Field Of Environmental Remediation Research Articles

Knowledge graph and development hotspots of biochar as an emerging aquatic antibiotic remediator: A scientometric exploration based on VOSviewer and CiteSpace

As an emerging material in the field of environmental remediation, biochar produced by carbonisation of organic solid waste has been widely used in the remediation of antibiotic wastewater due to its environmental friendliness and excellent adsorption properties. This study analyses the current literature in the field in a comprehensive and scientific manner using CiteSpace and VOSviewer technologies. Between 2011 and 2023, a total of 1162 papers were published in this domain, spanning three distinct stages: applied methods, mechanism investigation, and enhanced improvement. The results of keyword clustering indicate that the remediation of antibiotics complexed with multiple pollutants by biochar is the main research topic, followed by the remediation of antibiotics by biochar in combination with other technologies. Furthermore, drawing from current research hotspots in antibiotic remediation using biochar, this study identified the pivotal mechanisms involved: (1) The primary mechanisms by which raw biochar remediates antibiotics include π-π electron donor-acceptor interactions, hydrophobic interactions, electrostatic interactions, hydrogen-bonding, and pore filling. (2) Steam activation, acid/base, metal salt/metal oxide, and clay mineral modification can improve the physical/chemical properties of biochar, enhancing its adsorptive removal of antibiotics. (3) Biochar activated persulfate and degraded antibiotics via free radical pathways (SO4−•, •OH and O2−•) as well as non-free radical pathways (1O2 and electron transfer). In addition, the challenge and prospect of biochar engineering applications for antibiotic remediation lies in improving the main mechanism of antibiotic remediation by biochar. The prospective utilization of biochar in enhancing the remediation of antibiotic-related pollutants holds tremendous value for the future.

Comprehensive review on fly ash: Turning waste into a valuable resource for sustainable development

Fly ash, a byproduct of coal combustion in the power plants has long been viewed as a waste material with potential environmental hazards. However, in recent years, there has been a paradigm shift in the perception of fly ash, as it is increasingly recognized as a valuable resource with numerous applications in field of construction, agriculture, and environmental remediation. This Paper explores the various facets of fly ash and the diverse ways in which it is being harnessed for sustainable development for the society.

Chemical Synthesis of Bimetallic Ag/Co Nanoparticles for Colorimetric Detection of Cr3+ and Fe3+ and Its Catalytic Performance

Precious metal nanoparticles, especially Ag-based nanoparticles due to their strong surface plasma effect and excellent catalytic performance, have been widely applied in environmental remediation and detection of heavy metal ions in aqueous solution. In this study, first, bimetallic Ag/Co nanoparticles (Ag/Co NPs) modified by sodium citrate were synthesized by chemical reduction method. Second, bimetallic Ag/Co NPs were used as colorimetric probe for detecting [Formula: see text] and [Formula: see text] in aqueous solution simultaneously for the first time. The results showed that the probe had high specificity towards [Formula: see text] and [Formula: see text] among the tested metal ions. When [Formula: see text] was mixed with Ag/Co NPs, the solution quickly changed from yellow to pink, meanwhile, the UV–Vis absorption intensity declined at 400[Formula: see text]nm and a new prominent absorption band was formed at 530[Formula: see text]nm. While [Formula: see text] was mixed with Ag/Co NPs, the solution quickly changed from yellow to nearly colorless. The linear relationship between absorbance of bimetallic Ag/Co NPs at 400[Formula: see text]nm and −log of [Formula: see text] concentration is 1[Formula: see text]nM to 10[Formula: see text][Formula: see text]M, which [Formula: see text] and [Formula: see text]. The limit of detection (LOD) for this study was 1.14[Formula: see text]nM. Similar to [Formula: see text], the LOD for [Formula: see text] was calculated 16.3[Formula: see text][Formula: see text]M. In addition, the catalytic performance of bimetallic Ag/Co NPs was evaluated by methylene blue (MB) in the presence of H2O2. The catalytic degradation efficiency of bimetallic Ag/Co NPs was about 4.8 times greater than monometallic Ag NPs, confirming Ag and Co NPs had obviously synergistic effect. Therefore, this result made bimetallic Ag/Co NPs had potential application in the field of environmental remediation.

