Adsorption of tetracycline hydrochloride onto ball-milled biochar: Governing factors and mechanisms

Soybean straw biochar activating peroxydisulfate to simultaneously eliminate tetracycline and tetracycline resistance bacteria: Insights on the mechanism

Tetracycline (TC) has been frequently detected in various environments, thus promoting the occurrence of resistance in bacterial populations. In this study, a suite of soybean straw biochars (SSBs) were fabricated under different pyrolysis temperatures (600-1000 °C), which were utilized as peroxydisulfate (PS) activators for TC degradation and TC resistant Escherichia coli (E. coli) disinfection. The purification effect of SSBs/PS systems manifested obvious positive dependence on pyrolysis temperature of SSBs with SSB1000/PS system obtained the superior TC degradation, E. coli disinfection and coexisting TC and E. coli elimination capacity. The leakage of intracellular DNA and the degradation of total DNA and extracellular DNA was revealed no matter in alone E. coli or combined pollution which can also be supported by the gradual ruptured bacterial morphology and attenuated internal components. It can be found that TC adsorption in SSBs played a significant role on TC degradation, while the electrostatic repulsion always existed between E. coli and SSB1000. Furthermore, a battery of solid evidences collectively demonstrated the significant different purification mechanism of TC and E. coli. The TC degradation was achieved dominantly by surface-bound radicals, while bactericidal activity should be attributed to free SO4·- in bulk solutions. In contrast to other SSBs, the largest mesopore volumes, highest C=O content, lowest interfacial charge transfer resistance and strongest electron donating capacity explained the outperformed catalytic performance of SSB1000.

Microwave biochars produced with activated carbon catalyst: Characterization and sorption of volatile organic compounds (VOCs)

A series of microwave biochars derived from wheat straw in the presence of a granulated activated carbon (GAC) catalyst, using a range of microwave conditions, were produced, characterized and tested as sorbents of three benzene series volatile organic compounds (VOCs). The microwave biochar with the greatest specific surface area (SSA), total pore volume (TPV), and micropore volume (312.62 m² g^-1, 0.2218 cm³ g^-1, and 0.1380 cm³ g^-1, respectively), were produced with 1:3 biomass:GAC catalyst mass ratio, 10 min microwave irradiation time, and at 500 W power level (WB500). Maximum adsorption capacities of WB500 to benzene, toluene and o-xylene were 53.9 mg g^-1, 75.8 mg g^-1 and 63.0 mg g^-1, respectively, and were directly correlated to microwave biochar properties such as SSA, TPV or micropore volume, but were also influenced by VOC properties such as molecular polarity and boiling point. Kinetic modeling suggested that adsorption was governed by both physical partitioning and chemisorption mechanisms. In addition, microwave biochars maintained 79% to 92% of their initial adsorption capacity after ten adsorption/desorption cycles. These results suggest that microwave biochars produced with an GAC catalyst have excellent potential for efficient use in the removal of VOCs from waste gas.

Chemical Vapor Deposition Growth of MoS2 on g-C3N4 Nanosheets for Efficient Removal of Tetracycline Hydrochloride

MoS₂ was vertically grown on g-C₃N₄ nanosheets by chemical vapor deposition to prepare nanocomposites named MS-CN samples. Because of a large-surface area of 545.2 m²·g^-1 and a total pore volume of 1.7 cm³·g^-1, the sample MS-CN revealed fast and large adsorption capacity for tetracycline hydrochloride (TCH). The adsorption kinetics model proved that TCH could be rapidly adsorbed within 5 min, and chemical adsorption was dominant. For single-component adsorption of TCH, the maximum adsorption capacity was ∼154 mg/g. The monolayer adsorption was carried out on the surface of MS-CN. Both of the film and intra-particle diffusion were considered as significant processes to facilitate adsorption. Thermodynamic parameters indicate that the adsorption of TCH is a spontaneous endothermic process. The adsorption of TCH was highly pH-dependent. The maximum adsorption capacity of TCH was obtained in the case of pH ∼ 7. After four adsorption and desorption cycles, MS-CN still maintained well-adsorption performance. Multiple adsorption mechanism, pore filling, electrostatic force, π-π conjugation, and hydrogen bonding interactions were studied. Because of fast adsorption, large adsorption capacity, and high stability, it is a promising adsorbent for antibiotics.

