Photodegradation Of Tetracycline Research Articles

The significantly boosted photodegradation of tetracycline over a novel hierarchical 0D/3D S-scheme heterojunction ZnSnO3/CdIn2S4

In recent years, constructing S-scheme heterostructure, as a novel and desirable strategy for the improvement of the photocatalytic performance, has attracted extensive interest. Herein, a novel hierarchical 0D/3D S-scheme heterostructure ZnSnO3/CdIn2S4 was constructed. The synthesized ZnSnO3/CdIn2S4 was characterized by various measures. The photodegradation of tetracycline (TC) was conducted under visible light to investigate the photocatalytic activity and stability of ZnSnO3/CdIn2S4. The impacts of pH and typical environmental factors on TC degradation were also explored. The S-scheme electron transfer mode in ZnSnO3/CdIn2S4 heterostructure was proposed based on Fermi level, in situ irradiated X-ray photoelectron spectroscopy (ISI-XPS), and identification of the active species. The ZnSnO3/CdIn2S4 heterojunction exhibits outstanding photocatalytic activity and stability. The degradation efficiency and mineralization rate of TC reach 87% and 33.5%, respectively. After five reuses of ZnSnO3/CdIn2S4, degradation efficiency of TC decreases by only 6.5%. The rate constant (0.0140 min−1) of TC degradation over ZnSnO3/CdIn2S4 is 2.41 and 43.75 times as high as those over CdIn2S4 and ZnSnO3. The dramatically boosted activity of ZnSnO3/CdIn2S4 is owing to the superior visible-light response and the significantly accelerated separation and migration of the photoproduced charge carriers due to the construction of the hierarchical S-scheme heterojunction. Moreover, the photodegradation of TC is enhanced marginally with the rising pH and is slightly inhibited by the typical ions and natural organic matters (NOM). This work brings a new strategy to design highly efficient photocatalysts applied in environmental restoration.

Visible Light-Driven Photocatalytic Degradation of Tetracycline Using p-n Heterostructured Cr2O3/ZrO2 Nanocomposite

Antibiotic pollution beyond the safety limits poses a significant threat to the environmental sustainability and human health which necessitates the development of efficient methods for reducing antibiotics in pharmaceutical wastewater. Photocatalysis is a proven technology which has drawn considerable attention in semiconductor photocatalysts. Our study aims to develop a highly efficient Cr2O3/ZrO2 photocatalyst for the degradation of tetracycline (TCL) under visible light. The synthesized catalyst was well characterized by XRD, HR-TEM-SAED, XPS, FT-IR, BET and UV-Vis-DRS methods. The effects of various parameters on photocatalytic degradation were evaluated in detail, showing that 97.1% of 50 mgL−1 tetracycline concentrations could be degraded within 120 min at pH 5 with a 0.1 gL−1 photocatalyst-loading concentration under visible light (300 W Xe lamp). The uniform distribution of spherical ZrO2 nanoparticles on the surface of the Cr2O3 nano-cubes efficiently reduced the recombination rate with an energy bandgap of 2.75 eV, which provided a faster photodegradation of tetracycline under visible light. In addition, a plausible degradation pathway and photoproducts generated during the photocatalytic degradation of TCL are proposed based on the LC-ESI/MS results, which suggested that efficient photodegradation was achieved during the visible light irradiation. Thus, our study reveals that the cost-effective Cr2O3-based photocatalyst with multi-reusability and efficient energy consumption could be an efficient photocatalyst for the rapid degradation of TCL during the wastewater treatment process.

