Novel BiOBr by compositing low-cost biochar for efficient ciprofloxacin removal: the synergy of adsorption and photocatalysis on the degradation kinetics and mechanism insight

Boosting the photocatalytic activity of g-C3N4 via loading bio-synthesized Ag0 nanoparticles and imidazole modification for the degradation and mineralization of fluconazole

The emergence of fluorinated organic compounds in the pharmaceutical, agrochemical, and textile industries has led to a potential increase in the environmental issues and health problems. Herein, a modified heterojunction of bio-synthesized Ag nanoparticles (Ag0 NPs) immobilized on imidazole-modified graphite carbon nitride (Im/g-C3N4) as a suitable support (Ag0/Im/g-C3N4) was hydrothermally synthesized and studied for the photocatalytic removal of the most widely used antifungal organo-fluorine compound-fluconazole (FCZ). The optical properties were thoroughly investigated in the present study, and it was observed that the proposed modification to g-C3N4 has led to the shifting of conduction and valance band edge position (for g-C3N4, -0.73 and 1.54 eV and for ICA, -1.14 and 1.28 eV), narrowing of band gap energies, i.e., 2.01 eV, and reduced charge recombination rate. The external and internal surface morphologies were scrutinized through FE-SEM and HR-TEM analyses. Functionalities and potential crystallinity were investigated using FTIR and XRD techniques. The elemental state and composition of the composite were analyzed via XPS. The obtained results substantiate the intended modifications in the ICA composite. The photocatalyst Ag0/Im/g-C3N4 (ICA) was able to degrade 95.74% of FCZ with a high degradation rate (k1) of 0.0289 min-1 within 2-h of the solar illumination experiment. The overall degradation process was observed to be governed by a pseudo-first-order kinetic model. Detailed parameters such as effects of ions, pH (optimized pH 4, highest degradation rate k1 =0.039 min-1), dissolved organic matter (DOM), and optimization of catalysts dosage were studied. The major reactive oxygen species (ROS) was identified as super-oxide radicals (O2●-). The HR-MS and COD-TOC analysis were used to evaluate the degradation and mineralization of FCZ forced by ICA catalysts. The ICA catalyst was found to be stable and reusable for up to five cycles suggesting towards its potential towards the mitigation of environmental pollutants.

Small microplastic particles promote tetracycline and aureomycin adsorption by biochar in an aqueous solution

Biochar (BC) has been used to remove antibiotics from wastewater. Microplastics are emerging contaminants of wastewater. The capacities of microplastics for adsorbing antibiotics and the effects of microplastics of different types and particle sizes on antibiotic adsorption by BC have not been studied. Here, adsorption isotherm and kinetics experiments were performed to investigate tetracycline and aureomycin adsorption to polyvinyl chloride particles with diameters of 10, 100, 500, and 2000 μm, polylactic acid particles with diameters of 30, 100, 500, and 2000 μm (PLA30, PLA100, PLA500, and PLA2000, respectively), and wheat straw BC. The highest tetracycline adsorption capacity (25.00 mg g-1) was found for a PLA30 + BC. The tetracycline adsorption capacities of the other microplastic particles were 20.44-24.57 mg g-1. The highest aureomycin adsorption capacity (39.50 mg g-1) was found for 10 μm polyvinyl chloride particles and BC. The aureomycin adsorption capacities of the other microplastic particles were 32.21-38.42 mg g-1. The tetracycline adsorption capacities were 13.69%, 6.28%, 5.49%, and 4.54% higher for PLA30 + BC, PLA100 + BC, PLA500 + BC, and PLA2000 + BC, respectively, than for only BC. This may have been because there were more sites available per unit mass of microplastic for adsorbing tetracycline and dissolved organic carbon on small microplastic particles than large microplastic particles. The results indicated that microplastics can adsorb antibiotics and increase the amounts of antibiotics adsorbed by BC. Therefore, it is essential to consider potential interactions between BC and microplastics when BC is used to remove antibiotics from wastewater.

Efficient Degradation of Ciprofloxacin in Water over Copper-Loaded Biochar Using an Enhanced Non-Radical Pathway

The development of an efficient catalyst with excellent performance using agricultural biomass waste as raw materials is highly desirable for practical water pollution control. Herein, nano-sized, metal-decorated biochar was successfully synthesized with in situ chemical deposition at room temperature. The optimized BC-Cu (1:4) composite exhibited excellent peroxymonosulfate (PMS) activation performance due to the enhanced non-radical pathway. The as-prepared BC-Cu (1:4) composite displays a superior 99.99% removal rate for ciprofloxacin degradation (initial concentration 20 mg·L-1) within 40 min. In addition, BC-Cu (1:4) has superior acid-base adaptability (3.98~11.95) and anti-anion interference ability. The trapping experiments and identification of reactive oxidative radicals confirmed the crucial role of enhanced singlet oxygen for ciprofloxacin degradation via a BC-Cu (1:4)/PMS system. This work provides a new idea for developing highly active, low-cost, non-radical catalysts for efficient antibiotic removal.

