Renewable Adsorbent Research Articles

Structural characteristics of biochars made from different parts of corn straw and their adsorption performances for methylene blue

Corn straw husk-derived biochars (HBC), corn straw leaf-derived biochars (LBC), and corn straw pith-derived biochars (PBC) were prepared through a hydrothermal carbonization method and subsequently employed for the dye wastewater. The different adsorption behaviors of three biochars on Methylene blue (MB) were investigated through adsorption kinetics, adsorption isotherms, pH influence, and ion coexistence experiments. The surface characterization results indicated that PBC showed a relatively rough surface, while HBC and LBC exhibited smooth strip and block-like structures. The pseudo-second-order kinetic model and the Langmuir model could describe the adsorption process of the three biochars more accurately. The adsorption capacities of three corn straw biochar (CSBC) for MB were 251.08 mg/g PBC, 134.79 mg/g HBC, and 99.9 mg/g LBC, respectively. Furthermore, the removal efficiency of MB by PBC remained as high as 82.6 % after five adsorption-desorption cycles, indicating that PBC was an efficient and renewable adsorbent. Based on the characterization of biochar combined with Density Functional Theory (DFT) analysis, it was proposed that the main adsorption mechanisms include electrostatic attraction, hydrogen bonding, ion exchange, and π-π conjugation.

Research Progress on Physical and Chemical Remediation Methods for the Removal of Cadmium from Soil

Soil cadmium contamination is a global environmental issue, threatening ecosystem health and human safety. Common remediation strategies, including phytoremediation and soil replacement, are typically hampered by their lengthy processes or high costs. The aim of this review is to explore and evaluate innovative physical and chemical remediation techniques to address cadmium pollution effectively. This review focuses on three promising approaches: the co-application of phosphate fertilizers and sepiolite, CaAl-layered double hydroxide (LDH) immobilization, and hydrochar treatments. The primary methodologies involved evaluating the adsorption capacity, ion exchange mechanisms, and remediation efficiency under varying environmental conditions. Results indicate that these techniques significantly enhance cadmium immobilization, with the co-application of phosphate fertilizers and sepiolite demonstrating up to 72.6% removal of HCl-extractable cadmium. The review concludes that these techniques offer superior cost-effectiveness and scalability for large-scale applications and recommends future research to optimize amendment formulations and develop renewable adsorbents to further improve sustainability.

CARBON NANOTUBES AS EFFECTIVE REMEDY FOR THIN OIL-WATER FILMS REMOVAL

This article describes the process of synthesis of multi-walled carbon nanotubes (MWCNTs) as well as the results of their use as adsorbents for removing the oil contaminants from the surface of water. SEM and TEM analyses were employed to characterize the synthesized MWCNTs. The sorption capacity of MWCNTs for crude oil was 3–4 ml/g, and with an increase in the specific gravity of the petroleum product, this value also increased. Keywords: oil-water films, environmental pollution, multi-walled carbon nanotubes, renewable adsorbents.

Sulphonated date palm (Phoenix dactylifera) stone via microwave‑assisted H2SO4 activation: optimisation with desirability function for methylene blue adsorption

ABSTRACT In this work, a sulphonated date palm (Phoenix dactylifera) stone (SDPS) was produced as a cost-effective and renewable adsorbent for the removal of a cationic dye called methylene blue (MB). The production process involved the use of microwave irradiation combined with H2SO4 activation under the condition of 600 W microwave radiation for 15 min. The physicochemical characteristics of SDPS were evaluated using various analytical techniques, including XRD, BET, FTIR, pHpzc, and SEM. The Box-Behnken design (BBD) was employed to optimise key adsorption variables, including A: SDPS dosage (0.02–0.1 g/100 mL), B: pH (4–10), and C: contact time (5–25) min. According to the BBD model, the most effective removal of MB (98.4%) occurred with a dosage of 0.06 g/100 mL of SDPS, a pH of 10, and a contact time of 25 min. The rate of adsorption of the MB dye followed a pseudo second order (PSO) model, whereas the equilibrium adsorption was described by the Langmuir and Temkin models. The maximum adsorption capacity (q max ) of SDPS for MB dye was found to be 122.3 mg/g at 25°C. Several contributions to the MB dye adsorption process include electrostatic interactions, H-bonding, pore filling, and π-π stacking onto the SDPS adsorbent surface.