Single W, Cu, Co atom oxide embedded in Co3O4-rGO for boosting electrocatalytic oxygen evolution reaction and for photodegradation of tetracycline

One of the most important phenomena in developing renewable and sustainable energy methods is electrocatalytic water splitting. Higher loadings of single metal atom oxide (SMAO) (M: W, Cu, and Co) in Co3O4-rGO catalysts are credited with boosting their efficiency in electrocatalytic oxygen evolution reaction (OER) and photodegradation of tetracycline (TC). In this work, we investigated the catalytic activity of electrocatalysts for OER by preparing ultrathin Co3O4 nanosheets and reduced graphene oxide (rGO) embedded with SMAO (rGO-ED-Co3O4-WCuCo-30) using a simple one-pot sonication process. The well-designed rGO-ED-Co3O4-WCuCo-30 electrocatalyst allows for the delivery of current densities of 10 and 100 mA cm−2 at overpotentials of 291 and 365 mV, respectively, with a relatively modest Tafel slope of 57.9 mV dec−1 during OER. The densely embedded SMAO particles on the Co3O4 surface are responsible for this behavior because they increase the electrochemical surface area with a large number of active sites in a synergistic manner. The rGO-ED-Co3O4-WCuCo-30 catalyst was used effectively in OER with outstanding long-term stability for more than 24 h. The photocatalytic results further show that the activity of Co3O4 was significantly enhanced by the addition of SMAO, with the TC degradation efficiency of 97.57%.

Synergy of Cu2+-Cu(OH)2-CuO with TiO2 coatings, fabricated via plasma electrolytic Oxidation: Insights into the multifaceted mechanism governing visible light-driven photodegradation of tetracycline

In this study, copper oxide-embedded TiO2 coatings were introduced on pure titanium via plasma electrolytic oxidation (PEO), which exhibited photocatalytic capacity for tetracycline (TC) degradation. Moreover, the impact of the ionization process and its temperature on the photocatalytic efficiency were investigated. All coatings containing CuO nanoparticles (NPs) exhibited finer micropores, higher specific areas, and higher wettability. The phase analysis results prove that coatings containing CuO NPs are composed of anatase and CuO phases, whereas the addition of ionized CuO NPs into the electrolyte leads to the formation of anatase, rutile, CuO, TiP2O7, and Cu(OH)2. All the CuO-incorporated coatings resulted in highly efficient TC photodegradation, the highest of which was 70 % for the coating containing 1 g/L CuO NPs. Most importantly, the introduction of1 g/L CuO-ionized NPs at 25 °C increased the photocatalytic efficiency to 92 %, whereas increasing the ionization process to 60 °C significantly decreased the photocatalytic activity to 60 % after 6 h of visible light illumination. Moreover, the optimum coating satisfied the photocatalytic efficiency requirement even after five cycles. An in-depth investigation of the effect of photocatalytic parameters, including the concentration and pH of pollutants, as well as the light intensity, was also performed. Appropriate scavenger tests were employed to examine the impact of different reactive oxygen species and photocatalytic mechanisms. Finally, based on the intermediate products, a probable TC photodegradation pathway was suggested.

Constructed a novel of Znln2S4/S-C3N4 heterogeneous catalyst for efficient photodegradation of tetracycline.

Despite S-doped C3N4 can exhibit more efficient photo-reactivity than pure C3N4, there is still some space to further improve the detaching efficiency of electron-hole and enhance the photocatalytic efficiency of S-C3N4. The construction of heterojunction is an effective method to promote the photocatalytic efficiency. ZnIn2S4, as a novel photocatalyst, its VB (1.37 V) and CB (- 1.09 V) can match with S-C3N4. Therefore, we hope to construct the ZnIn2S4/S-C3N4 heterojunction for boosting the photocatalytic activity of S-C3N4. In this paper, ZnIn2S4/S-C3N4 heterojunction was prepared through hydrothermal method using S-C3N4, ZnCl2, InCl3·4H2O, and thioacetamide as raw materials and heated at 160 °C for 16 h. The optimum 18% ZnIn2S4/S-C3N4 nanocomposites exhibit dramatically enhanced photocatalytic performance for degradation of tetracycline with 86.3% removal rate within 120 min, higher than 50% degradation efficiency of pure S-C3N4. And in the process of photodegradation for tetracycline, the largest contribution rate is the photo-excited cavity (h+), followed by ·O2- and ·OH. Herein, we have provided a good example for removing antibiotic residues by using S-C3N4-based heterojunction towards environmental remediation.

