Development of a novel and efficient biochar produced from pepper stem for effective ibuprofen removal

Low-Cost Chestnut-Based Biocarbons Physically Activated via CO2 or Steam: Evaluation of the Structural and Adsorption Properties

The aim of this paper was to obtain activated biocarbons from the natural biomass of horse chestnut seeds (Aesculus hippocastanum) by physical activation with two different activating agents, carbon dioxide and water vapor, and to evaluate their structural and adsorption properties. The effect of the pyrolysis atmosphere on the surface development and porosity as well as the structure and adsorption properties of the materials in relation to the selected organic adsorbates (tetracycline (TC), naproxen (NPX), and methyl orange (MO)), which may constitute a potential contamination of the aquatic environment, was evaluated. Activated biocarbons were characterized using N2 low-temperature adsorption/desorption, Raman and FT-IR spectroscopy, and thermogravimetric analysis (TGA). The nature of the surface (pHpzc and Boehm titration) was also studied. Micro/mesoporous biocarbons were obtained with an SBET area in the range of ~534 to 646 m2/g, in which micropores constituted ~70%. It was proved that the obtained materials are characterized by high adsorption values (~120 mg/g, ~150 mg/g, and ~252 mg/g) and removal rates %R (~80%, ~95%, and ~75%) for TC, NPX, and MO, respectively. The results indicate that chestnut-derived activated biocarbons are a promising, cost-effective and environmentally friendly alternative for removing organic contaminants from aqueous solutions. Future research should focus on optimizing activation parameters and assessing the long-term performance of adsorbents.

Biochar for mitigating pharmaceutical pollution in wastewater: A sustainable solution

Pharmaceutical contaminants (PCs), including antibiotics, analgesics, and other medications, pose a growing threat to aquatic ecosystems and human health due to their persistence and bioaccumulation potential. Biochar, a carbonaceous material derived from biomass pyrolysis, has emerged as a sustainable adsorbent for removing PCs from wastewater. Biochar is reported to remove PCs from water with an average range of 58 to 91 %, depending on the nature of feedstock, pyrolysis conditions, and characteristics of the pharmaceuticals. Biochar's effectiveness is attributed to its unique properties, including high porosity, large surface area and diverse functional groups, which enable the adsorption of various pharmaceutical compounds through physical and chemical interactions. Common PCs such as tetracycline, ciprofloxacin, ibuprofen, paracetamol, sulfamethoxazole, and cephalexin can be effectively removed using biochar. The adsorption process involves different mechanisms such as Van der Waals forces, electrostatic interactions, hydrogen bonding, and surface complexation. This review summarizes the current state of knowledge on biochar-based adsorption mechanisms, highlights successful applications in wastewater treatment, and identifies areas for future research. While promising, a deeper understanding of adsorption mechanisms, optimization of biochar production, and the development of effective regeneration methods are crucial for maximizing biochar's efficacy and ensuring its sustainable implementation in wastewater treatment systems.

Valorizing date palm spikelets into activated carbon-derived composite for methyl orange adsorption: advancing circular bioeconomy in wastewater treatment-a comprehensive study on its equilibrium, kinetics, thermodynamics, and mechanisms

Leveraging date palm spikelets (DPS) as a precursor, this study developed a DPS-derived composite (ZnO@DPS-AC) for water treatment, focusing on methyl orange (MO) removal. The composite was synthesized through ZnCl2 activation and pyrolysis at 600 °C. Comprehensive characterization was conducted using TGA, FTIR, XRD, SEM/EDS, and pHPZC. Characterization revealed a highly carbonaceous material (> 74% carbon) with significant porosity and surface functional groups. ZnO@DPS-AC demonstrated rapid MO removal, achieving over 45% reduction within 10 min and up to 99% efficiency under optimized conditions. The Langmuir model-calculated maximum adsorption capacity reached 226.81 mg/g at 20 °C. Adsorption mechanisms involved hydrogen bonding, π-π interactions, and pore filling. The composite showed effectiveness in treating real wastewater and removing other pollutants. This study highlights the potential of agricultural waste valorization in developing efficient, sustainable adsorbents for water remediation, contributing to circular bioeconomy principles.

