Preparation of mesoporous batatas biochar via soft-template method for high efficiency removal of tetracycline

Improving the adsorption properties of low surface area hardwood biochar for the removal of Fe+ and PO₄3- from aqueous solution

Biochar produced from wood residues may provide a new method and material for managing the environment, particularly in terms of carbon sequestration and contaminant remediation. Additionally, biochar produced from wood residues is free of chemical fertilizers, likewise in rice straw, wheat straw, corn straw, etc. This study investigated the removal of iron from aqueous solutions by a novel low-cost and eco-friendly biochar made from hardwood trees and modified by adding MgCl2 for effective phosphate removal. Optimal adsorption conditions were determined through studies of adsorption time, pH, and adsorbent dosage. Batch equilibrium isotherm and kinetic experiments and pre/post-adsorption characterizations using FESEM-EDS, XRD, and FTIR suggested that the presence of carboxyl group elements and colloidal and nano-sized MgO (periclase) particles on the biochar surface were the main adsorption sites for aqueous iron and phosphate respectively. In this study, the HW and MgO-HW biochar showed excellent Dubinin-Radushkevich isotherm (D-R) maximum adsorption capacities of 289.45 and 828.82 mg/g for iron and phosphate. The kinetic study for iron and phosphate adsorption was described well by pseudo second-order model and pseudo second-order model respectively. The HW biochar and the prepared MgO-HW biochar exhibited commendable iron adsorption (98.25%) performance at 10 pH units and phosphate (96.22%) at pH 6 respectively. Thus, this research reveals a waste-to-wealth strategy by converting hardwood waste into mineral-biomass biochar with excellent Fe and P adsorption capabilities and environmental adaptability.

Recent Advances in Functionalized Biomass-Derived Porous Carbons and their Composites for Hybrid Ion Capacitors

Hybrid ion capacitors (HICs) have aroused extreme interest due to their combined characteristics of energy and power densities. The performance of HICs lies hidden in the electrode materials used for the construction of battery and supercapacitor components. The hunt is always on to locate the best material in terms of cost-effectiveness and overall optimized performance characteristics. Functionalized biomass-derived porous carbons (FBPCs) possess exquisite features including easy synthesis, wide availability, high surface area, large pore volume, tunable pore size, surface functional groups, a wide range of morphologies, and high thermal and chemical stability. FBPCs have found immense use as cathode, anode and dual electrode materials for HICs in the recent literature. The current review is designed around two main concepts which include the synthesis and properties of FBPCs followed by their utilization in various types of HICs. Among monovalent HICs, lithium, sodium, and potassium, are given comprehensive attention, whereas zinc is the only multivalent HIC that is focused upon due to corresponding literature availability. Special attention is also provided to the critical factors that govern the performance of HICs. The review concludes by providing feasible directions for future research in various aspects of FBPCs and their utilization in HICs.

Advances in sustainable nano-biochar: precursors, synthesis methods and applications

Nano-biochar, characterized by its environmentally friendly nature and unique nanostructure, offers a promising avenue for sustainable carbon materials. With its small particle size, large specific surface area, abundant functional groups and tunable pore structure, nano-biochar stands out due to its distinct physical and chemical properties compared to conventional biochar. This paper aims to provide an in-depth exploration of nano-biochar, covering its sources, transformation mechanisms, properties, applications, and areas requiring further research. The discussion begins with an overview of biomass sources for nano-biochar production and the conversion processes involved. Subsequently, primary synthesis methods and strategies for functionalization enhancement are examined. Furthermore, the applications of nano-biochar in catalysis, energy storage, and pollutant adsorption and degradation are explored and enhanced in various fields.