The potential application of bio-based ceramic/organic xerogel derived from the plant sources: A new green adsorbent for removal of antibiotics from pharmaceutical wastewater

A bio-based ceramic/organic xerogel (BCO-xerogel) was obtained from the combination of sugarcane bagasse ash, polyvinyl alcohol, and pine cone-derived tannin extract, which are abundant, non-toxic, and renewable sources. The as-prepared BCO-xerogel was used as a low-cost green adsorbent for the eliminate of four types of the most widely used antibiotics, including amoxicillin (AMX), tetracycline (TC), cefalexin (CLX), and penicillin G (PEN G) residuals from contaminated water. The simultaneous effects conventional variables including adsorbent dosage, antibiotic concentrations, solution pH, and contact time were studied and optimized by central composite design (CCD) under response surface methodology (RSM). Analysis of variance (ANOVA) was employed as a statistical formula to determine the significance of operating environmental conditions and their interactions with 95% confidence limits. Under optimized conditions, the experimental removal efficiencies for AMX, TC, CLX, and PEN G were 98.78 ± 3.25, 99.12 ± 2.52, 98.02 ± 1.98, and 98.42 ± 2.19, respectively. The adsorption isotherms and kinetics were better fitted with Langmuir and pseudo-second-order models, respectively. Thermodynamic studies showed that the adsorption process was endothermic, spontaneous, and occurred by combination of physical and chemical mechanisms. Also, evaluating the ability of BCO-xerogel to adsorptive removal of AMX, TC, CLX, and PEN G antibiotics in real wastewaters showed about 97.4-98.6% adsorption efficiency in river water and about 67.1-71.3% in three hospital effluents. After the adsorption process, the antibiotic-loaded adsorbent was regenerated by NaOH (0.01 mol L^-1), and the reusability tests showed that the removal efficiencies of the antibiotics in the four recovery steps were still above 90%. This work explored the development of green, efficient, and economical bio-adsorbent that can be utilized for the removal of antibiotics from contaminated wastewaters.

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.

Removal of fluconazole from aqueous solution by magnetic biochar treated by ball milling: adsorption performance and mechanism

The problem of low adsorption capacity of pristine magnetic biochar for organic pollutants always occurs. It is of great significance to select a suitable method to improve the adsorption performance of magnetic biochar. In this study, magnetic biochar was treated by ball milling and tested for its fluconazole adsorption capacity. The maximum adsorption capacity of ball-milled magnetic biochar (BMBC) for fluconazole reached nearly 15.90 mg/g, which was approximately five times higher than that of pristine magnetic biochar (MBC). Fluconazole adsorption by BMBC was mainly attributed to π-π interactions, hydrogen bonding, and surface complexation with oxygen-containing functional groups. The enhancement in fluconazole adsorption by BMBC was attributed to an increase in oxygen-containing functional groups. Batch adsorption experiments also illustrated that BMBC could be successfully applied in a wide range of pH values. The high efficiency of fluconazole removal confirmed that ball milling was an effective strategy to enhance the adsorptive performance of magnetic biochar.

Performance and mechanism of sycamore flock based biochar in removing oxytetracycline hydrochloride

In this study, sycamore flocs (SF), which caused environmental and health problems, were utilized to prepare biochar. SFB_2-900 obtained under the conditions of activation agent K₂CO₃, pyrolysis temperature 900℃ and m(K₂CO₃):m(BC) 2 had the strongest adsorption capacity (730 mg/g) for oxytetracycline hydrochloride (OTC-HCl). The pseudo-second-order kinetic model and Langmuir model described the adsorption kinetics and isotherms best. SFB_2-900 exhibited high OTC-HCl adsorption capacity in both higher ionic strength and wide pH range. The theoretical simulation indicated that the closest interaction distance between OTC-HCl and SFB_2-900 was 2.44 Å via π-π stacking configuration. Pore filling, π-π electron donor acceptor (EDA) interaction, H-bonding and electrostatic interactions were also involved in the process of OTC-HCl removal. SFB_2-900 showed great removal efficiency for OTC-HCl in different water matrices and good regeneration ability. This study solved the problems caused by SF, realized waste biomass recycling, and achieved preparing high-efficient adsorbent for antibiotic.