The enhanced photocatalytic reduction of U(VI) on MoS2/g-C3N4 in the presence of Cr(VI) and tetracycline

The synergistic removal of various pollutants is the challenge of environmental remediation due to mutual interference. The effect of Cr(VI) and tetracycline (TC) on photocatalytic reduction of U(VI) by MoS2/g-C3N4 was investigated by batch and spectroscopic techniques. The high adsorption of U(VI) on MoS2/g-C3N4 and the negative influence of photo-irradiation on U(VI) removal at pH 4.5 were observed. The batch experiments showed that the presence of TC and Cr(VI) improved the photoreduction of U(VI), whereas photocatalytic removal of Cr(VI) and TC were not influenced significantly. The adsorbed U(VI) was primarily photo-reduced into U(IV), while U(IV) was re-oxidized into U(VI) with further increasing irradiation by XPS analysis. According to quenching experiments, photo-degradation of TC was attributed to photogenerated holes, while the photo-reduction of Cr(VI) and U(VI) were due to •O2− and •OH radicals, respectively. These findings are crucial for the application of g-C3N4-bearing composites in the synergistic removal of radionuclide, heavy metal and organic at actual environmental cleanup.

Titanium‐based MOFs‐derived Cabon‐supported Photocatalysts for the Efficient Degradation of Tetracycline

AbstractIn order to eliminate the public health hazard of tetracycline in a more environmentally friendly and efficient manner, a titanium‐based metal‐organic framework material containing Co ions was synthesised as a precursor by the traditional solvothermal method. Subsequently, a series of titanium‐based MOFs‐derived carbon‐supported photocatalysts were synthesised by calcining the precursor at different temperatures in air. All the prepared catalysts achieved effective degradation of the model pollutant tetracycline (TC). By adjusting the parameters such as TC concentration, catalyst dosage and irradiation time, the optimised composite material (TiCoOC‐800‐1) has a degradation rate of 99.4 % for the model pollutant TC with a concentration of 100 mg/L after under the UV irradiation during 30 min. Radical scavenging experiments showed that the main oxide species responsible for the rapid photodegradation of tetracycline were superoxide radicals (⋅O2−) and holes (h+). Finally, the liquid chromatography mass spectrometry (LC–MS) method was used to detect the molecular degradation intermediates of TC and a possible degradation pathway was proposed. This work will provide new ideas for the development of more efficient photocatalysts for the degradation of TC in wastewater.

Rational design and construction of S-scheme CeO2/AgCl heterojunction with enhanced photocatalytic performance for tetracycline degradation

Semiconductor-based photocatalysis has attracted extensive attentions in waste water treatment and environment remediation. However, a single semiconductor photocatalyst inevitably encounters a dilemma between light absorption and redox ability of photoinduced holes and electrons. In this work, an S-scheme CeO2/AgCl heterojunction photocatalyst was designed, prepared and characterized by various techniques. The as-prepared CeO2/AgCl composite photocatalyst exhibited enhanced photocatalytic activity compared with single CeO2 and AgCl as revealed by the photodegradation of tetracycline (TC), a widely used antibiotic. According to UV–Vis spectral changes and degradation mass spectra of TC, the CeO2/AgCl composite photocatalyst not only can destroy the B, C, D rings, but also the A ring of TC, which cannot be destroyed by most of previously reported photocatalysts. The enhanced photocatalytic ability of CeO2/AgCl composite was due to the formation of an S-scheme heterojunction structure between CeO2 and AgCl, which simultaneously retained the maximum redox ability of photoinduced holes and electrons in the valence band of AgCl and in the conduction band of CeO2, respectively, resulting in the production of highly efficient O2−, OH and h+. This work provided insight into the rational design and construction of S-scheme heterojunction composites and new possibility of photocatalytic degradation of antibiotic wastewater.

Photocatalysis-PMS oxidation system based on CQDs-doped carbon nitride nanosheets for degradation of residual drugs in water.