Polyethyleneimine-functionalized magnetic sugarcane bagasse cellulose film for the efficient adsorption of ibuprofen

Polyethyleneimine-modified magnetic sugarcane bagasse cellulose film (P-SBC/Fe3O4 film) was simply fabricated for the removal of ibuprofen (IBP), a typical emerging organic contaminant. The P-SBC/Fe3O4 film exhibited an equilibrium adsorption amount of 370.52 mg/g for IBP and a corresponding removal efficiency of 92.63 % under following adsorption conditions: 318 K, pH 4, and 0.25 mg/mL dosage. Thermodynamic studies indicated that adsorption of IBP on the P-SBC/Fe3O4 film was spontaneous (∆G < 0) and endothermic (∆H > 0). The adsorption data conformed to the Freundlich isotherm model and multilayer adsorption model (two layers), and an average of 3-4 active sites on the P-SBC/Fe3O4 film share an IBP molecule. Both the EDR-IDR and AOAS models vividly described the dynamic characteristics of adsorption process. Model fitting results, theoretical calculations, and comprehensive characterization revealed that adsorption is driven by electrostatic interactions between the primary amine of P-SBC/Fe3O4 film and the carboxyl group of IBP molecule, while other weak interactions are also non-ignorable. Furthermore, quantitative calculations based on density functional theory (DFT) underscored the importance of PEI functionalization. In conclusion, P-SBC/Fe3O4 film is an environmentally friendly and cost-effective adsorbent with significant potential for effectively removing IBP, while maintaining its efficacy over multiple cycles.

Evaluation of Phenobarbital Adsorption Efficiency on Biosorbents or Activated Carbon Obtained from Adansonia Digitata Shells

The removal of pharmaceutically active compounds present in relatively low concentration in wastewater is critical. This is because they have a severe, negative impact on life and the environment. To address this issue, adsorption was used, which is an effective wastewater treatment method for removing substances found in low concentrations in water. This study compared the adsorption performance of active carbon to three biosorbents derived from Adansonia digitata shells. The adsorbents were prepared and characterized using TGA, SEM, EDX, and FTIR analyses and pHPZC. To better understand the adsorption process, equilibrium and reaction kinetics studies were conducted. The effect of contact time, initial phenobarbital concentration, adsorbent mass, and pH was investigated in static conditions. The adsorption results revealed that the biosorbent B3 has a higher affinity for the eliminated compound, with an equilibrium time of 60 min and an adsorption capacity of 47.08 mg/g at an initial concentration of 50 mg/L. The experimental data are consistent with Langmuir and Sips adsorption isotherm models, and with the pseudo-second order and Elovich models for kinetics description. This indicates strong interactions between the adsorbent materials and the pharmaceutical micropollutant. Based on these findings, it appears that, among the tested materials, B3 biosorbent is the most efficient for removing phenobarbital present in low concentrations in water.

Highly effective degradation of ibuprofen by alkaline metal-doped copper oxides via peroxymonosulfate activation: Mechanisms, degradation pathway and toxicity assessments

Redox ratios of Cu2+/Cu+ and adsorbed oxygen species (Oads) have shown great activity toward radical generation by activating peroxymonosulfate (PMS). Herein, different alkaline metal oxides (CaO, MgO and BaO) and various amounts of CaO are incorporated into CuO, which could tune the main active sites of redox ratios of Cu2+/Cu+ and Oads. The results show that CaO-CuO-5% exhibits the outstanding performance of PMS activation toward ibuprofen (IBF) degradation with excellent kinetics (k = 0.812 min-1). The X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculation show that the CaO-CuO-5% has the higher electron density with superior electron transfer ability and lower PMS adsorption energy. Based on radical scavengers and electron paramagnetic resonance spectrometer (EPR), a nonradical process is proposed to play the dominant role. The degradation pathway and the corresponding toxicity of degraded intermediates with residue PMS after reaction is evaluated by LC-MS/MS and bioassay experiments, indicating the lower antagonistic influence on human hormone receptors after advanced oxidation process. Mitigation of the Cu leaching with cyclic stability can be achieved. This study provides a facile method to optimize high-performance catalysts to activate PMS and offer practical environmental applications in the remediation of emerging contaminants.