Enhanced photocatalytic performance of milkvetch-derived biochar via ZnO-Ce nanoparticle decoration for reactive blue 19 dye removal

In this research, the photocatalytic removal of reactive blue 19 (RB19) dye is investigated employing zinc oxide/cerium (ZnO@Ce) nanoparticles decorated with biochar under LED irradiation. Synthesis of ZnO@Ce nanoparticles decorated with biochar was performed utilizing the co-precipitation procedure and, then, the texture and morphology of the fabricated nanocomposite were analyzed using energy dispersive X-ray (EDX), field emission scanning electron microscopy (FE-SEM), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), and Fourier transform infrared (FTIR) spectroscopy techniques. Moreover, FE-SEM images demonstrate that ZnO-Ce nanoparticles were successfully decorated on the surface of biochar. The specific surface areas of biochar and biochar/ZnO-Ce were 519.75 and 636.52 m2/g, respectively. To achieve the maximum yield in the removal of RB19 dye, the effects of operating variables including dye concentration, LED lamp power, biochar@ZnO-Ce catalyst dose, pH and H2O2 dose were explored. Besides, the maximum percentage of RB19 dye removal was 96.47% under optimal conditions, i.e. catalyst dosage of 100 mg, H2O2 dosage of 1 mL, pH of 9, initial dye concentration of 5 ppm, LED power of 50 W, and reaction time of 140 min. Furthermore, the kinetic analysis reveals that the removal of RB19 dye follows the pseudo-first order kinetic model, with calculated values of a reaction rate constant of 0.045 min-1 and a correlation coefficient of R2 = 0.99, respectively. Moreover, the reusability and recyclability of biochar@ZnO/Ce nanocatalyst was promising over five runs, with only a 6.08% decrease in RB19 dye removal efficiency. Therefore, it can be concluded that the biochar @ZnO/Ce photocatalyst can be promisingly applied for the removal of azo dyes in aqueous solutions.

Visible-light-driven simultaneous decontamination of multi-antibiotics by facile synthesized BiOCl loaded food wastes biochar

Environmental dissemination caused by widespread use of antibiotics has been regarded as a possible hazard to aquatic ecosystem and human health. The increasing misgivings make it imperative to develop a novel catalyst with remarkable visible-light-driven activity to remove antibiotics, especially for their simultaneous decontamination. Herein, C/BiOCl composites were successfully prepared by decorating BiOCl nanosheets on food wastes biochar (C) by a simple hydrolysis strategy. Not only the binary system of tetracycline antibiotics, but also the ternary mixture could be simultaneously photodegraded over 25% C/BiOCl within 15 min irradiation. The improved photocatalytic activities could be ascribed to the introduction of biochar, endowing increased surface area, enhanced separation of photo-generated charge carriers, and better light absorption. The as-prepared 25% C/BiOCl also demonstrated satisfactory stability and positive removal effect in actual water samples. The present work provides new insights into the development of biochar-based photocatalysts for simultaneous degradation of multiple antibiotics.

Biochar based photocatalyst for degradation of organic aqueous waste: A review

The advancement in the treatment technology for wastewater containing recalcitrant pollutants to lower the overall cost and time of the treatment processes is the prime demand. Biochar (BC) based photocatalyst have proved their potential application in the photo-degradation of a wide range of organic pollutants. The structural and chemical properties of the BC enhance the efficacy of photocatalyst, improving its optical properties with increased stability. This review gives an overview of the progress that occurred during the last five years in BC-based photocatalyst for degradation of recalcitrant organic waste in the aqueous system, emphasizing the role of BC in the photocatalytic performance with a brief discussion regarding the various sources of BC and different strategies used to modify the BC. Further, the critical challenges are discussed, which would be confronted during the scaling up and real-time application in wastewater treatment.

Coupling Adsorption-Photocatalytic Degradation of Methylene Blue and Maxilon Red

The MB and MR removal process by two mechanisms of adsorption using rice straw (absence of UV light) and photodegradation on TiO₂ surfaces was investigated. MB and MR removal efficiency were further intensified upon the sequential operation of adsorption followed by photocatalytic degradation over TiO₂ under visible light irradiation. The TiO₂ was used to remove methylene blue (MB) and Maxilon Red (MR) dye from aqueous media by continuous mode at 25 ± 2 °C, at pH 6.8 ± 0.2. Photo-illumination study revealed 75.81 and 65.51% MB and MR removal with the dose of 1 g/L TiO₂ with an initial concentration of 5 mg/L within 120 min. This study can be deemed of potential applications for the removal of MB and MR dyes on an industrial level using the synergistic adsorption-photocatalytic oxidation approach. A probable photodegradation mechanism was proposed.

Biochar-Supported TiO2-Based Nanocomposites for the Photocatalytic Degradation of Sulfamethoxazole in Water-A Review

Sulfamethoxazole (SMX) is a frequently used antibiotic for the treatment of urinary tract, respiratory, and intestinal infections and as a supplement in livestock or fishery farming to boost production. The release of SMX into the environment can lead to the development of antibiotic resistance among the microbial community, which can lead to frequent clinical infections. SMX removal from water is usually done through advanced treatment processes, such as adsorption, photocatalytic oxidation, and biodegradation. Among them, the advanced oxidation process using TiO2 and its composites is being widely used. TiO2 is a widely used photocatalyst; however, it has certain limitations, such as low visible light response and quick recombination of e-/h+ pairs. Integrating the biochar with TiO2 nanoparticles can overcome such limitations. The biochar-supported TiO2 composites showed a significant increase in the photocatalytic activities in the UV-visible range, which resulted in a substantial increase in the degradation of SMX in water. The present review has critically reviewed the methods of biochar TiO2 composite synthesis, the effect of biochar integration with the TiO2 on its physicochemical properties, and the chemical pathways through which the biochar/TiO2 composite degrades the SMX in water or aqueous solution. The degradation of SMX using photocatalysis can be considered a useful model, and the research studies presented in this review will allow extending this area of research on other types of similar pharmaceuticals or pollutants in general in the future.