Conjugating HA bundles with ZIF-8 for catalytic degradation of tetracycline and antibacterial capacity

The overused of antibiotics had led to major environmental issues and drug-resistant bacteria, which inevitably harmed the environment and public health. In this work, in order to obtain environmentally friendly bi-functional materials to combat with residual antibiotics and bacterial contamination, ZIF-8, a typical Zn based zeolitic imidazolate framework (ZnZIF) with excellent chemical stability, was conjugated to hydroxyapatite nanowire bundles (HAnBs) by a simple in-situ synthesis. The obtained ZnZIFs@HAnBs was characterized by SEM, EDS, XPS, FT-IR, XRD and BET. The effects of catalysts, catalyst dosage, TC initial concentration, PMS concentration and pH on TC degradation were investigated. Notably, ZnZIFs@HAnBs (94.0 %) exhibited excellent degradation effect of tetracycline (TC) within 15 min, which was 1.7 and 5.2 times than that of ZIF-8 (55.9 %) and HAnBs (18.1 %) under optimal conditions, respectively. Moreover, after recycling 10 times, the degradation rate still more than 86.8 %. The degradation mechanism was confirmed by free radical quenching experiment coupling with electron paramagnetic resonance (EPR), and the 1O2 and O2•- were the major reactive oxygen species in TC degradation. Furthermore, it presented excellent antibacterial activity (95.0 %) against E. coli and S. aureus, which was attributed to the synergistic effect of sustained release of Zn2+ and phosphate in ZnZIF@HAnBs. In summary, an eco-friendly bi-functional materials of HA nanowire bundles could be synthesized by simple strategy, and it could be applied in the fields of environmental remediation, as well as in treatment of antibiotic and bacterial pollution.

Photocatalytic performance of Au/Bi4Ti3O12 composite improved by synergistic piezoelectric effect and exciton-plasmon

Bi4Ti3O12 (BiTO) is a typical bismuth-layered Aurivillius ferroelectric material for its potential application in photocatalysis. In this study, Au/BiTO hybrid was fabricated by precipitating Au nanoparticles onto BiTO nanoflake using a sodium citrate reduction route. This integration has led to a remarkable enhancement in the photocatalytic efficiency, which is attributed to the synergistic coupling of piezoelectric effect of BiTO with the localized surface plasmon resonance (LSPR) of Au nanoparticles. The incorporation of Au nanoparticles onto the BiTO matrix has significantly boosted the light absorption and charge carrier separation, thereby augmenting the photocatalytic activity. Notably, Au/BiTO-2 composite exhibits exceptional photocatalytic performance, demonstrating the complete degradation of RhB within 40 min under full-spectrum light irradiation. Moreover, Au/BiTO-2 displays a robust photocatalytic action against other organic pollutants, including methyl orange (MO), ofloxacin (OFLX) and tetracycline hydrochloride (TC). Further enhancement of photocatalytic process is achieved when combing light irradiation with ultrasonic excitation. The ultrasonic waves break the static spontaneous polarization through alternating piezoelectric potential, which accelerates the catalytic reaction. The photocatalytic action rate of Au/BiTO-2 toward RhB reaches a value as high as 0.0984 min−1, which is nearly 2.3 folds increasement compared to that of pristine BiTO. The possible synergistic mechanism caused by piezoelectric effect and exciton-plasmon effect is discussed in detail. The work not only enriches our understanding of the underlying principles but also supply a new strategy to design high-performance catalysts in the field of environmental remediation and energy conversion.