The efficient removal of ibuprofen, caffeine, and bisphenol A using engineered egusi seed shells biochar: adsorption kinetics, equilibrium, thermodynamics, and mechanism

Contaminants of emerging concern (CECs), also known as micropollutants, have been recognized in recent years as substantial water pollutants because of the potential threats they pose to the environment and human health. This study was aimed at preparing biochar (BC) based on egusi seed shells (ESS) with well-developed porosity and excellent adsorption capacity towards CECs including ibuprofen (IBP), caffeine (CAF), and bisphenol A (BPA). BC samples were prepared by pyrolysis at different temperatures (400 to 800 °C) and were characterized using nitrogen sorption, FTIR, powder X-ray diffraction (PXRD), SEM/EDS, elemental analysis, and thermal analysis. The nitrogen sorption and SEM results showed that the textural properties were more prominent as the pyrolysis temperature increased. The BC sample obtained at 800 °C which exhibited the largest specific surface area (688 m2/g) and the highest pore volume (0.320 cm3/g) was selected for the adsorption study of CECs. The kinetic study shows that the adsorption equilibrium of CAF and BPA was faster than that of IBP. The pseudo-first- and pseudo-second-order kinetic models best fitted the adsorption data. The Langmuir maximum monolayer adsorption capacities of biochar were found to be ~ 180, 121, and 73 mg/g respectively for IBP, CAF, and BPA. The thermodynamic study shows that the adsorption process was spontaneous and endothermic for the three CECs. The results of the adsorption and the analysis of BC after adsorption showed that hydrogen bonding, van der Waals, π-π, n-π interactions, and pore filling were involved in the adsorption mechanism. The prepared biochar BC from ESS displayed a large surface area and good morphology and significantly promotes adsorption of CECs and good efficiency on synthetic effluent. Finally, it offers a low-cost and cleaner production method.

The use of agro-waste-based adsorbents as sustainable, renewable, and low-cost alternatives for the removal of ibuprofen and carbamazepine from water

The occurrence of residual pharmaceuticals in the aquatic environment poses major toxicological impacts and adds to the increasing pressure on water resources. Many countries are already suffering from water scarcity, and with the burdening costs of water and wastewater treatment, the race towards innovative sustainable strategies for pharmaceutical remediation is ongoing. Out of the available treatment methods, adsorption proved to be a promising, environmentally friendly technique, particularly when efficient waste-based adsorbents are produced from agricultural residues, thus maximizing the value of wastes, minimizing production costs, and saving natural resources from depletion. Among the residual pharmaceuticals, ibuprofen and carbamazepine are heavily consumed and highly occurring in the environment. This paper aims to review the most recent literature on the application of agro-waste-based adsorbents as sustainable alternatives for the removal of ibuprofen and carbamazepine from contaminated waters. Highlights on the major mechanisms implicated in the adsorption of ibuprofen and carbamazepine are presented, and light is shed on multiple operational parameters that hold a key role in the adsorption process. This review also highlights the effects of different production parameters on adsorption efficiency and discusses many limitations currently encountered. Finally, an analysis is included to compare the efficiency of agro-waste-based adsorbents relative to other green and synthetic adsorbents.

One-pot preparation of layered double oxides-engineered biochar for the sustained removal of tetracycline in water

Tetracycline (TC) and sugarcane bagasse had both exerted enormous strain on environmental security. In this work, new composite adsorbent designed by impregnating bio-waste bagasse with magnesium-aluminum layered double oxides (BC-MA) was innovatively brought forward for TC removal. Benefiting from the abundant adsorption sites supplied by developed pores structure (0.308 cm³·g^-1), enlarged surface area (256.8 m²·g^-1) and reinforced functional groups, the maximum adsorption amount of BC-MA for TC reached 250.6 mg g^-1. Moreover, BC-MA displayed desirable adsorption capacity in diverse water environments coupled with excellent sustainable regeneration ability. The absorption process of TC by BC-MA was spontaneous and endothermic, and the pivotal rate-limiting stage pertained to intraparticle diffusion. The mechanisms proposed here mainly concerned π-π interactions, pore filling, complexation and hydrogen bonding. These findings suggested that the synthesis of modified biochar from bagasse would offer new opportunities for simultaneous waste resource reuse and water pollution control.