Facile fabrication of sulfonated porous yeast carbon microspheres through a hydrothermal method and their application for the removal of cationic dye

Water pollution containing dyes become increasingly serious environmental problem with the acceleration of urbanization and industrialization process. Renewable adsorbents for cationic dye wastewater treatment are becoming an obstacle because of the difficulty of desorbing the dye from the adsorbent surface after adsorption. To overcome this dilemma, herein, we report a hydrothermal method to fabricate sulfonic acid modified yeast carbon microspheres (SA/YCM). Different characterization techniques like scanning electron microscopy, FTIR spectroscopy, and X-ray diffraction have been used to test the SA/YCM. Decorated with sulfonic acid group, the modified yeast carbon microspheres possess excellent ability of adsorbing positively charged materials. The removal rate of Methyl blue (MB) by renewable adsorbent SA/YCM can reach 85.3% when the concentration is 500 mg/L. The SA/YCM regenerated by HCl showed excellent regeneration adsorption capacity (78.1%) after five cycles of adsorption–desorption regeneration experiment. Adsorption isotherm and kinetic behaviors of SA/YCM for methylene blue dyes removal were studied and fitted to different existing models. Owing to the numerous sulfonic acid groups on the surface, the SA/YCM showed prominent reusability after regeneration under acidic conditions, which could withstand repeated adsorption–desorption cycles as well as multiple practical applications.

Response Surface Methodology—Central Composite Design Optimization Sugarcane Bagasse Activated Carbon under Varying Microwave-Assisted Pyrolysis Conditions

Sugarcane bagasse (SB) is a widely available agro-industrial waste residue in China that has the potential to be converted into a cost-effective and renewable adsorbent. In this study, activated carbon (AC) was prepared from SB by microwave vacuum pyrolysis using H3PO4 as the activator. To enhance the sorption selectivity and yield, the pyrolysis process of SB-activated carbon (SBAC) should be well-designed. Central composite design was employed as an optimized experiment design, and response surface methodology was used to optimize the process parameters for maximized SBAC yield and its iodine number. The results showed that the optimized parameters obtained for the SBAC are 2.47 for the impregnation ratio (IR), 479.07 W for microwave power (MP), 23.86 mm for biomass bed depth, and 12.96 min for irradiation time, with responses of 868.7 mg/g iodine number and 43.88% yield. The anticipated outcomes were substantiated, revealing a marginal 5.4% variance in yield and a mere 1.9% discrepancy in iodine number from the forecasted values. The synthesized adsorbents underwent comprehensive characterization through instrumental methodologies, including FT-IR, BET, and SEM. The SBAC produced by the pyrolysis method contained a regular and homogeneous porous structure with a specific surface area of up to 1697.37 m2/g and a total 1.20 cm 3/g volume, which has favorable adsorption of toxic and harmful substances in the environment.

Carbon Microspheres with Cr(VI) Adsorption Performance were Prepared by In-situ Hydrothermal Carbonization Method

Biochar material is a renewable adsorbent widely used for treating contaminated wastewater. The hydrothermal carbon (HTC) were prepared from low polymeric sugars and low concentration glucose under hydrothermal carbonization reactions without using dispersants. The composition and structure of the biochar produced were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Raman spectroscopy (Raman), and N2 adsorption-desorption, indicating that amorphous graphitic carbon was obtained. Experimental results from the static adsorption of Cr(VI)-contaminated wastewater showed that HTCP-2 exhibited the highest adsorption capacity for Cr(VI), with a maximum adsorption capacity of 22.62 mg.g−1.The adsorption Cr(VI), MB, and RhB by the synthesized biochar all conformed to the pseudo-second-order kinetic model and Freundlich isotherm, suggesting a multilayer chemical adsorption process. Additionally, the synthesized HTC surface is enriched with a significant amount of oxygen-rich functional groups, which also has good adsorption performance for cationic dyes. Furthermore, the test results of fluorescence, photocurrent, and impedance indicate that HTCP-2 possesses the ability to generate and separate photoinduced charge carriers. This implied that HTCP-2 can be used for the preparation of adsorption photocatalysts, which effectively remove environmental pollutants through the synergistic effect of adsorption-photocatalysis. This study provides a research foundation for advancing water treatment technologies. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Fabrication of engineered biochar-iron oxide from date palm frond for the effective removal of cationic dye from wastewater