Constructing 3D magnetic MXenes/chitosan composites to reinforce U(VI) and Cr(VI) trapping: Excavating from performance to mechanism

Herein, we proposed a novel chitosan-induced self-assembly strategy to construct three-dimensional magnetic MXenes/chitosan composites to eliminate U(VI)/Cr(VI). Spectroscopic analysis elucidated that the magnetic composites exhibited a three-dimensional network structure, and the abundant –OH and –NH2 groups played a pivotal role in boosting elimination performance of the composites. Batch experiment demonstrated that the synergistic effect of the amino and hydroxyl groups contributed greatly to adsorption, and the maximum adsorption capacity of U(VI) and Cr(VI) was up to 106.2 and 83.1 mg/g, respectively. Meanwhile, the kinetic studies showed that an obvious transition between diffusion control and mass transfer control, and the adsorption behavior was endothermic and spontaneous. Furthermore, a comprehensive synergistic adsorption mechanism was proposed based on the systematic spectra analysis. Namely, the target contaminant was rapidly immobilized on the 3D composites via electrostatic interaction, then the U(VI) was complexed with the amino groups, while a part of Cr(VI) was reduced to Cr(III) by the hydroxyl groups. Thus, this study not only paved the way for mitigating the increasing heavy metal/radionuclide contamination, but also promoted the application of MXexes-based materials in the field of environmental remediation.

EVALUATION OF THE BIOSORPTION OF Mn²⁺ AND Zn²⁺ BY PASSION FRUIT PEEL: STUDY OF DOSAGE AND CONTACT TIME

Objective: The objective of this study is to investigate he effectiveness of Mn2+ and Zn2+ biosorption by passion fruit peel as a sustainable and economically viable alternative to the biosorption process. Method: The methodology adopted for this research comprises the characterization of the biomass and batch tests. Tests were carried out with different masses of biomass in standard solutions of the metals investigated. The biosorption capacity of the biomass and the removal efficiency were calculated based on the differences in concentration of the metal ions. Results and Discussion: The results obtained revealed that the biomass showed high efficiency (close to 100%) for both cations. The contact time of 30 minutes was sufficient to reach equilibrium in the biosorption capacity of the metals, indicating the speed and effectiveness of the process. Research Implications: The practical and theoretical implications of this research provide valuable information on the application of passion fruit peel as a biosorbent in the removal of potentially toxic metals from contaminated wastewater. These results may influence practices in the field of environmental remediation and environmental engineering, as well as in agro-industrial waste management. Originality/Value: This study contributes to the literature by highlighting the originality of using passion fruit peel in natura as a biosorbent, presenting an innovative and sustainable approach to the remediation of contaminated effluents. The high efficiency of ion removal with low biomass dosages and short contact times adds knowledge to the field of biosorption using agro-industrial waste.

Guar gum, Ulva lactuca L. biomass, and xanthan gum-based copolymer novel biosorbent for adsorptive removal of acid orange 10

The textile industry's wastewater discharge into water bodies has become a significant environmental concern due to its toxicity and adverse impact on the ecosystem. In response, this study presents the development of a highly effective adsorbent (GG@ULB@XG composites) by employing guar gum (GG), Ulva lactuca L. biomass (ULB), and xanthan gum (XG), using the ionic gelation method. Various characterization techniques including XRD, SEM, TGA, Zeta Sizer, Zeta Potential, BET, FTIR, and Point of Zero charge (pHPZC) were utilized to analyze the properties of the GG@ULB@XG composites. The removal efficiency of the composite for Acid Orange 10 dye was found to be exceptional, achieving a remarkable 93% removal rate. Optimal adsorption parameters were determined, including initial AO10 concentration (100 ppm), temperature (298K), pH (3), adsorbent concentration (100 mg), and contact time (15 min) at 480 λmax. The thermodynamic analysis provided valuable insights into the thermal stability of the adsorbent. Additionally, a comprehensive investigation of adsorption isotherms (linear and non-linear), such as Elovich, Freundlich, D-R, Langmuir, and Temkin Isotherms, was conducted to better understand the adsorption behavior. Various linear and non-linear adsorption kinetics models, including Elovich, first-order, interparticle diffusion, and second-order kinetic models, were employed to gain deeper insights into the chemistry of the adsorption process. This study highlights the potential of GG@ULB@XG composites as an effective and environmentally friendly solution for water treatment and dye removal in industrial wastewater and sets a foundation for future studies in the field of environmental remediation.