Systematic Research on the Transport of Ball-Milled Biochar in Saturated Porous Media: Effect of Humic Acid, Ionic Strength, and Cation Types

Ball-milled biochar (BMBC) is a typical engineering material that has promising application prospects in remediating contaminated soil and water. It is fundamental to rate the transport behaviors of BMBC in the underground environment before extensive use. In this study, the effects of the ubiquitous cations (Na+, Mg2+, and Al3+) and model organic matter (humic acid) on the transport of BMBC were investigated using laboratory column experiments. The results demonstrated the facilitated effect of HA on the transport of BMBC due to the negatively charged surface and steric effect under neutral conditions. HA and ionic strength manifested an antagonistic effect on the transport of BMBC, where the presence of one could weaken the effect from the other. We also found the charge reversal of the BMBC surface in the presence of Mg2+, thus enhancing the deposition of BMBC onto the medium surface. On the other hand, the charge reversal from Al3+-coupled acid conditions led to the restabilization and transport of BMBC in porous media. Therefore, the rational usage of BMBC is indispensable and more attention should be paid to the composition and change in underground water that might facilitate the transport of BMBC and thus lead to negative environmental implications.

Insight into the mechanisms of ball-milled biochar addition on soil tetracycline degradation enhancement: Physicochemical properties and microbial community structure

A set of soil under the addition of ball-milled biochar (BM-biochar) from different feedstocks (wheat straw (WS) and rice husk (RH)) and pyrolysis temperature (300 °C, 500 °C, and 700 °C) was established to analyze the tetracycline (TC) degradation performance enhancement and greenhouse gas carbon dioxide (CO₂), and nitrous oxide (N₂O) emission reduction from various angles, including physicochemical properties of soil and microbial community structure. After 45 days' incubation, the pH value decreased slightly from 7.34 to 7.22 for WS biochar-treated soil, while slightly increased from 7.34 to 7.50 for RH biochar-treated soil. The lowest KCl-leachable TC concentrations of BMWS700 and RH700 was about 0.0037 mg/L. Ball-milled 500 °C and 700 °C biochars enhanced the removal rate of TC significantly. The maximum reduction of TC was from 2.17 to 0.079 mg/kg, equivalent to 96% removal after ball-milled 500 °C wheat straw biochar (BMWS500) addition, suggesting the promoting effect of biochars on microorganisms for adsorption and degradation of TC. Biochars' addition reduced CO₂ and N₂O emissions, BM-biochar enlarged this effect under the pyrolysis temperature 500 °C for both feedstock types. Ball milled rice husk biochar pyrolyzed under 500 °C (BMRH500) presented the maximum inhibitory effect CO₂ emission. The addition of BM-biochar changed the microbial community and diversity. The relative abundance of bacterium and fungus such as Proteobacteria, Acidobacteria, Chlorofexi, Mortierella, and Chaetomium increased due to BM-biochar addition, which promoted the degradation of TC and gave rise to more healthy soil environment for plant or microbes. The larger specific surface area, π-π interactions, hydrophobic interaction, and hydrogen bonding are account for better adsorption and degradation of TC by BM-biochars. This work elucidated the management of organic contaminants in real soil by BM-biochar.