Catalytically Active Carbon for Oxygen Reduction Reaction in Energy Conversion: Recent Advances and Future Perspectives

The shortage and unevenness of fossil energy sources are affecting the development and progress of human civilization. The technology of efficiently converting material resources into energy for utilization and storage is attracting the attention of researchers. Environmentally friendly biomass materials are a treasure to drive the development of new-generation energy sources. Electrochemical theory is used to efficiently convert the chemical energy of chemical substances into electrical energy. In recent years, significant progress has been made in the development of green and economical electrocatalysts for oxygen reduction reaction (ORR). Although many reviews have been reported around the application of biomass-derived catalytically active carbon (CAC) catalysts in ORR, these reviews have only selected a single/partial topic (including synthesis and preparation of catalysts from different sources, structural optimization, or performance enhancement methods based on CAC catalysts, and application of biomass-derived CACs) for discussion. There is no review that systematically addresses the latest progress in the synthesis, performance enhancement, and applications related to biomass-derived CAC-based oxygen reduction electrocatalysts synchronously. This review fills the gap by providing a timely and comprehensive review and summary from the following sections: the exposition of the basic catalytic principles of ORR, the summary of the chemical composition and structural properties of various types of biomass, the analysis of traditional and the latest popular biomass-derived CAC synthesis methods and optimization strategies, and the summary of the practical applications of biomass-derived CAC-based oxidative reduction electrocatalysts. This review provides a comprehensive summary of the latest advances to provide research directions and design ideas for the development of catalyst synthesis/optimization and contributes to the industrialization of biomass-derived CAC electrocatalysis and electric energy storage.

Effective Use of Sugarcane-Bagasse-Derived KOH-Activated Biochar for Remediating Norfloxacin-Contaminated Water

Bagasse-derived biochar (SCB750) was prepared at 750 °C using Chinese sugarcane bagasse as a carbon source and then modified with KOH for the removal of the antibiotic norfloxacin (NOR) from aqueous solutions. 3K-SCB750, prepared using a solid-to-liquid mass ratio of bagasse:KOH = 1:3, was found to have the best adsorption performance for NOR. Under the conditions of pH 5, 25 °C, 2.4 g L-1 adsorbent, and 300 mg L-1 NOR, its adsorption of NOR reached equilibrium (97.5% removal) after 60 min. The adsorption behaviours were in line with the quasi-second-order kinetic and Langmuir isotherm models, respectively. The maximum theoretical adsorption capacity reached up to 157.4 mg·g-1 at 40 °C. The thermodynamic parameters showed that the adsorption of NOR onto 3K-SCB750 was a spontaneous, endothermic, and physical process. In addition, Brunauer-Emmett-Teller analysis (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy were conducted to investigate the structural and adsorption properties of 3K-SCB750. Fourier transform infrared spectroscopy (FTIR) was also applied to understand the mechanism of adsorption of NOR onto 3K-SCB750. All of the results indicated that 3K-SCB750 had a large specific surface area of 1038.8 m2·g-1, an average pore size of 1.9 nm, and hierarchical structures with random pores and cracks for efficient removal of NOR. NOR adsorption mechanisms on 3K-SCB750 were related to the pore-filling effect and electrostatic attraction. Therefore, 3K-SCB750 biochar may be used as a promising adsorbent of antibiotics in wastewaters.

The Removal of Pollutants from Wastewater Using Magnetic Biochar: A Scientometric and Visualization Analysis

In recent years, the use of magnetic biochar in wastewater treatment has shown significant effects and attracted scholars' attention. However, due to the relatively short research time and the lack of systematic summaries, it is difficult to provide a more in-depth analysis. This study utilizes RStudio and CiteSpace software to comprehensively analyze the research trends and progress of magnetic biochar in wastewater treatment. The analysis of bibliometrics is performed on 551 relevant papers retrieved from the Web of Science, spanning the period between 2011 and 2022. The most influential countries, institutions, journals, disciplinary distribution, and top 10 authors and papers in this field have been identified. The latest dataset has been used for keyword clustering and burst analysis. The results indicated that: (1) Bin Gao is the most influential author in this field, and high-level journals such as Bioresource Technology are more inclined to publish articles in the field of magnetic biochar. (2) Research in this field has predominantly focused on the removal of heavy metals and organic compounds. Keyword burst analysis shows a shift in research direction towards the removal of complex organic pollutants recently. (3) For the future development of magnetic biochar, an environment-friendly approach, economic viability, and joint technology are the directions that need more exploration. Finally, this paper provides a summary of the various adsorption mechanisms of magnetic biochar and several common modification methods, aiming to assist scholars in their research endeavors.