Nanoconfinement-induced high activity of ZIF-8 derived atomic Zn-N-C materials for fenton-like reactions

Atomic Zn-N-C materials are synthesized by direct carbonization of ZIF-8, which maintains the rhombic dodecahedron morphology (RDM) with abundant nanopores. Zn-N-C-RDM shows enhanced catalytic activity with bisphenol A (BPA) as model pollutant and peroxydisulfate (PDS) as oxidant. Molecular dynamic (MD) calculations show that mean square displacement (MSD) of PDS, BPA, and H2O molecules in the nanotunnels decreases obviously with smaller pore size. Due to the confinement, the BPA (di = 1.0 nm) and PDS (di = 0.5 nm) can easily enter and confined in the cavities of Zn-N-C-RDM. PDS can be therefore activated more easily to degrade BPA due to their faster diffusion and shorter transfer routes. > 97 % degradation of BPA can therefore be achieved by Zn-N-C-RDM within 20 min. Quenching experiments, electron paramagnetic resonance (EPR) and open circuit potential (OCP) results indicate that O2•− radical dominate the degradation. According to the density functional theory (DFT) results, the binding sites of Zn-pyridinic N are the main active sites. This work provides new insights for improving activity in Fenton-like reactions in the field of environmental remediation.

Optimizing levofloxacin decontamination in aquatic environment: Iron-modified biochar in heterogeneous Fenton processes with peroxide and persulfate

This study evaluates the effectiveness of iron-modified biochar (Fe-BC) in fixed-bed heterogeneous Fenton processes for levofloxacin (LFX) removal, a widely-used fluoroquinolone antibiotic. The objective is to optimize parameters such as pH, oxidants (H2O2 and S2O82−), and biochar forms (functionalized and raw) using factorial analysis of mixed data (FAMD) and response surface methodology (RSM). These optimizations identified the ideal conditions for maximal LFX removal. The most effective removal with Fe-BC occurred at 2.5 mM H2O2 and pH 7.5, while the optimal S2O82− conditions were 1.6 mM at pH 2.8. Both Fe-BC and raw biochar (RBC) showed the highest adsorption at pH 5.8. In adsorption-only, RBC and Fe-BC reduced LFX to 530 μg/L and 335 μg/L, respectively, in 60 min. The oxidation process further decreased LFX levels to between 8.9 μg/L and 0.1 μg/L using S2O82− and H2O2, respectively. The research expanded upon a kinetic model, incorporating the calculation of kinetic constants for both adsorption and oxidation processes, to deepen our understanding of the intricate degradation dynamics at play. Identifying by-products was crucial in elucidating degradation pathways. These findings are vital for environmental remediation, demonstrating the efficiency of Fe-BC in removing harmful antibiotics from water. This research highlights the potential of modified biochar in environmental clean-up, especially for water contaminated with antibiotics. The results emphasize the importance of optimizing treatment conditions for effective antibiotic removal, contributing valuable insights to the field of environmental remediation.

Theoretical study on the capture of toxic gases by ionic liquids encapsulated in assembled belt[14[pyridine