Graphite-like carbon nitride (g-C3N4) is favored for its excellent physicochemical properties. However, the high complexation rate of photogenerated carriers greatly limits its practical applications. Based on this, a novel CQDs-doped carbon nitride nanosheets composite (CNS/CQDs) was prepared and applied to the visible light-induced activation of peroxymonosulfate (PMS) for meloxicam (Mel) and tetracycline (TC) degradation. The photocatalytic degradation of Mel and TC were remarkably promoted in the CNS/CQDs+PMS+vis system. Mel photodegradation of 99.90% was achieved over 30 min with 20 mg CNS/CQDs and 20 mg PMS at pH11. And TC photodegradation of 95.97% was achieved over 45 min with 20 mg CNS/CQDs and 20 mg PMS at nature pH6.5. The TOC mineralization rates of Mel and TC were 75.49% and 52.00%, respectively. The transient photocurrent response and electrochemical impedance measurements (EIS) results indicated that the doping of CQDs could improve the charge transfer efficiency of pure g-C3N4, and CNS/CQDs had a low charge transfer resistance. Capture experiments and EPR tests explored the effective actives in the CNS/CQDs+PMS+vis system. Possible degradation pathways of Mel were also analyzed. This study provides valid residual drugs degradation under the dual conditions of visible light catalytic oxidation and persulfate oxidation, which will be a novel perspective for advanced oxidation technology to effectively remove organic pollutants from water.

Highly Water-Stable Zinc Based Metal-Organic Framework: Antibacterial, Photocatalytic Degradation and Photoelectric Responses.

A reported water-stable Zn-MOF ([Zn(L)2(bpa)(H2O)2]·2H2O, H2L = 5-(2-cyanophenoxy) isophthalic acid has been prepared via a low-cost, general and efficient hydrothermal method. It is worth noting the structural features of Zn-MOF which exhibit the unsaturated metal site and the main non-covalent interactions including O⋯H, N⋯H and π-π stacking interactions, which lead to strong antibacterial and good tetracycline degradation ability. The average diameter of the Zn-MOF inhibition zone against Escherichia coli and Staphylococcus aureus was 12.22 mm and 10.10 mm, respectively. Further, the water-stable Zn-MOF can be employed as the effective photocatalyst for the photodegradation of tetracycline, achieving results of 67% within 50 min, and it has good cyclic stability. In addition, the photodegradation mechanism was studied using UV-vis diffuse reflection spectroscopy (UV-VIS DRS) and valence-band X-ray photoelectron spectroscopy (VB-XPS) combined with the ESR profile of Zn-MOF, which suggest that ·O2- is the main active species responsible for tetracycline photodegradation. Also, the photoelectric measurement results show that Zn-MOF has a good photocurrent generation performance under light. This provides us with a new perspective to investigate Zn-MOF materials as a suitable multifunctional platform for future environmental improvement applications.

Phyto-mediated hydrothermal synthesis of NiFe2O4 as photocatalyst in tetracycline photodegradation

Tetracycline is one of the most important compounds in pharmaceutical industry, furthermore the controlling tetracycline in wastewater is important aspect for sustainable pharmaceutical industry. This study explores a photocatalytic degradation approach for the tetracycline removal by using magnetic nanomaterial of NiFe2O4 nanoparticles as photocatalyst. As a strategy in green chemistry approach, hydrothermal synthesis by using plant extract of Aloe vera extract was performed. Different techniques such x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV–Visible spectrophotometry (UV-DRS) and magnetism analysis have been performed to characterize the sample. From TEM identification, the irregular shapes of NiFe2O4 NPs with particle size ranging at 5–40 nm was produced, and from XRD analysis, the crystallite size of the sample is 39.2 nm. The material demonstrates superparamagnetic behavior, and has the band gap energy of 1.84 eV. The photocatalytic activity assessment of the NiFe2O4 showed the degradation efficiency of about 75% and 65.53% under UV and visible lights, respectively. The easiness in separation of the rest photocatalyst supports the recoverability and stability until 5th cycle of usage with insignificant change of degradation efficiency.