Facile construction of high-performance 3D Co2C-doped CoAl2O4 fiber composites for capturing and decomposing tetracycline from aqueous solution

Herein, novel 3D hollow-carved Co₂C-doped CoAl₂O₄ fiber composites (3D-CA-FC) were successfully synthesized via a simple-green pyrolysis method and exhibited remarkably outstanding elimination performance for tetracycline (TC) by adsorption and degradation. The results indicated that the TC adsorption process of the samples could be accurately described by the pseudo-second-order and Langmuir isothermal model, and the maximum TC uptake reached up to 1889.63 mg/g under neutral conditions. Meanwhile, 3D-CA-FC showed good affinity for TC and its adsorption capacity was greatly promoted due to the presence of humic acid, CO₃^2- ion and weakly alkaline environment. About complete degradation of TC could be completed within 60 min under suitable conditions. A significant improvement of catalyst rate was observed after the addition of CO₃^2- ion, because of the selective degradation of CO₃^•- to TC. BET, XPS and FT-IR analysis indicated that the mechanisms of TC uptake can be ascribed to pore-filling, H-bonds and complexation. Radical trapping experiments showed that ¹O₂ should serve as predominant contributions, and SO₄^•- and •OH also played a role in the degradation process. This study provides some inspiration for the construction of 3D-CA-FC as a novel and promising bifunctional material for the elimination of contaminants in water treatment.

Porous multifunctional phenylcarbamoylated-β-cyclodextrin polymers for rapid removal of aromatic organic pollutants

In this work, polymers containing a large number of benzene rings and multiple functional groups were designed to remove aromatic organic pollutants. Using tetrafluoroterephthalonitrile (TFTPN) as a rigid crosslinking agent to crosslink different functionalized phenylcarbamoylated-β-cyclodextrin derivatives to prepare a series of porous multifunctional cyclodextrin (CD) polymerizations, including three preliminary polymerized adsorption materials and a mix β-cyclodextrin polymer (X-CDP) prepared via a secondary crosslinking procedure of the above three materials. The X-CDP preparation process connects the pre-formed nanoparticles and increases the presence of linkers inside the particles. At the same time, X-CDP exhibited porous structure with various functional groups such as nitro, chlorine, fluorine, and hydroxyl. Those special characteristics render this material with good adsorption ability towards various aromatic organic pollutants in water, including tetracycline, ibuprofen, dichlorophenol, norfloxacin, bisphenol A, and naphthol. Especially, the maximum adsorption capacity for tetracycline at equilibrium reached 110.56 mg·g^-1, which is competitive with the adsorption capacities of other polysaccharide adsorbents. X-CDP removed organic contaminants much more quickly than other adsorbents, reaching almost ~95% of its equilibrium in only 30 s, and the rate constant reaches 2.32 g·mg^-1·min^-1. The main adsorption process of the pollutants by X-CDP fitted the pseudo-second-order kinetic and Langmuir isotherm well, indicating that the adsorption process is monolayer adsorption. Moreover, X-CDP possessed the good reusability where the pollutant removal rate was only reduced 8.3% after five cycles. Such advantages render the polymer great potential in the rapid treatment of organic pollutants in water bodies.

Effect of light on concomitant sequestration of Cu(II) and photodegradation of tetracycline by H-MOR/H-β/H-ZSM5 zeolites

It is important that a pollution remediation system be able to cater for a variety of pollutant species present in the water to be treated. The aim of this study was to utilise a series of commercial zeolites (H-MOR, H-β, and H-ZSM5) for the concomitant adsorption and photodegradation of Cu²⁺ and tetracycline (TC) molecules. The adsorbent cum photocatalyst was characterised by SEM and FTIR. FTIR confirmed the key functional groups (Si-O-Si and Al-O-Si) in the series of zeolites, and H-β zeolite was demonstrated to be the most effective adsorbent cum photocatalyst for both adsorption and photodegradation of Cu²⁺ and TC molecules. These results were further corroborated from the pseudo-first-order rate constant values. Among the investigated zeolites, H-ZSM5 displayed the least adsorption and photodegradation performance for Cu²⁺ and TC molecules. The photolysis reaction confirms the significant role of zeolites in the photodegradation test, as low performance was recorded in the absence of the zeolites.