In the current study, self-assembled belt[14]pyridine (BP) encapsulated IL (tetramethylammonium chloride (TMACl)) is theoretically explored to capture greenhouse gases (GHGs) at B3LYP-D3/6-311G(d,p) level of theory. The encapsulation of TMACl in assembled belt[14]pyridine is thermodynamically feasible as revealed through high interaction energy value of −50.7 kcal/mol. Moreover, the results of capturing of gas molecules (SO2, CO2, CO and CH4) show that attractive forces involved in capturing of gases are strong van der Waals forces i.e., London dispersion forces and electrostatic interactions. The synergic effect of self-assembled belts and ionic liquid results in significantly high interaction energy values ranging from −7.88 to −25.92 kcal/mol for capturing of gas molecules. Furthermore, the interaction between BP-TMACl and gas molecules is studied in detail through natural bond orbital (NBO) analysis. NBO results show the charge transfer between the fragments (BP-TMACl and gases) which is further validated through EDD analysis. The charge shifts towards all of the captured gas molecules but the most prominent change in NBO charges is shown by captured SO2. The successful charge transfer indicates better interaction in the designed systems. Additionally, the type and strength of interactions involved in the process of encapsulation is studied through quantum theory of atoms in molecules (QTAIM) and noncovalent interactions (NCI) analysis. NCI analysis clearly shows that gases are captured by BP-TMACl complex through strong van der Waals forces. However, in capturing of SO2, strong electrostatic attractive forces are also involved. The nature of attractive forces is confirmed through QTAIM analysis. Furthermore, the relation between recovery time and desorption energy of captured gas molecules has been studied. The strongest absorption for SO2 results in prolonged recovery time for it (as compared to the other gas molecules). AIMD analysis is performed to find the dynamical stability of assembled-belts before and after loading ionic liquids along with gases to be captured. These results reveal that assembled-belts are suitable for encapsulation of ionic liquids along with capturing of gases. Overall, the best results are shown for SO2 capture. The study intends to deliver valuable information on the important progress in the environmental-remediation field and we hope our work is going to inspire more investigators to provide novel research on such challenging tasks.

Introduction and Advancements in Room-Temperature Ferromagnetic Metal Oxide Semiconductors for Enhanced Photocatalytic Performance

Recent advancements in the field of room-temperature ferromagnetic metal oxide semiconductors (RTFMOS) have revealed their promising potential for enhancing photocatalytic performance. This review delves into the combined investigation of the photocatalytic and ferromagnetic properties at room temperature, with a particular focus on metal oxides like TiO2, which have emerged as pivotal materials in the fields of magnetism and environmental remediation. Despite extensive research efforts, the precise mechanism governing the interplay between ferromagnetism and photocatalysis in these materials remains only partially understood. Several crucial factors contributing to magnetism, such as oxygen vacancies and various metal dopants, have been identified. Numerous studies have highlighted the significant role of these factors in driving room-temperature ferromagnetism and photocatalytic activity in wide-bandgap metal oxides. However, establishing a direct correlation between magnetism, oxygen vacancies, dopant concentration, and photocatalysis has posed significant challenges. These RTFMOS hold immense potential to significantly boost photocatalytic efficiency, offering promising solutions for diverse environmental- and energy-related applications, including water purification, air pollution control, and solar energy conversion. This review aims to offer a comprehensive overview of recent advancements in understanding the magnetism and photocatalytic behavior of metal oxides. By synthesizing the latest findings, this study sheds light on the considerable promise of RTFMOS as effective photocatalysts, thus contributing to advancements in environmental remediation and related fields.

Combined exposure to decabromodiphenyl ether and nano zero-valent iron aggravated oxidative stress and interfered with metabolism in earthworms

Decabromodiphenyl ether (BDE-209) is a common brominated flame retardant in electronic waste, and nano zero-valent iron (nZVI) is a new material in the field of environmental remediation. Little is known about how BDE-209 and nZVI combined exposure influences soil organisms. During the 28 days study, we determined the effects of single and combined exposures to BDE-209 and nZVI on the oxidative stress and metabolic response of earthworms (Eisenia fetida). On day 7, compared to CK, malondialdehyde (MDA) content increased in most combined exposure groups. To remove MDA and reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activities were induced in most combined exposure groups. On day 28, compared to CK, the activities of SOD and CAT were inhibited, while POD activity was significantly induced, indicating that POD plays an important role in scavenging ROS. Combined exposure to BDE-209 and nZVI significantly affected amino acid biosynthesis and metabolism, purine metabolism, and aminoacyl-tRNA biosynthesis pathways, interfered with energy metabolism, and aggravated oxidative stress in earthworms. These findings provide a basis for assessing the ecological impacts of using nZVI to remediate soils contaminated with BDE-209 from electronic waste.