Wastewater containing dye is harmful to the environment. Methylene blue (MB) dye can be removed from wastewater using low-cost, renewable adsorbents. In this study, modified biochar (Biochar-FexOy), pristine biochar and FexOy were fabricated, characterized, and investigated for their performance to remove MB dye from wastewater. The Biochar-FexOy (85.1 mg/g) showed increased adsorption capacity in comparison to biochar (60.1 mg/g) and FexOy (50 mg/g) at an optimum pH of 8 due to the increase in surface area, porosity, and deposition of metal ions on its surface for adsorption. The enhanced MB adsorption by the Biochar-FexOy can be attributed to electrostatic attraction, hydrogen bonding, π-π interactions, and possible cationic exchange as evidenced by the result of the FTIR, EDX, and XRD analysis. Moreover, the adsorption of MB dye by the Biochar-FexOy showed an antagonistic effect in the presence of NaHCO3− and NaCl salt but showed a synergistic effect in the presence of Cu (II) ions. The Langmuir and pseudo-second-order isotherm model best describe the adsorption process of MB dye over the Biochar-FexOy. The adsorption capacity was still high after 4 regeneration cycles for the Biochar-FexOy which concludes that modified biochar can be effectively utilized for dye wastewater treatment. Finally, the fixed-bed column adsorption performance demonstrated that Biochar-FexOy could be used to polish real secondary textile industry effluents prior to treatment.

Magnetic Core@Shell Fe3O4@Polypyrrole@Sodium Dodecyl Sulfate Composite for Enhanced Selective Removal of Dyestuffs and Heavy Metal Ions from Complex Wastewater.

Adsorption materials have demonstrated huge potential in treating sewage; however, it is a great challenge to fabricate an adsorbent effectively adsorbing multiple dyestuffs and heavy metal ions simultaneously. Here, a magnetic core@shell Fe3O4@polypyrrole@sodium dodecyl sulfate (Fe3O4@PPy@SDS) composite is prepared through the combination of a hydrothermal method, an in situ polymerization method, and modification, exhibiting enhanced selective removal of five dyestuffs (methylene blue (MB), malachite green (MG), rhodamine B (RhB), Congo red (CR), acid red 1 (AR1)), and heavy metal ions (Mn(VII)). The effects of adsorbent type, time, initial concentration of the adsorbate, and temperature on adsorption performances are investigated in detail. Kinetics and isotherm studies indicate that all adsorption processes are more in line with the pseudo-second-order kinetic model and the Langmuir model, the diffusion behavior is controlled by intraparticle diffusion and liquid film diffusion, and research of thermodynamics reveals a spontaneous endothermic behavior. The removal efficiency after five desorption-adsorption cycles can still reach more than 90%. The prepared Fe3O4@PPy@SDS composite is an efficient and promising renewable adsorbent for the treatment of dyestuffs and Mn(VII), exhibiting a wide range of applications in the field of adsorption.

Renewable Adsorbents for Selective Phosphorus Removal: Co(OH)2-Derived ZIF-67 on Anion Exchange Resin.

Metal organic framework (MOF)-based adsorbents are appealing for removing low-concentration phosphates with interfering ions in wastewater purification, a new strategy developed to maintain the good activity of metal sites. Here, ZIF-67 was immobilized onto the porous surface of anion exchange resin (D-201) with a high loading amount of 22.0 wt % by a modifiable Co(OH)2 template. We observed that the removal rate of low-concentration phosphate (2 mg P/L) by ZIF-67/D-201 nanocomposites was 98.6%, and more than 90% phosphate adsorption capacity was still maintained, with 5 times molar concentration of interfering ions in the solution. Moreover, after six times of regeneration by solvothermal reaction in the ligand solution, the structure of ZIF-67 was better preserved in D-201 with more than 90% phosphate removal rate. ZIF-67/D-201 could be employed effectively in fixed-bed adsorption runs. By the analysis of experiment and characterization, we found that during the adsorption-regeneration process of ZIF-67/D-201 for phosphate, reversible structural transformation of ZIF-67 and Co3(PO4)2 occurred in D-201. In general, the study reported a new method to develop MOF adsorbents for wastewater treatment.

Activated carbon modified with polyethyleneimine and MgO: Better adsorption of aldehyde and production of regenerative VOC adsorbent using a photocatalyst

In this study, a renewable adsorbent containing a photocatalyst is developed that exhibits effective adsorption performance for polar volatile organic compounds (VOCs) that are not well adsorbed by activated carbon (AC). AC is used as the basic adsorbent, and the surface of the AC is modified with polyethyleneimine (PEI) and magnesium oxide (MgO) for the effective adsorption of polar VOCs. In addition, a renewable VOC adsorbent and filter are demonstrated by introducing titanium dioxide (TiO2) as a photocatalyst to impart regeneration. The changes in the physical and chemical structures of the AC surface due to the modification with PEI and the loading of MgO and its effects are confirmed through scanning electron microscopy, Brunauer–Emmett–Teller (BET) analysis, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy analyses. Developing slit pores containing polar functional groups on the AC through PEI deposition and loading MgO in the pore of AC increase the adsorption capacity of acetaldehyde by four times (3.08–13.8 mg g−1). In addition, PEI deposition shows high regeneration efficiency (86.4 %) with the application of TiO2. This study provides important insights into the development of renewable VOC filters that can be used for various VOCs.