Ultra-efficient adsorption of diclofenac sodium on fish-scale biochar functionalized with H3PO4 via synergistic mechanisms

Developing safe and efficient diclofenac sodium (DS) removal technology has become a critical issue. This study synthesized the fish-scale biochar by co-pyrolysis of fish scale and phosphoric acid (H₃PO₄). In addition to increasing the specific surface area and pore volume of fish-scale biochar, H₃PO₄ assisted in the formation of Graphitic N and sp² C, as well as reacting with C═O groups to form a significant number of phosphorus-containing groups. All these functional groups could act as major active sites for DS adsorption. Adsorption data could well fit pseudo-second-order and Langmuir models. The maximum adsorption capacity of FSB_600-15 for DS was 967.1 mg g^-1, which was much better than that reported in the literature. Under the synergistic effect of various mechanisms (pore-filling effect, electrostatic attraction, H-bonding, π-π, and n-π electron donor-acceptor interactions), the DS ultra-efficient adsorption on FSB_600-15 was realized. Meanwhile, the DS adsorption by FSB_600-15 was an endothermic, spontaneous, and entropy-increasing process. Furthermore, the DS adsorption capacity was more than 426.5 mg g^-1 in the actual water, which was sufficient for practical applications.

Characterization of ibuprofen removal by calcined spherical hydrochar through adsorption experiments, molecular modeling, and artificial neural network predictions

Ibuprofen (IPF) is one of the most prescribed nonsteroidal anti-inflammatory drugs in recent times, but it is not readily removed in conventional wastewater treatments. Here, we investigate the adsorption characteristics of IPF onto calcined spherical hydrochar (CSH), which was synthesized through hydrothermal carbonization of sucrose followed by calcination. The adsorption experiments show that the equilibration time for IPF was 360 min, and a pseudo-second-order model was best fitted to the kinetic data. The isotherm data were best described by the Liu model with a theoretical maximum adsorption capacity of 95.6 mg/g. The thermodynamic data indicate the endothermic nature of the adsorption at 10-40 °C. The CSH was favorably regenerated and reused using methanol. In pH experiments, the IPF adsorption capacity declined gradually as pH rose from 2 to 8, dropped rapidly at pH 10, and became negligible at pH 12. The IPF adsorption to the CSH could occur through various adsorption mechanisms. Hydrogen-bond formation, π-π interactions, n-π* interactions, and electrostatic repulsion were explored and visualized with molecular modeling using CHEM3D. The Raman, FTIR, and XPS spectra suggest that π-π interactions could take place between the CSH and IPF. Considering the pK_a value of IPF (4.91) and pH_iep of the CSH (3.21), electrostatic repulsion between the negatively-charged CSH and anionic IPF could play a negative role in the adsorption. A pore-filling mechanism could contribute to the adsorption in view of the molecular size of IPF (9.43 Å × 7.75 Å × 6.23 Å) and the average pore diameter of the CSH (2.27 nm). In addition, hydrophobic interactions could be involved in the adsorption. Multi-factor adsorption experiments were executed with pH, temperature, CSH dosage, and initial IPF concentrations as input variables and IPF removal rate as an output variable, and an artificial neural network (ANN) model with a topology of 4:9:11:1 was developed to sufficiently describe the adsorption data (R > 0.99). Further analyses with additional experimental data confirm that the ANN model possessed good predictability for multi-factor adsorption.

Removal of micropollutants through bio-based materials as a transition to circular bioeconomy: Treatment processes involved, perspectives and bottlenecks

The recent increase in micropollutant levels in water bodies is a growing concern globally. The generation of new materials and techniques for wastewater treatment often involves the release of hazardous wastes and the utilization of energy related to it. This can be resolved by the synthesis of bio-based materials through the use of already released wastes and naturally occurring components, adding their value as reusable resources. These bio-based materials find wide applications for micropollutant elimination and energy tapping due to the presence of various functional groups, large surface area, high stability, and reusability. The processes involved in micropollutant elimination through biomaterials generally include adsorption and degradation. These treatment processes are suggested to depend on various operational parameters like pH, temperature, dose, reaction time, presence of other contaminants, ions, etc. in the system, which may influence the process efficiency. Understanding the potential of bio-based materials many steps can be taken towards its large-scale application to upgrade wastewater treatment plants for micropollutant elimination. Furthermore, the recent advances of bio-based materials in energy storage and conversion have widened its scope for implementation in a circular bioeconomy. The bottlenecks towards such a transition and future recommendations are also presented and discussed.