Co-immobilization of laccase-mediator system to catalyze the synthesis of theaflavins from tea polyphenols

The co-immobilized laccase-mediator system (LMS) has broad development prospects in the fields of biocatalysis, biochemistry, and environmental remediation. In this study, laccase and mediator molecules were co-immobilized in functionally modified calcium alginate microspheres to improve their catalytic activity and stability and to systematically characterize the physicochemical properties and evaluate the catalytic performance of the co-immobilized laccase-mediator system. The co-immobilized LMS was used to catalyze the synthesis of theaflavins (TFs) from tea polyphenols, improve the catalytic efficiency, realize the recycling of the system, and explore the safety of the catalytic products. The results showed that the catalytic efficiency of the co-immobilized LMS was significantly improved and the relative activity remained above 50% after 10 cycles. The in vitro safety of the catalytic product was verified by Human hepatocellular carcinoma (HepG2) cell-related indexes. The results show that the co-immobilized laccase mediator system has great development potential in the industrial application of theaflavins.

Research on the Adsorption of Soil Heavy Metals by Microalgal Biofilms: Mechanisms, Applications, and Prospects

Soil heavy metal pollution stands as one of the significant challenges facing the global environment today, posing serious threats to human health and ecosystems. In addressing this issue, microalgal biofilms have emerged as a promising bioremediation tool due to their efficient adsorption capabilities. This article provides a comprehensive review of the current status, application cases, and future developments of microalgal biofilms in soil heavy metal adsorption research, aiming to offer insights and guidance for research and practices in the field of environmental remediation.

Complementary metalloporphyrin-based nanostructure decorated with silver nanoparticles for photocatalytic degradation of organic dyes

A hybrid composite photocatalyst, SA-T@Ag, was fabricated by the photoreduction of silver salts in the presence of nanomaterials composed of self-assembled complementary porphyrin triad SA-T. We confirmed the formation of SA-T@Ag from SA-T using various spectroscopic techniques, including X-ray diffraction (XRD), infrared (IR) spectroscopy, UV–visible spectroscopy, and fluorescence spectroscopy. Field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) investigations revealed that a substantial amount of silver nanoparticles (AgNPs) were deposited on the surface of SA-T and that the microstructure of SA-T was intact during photoreduction. The formation of AgNPs on the surface of SA-T reduced the band gap energy (Eg) of SA-T@Ag compared to that of SA-T. This not only improves its light-harvesting properties but also delays the recombination of photogenerated electron-hole pairs, which promotes more reactivity under visible light irradiation and improves the efficiency of polluted dye degradation. These photophysical properties are reflected in the degradation of methylene blue (MB) dye under visible light irradiation. The first-order degradation rate constant of MB dye within 45 min of visible light irradiation is much higher for SA-T@Ag (0.081 min−1) than SA-T (0.028 min−1). This report is of great importance in the field of environmental remediation and provides new opportunities for designing porphyrin-based photocatalytic systems as alternatives to conventional photocatalysts.

S defect-rich MoS2 aerogel with hierarchical porous structure: Efficient photocatalysis and convenient reuse for removal of organic dyes

To avoid the difficulty of separating solids from liquids when reusing powder photocatalysts, 3D stereoscopic photocatalysts were constructed. In this study, three-dimensional S defect-rich MoS2 hierarchical aerogel was prepared by chemical cross-linking of functional ultrathin 2D MoS2. Its phase, micro-morphology and structure were characterized, and it was used in the study of photocatalytic degradation of organic pollutants. Of the samples tested, MS@CA-3 (i.e., defect-rich 3D MoS2 aerogel with a loading of 30 mg of defect-rich MoS2) exhibited the best photocatalytic activity due to its suitable load, good light transmission, and a degradation rate of up to 91.0% after 3 h. In addition, MS@CA-3 aerogel offers high recyclability and structural stability, and the degradation rate of the organic pollutant methylene blue decreases only 9.8% after more than ten cycles of photocatalytic degradation. It combines the high catalytic performance of S defect-rich 2D MoS2 and the convenient reusability of hierarchical porous aerogel. This study provides valuable data and a reference for the practical promotion and application of photocatalytic technology in the field of environmental remediation.