Biochar-induced priming effects in soil via modifying the status of soil organic matter and microflora: A review

Biochar (BC) application has the potential to be integrated into a carbon-trading framework owing to its multiple environmental and economic benefits. Despite the increasing research attention over the past ten years, the mechanisms of BC-induced priming effects on soil organic carbon mineralization and their influencing factors have not been systematically considered. This review aims to document the recent progress in BC research by focusing on (1) how BC-induced priming effects change the soil environment, (2) the factors governing the mechanisms underlying BC amendment effects on soils, and (3) how BC amendments alter soil microbial communities and nutrient dynamics. Here, we carried out a detailed examination of the origins of different biochar, its pyrolysis conditions, and potential interactions with various factors that affect BC characteristics and mechanisms of C mineralization in primed soil. These findings clearly addressed the strong linkage between BC properties and abiotic factors that leads to change the soil microclimate, priming effects, and carbon stabilization. This review offers an overview of a fragmented body of evidence and the current state of understanding to support the application of BC in different soil environments with the aim of sustaining or improving the agricultural crop production.

Bifunctional two-dimensional copper-aluminum modified filter paper composite for efficient tetracycline removal: Synergy of adsorption and reusability by degradation

Herein, bifunctional two-dimensional copper-aluminum modified filter paper composite (2D-Cu/Al-C) was successfully prepared by simple calcination and showed ultrahigh adsorption performance and degradation potential. The adsorption removal of TC on 2D-Cu/Al-C all exceeded 92.2% under solution conditions of 10-200 mg/L TC, 100 mg/L 2D-Cu/Al-C, pH 8 and 298 K. The pseudo-second-order kinetic and Langmuir models better fitted the kinetic and isotherm data via spontaneous and exothermic process, and the maximum capacity of the 2D-Cu/Al-C was 2391.78 mg/g. Additionally, 2D-Cu/Al-C showed desired specific adsorption for TC (TC: 98.7%, norfloxacin: 5.8%, sulfamethoxazole: 2.1%, and ciprofloxacin: 1.8%) and it could effectively adsorbed TC even in the binary system (various coexisting ions or natural organic matter). After TC adsorbed on adsorbent was mineralized into CO₂ and H₂O by adding peroxydisulfate to generate high electrode potential radical in another limited systems, the 2D-Cu/Al-C still had ∼89.12% on TC removal (initial concentration of 50 mg/L) after five experimental cycles. Zeta potential, FT-IR and XPS results indicated that the multi-adsorption mechanism, including electrostatic interactions, complexation, and H-bonds, played a vital role in the fast and efficient adsorption process. Thus, the way of combining adsorption and regeneration via degradation are green, non-polluting strategy which are expected to be applied for water purification in future environmental remediation.

Fabrication of easy separable and reusable MIL-125(Ti)/MIL-53(Fe) binary MOF/CNT/Alginate composite microbeads for tetracycline removal from water bodies

In this investigation, we aimed to fabricate easy separable composite microbeads for efficient adsorption of tetracycline (TC) drug. MIL-125(Ti)/MIL-53(Fe) binary metal organic framework (MOF) was synthetized and incorporated with carbon nanotube (CNT) into alginate (Alg) microbeads to form MIL-125(Ti)/MIL-53(Fe)/CNT@Alg composite microbeads. Various tools including FTIR, XRD, SEM, BET, Zeta potential and XPS were applied to characterize the composite microbeads. It was found that the specific surface area of MIL-125(Ti)/MIL-53(Fe)/CNT@Alg microbeads was 273.77 m2/g. The results revealed that the adsorption of TC augmented with rising CNT proportion up to 15 wt% in the microbeads matrix. In addition, the adsorption process followed the pseudo-second-order and well-fitted to Freundlich and Langmuir models with a maximum adsorption capacity of 294.12 mg/g at 25 ◦C and pH 6. Furthermore, thermodynamic study clarified that the TC adsorption process was endothermic, random and spontaneous. Besides, reusability test signified that MIL-125(Ti)/MIL-53(Fe)/CNT@Alg composite microbeads retained superb adsorption properties for six consecutive cycles, emphasizing its potentiality for removing of pharmaceutical residues.

