High values of adsorption efficiency (88-100 %) and Langmuir adsorption capacities (29.45-194.7 mg/g) imply that examined materials, especially mesoporous carbon cryogel and multi-walled carbon nanotubes, can be used as powerful adsorbents for relatively fast removal of estrogen hormones from water.

Preparation and Characterization of Sulfonated Carbon Cryogel Doped Zinc as a Catalyst for Glucose Ethanolysis to Ethyl Levulinate

In this study, sulfonated carbon cryogel (CC) doped with zinc was prepared and used as a solid catalyst. Carbon cryogel was prepared by mixing urea and furfural, freeze-drying, and calcination. The CC was then sulfonated and impregnated with zinc (II) nitrate for ethyl levulinate production from ethanolysis of glucose. Experiment results showed that different types of catalyst prepared from CC precursor had different catalytic effects on the ethanolysis of glucose. Sulfonated carbon cryogel doped with zinc (SCC-Zn) which prepared at a calcination temperature of 300 °C showed better performance as a catalyst for the ethanolysis reaction of glucose. In addition, the 10 wt.% of Zn was recommended as optimum loading for the impregnation on the catalyst. The ethyl levulinate yield of 19.6 mol% was obtained at 180 °C for 6 h with 0.15 g catalyst loading and 0.4 g of glucose feed. The selected SCC-Zn catalyst was further characterized by using FTIR, TGA XRD, and SEM-EDX to evaluate its physical and chemical properties as a catalyst.

Biomass Related Highly Porous Metal Free Carbon for Gas Storage and Electrocatalytic Applications.

In this paper we report the synthesis of a N, S co-doped metal free carbon cryogel obtained from a marine biomass derived precursor using urea as nitrogen source. Natural carrageenan intrinsically contains S and inorganic salt. The latter also serves as an activating agent during the pyrolytic step. The overall 11.6 atomic % surface heteroatom concentration comprises 5% O, 4.6% N and 1% S. The purified and annealed final carbon (CA) has a hierarchical pore structure of micro-, meso- and macropores with an apparent surface area of 1070 m2/g. No further treatment was applied. The gas adsorption potential of the samples was probed with H2, CO2 and CH4, while the electrocatalytic properties were tested in an oxygen reduction reaction. The atmospheric CO2 and CH4 storage capacity at 0 °C in the low pressure range is very similar to that of HKUST-1, with the CO2/CH4 selectivity below 20 bar, even exceeding that of the MOF, indicating the potential of CA in biogas separation. The electrocatalytic behavior was assessed in an aqueous KOH medium. The observed specific gravimetric capacitance 377 F/g was exceeded only in B, N dual doped and/or graphene doped carbons from among metal free electrode materials. The CA electrode displays almost the same performance as a commercial 20 wt% Pt/C electrode. The oxygen reduction reaction (ORR) exhibits the 4-electron mechanism. The 500-cycle preliminary stability test showed only a slight increase of the surface charge.

Modified Carbon Cryogel As Tunable Electrocatalyst for Oxygen Reduction Reaction in Proton Exchange Membrane Fuel Cells