Hydrogen Nanobubbles Generated In Situ from Nanoscale Zerovalent Iron with Water to Further Enhance Selenite Sequestration.

Gas nanobubbles used for water treatment and recovery give rise to great concern for their unique advantages of less byproducts, higher efficiency, and environmental friendliness. Nanoscale zerovalent iron (nZVI), which has also been widely explored in the field of environmental remediation, can generate gas hydrogen by direct reaction with water. Whether nanoscale hydrogen bubbles can be produced to enhance the pollution removal of the nZVI system is one significant concern involved. Herein, we report direct observations of in situ generation of hydrogen nanobubbles (HNBs) from nZVI in water. More importantly, the formed HNBs can enhance indeed the reduction of Se(IV) beyond the chemical reduction ascribed to Fe(0), especially in the anaerobic environment. The possible mechanism is that HNBs enhance the reducibility of the system and promote electron transport in the solution. This study demonstrates a unique function of HNBs combined with nZVI for the pollutant removal and a new approach for in situ HNB generation for potential applications in the fields of in situ remediation agriculture, biotechnology, medical treatment, health, etc.

High-efficiency decontamination of pharmaceutical wastewater: Synergistic effects from NaGdF4:Tm,Yb@Mn-MOFs composite photocatalysts

Water pollution caused by antibiotics poses a serious threat to human health and ecosystems. Rapid and efficient removal of antibiotic pollution in water by photocatalysts is one of the effective means to protect the environment and public health. Herein, a wide-spectral responsive upconversion NaGdF4:Yb,Tm@Mn-MOFs core-shell nanostructures were built by coating hexagonal NaGdF4:Yb,Tm cores with amino-functionalized manganese carboxylate MOFs (Mn-MOFs) shells, which exhibited good water dispersibility. Mn-MOFs catalysts is mainly concentrated in the ultraviolet region, while NaGdF4:Yb,Tm nanoparticles can transform infrared light into visible light or even higher energy ultraviolet light, which is harvested by the Mn-MOFs. The optimized nanostructures were tested under simulated solar light (After 120 min irradiation) in the degradation of tetracycline, oxytetracycline hydrochloride and tetracycline hydrochloride, while their degradation rates reached 70%, 72% and 75%, respectively. The better photocatalytic mechanism for antibiotics than its individual components was elucidated, which provides a potential strategy to broaden the full spectrum absorption of the wide bandgap semiconductors and apply for the field of environmental remediation.

P-n Junction catalysis in action: Boosting norfloxacin photodegradation with ZIF-67-based Co3O4 wrapped in MoS2 with surface functionalized graphene quantum-dot

The primary challenge in photocatalytic application is to address the inefficiency in exploiting the photo-induced charge carriers. The dynamic behaviors of photogenerated carriers can be controlled through an internal electric field by building a p-n heterojunction. In this respect, p-n heterojunctions constructed from zeolitic imidazolate frameworks (ZIFs) with further surface functionalization are uniquely active and can increase the charge separation due to a favorable band structure. Thus, the present work demonstrates the preparation of an excellent visible-light absorbing photocatalyst based on a Co3O4 from ZIF-67 wrapped with MoS2 and functionalized with graphene quantum dots (GQDs), which is evaluated for the photodegradation of norfloxacin. Under visible light irradiation, the as-designed GQDs-functionalized MoS2@Co3O4 p-n heterojunction photocatalyst outperforms the individual MoS2 and Co3O4 semiconductors. The remarkable degradation efficiency is mostly due to the formation of a p-n heterojunction between MoS2 and the ZIF-67-based Co3O4. The photocatalytic mechanism of the as-designed system is deduced from reactive species trapping studies. This study sheds light on the design of a photocatalytic system based on ZIF-67, and on the effect of surface functionalization, thereby expanding the potential practical application of these materials in the field of environmental remediation.