Porous activated carbons derived from bamboo pulp black liquor for effective adsorption removal of tetracycline hydrochloride and malachite green from water

Sustainable activated carbon from copper pod tree leaves for efficient tetracycline removal and regeneration

The persistence of tetracycline (TC) in water poses environmental risks, including antibiotic resistance, necessitating effective removal. This study explores the synthesis and application of activated carbon from copper pod tree leaves for TC adsorption. The adsorbent was produced through orthophosphoric acid activation at low temperature and characterized using multiple techniques. FESEM revealed a porous structure favorable for adsorption, while EDS confirmed the presence of carbon, oxygen, and phosphorus. FTIR identified hydroxyl and carbonyl groups facilitating hydrogen bonding with TC, enhancing adsorption. XRD confirmed the adsorbent's amorphous nature, while BET revealed a high surface area (865.06 m²/g). XPS further identified C-O and C = O bonds, further supporting adsorption. Kinetic experiments showed that the adsorption fitted to pseudo-second-order kinetics (R² = 0.9765), indicating chemisorption as the dominant mechanism. The isotherm modeling results indicated that the Langmuir model provided an excellent fit to the experimental data (R² = 0.9952), demonstrating a high monolayer adsorption capacity of 103.32 mg/g. Thermodynamics confirmed spontaneity and endothermicity with a ΔH° of 50.75 kJ/mol. The prepared adsorbent effectively removed TC across natural water matrices, retaining high performance after five regeneration cycles.

Valorizing Xanthoceras Sorbifolia Bunge seed coats: A novel lignin-based activated carbon for effective malachite green adsorption and wastewater treatment

In order to increase the added value of Xanthoceras Sorbifolia Bunge (XSB) and to obtain green biomass activated carbon with abundant pores for efficient MG removal, this study was the first to prepare XSB-based high-performance activated carbon using KOH activation. Activated at temperatures between 600 and 800 °C, XSBAC-800 exhibited the highest specific surface area (1580 m2/g) and pore volume (0.732 cm3/g), leading to superior MG adsorption. The maximum adsorption capacity (Qm) of XSBAC-800 for MG was 1241.25 mg/g at 313 K, pH=7, and 0.2 g/L concentration. The adsorption process was spontaneous, endothermic, and driven by physical mechanisms such as pore filling and electrostatic interactions. XSBAC-800 also demonstrated excellent reusability, maintaining a removal percentage above 89 % after five regeneration cycles. These findings highlight the effectiveness of XSB-based activated carbon as a sustainable adsorbent for the removal of MG dyes, providing a promising solution for water pollution control.

Bimetallic-nitrogen-carbon aerogel Co/Ni-N-C derived from 2D ordered nanosheet arrays activate PMS-AOPs for effective antibiotic removal: performance, mechanism, and toxicity

In recent years, peroxymonosulfate-based advanced oxidation processes (PMS-AOPs) have garnered increasing attention for their efficacy in eliminating persistent organic pollutants. Metal-nitrogen-carbon (M-N-C) materials are frequently employed as efficient catalysts for the activation of PMS, leading to the effective production of various reactive species. In this study, a novel 3D porous cobalt/nickel bimetallic-nitrogen-carbon aerogel (Co/Ni-N-C) with well-dispersed CoNi-nanosheets that enhance electron transfer and provide a large active surface area was prepared through an in situ growth and a straightforward pyrolysis procedure of 2D cobalt/nickel metal-organic framework (CoNi-MOF) which was contained by a bamboo cellulose aerogel as a precursor. Rapid tetracycline (TC) removal (efficiency of 99.83% and mineralization rate of 69.8%) was achieved via PMS activation, facilitated by a synergistic enhancement effect of well-dispersion CoNi-nanosheet array. The evenly dispersed Co/Ni-N active sites and high Co:Ni ratio (PCo:Ni = 0.21) producing multiple reactive oxygen species (ROS) were essential in accelerating removal of contaminant. The toxicity assessment results of the intermediates further confirmed that the catalytic degradation in the Co/Ni-N-C-800/PMS system reduced the ecological toxicity of TC through dehydroxylation, demethylation, ring-opening, and deamidation. Furthermore, the Co/Ni-N-C-800/PMS system demonstrated exceptional degradation efficiency for various aromatic compounds with diverse substituents and showed good cyclic stability. These findings offer insights into the development of highly effective bimetallic-nitrogen-carbon catalytic materials.