Removal of tetracycline in aqueous solution by iron-loaded biochar derived from polymeric ferric sulfate and bagasse

In this study, the tetracycline (TC) removal performance of iron-loaded biochar (BPFSB) derived from sugarcane bagasse and polymerized iron sulfate was investigated, and the mechanism of TC removal was also explored by study of isotherms, kinetics and thermodynamics and characterization of fresh and used BPFSB (XRD, FTIR, SEM and XPS). The results showed that under optimized conditions (initial pH 2; BPFSB dosage 0.8 g·L-1; TC initial concentration 100 mg·L-1; Contact time 24 h; temperature 298 K), the removal efficiency of TC was as high as 99.03%. The isothermal removal of TC followed well the Langmuir, Freundlich, and Temkin models, indicating that multilayer surface chemisorption dominated the TC removal. The maximum removal capacity of TC by BPFSB at different temperatures was 185.5 mg·g-1 (298 K), 192.7 mg·g-1 (308 K), and 230.9 mg·g-1 (318 K), respectively. The pseudo-second-kinetic model described the TC removal better, while its rate-controlling step was a combination of liquid film diffusion, intraparticle diffusion, and chemical reaction. Meanwhile, TC removal was also a spontaneous and endothermic process, during which the randomness and disorder between the solid-liquid interface was increased. According to the characterization of BPFSBs before and after TC removal, H-bonding and complexation were the major interactions for TC surface adsorption. Furthermore, BPFSB was efficiently regenerated by NaOH. In summary, BPFSB had the potential for practical application in TC removal.

Unveiling the drives behind tetracycline adsorption capacity with biochar through machine learning

This study aimed to develop a robust predictive model for tetracycline (TC) adsorption onto biochar (BC) by employing machine learning techniques to investigate the underlying driving factors. Four machine learning algorithms, namely Random Forest (RF), Gradient Boosting Decision Tree (GBDT), eXtreme Gradient Boosting (XGBoost) and Artificial Neural Networks (ANN), were used to model the adsorption of TC on BC using the data from 295 adsorption experiments. The analysis revealed that the RF model had the highest predictive accuracy (R² = 0.9625) compared to ANN (R² = 0.9410), GBDT (R² = 0.9152), and XGBoost (R² = 0.9592) models. This study revealed that BC with a specific surface area (S (BET)) exceeding 380 cm³·g^-1 and particle sizes ranging between 2.5 and 14.0 nm displayed the greatest efficiency in TC adsorption. The TC-to-BC ratio was identified as the most influential factor affecting adsorption efficiency, with a weight of 0.595. The concentration gradient between the adsorbate and adsorbent was demonstrated to be the principal driving force behind TC adsorption by BC. A predictive model was successfully developed to estimate the sorption performance of various types of BC for TC based on their properties, thereby facilitating the selection of appropriate BC for TC wastewater treatment.

Functional Carbon from Nature: Biomass-Derived Carbon Materials and the Recent Progress of Their Applications

Biomass is considered as a promising source to fabricate functional carbon materials for its sustainability, low cost, and high carbon content. Biomass-derived-carbon materials (BCMs) have been a thriving research field. Novel structures, diverse synthesis methods, and versatile applications of BCMs have been reported. However, there has been no recent review of the numerous studies of different aspects of BCMs-related research. Therefore, this paper presents a comprehensive review that summarizes the progress of BCMs related research. Herein, typical types of biomass used to prepare BCMs are introduced. Variable structures of BCMs are summarized as the performance and properties of BCMs are closely related to their structures. Representative synthesis strategies, including both their merits and drawbacks are reviewed comprehensively. Moreover, the influence of synthetic conditions on the structure of as-prepared carbon products is discussed, providing important information for the rational design of the fabrication process of BCMs. Recent progress in versatile applications of BCMs based on their morphologies and physicochemical properties is reported. Finally, the remaining challenges of BCMs, are highlighted. Overall, this review provides a valuable overview of current knowledge and recent progress of BCMs, and it outlines directions for future research development of BCMs.