Reversible lewisite adsorption/desorption on the transition-metal-doped graphene: first-principle calculations

Arsenical compound lewisite was developed as a potent chemical warfare agent in the blister agent class and later abandoned in the war areas. Exposure to lewisite can cause serious damage to human skin, eyes, and respiratory tract. Consequently, it is essential to develop materials that can detect and remove abandoned lewisite efficiently. In the present work, we investigated the ability of transition-metals-doped (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) graphene (TM/G) to eliminate lewisite using density functional theory. The adsorption geometry, adsorption energy, charge transfer, density of states, and UV spectra of the adsorption system of lewisite on TM/G (L@TM/G) were calculated and analyzed. Computational results demonstrate the presence of a strong chemical interaction between TM/G substrate and the lewisite molecule. More importantly, the adsorption of lewisite on TM/G can be tuned by introducing an electric field with proper direction and intensity, resulting in reversible adsorption/desorption. Furthermore, the electronic and optical properties of TM/G significantly change following the lewisite adsorption, rendering TM/G a promising material for the detection of lewisite. Herein, we suggest TM/G as a potential sensor and renewable adsorbent for lewisite.

Extractives-free sugarcane bagasse as adsorbent for the removal of Rhodamine B (Basic Violet 10) with high capacity and reusability

The use of extractives-free SCB (eSCB) as a renewable adsorbent for removing rhodamine B (RhB) in water was explored to contribute to strategies for conserving the environment and better use of natural resources. Different initial pH (3–9) and RhB concentrations (10–1100 mg/L) at various temperatures (303–333 K) during adsorption were carried out to assess the uptake kinetics and equilibrium uptake. The Elovich and the multi-mechanistic models best describe the adsorption kinetics. The adsorption of RhB on eSCB is primarily physisorption but may also involve chemisorption under certain conditions. The adsorption process co-occurs within and on the surface of the eSCB matrix. The adsorption capacity of eSCB for RhB is 88.71 mg/g at 318 K, and the Brouers-Sotologo model best describes the equilibrium uptake isotherm. The adsorption of RhB on eSCB is a spontaneous and exothermic process. This study is the first to report on the regeneration and reuse of eSCB as an adsorbent for RhB. Extractives-free SCB can be reused for at least 7 cycles, using 95% ethanol to remove the adsorbed dyes between cycles. The reused eSCB adsorbent retains 80 % of its adsorption capacity even after its 7th reuse.

Agricultural Wastes as Renewable Biomass to Remediate Water Pollution

Increases in agricultural waste, population, and industrialization are leading to serious environmental problems, in particular drinking water contamination. Continuous efforts have been made to remediate water pollution through different approaches, either by decreasing the interring of pollutants or treatment of already contaminated water. The development of an efficient, cheaper, and renewable adsorbent is the focus of the current research. Agricultural wastes are cheap materials for this purpose and have attracted much attention of researchers. These agricultural wastes are either field residues such as stems, stalks, and leaves, or process residues such as husks, roots, and bagasse, as they have the same chemical composition (cellulose, hemicelluloses, and lignocelluloses). These wastes are processed using different methods to yield an efficient adsorbent. Chemical modification is used to prepare novel efficient adsorbents using agricultural wastes, rather than incineration of these materials. This review summarizes the research outcomes in terms of chemical modification and application of agricultural wastes used for the eradication of organic and inorganic pollutants from water.