A novel oxidized hierarchical porous carbon with vesicule-like ultrathin graphitic walls for efficient removal of anionic and cationic dyes

This work developed a novel oxidized hierarchical porous carbon (OHPC) with vesicule-like ultrathin graphitic walls via a method of air oxidation and used as an efficient adsorbent for Congo red (CR) and Malachite green (MG) removal. Results show that the OHPC2 oxidized at 400 °C possesses three-dimensional hierarchical pores with vesicule-like ultrathin graphitic walls. The prepared OHPC2 not only has a large specific surface area of 1020 m2 g-1 with a high pore volume, but also has abundant oxygen-containing functional groups. These unique structural features endow the OHPC2 with high adsorption capacities for CR (2729.5 mg g-1) and MG (1697.3 mg g-1) removal. The adsorption processes of CR and MG are in accordance with the Langmuir isotherm and Quasi-second-order kinetic models. The thermodynamic studies illustrate that the adsorption processes were thermodynamically feasible and spontaneous. Various characterization analysis explained that the adsorption mechanism may involve pore-filling effect, π-π conjugation, hydrogen bonding, and electrostatic attraction. Moreover, the OHPC2 exhibits good cycling stability and is identified as a desirable adsorbent for actual wastewater treatment.

Promising adsorbent for dye detoxification: Exploring the potential of chitosan sodium carboxymethylcellulose silk fibroin aerogel

The main goal of this study is to create a CS-CMC-SF aerogel consisting of chitosan sodium carboxymethylcellulose and silk fibroin. The aerogel is designed to remove types of dyes from water while also being environmentally friendly. This innovative adsorbent has been optimized for extracting both cationic and anionic dyes from solutions. It incorporates chitosan sodium carboxymethylcellulose and silk filament fibers to enhance its strength. Experimental data illustrates that the CS-CMC-SF aerogel possesses remarkable adsorption capabilities - 5461.77 mg/g for Congo Red (CR), 2392.83 mg/g for Malachite Green (MG), and 1262.20 mg/g for Crystal Violet (CV). A kinetic study aligns with the pseudo-second-order kinetic model suggesting predominant chemisorption phenomena occur during adsorption process. Isotherm analysis further identifies multilayered adsorption occurring on irregularly shaped surfaces of the aerogel while thermodynamic assessments validate exothermic and spontaneous characteristics inherent in its absorption mechanism. Several analytical methods such as SEM, FT-IR, XRD, and XPS were employed to examine physicochemical attributes tied to this unique material design conceptually; identifying mechanisms including pore filling, π-π interactions, ion exchange activity, electrostatic connections along with hydrogen bonding inducing overall superior performance output. Furthermore substantial soil biodegradability alongside compostable features associated with our proposed CS-CMC-SF aerogels established it's potential suitability within applications demanding sustainable options thereby validating its underlying ecological credibility.

Biobased chitosan-derived self-nitrogen-doped porous carbon nanofibers containing nitrogen-doped zeolites for efficient removal of uremic toxins during hemodialysis

Highly efficient adsorbents are needed to remove uremic toxins and reduce the economic and societal burden of the current dialysis treatments in resource-limited environments. In this study, nanostructured porous carbon nanofibers with nitrogen-doped zeolites (NZ-PCNF) were prepared, by electrospinning zeolites with chitosan-poly(ethylene oxide) blends, followed by a one-step carbonization process, without further activation steps or aggressive chemical additives for N-doping. The results showed that N-zeolites were successfully integrated into an ultrafine carbon nanofiber network, with a uniform nanofiber diameter of approximately 25 nm, hierarchical porous structure (micro- and mesopores), and high specific surface area (639.29 m2/g), facilitating uremic toxin diffusion and adsorption. The self-N-doped structure in the NZ-PCNF removed more creatinine (∼1.8 times) than the porous carbon nanofibers when using the same weight of precursor materials. Cytotoxicity and hemolysis tests were performed to verify the safety of NZ-PCNF. This study provides a novel strategy for transforming chitosan-based materials into state-of-the-art porous carbon nanofiber/zeolite self-N-doped composites, affording an efficient bioderived adsorbent for the removal of uremic toxins in patients with chronic kidney disease.

Microwave-Assisted Synthesis of MoS2/BiVO4 Heterojunction for Photocatalytic Degradation of Tetracycline Hydrochloride

Compared with traditional hydrothermal synthesis, microwave-assisted synthesis has the advantages of being faster and more energy efficient. In this work, the MoS₂/BiVO₄ heterojunction photocatalyst was synthesized by the microwave-assisted hydrothermal method within 30 min. The morphology, structure and chemical composition were characterized by X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and high-resolution transmission electron microscopy (HRTEM). The results of characterizations demonstrated that the synthesized MoS₂/BiVO₄ heterojunction was a spherical structure with dimensions in the nanorange. In addition, the photocatalytic activity of the samples was investigated by degrading tetracycline hydrochloride (TC) under visible light irradiation. Results indicated that the MoS₂/BiVO₄ heterojunction significantly improved the photocatalytic performance compared with BiVO₄ and MoS₂, in which the degradation rate of TC (5 mg L^-1) by compound where the mass ratio of MoS₂/BiVO₄ was 5 wt% (MB5) was 93.7% in 90 min, which was 2.36 times of BiVO₄. The active species capture experiments indicated that •OH, •O₂^- and h⁺ active species play a major role in the degradation of TC. The degradation mechanism and pathway of the photocatalysts were proposed through the analysis of the band structure and element valence state. Therefore, microwave technology provided a quick and efficient way to prepare MoS₂/BiVO₄ heterojunction photocatalytic efficiently.