Zinc and cadmium change the metabolic activities and vegetable cellulose degradation of Bacillus cellulasensis in vegetable soils

Bacillus cellulasensis Zn-B isolated from vegetable soil was highly adaptable to Zinc (Zn) and Cadmium (Cd). Cd, but not Zn, adversely affected the total protein spectrum and functional groups of Bacillus cellulasensis Zn-B. Up to 31 metabolic pathways and 216 metabolites of Bacillus cellulasensis Zn-B were significantly changed by Zn and Cd (Zn&Cd). Some metabolic pathways and metabolites related to functional groups of sulfhydryl (-SH) and amine (-NH-) metabolism were enhanced by Zn&Cd addition. The cellulase activity of Bacillus cellulasensis Zn-B was up to 8.58 U mL^-1, increased to 10.77 U mL^-1 in Bacillus cellulasensis Zn-B + 300 mg L^-1 Zn, and maintained at 6.13 U mL^-1 in Bacillus cellulasensis Zn-B + 50 mg L^-1 Cd. The vegetables' cellulose content was decreased by 25.05-52.37% and 40.28-70.70% under the action of Bacillus cellulasensis Zn-B and Bacillus cellulasensis Zn-B + 300 mg L^-1 Zn. Those results demonstrated that Zn could significantly enhance cellulase activity and biodegradability of Bacillus cellulasensis Zn-B to vegetable cellulose. Bacillus cellulasensis Zn-B can survive in vegetable soil accumulated with Zn&Cd. The tolerance concentration and adsorption capacity of Bacillus cellulasensis Zn-B to Zn were up to 300 mg L^-1 and 56.85%, indicating that Bacillus cellulasensis Zn-B acting as a thermostability biological agent had an essential advantage in accelerating the degradation of discarded vegetables by Zn and were beneficial to maintain organic matter content of vegetable soil.

Tea biochar-immobilized Ralstonia Bcul-1 increases nitrate nitrogen content and reduces the bioavailability of cadmium and chromium in a fertilized vegetable soil

Pyrolytic biochar (PL-BC, pyrochar) and hydrothermal biochar (HT-BC, hydrochar) derived from branches and leaves of tea plants had different pH, electrical conductivity (EC), total carbon nitrogen content, BET surface area, total pore volume, average pore diameter, and functional groups. HT-BC had a larger specific surface area and more functional groups than PL-BC. Ralstonia Bcul-1 (R-B) was the dominant and functional bacteria in a fertilized vegetable soil supplemented with TBB-immobilized R-B (TBB + R-B). R-B vitality was more closely related to BET surface area, total pore volume, and functional groups of tea-based biochar (TBB: PL-BC and HT-BC). R-B was able to maintain high oxidase activity. R-B and TBB + R-B can increase the activities of urease and peroxidase in vegetable soil playing an essential role in the biotransformation of ammonium nitrogen (NH₄⁺-N) and nitrate nitrogen (NO₃^--N). TBB was able to simultaneously increase the content of NO₃^--N and NH₄⁺-N, and TBB + R-B also significantly increased NO₃^--N content but decreased NH₄⁺-N content in a fertilized vegetable soil. These results indicated that R-B promoted nitrification in the soil, i.e. conversion of NH₄⁺-N into NO₃^--N, by enhancing the activities of urease and peroxidase. R-B had high adsorption capacity for cadmium (Cd) and chromium (Cr) (Cd&Cr: Cd and Cr). Moreover, TBB + R-B was able to convert weak acid extractable and reducible Cd&Cr into a more stable residual fraction and oxidizable Cd&Cr. The overall effect of the treatments was to reduce plant uptake of Cd&Cr by cabbage. TBB + R-B significantly promoted R-B growth, changed inorganic nitrogen speciation, increased NO₃^--N supply, reduced Cd&Cr bioavailability, and decreased plant tissue Cd&Cr content.