Optimization of activated carbon production from corn cob using response surface methodology

Waste management and valorization of waste is a major global issue. Low-cost and renewable adsorbent activated carbon (AC) from agriculture residues is a focus of worldwide concern. Microwave heating is an efficient technology for production of AC. CCAC was synthesized from corn cob via microwave vacuum pyrolysis under ambient vacuum, and the optimization process for maximized CCAC yield and its iodine number was developed using response surface methodology (RSM). These regression models have high Fisher test value and lower p-value, which ensure its reliability and applicability. The optimized parameters obtained are 550.62 W, 9.26 min, -0.05 Mpa, and 1.7 IR with responses of 37.57% yield and 933.38 mg/g iodine number. The predicted results were validated, and it was found that the experimental data varied only by 4.21% in yield and 4.02% in iodine number from the predicted values. The prepared adsorbent was characterized using instrumental techniques like FT-IR, BET, and SEM. The pyrolysis approach produced CCAC containing regular and homogeneous porous structure with a specific surface area of up to 995.05 m2/g and total volume of 0.708 cm3/g.

Construction of porous biochar decorated with NiS for the removal of ciprofloxacin antibiotic from pharmaceutical wastewaters

The employment of residual biomass to produce promising sorbents with highly adsorption characteristics and their successful application for the removal of antibiotics from wastewater has gained considerable interest because of their low production cost and sustainability. Herein, the banana peel waste (BP), its modified biochar (BC), and activated biochar decorated with NiS (BC-NiS) were assessed as renewable adsorbents for efficient removal of ciprofloxacin antibiotic (CIP) from wastewater. The modification of BP with H3PO4 followed by the carbonization process produced porous banana peel biochar (BC) with larger acidic functional groups that formed on the carbon surface. This activation facilitated the effective synthesis of biochar decorated with NiS (BC-NiS) using a facile hydrothermal approach. The samples were characterized by XRD, FE-SEM, EDX, HR-TEM, BET, FTIR, and XPS analysis. The influence of operating factors including pH, contact time, initial CIP concentration, adsorbents dose, interfering ions, and solution temperature on the removal of ciprofloxacin by banana peel waste and its porous biochar modified with NiS was also evaluated. The maximum adsorption capacity of the BC-NiS hybrid structure was found to be 41.66 mg/g, which was highly effective compared with BP (20.83 mg/g) and BC (35.71 mg/g) for CIP removal without pH adjustment. A good fit was observed by the pseudo-second-order model and the Langmuir adsorption isotherm. The values of △ H° and △G° indicated the endothermic and spontaneous character of the adsorption process. The adsorption mechanism has been comprehensively elucidated by electrostatic interaction, π-π stacking, coordination affinities, and pore-filling effect. Desorption and recycling studies of the BC-NiS hybrid structure were also carried out to investigate its stability, and the results showed that it can be recycled without a substantial loss in the adsorption process after three recycle runs.

Hydroxyl-modified zirconia/porous carbon nanocomposite used as a highly efficient and renewable adsorbent for removal of carbamazepine from water

Metal-organic frameworks (MOFs) derived metal oxides/porous carbon nanocomposites were used as adsorbents to remove pollutants from wastewater. The adsorption performance of the metal oxides/porous carbon nanocomposites could be improved by introducing functional groups. In this study, hydroxyl-modified zirconia/porous carbon nanocomposite (C-UiO-66-OH) was prepared and tested, choosing carbamazepine as a typical pollutant. The results showed that the adsorption capacity (186.21 mg g−1) of C-UiO-66-OH was 6.96 times to that of normal UiO-66. The Langmuir isotherm model and pseudo-first-order kinetic model was well fit the adsorption process. The thermodynamic parameters indicated that the adsorption process was spontaneous and endothermic. The adsorbent regeneration could be accomplished by washing C-UiO-66-OH with ethanol and DI water. The good adsorption/desorption performance comes from the synergistic effect of (EDA) interaction and hydrogen bond between C-UiO-66-OH and CBZ molecule. A membrane prepared by immobilizing C-UiO-66-OH into melamine foam (MF) with sodium alginate (SA) was also investigated for CBZ adsorption. The results indicated the excellent removal efficiency (86.0%) and good regeneration of the prepared membrane. Therefore, this paper provides an efficient and applicable way to remove CBZ from water.

Renewable adsorbents from the solid residue of sewage sludge hydrothermal liquefaction for wastewater treatment