Pt-free catalysts for Oxygen Reduction Reaction (ORR) are broadly studied for Proton Exchange Membrane Fuel Cells (PEMFC) in order to widely develop hydrogen as a fuel for individual transportation. To reduce the performance gap between noble and non-noble catalysts, kinetics and thermodynamics are to be considered. The kinetics of the reaction is influenced by both the turn over frequency of the catalytic site and the density of said sites in the materials. The diffusion of gaseous reactants and liquid water produced is equally important as it modifies the thermodynamic of the reaction. For a long time now, Fe-C-N materials have been identified as the most promising Pt-free electrocatalysts for ORR despite the limited knowledge on the actual structure of the involved sites. Several approaches are currently studied to produce materials with high active site density and high porosity. Different carbon structures are modified to include active sites. The most reported and promising routes are Metal Organic Frameworks, polymers on carbon nanoparticles and silica templated organic structures[1], [2]. With the recent works on the structure and activity of Fe-N4 active sites[3], the carbon plane surrounding active sites seem to have a great impact on the sites’ Turn-Over Frequency (TOF). Cheaper routes are explored to produce tunable carbon structure adapted to the requirement of ORR catalysis. The sol-gel polymerization of organic polymer is a newly investigated route[4], [5]. In this approach, carbon cryogels are chosen for the tenability of their porous structure and the versatility of precursors that can be tested. Porous Fe-C-N catalysts are synthesized in one-step by a modified resorcinol-formaldehyde aerogel method. Gelation, drying and pyrolysis steps are carefully studied and optimized to obtain a high density of accessible catalytic sites. As iron is both a precursor of the active site and a catalyst for the graphitization of carbon during the pyrolysis, its impact on the final structure is studied. Different types of precursors are used in several loadings. The family of materials therefor obtained presents various degrees of graphitization and TOF of the active sites. Structure-Performance relationships are investigated for this family of materials. Electrochemical performances of the materials are assessed in RDE-setup in acidic electrolyte as well as in differential cell of PEMFC. The porosity of the formed materials is measured with nitrogen adsorption. The electrochemical performances in acidic electrolyte are comparable with state of the art materials.[1] A. Serov, K. Artyushkova, et P. Atanassov, « Fe-N-C Oxygen Reduction Fuel Cell Catalyst Derived from Carbendazim: Synthesis, Structure, and Reactivity », Adv. Energy Mater., vol. 4, no 10, p. 1301735, 2014, doi: 10.1002/aenm.201301735.[2] E. Proietti et al., « Iron-based cathode catalyst with enhanced power density in polymer electrolyte membrane fuel cells », Nat. Commun., vol. 2, p. 416, 2011, doi: 10.1038/ncomms1427.[3] T. Asset et P. Atanassov, « Iron-Nitrogen-Carbon Catalysts for Proton Exchange Membrane Fuel Cells », Joule, vol. 4, no 1, p. 33–44, janv. 2020, doi: 10.1016/j.joule.2019.12.002.[4] A. Sarapuu, L. Samolberg, K. Kreek, M. Koel, L. Matisen, et K. Tammeveski, « Cobalt- and iron-containing nitrogen-doped carbon aerogels as non-precious metal catalysts for electrochemical reduction of oxygen », J. Electroanal. Chem., vol. 746, p. 9–17, 2015, doi: 10.1016/j.jelechem.2015.03.021.[5] Y. Wang et S. Berthon-Fabry, « One-Pot Synthesis of Fe-N-Containing Carbon Aerogel for Oxygen Reduction Reaction », Electrocatalysis, nov. 2020, doi: 10.1007/s12678-020-00633-8.

Activated Carbon Cryogel as a Potential Adsorbent for Removal of Aspirin

Pharmaceutical substances are urged to be removed from wastewater as the pollutants bring adverse effects to both humans and the environment. Among the pharmaceutical substances, aspirin is selected as the targeted pharmaceutical waste due to its extremely high consumption. Aspirin is widely used in the world and is produced about 35,000 t/y. Carbon cryogel was chosen as the potential adsorbent to remove aspirin from wastewater, and it was synthesized from urea and furfural before activation with H3PO4. The effects of experimental parameters on aspirin adsorption such as pH, contact time, initial concentration, adsorbent dosage, and temperature were investigated. A maximum of 30 % of percentage removal and 30 mg/g of adsorption capacity were achieved at an initial concentration of 60 mg/L, pH 6, and 0.05 g of adsorbent at room temperature after 45 min of contact time. The activated carbon cryogel synthesized in this study is useful for application in wastewater treatment and sanitation of

Controlled Preparation of Nitrogen-Doped Hierarchical Carbon Cryogels Derived from Phenolic-Based Resin and Their CO &lt;sub&gt;2&lt;/sub&gt; Adsorption Properties

Controlled Preparation of Nitrogen-Doped Hierarchical Carbon Cryogels Derived from Phenolic-Based Resin and Their CO &lt;sub&gt;2&lt;/sub&gt; Adsorption Properties