Nitrogen-doped magnetic porous carbon material from low-cost anion-exchange resin as an efficient adsorbent for tetracyclines in water

In this work, nitrogen-doped magnetic porous carbon material (N-MPC) was prepared through the high-temperature calcination of low-cost [Fe(CN)₆]^3--loaded anion-exchange resin, which was experimentally demonstrated to have significant adsorption performance for tetracycline (TC) in water. The N-MPC adsorbent with a large specific surface area (781.1 m² g^-1) was able to maintain excellent performance in a wide pH range from 4 to 10 or in high ionic strength solution. The adsorption of TC on N-MPC was found to be more consistent with the pseudo-second-order model and Langmuir adsorption model, and the maximum adsorption capacity (q_{m, cal}) was calculated to be 603.4 mg g^-1. As a recoverable magnetic adsorbent, the N-MPC remained a TC removal rate higher than 70% after four adsorption cycles. The adsorption mechanism was speculated on the basis of characterizations, where pore filling, hydrogen bonding interaction, and π-π electron donor-acceptor (EDA) interaction were crucial adsorption mechanisms. A variety of antibiotics were selected for adsorption, and excellent performance was found especially for TCs, indicating that the N-MPC can be used for the efficient removal of TCs from water.

Bamboo cellulose-derived activated carbon aerogel with controllable mesoporous structure as an effective adsorbent for tetracycline hydrochloride

Activated carbon has been widespread applied in the removal of pollutants in wastewater. However, many biomass-derived activated carbon suffer from the challenge of controllable pore size regulation, hindering their efficient adsorption of pollutants. Herein, bamboo-derived activated carbon aerogel (BACA) has been successfully prepared through KOH high-temperature activation of cellulose aerogel which was prepared using cellulose extracted from bamboo. Bamboo cellulose aerogel provides sufficient reaction sites for KOH, which is conducive to the formation of a mass of mesoporous structures on the pore walls of the activated carbon aerogel. The optimal BACA adsorbent shows high specific surface area (2503.80 m²/g), and maximum adsorption capability for tetracycline hydrochloride (TCH) reaches 863.8 mg/g at 30 ℃. The removal efficiencies of TCH are 100% and 98.4% at 40 ℃ when the initial concentrations are 500 and 700 mg/L, respectively. Adsorption kinetics and isotherm indicate that the adsorption of BACA for TCH is monolayer adsorption based on chemical adsorption. Spontaneous and endothermic adsorption processes are proved by adsorption thermodynamic studies. Additionally, coexisting ions have insignificant effect on TCH adsorption, and the BACA sample displays excellent adsorption property for five reuse cycles with a removal efficiency of 80.95%, indicating the outstanding adsorption capacity of BACA in practical application. The excellent adsorption performance provides BACA with a promising perspective to remove TCH from wastewater, and the prepared method of BACA can be widely extended to other biomass materials.

Efficient removal of tetracycline from aqueous solution by K2CO3 activated penicillin fermentation residue biochar

In this study, biochar was prepared using penicillin fermentation residue (PR) as the raw material by different methods. The adsorption behavior and adsorption mechanism of biochar on tetracycline (TC) in an aqueous environment were investigated. The results showed that K₂CO₃ as an activator could effectively make porous structures, and that biochar with mesoporous or microporous could be prepared in a controlled manner with two kinds of different activation methods, the dry mixing method and the impregnation method. The dry mixing method could create more mesopores, while the impregnation method could prepare more micropores. Microporous biochar (IKBCH) with a high specific surface area could be prepared by the impregnation method combined with HCl soaking, which has an excellent adsorption effect on tetracycline. When the concentration of tetracycline was 200 mg/L, the removal rate of 99.91% could be achieved with the dosage of microporous biochar at 1 g/L. The adsorption process was in accordance with the Langmuir model and the pseudo-second-order model, respectively. The maximum adsorption capacity of IKBCH was 268.55 mg/g (25°C). The adsorption mechanisms were pore filling, π-π interaction, electrostatic adsorption, and hydrogen bond. Its stable and wide applicability adsorption process does not cause ecological pollution in the aqueous environment, and it is a promising biochar adsorbent.