Solid residue from hydrothermal liquefaction (HTL) of nutrient rich feedstock presents a promising source to recover valuable nutrients, such as phosphorus, in the solid form. The present work shows for the first time the potential of utilizing the waste residue remaining after nutrients extraction from HTL of sewage sludge, as renewable adsorbents. A parametric study was undertaken to investigate the influence of chemical activation conditions (temperature, residence time, activation agent loading, washing after activation) on raw and partially demineralized HTL solids. Kinetic and equilibrium adsorption investigation was undertaken for the removal of methylene blue (MB) from aqueous solution. For comparison purposes, a commercial activated charcoal (AC) was used. Demineralization was found to have a significant influence in the adsorption capacity of the resultant adsorbents. Three adsorbents were found to follow the Langmuir adsorption model, while the acid washed demineralized adsorbent had higher adsorption capacity than AC and was found to follow the Freundlich adsorption model. The superior performance of the acid washed demineralized adsorbent was verified from the kinetic study where all adsorbents were found to best fit the pseudo-second order model. Adsorption capacities for MB at equilibrium were 367.1, 332.3, 297.4 and 87.6 mg/g, for acid washed demineralized adsorbent, AC, demineralized adsorbent, and raw adsorbent, respectively. Finally, the most promising adsorbents were assessed for their adsorption capacity to remove pharmaceuticals present in a real wastewater treatment effluent. Results indicated ultimate concentration for all targeted compounds below the detection limits for acid washed demineralized adsorbent, AC and demineralized adsorbent. Future implementation of HTL technology in wastewater treatment facilities, will not only provide an efficient way to valorize sewage sludge into bio-crude and nutrients, but can also enhance technology integration by providing the precursors for renewable adsorbents needed in tertiary treatment of wastewater.

Investigation of hydrothermal carbonization and chemical activation process conditions on hydrogen storage in loblolly pine-derived superactivated hydrochars

While the challenge of storing hydrogen in inexpensive and renewable adsorbents is relentlessly pursued by researchers all over the world, application of hydrochar derived from biomass is also gaining attention as it can be subsequently chemically activated using activating agents like KOH in order to tailor the development of favorable porosity. However, the synergistic effect of hydrothermal carbonization (HTC) process conditions as well as KOH activating conditions on the development of surface morphology is required to be assessed with the application of such porous superactivated hydrochars in hydrogen storage application. In this study, highly porous superactivated hydrochars were fabricated from inexpensive and abundant loblolly pine. Loblolly pine was hydrothermally carbonized at 180 °C, 220 °C and 260 °C and the hydrochars were then activated at different experimental conditions of 700 °C, 800 °C and 900 °C using solid KOH to loblolly pine hydrochar ratio of 2:1, 3:1 and 4:1 to produce superactivated hydrochars. Superactivated hydrochars as well as loblolly pine and its corresponding hydrochars underwent physicochemical analysis as well as surface morphology analysis by SEM and nitrogen adsorption isotherms at 77 K in order to investigate the effect on BET, pore volume, and pore size distribution due to various process conditions. The superactivated hydrochars were then analyzed to quantify total hydrogen storage capacity of these materials at 77 K and up to pressure of 55 bar. Porosity of superactivated hydrochars were as high as 3666 m2/g of BET specific surface area (SSA), total pore volume of 1.56 cm3/g and micropore volume of 1.32 cm3/g with the hydrogen storage capacity of 10.2 wt% at 77 K and 55 bar. It was conclusive from principal component analysis that higher HTC temperature with moderate activation condition demonstrated favorability in developing porous superactivated hydrochars for hydrogen storage applications.

Efficient adsorption of acetaminophen from the aqueous phase using low-cost and renewable adsorbent derived from orange peels

Pharmaceutically active compounds (PhACs) are frequently detected emerging pollutants in water resources worldwide that provoke pernicious influences on human health and the ecosystem. Developing effective carbonaceous adsorbents from biomass for the efficient removal of PhACs has lately drawn significant research attention. Herein, an efficient and cost-effective activated carbon was produced via ZnCl2-activation, employing orange peels as a precursor (named hereafter as OPAC). OPAC was well-characterized and applied in the sequestration of acetaminophen (N-acetyl-para-aminophenol, APAP), a broadly used non-steroidal anti-inflammatory drug, from water media using the batch technique. OPAC exhibited excellent performance, and more than 95.5% APAP was removed after 90 min, in the pH range of 2.0–8.0, using 1 g/l adsorbent at 25 °C. Additionally, the equilibrium and the kinetic studies outcomes unveiled the suitability of the Langmuir and the pseudo-second-order kinetic models, respectively, to describe the adsorption process. Based on the pH-adsorption dependence and OPAC properties, the presumable mechanism was mainly dominated by non-electrostatic interactions, including hydrogen bonding, π-π interactions, and pore diffusion. Thermodynamically, the process was found to be spontaneous and endothermic. Ultimately, OPAC manifested outstanding recyclability, with at least 95% of the initial efficiency being preserved after five cycles, making it more attractive from the environmental and economic perspectives.