Soybean residue based biochar prepared by ball milling assisted alkali activation to activate peroxydisulfate for the degradation of tetracycline

The advanced oxidation process (AOPs) has caused great concern in recent years. Among them, biochar has been widely studied as a catalyst for advanced oxidation process because of its low price and low environmental risk. In this study, a novel ball milling assisted KOH activation biochar (MKBC) was prepared and applied in peroxydisulfate (PDS) activation to degrade tetracycline hydrochloride (TC-H). In comparison with the oxidation (3.48%) by PDS alone and adsorption (36.19%) by MKBC alone, the removal rate of TC-H was increased to 84.15% in the MKBC/PDS system, indicating that MKBC can successfully activate PDS. Besides, the catalytic activity of the MKBC to activate PDS for the degradation of TC-H is 58.33% higher than that of pristine biochar (PBC). In addition, MKBC has outstanding stability that after three repeated experiments, the removal rate of TC-H by the MKBC/PDS system still remains 77.35%. Meanwhile, the mechanism was investigated that the singlet oxygen (1O2) seized the principal position in the degradation of TC-H in the PDS/MKBC system. This study explored a novel, solvent-free and economic method to propose this extraordinary biochar, which provided a new strategy for the future research of biochar.

Application of Magnetic Composites in Removal of Tetracycline through Adsorption and Advanced Oxidation Processes (AOPs): A Review

Water pollution induced by the tetracycline (TC) has caused global increasing attention owing to its extensive use, environmental persistence, and potential harm for human health. Adsorption and advanced oxidation processes (AOPs) have been promising techniques for TC removal due to ideal effectiveness and efficiency. Magnetic composites (MCs) which exploit the combined advantages of nano scale, alternative sources, easy preparation, and separation from wastewater are widely used for catalysis and adsorption. Herein, we intensively reviewed the available literature in order to provide comprehensive insight into the applications and mechanisms of MCs for removal of TC by adsorption and AOPs. The synthesis methods of MCs, the TC adsorption, and removal mechanisms are fully discussed. MCs serve as efficient adsorbents and photocatalysts with superior performance of photocatalytic performance in TC degradation. In addition, the TC can be effectively decomposed by the Fenton-based and SO4•− mediated oxidation under catalysis of the reported MCs with excellent catalytic performance. Based on the existing literature, we further discuss the challenge and future perspectives in MCs-based adsorption and AOPs in removing TC.

Enhanced adsorption capacity of tetracycline on tea waste biochar with KHCO3 activation from aqueous solution

Activation is an important pathway that can enhance the adsorption capacity of biochar. In this study, a modified tea waste biochar (MTWBC) was prepared via a two-step pyrolysis approach with KHCO₃ activation. Pristine tea waste biochar (TWBC) was also produced as control via one-step pyrolysis without activation. Various characterizations were undertaken to investigate the influence of modification on the morphology, composition, carbon structure, surface area, and functional group of biochar, including scanning electron microscope (SEM), surface area and pore analyzer, element analysis, point of zero charge (pH_PZC), X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). After KHCO₃ activation treatment, the surface area, total pore volume, and micropore volume of MTWBC reached 1981 m²·g^-1, 0.8547 cm³·g^-1, and 0.6439 cm³·g^-1 which were 7.34-fold, 7.27-fold, and 7.30-fold increases, respectively, compared with TWBC. The aromaticity, hydrophilicity, and polarity of the MTWBC increased after modification. More graphitization with less defective structures occurred in MTWBC after modification. The C-, O-, and N-containing groups in MTWBC also changed after the reaction of KHCO₃. The pseudo-second-order and Freundlich models best described the adsorption process on biochar. The maximum adsorption capacity of tetracycline (TC) on MTWBC reached 293.46 mg·g^-1, which was 15-fold more than that of TWBC (19.68 mg·g^-1). An alkaline environment decreased the TC adsorption on biochars. The presence of Na⁺, K⁺, Ca²⁺, and Mg²⁺ inhibited TC adsorption onto biochars. The influence of Cu²⁺ on TC adsorption by biochars depends on its initial concentration. The enhanced adsorption capacity of TC on MTWBC was mainly attributable to the large surface area, the improved pore volume, and more aromatic structure. The adsorption mechanism was based on pore filling and π-π EDA interaction. Therefore, KHCO₃ activated biochar has the potential to remove TC from aquatic environments.