A stable Fe/Co bimetallic modified biochar for ofloxacin removal from water: adsorption behavior and mechanisms

In this study, Fe-Co-modified biochar (FMBC) loaded with iron (Fe) and cobalt (Co) bimetals after NaOH activation was prepared by pyrolysis using forestry waste cedar bark as a raw material to study its properties and the adsorption of ofloxacin (OFX). The surface structure and chemical properties were analyzed by BET, SEM-EDS, XRD, XPS, and FTIR characterization, and the results showed that the FMBC possessed a larger specific surface area and abundant surface functional groups. FMBC conformed to pseudo-second-order kinetic and Langmuir isotherm models, indicating that the OFX adsorption process on FMBC was a monolayer adsorption process and controlled by chemisorption. The saturation adsorption capacity of FMBC was 10 times higher than that of cedar bark biochar (BC). In addition, the effects of initial pH and coexisting ions on the adsorption process were investigated, and FMBC showed good adsorption, with the best adsorption capacity at pH = 7. Multiple adsorption mechanisms, including physical and chemical interactions, were involved in the adsorption of OFX by FMBC. TG, metal leaching, different water sources, and VSM tests showed that FMBC had good stability and was easily separated from water. Finally, the reusability performance of FMBC was investigated by various methods, and after five cycles it could still reach 75.78-89.31% of the adsorption capacity before recycling. Therefore, the FMBC synthesized in this study is a promising new adsorbent.

Resource utilization of rice husk biomass: Preparation of MgO flake-modified biochar for simultaneous removal of heavy metals from aqueous solution and polluted soil

In general, the remediation performance of heavy metals can be further improved by metal-oxide modified biochar. This work used MgO-modified rice husk biochar (MgO-5%@RHB-450 and MgO-5%@RHB-600) with high surface activity for simultaneous remediation and removal of heavy metals in soil and wastewater. The adsorption of MgO-5%@RHB-450/MgO-5%@RHB-600 for Cd(II), Cu(II), Zn(II) and Cr(VI) followed the pseudo-second order, with the adsorption capacities reaching 91.13/104.68, 166.68/173.22, 80.12/104.38 and 38.88/47.02 mg g^-1, respectively. The addition of 1.0% MgO-5%@RHB-450 and MgO-5%@RHB-600 could effectively decrease the CaCl₂-extractable Cd concentration (CaCl₂-Cd) by 66.2% and 70.0%, respectively. Moreover, MgO-5%@RHB-450 and MgO-5%@RHB-600 facilitated the transformation of exchangeable fractions to carbonate-bound and residual fractions, and reduced the exchangeable fractions by 8.1% and 9.6%, respectively. The mechanisms for the removal of heavy metals from wastewater by MgO-5%@RHB-450 and MgO-5%@RHB-600 mainly included complexation, ion exchange and precipitation, and the immobilization mechanisms in soil may be precipitation, complexation and pore filling. In general, this study provides high-efficiency functional materials for the remediation of heavy metal pollution.

Applications of functionalized magnetic biochar in environmental remediation: A review

Magnetic biochar (MBC) is extensively applied on contaminants removal from environmental medium for achieving environmental-friendly remediation with reduction of secondary pollution owing to its easy recovery and separation. However, the summary of MBC synthesis methods is still lack of relevant information. Moreover, the adsorption performance for pollutants by MBC is limited, and thus it is imperative to adopt modification techniques to enhance the removal ability of MBC. Unfortunately, there are few reviews to present modification methods of MBC with applications for removing hazardous contaminants. Herein, we critically reviewed (i) MBC synthetic methods with corresponding advantages and limitations; (ii) adsorption mechanisms of MBC for heavy metals and organic pollutants; (iii) various modification methods for MBC such as functional groups grafting, nanoparticles loading and element doping; (iv) applications of modified MBC for hazardous contaminants adsorption with deep insight to relevant removal mechanisms; and (v) key influencing conditions like solution pH, temperature and interfering ions toward contaminants removal. Finally, some constructive suggestions were put forward for the practical applications of MBC in the near future. This review provided a comprehensive understanding of using functionalized MBC as effective adsorbent with low-cost and high-performance characteristics for contaminated environment remediation.

A feasible biochar derived from biogas residue and its application in the efficient adsorption of tetracycline from an aqueous solution

The recovery of carbon materials from biogas residue (BR) could efficiently promote the efficient utilization of waste and the preparation of novel materials. In this study, a green and feasible reagent of citric acid was introduced and applied in the modification of biogas residue biochar (BRC). The modified biogas residue biochar (CABRC) showed a superior adsorption ability due to its higher specific surface area (approximately 6 times that of the BRC). Additionally, the adsorption capacities of CABRC and BRC for TC were 58.25 mg/g and 20.77 mg/g, respectively, while the TC adsorption performance of CABRC was 2.8 times that of BRC. The adsorption of TC by both BRC and CABRC was primarily controlled by physical adsorption and chemical adsorption (including pore filling, hydrogen bonding, π-π DEA interaction, and electrostatic interaction). Therefore, CABRC should be considered an environmentally friendly material due to its higher adsorption performance, which could expand its application in wastewater treatment.

Sorbent Properties of Orange Peel-Based Biochar for Different Pollutants in Water

Efficient and reasonable utilization of waste biomass resources can not only avoid serious waste of material resources, but also solve the problem of environmental pollution. Therefore, the development of efficient and environmentally friendly waste biomass carbonization technology has important practical significance. Here, the activated carbon from orange peel (OAC) is prepared by potassium hydroxide (KOH) activation combined with high-temperature carbonization. The adsorption effects of OAC on three different pollutant aqueous solutions, methylene blue (MB), tetracycline (TC), and fluorescein sodium (NaFL), are examined. The OAC absorbent has excellent adsorption capacity for MB, TC, and NaFL pollutants of 10 mg L−1, with adsorption rates of 99.17%, 73.5%, and 94.24%, respectively. This study provides a new idea for turning waste biomass into treasure and eliminating the hidden danger of environmental pollution.

Obtaining high-value nitrogen-containing carbon nanosheets with ultrahigh surface area from waste sludge for energy storage and wastewater treatment

Recovering high value-added resources from waste activated sludge (WAS) is a potential way for the sustainable wastewater treatment. In this study, hydrothermal treatment at 180 °C was used to simultaneously improve sludge dewaterability and recover sludge organic matters (SOMs). The recovered SOMs were subsequently employed as precursors to prepare nitrogen-doped porous carbon nanosheets via a facile stepwise synthesis method. The as-prepared optimal carbon (AP-SOM₈₀₀) was characterized with an ultrahigh specific surface area (3473 m²/g), appropriate porosity (1.77 cm³/g), and abundant heteroatoms (1.47% N and 7.44% O). AP-SOM₈₀₀ exhibited a high specific capacitance (409 F/g at 0.25 A/g), low resistance (0.52 Ω), and superior cyclic stability (only 9.09% loss after 10,000 cycles) in 6 M KOH aqueous electrolyte. Furthermore, AP-SOM₈₀₀ demonstrated an extraordinary adsorption capacity (1528 mg/g for methyl orange (MO) and 1265 mg/g for tetracycline (TC)) that can be maintained (˃ 1200 mg/g) over a wide range of pH conditions. Specifically, 80.97% of MO and 66.67% of TC were rapidly absorbed through AP-SOM₈₀₀ within 10 min, and 90.27% of MO and 81.24% of TC were eventually removed from wastewater after 60 min. The adsorption processes fit closely with the pseudo-second-order kinetic (R² > 0.999) and Langmuir models (R² > 0.914), revealing that the adsorption processes were dominated by a monolayer chemical adsorption reaction. This study suggests that high value-added materials can be obtained from the WAS through improving and extending the traditional sludge treatment processes, which will enrich the technical options available for future sustainable sludge treatment and disposal.

Quickly and efficiently remove multiple pesticides in tea infusions by low-cost carbonized bacterial cellulose

Soaking tea leaves make tea consumers exposure to pesticide residues more easily. However, there are few studies on the removal of pesticides in tea infusions. Therefore, a low-cost carbonized bacterial cellulose material was prepared by direct calcination method, and used to remove multiple pesticides in tea infusions quickly and efficiently. CBC-350 has the best removal efficiency for 9 pesticides and then screened the best adsorption conditions. The adsorption isotherm experiment was carried out and indicated that the adsorption process was in consist with the Freundlich model. The thermodynamic parameters are also calculated. Moreover, the adsorption mechanism was discussed, which suggests that π-π interaction and hydrophobic action are the driving force during the adsorption process. Exhilaratingly, the CBC-350 also has excellent adsorption capacity compared to other adsorbents and can be reused at least five times.