Preparation of Eucommia ulmoides lignin-based high-performance biochar containing sulfonic group: Synergistic pyrolysis mechanism and tetracycline hydrochloride adsorption

In this study, the sulfonic group was introduced to prepare high-performance Eucommia ulmoides lignin-based biochar, which was used to remove tetracycline hydrochloride. The BET area (2008 m² g^-1) of sulfonated biochar was twice that of unmodified biochar. Through XRD and Raman analysis, the synergetic pyrolysis mechanism of the sulfonic group in the formation of the porous structure was discussed. Sulfonated biochar had excellent adsorption performance for tetracycline hydrochloride (Q_m: 1163 mg g^-1), while the adsorption performance of unmodified biochar was about only one-fourth (Q_m: 277.7 mg g^-1) of that. The adsorption of tetracycline hydrochloride by the sulfonated biochar was spontaneously endothermic and conformed to the Langmuir isotherm model. The adsorption process was confirmed by pseudo-second-order kinetic model. Moreover, the sulfonic group on the sulfonated biochar significantly promoted the formation of the hydrogen bond and greatly improved the adsorption performance.

High mesoporosity phosphorus-containing biochar fabricated from Camellia oleifera shells: Impressive tetracycline adsorption performance and promotion of pyrophosphate-like surface functional groups (C-O-P bond)

In China, more than 3.5 million tons of Camellia oleifera discarded shells are produced every year. This work first prepared phosphorus-containing biochar (PBC) from C. oleifera shells and was successfully applied to the efficient removal of tetracycline (TC) from solutions. The prepared PBC exhibits superior TC adsorption capacity of 451.5 mg/g, and TC uptake rapidly reached 315.5 mg/g at the first 5 min (C₀ = 50 mg/L). Furthermore, PBC also shows excellent applicability to the broad range pH value (1-9) and superior selective removal in the presence of various high concentration coexisting ions (1 mM). Mechanisms underlying TC adsorption were also put forward, and analysis suggested that pyrophosphate-like surface functional groups (C-O-P bond) played a critical role in this process. Notably, treating pharmaceutical wastewater with PBC can efficiently reduce chemical oxygen demand (COD) and total organic carbon (TOC) concentration below the discharge standard of China (GB21904-2008).

Effectively removing tetracycline from water by nanoarchitectured carbons derived from CO2: Structure and surface chemistry influence

Understanding of the correlation between physico-chemical property of adsorbent and the adsorption performance of contaminant is very significant for developing high-efficient materials to remove antibiotic contamination from water. In this work, a novel kind of carbon adsorbent (EC) derived from CO₂ and activated ECs with modified structure via a facile chemical method using H₂ and KOH were prepared. The synthetic carbon materials (EC, EC-H₂, and EC-KOH) were then applied to remove tetracycline (TC). The kinetics of adsorption for these three carbon materials all well fitted the pseudo-second-order kinetic model. The experimental data of adsorption isotherm had good compatibility with Langmuir and Freundlich models (R² > 0.90), but the Temkin model was the most applicable for all adsorbents (R² > 0.98). A super-high adsorption capacity of EC-KOH obtained from Langmuir fitting was 933.56 mg g^-1, which was much higher than that of EC-H₂ (538.91 mg g^-1) and EC (423.30 mg g^-1), possibly due to its larger specific surface area (S_BET), pore volume, and specific surface chemical structure. Moreover, it was found that surface functional groups and large aperture of adsorbents had a positive effect on adsorption rate. More adsorption sites and surface functional groups of adsorbents were beneficial to enhance the adsorption affinity. These results are of great benefit to the directional control of carbon structure to increase the adsorption performance in rate, capacity, and affinity of antibiotics.

Ball milling biochar with ammonia hydroxide or hydrogen peroxide enhances its adsorption of phenyl volatile organic compounds (VOCs)

Pristine biochar (CN600), ball-milled biochar (CN600-BM), H₂O₂ modified BM-biochar (CN600-O), and NH₄OH modified BM-biochar (CN600-N) derived from corn stalk were applied to adsorb phenyl volatile organic compounds (VOCs). H₂O₂ and NH₄OH modification of BM-biochar significantly improved its physicochemical characteristics and adsorption abilities. The specific surface area of CN600-O increased 2.05 and 1.23 times compared to CN600 and CN600-BM, respectively; while CN600-N increased 2.41 and 1.45 times, respectively. In addition, the ball milled biochars, especially CN600-O, showed higher acidity and polarity than CN600. The VOC adsorption amount onto biochars was 10.96-130.21 mg/g. CN600-O and CN600-N had high uptake of the VOCs and reached 100.07-111.79 mg/g and 110.49-130.21 mg/g, respectively. CN600-N showed the best performance with P-xylene adsorption up to 130.21 mg/g. VOC adsorption onto the CN600-O and CN600-N were mainly governed by surface adsorption and associated with morphology characteristics of the biochars as well as VOC properties such as boiling point and molecular size. Five cycles of adsorption-desorption experiments showed that CN600-O and CN600-N had good reusability with the reuse efficiencies of 88.01 %-92.21 % and 92.19 %-95.39 %, respectively. The results indicate that O- and N-doped ball-milled biochars are promising in adsorption for effective and sustainable VOC removal.

Unravelling the Environmental Application of Biochar as Low-Cost Biosorbent: A Review

In this age, a key target for enhancing the competitiveness of the chemical, environmental and biotechnology industries is to manufacture high-value products more efficiently and especially with significantly reduced environmental impact. Under this premise, the conversion of biomass waste to a high-value added product, biochar, is an interesting approach under the circular economy principles. Thus, the improvements in the biochar production and its new and innovative uses are hot points of interest, which are the focus of vast efforts of the scientific community. Biochar has been recognized as a material of great potential, and its use as an adsorbent is becoming a reliable strategy for the removal of pollutants of different streams, according to its high adsorption capacity and potential to eliminate recalcitrant compounds. In this review, a succinct overview of current actions developed to improve the adsorption capability of biochar, mainly of heavy metal and organic pollutants (dyes, pharmaceuticals and personal care products), is summarized and discussed, and the principal adsorption mechanisms are described. The feedstock and the production procedure are revealed as key factors that provide the appropriate physicochemical characteristics for the good performance of biochar as an adsorbent. In addition, the modification of the biochar by the different described approaches proved their feasibility and became a good strategy for the design of selective adsorbents. In the last part of this review, the novel prospects in the regeneration of the biochar are presented in order to achieve a clean technology for alleviating the water pollution challenge.

Sonication alkaline-assisted preparation of Rhizopus oryzae biomass for facile bio-elimination of tetracycline antibiotic from an aqueous matrix

The present study aimed to remove tetracycline (TET) antibiotic molecule from an aqueous medium using adsorbents prepared from Rhizopus oryzae biomass. The TET adsorption process was discontinuous and the adsorbent biomass was crude and NaOH-sonication-modified Rhizopus oryzae fungi. Specific active surface area for crude and modified Rhizopus oryzae was 10.38 m²/g and 20.32 m²/g, respectively. The results showed that the maximum TET adsorption efficiency was determined at pH 4, temperature 25 °C, initial TET concentration 10 mg/L, contact time 80 min, and biomass quantity 2 g/L. The equilibrium behavior showed that the Langmuir model suitably described the process. The maximum TET adsorption capacity was determined to be 38.02 mg/g and 67.93 mg/g, respectively, indicating that the method of biomass modification promoted the bio-adsorption capacity. A higher correlation coefficient (R²) and lower RMSE for the pseudo-first-order kinetic than other models showed its ability to describe the behavior of TET bio-adsorption. The enthalpy thermodynamic parameter (ΔH°) for the TET adsorption process was determined - 63.847 kJ/mol and - 85.226 kJ/mol for the raw and modified Rhizopus oryzae, respectively. Therefore, it can be suggested that the biomass of Rhizopus oryzae especially the modified version can be effectively used for the TET removal from aqueous environments.