Enhancing the photodegradation of tetracycline in aquaculture wastewater via iron(III)-alginate: Degradation pathway transformation and toxicity reduction

Tetracycline's (TC) incomplete self-photolysis by light irradiation generally produces toxic intermediate products, which posing serious harm to the aqueous environment. In order to diminish the environmental risks of TC self-photolysis, an iron(III)-alginate (Fe-SA) hydrogel assisted photocatalytic method was developed and the underlying mechanisms was also analyzed in this work. Under simulated sunlight, the photo-degradation efficiency of TC was 61.1% at pH 7.0 within 2 h. Importantly, four of the seven intermediate products that identified during the self-photolysis of TC were found toxic based on QSAR analysis. In contrast, the removal efficiency of TC could be improved to 87.4% by adding Fe-SA under the same conditions. Moreover, only two relatively weakly toxic intermediate products were detected after exposing to the Fe-SA photocatalytic system, indicating a significant reduction of the potential ecological risks caused by TC self-photolysis. Furthermore, the determination of reactive oxidation species (ROS) demonstrated that the addition of Fe-SA primarily facilitated the degradation of TC and the related toxic intermediate products through assisting the free radical (∙OH and ∙O2−) photocatalytic degradation pathway. Additionally, the photocatalytic application under actual sunlight conditions and the reusability experiments of Fe-SA further confirmed its effectiveness and low cost in removing TC. This study revealed the photodegradation mechanisms of TC from the perspective of the self-photolysis process, and also offering new insights into the removal of TC pollution in the environment.

Tailoring surface defects in Plasma Electrolytic Oxidation (PEO) treated 2-D black TiO2: Post-treatment role, and intensification by peroxymonosulfate activation in visible light-driven photocatalysis

Herein, we have developed a visible light-responsive black TiO2 photocatalytic coating with controlled formation of oxygen vacancies (OV) and Ti3+ species, crucial for enhancing photocatalytic reactions. The rational control of these semiconductor defects was achieved through plasma electrolytic oxidation (PEO), followed by NaOH post-treatment. The coating's effectiveness was evaluated by tetracycline (TC) degradation. The surface defects function as traps, reducing electron/hole recombination and forming mid-gap/localized-donor states, narrowing the band gap. Rigorous material characterization confirmed unaffected morphology and PEO coating phases, while increasing the density of OVs and Ti3+ species. As a result, TC photo-degradation was ∼3.5 times higher compared to plain PEO coatings. The material demonstrated exceptional stability and efficiency, while it was successfully intensified via peroxymonosulfate (PMS) activation, leading to high synergies (2.10). Scavenger tests revealed the existence of both radical/non-radical pathways, indicating the prevailing photocatalytic mechanism and the key differences achieved through this novel process.

Photodegradation of tetracycline using surface oxygen vacancy-enriched PEO coating under visible light

In this study, it was indicated that hydrothermal post-alkali-treated plasma electrolytic oxidation (PEO) coating using NaOH as the reducing agent is an effective catalyst for tetracycline (TC) visible light photodegradation. The post-alkali treatment can not only change the coating surface morphology but also introduce oxygen vacancies (OVs) into them, resulting in extending the light response to visible light and inhibiting the recombination of photogenerated electron-hole (e−-h+) pairs. The visible-light-driven photocatalytic degradation ratio of TC over NaOH hydrothermal post-alkali-treated PEO coating is up to 93.5%, and its degradation rate constant is 10.15 times higher than that of plain PEO coating. Several factors contribute to the excellent photocatalytic activity (PA) of the PEO coating that has undergone NaOH hydrothermal post-alkali treatment. These factors include a high concentration of surface OVs (Ti3+ defect energy level), the development of an anatase-rutile-Na2Ti3O7 ternary heterojunction, increased hydrophilicity, and a nanosheet-like morphology that provides more surface active sites. Finally, appropriate scavengers were utilized to investigate the role of various photogenerated reactive species and to detail the photocatalytic mechanism.

A CMP-based [FeFe]-hydrogenase dual-functional biomimetic system for photocatalytic hydrogen evolution coupled with degradation of tetracycline

A novel bio-inspired conjugated microporous polymer (CMP) had been designed, synthesized and characterized. The mimics of [FeFe]-hydrogenase active sites were covalently attached to the CMP skeleton, which facilitates charge transfer between the light-harvesting moiety and active sites, and exhibited high performance in visible-light photocatalytic hydrogen evolution (2120 μmol·h−1·g−1) in an aqueous solution. The flower-like morphology, covalently linked framework and the “single active-site” effect derived from the porous skeleton were deemed to go a long way toward boosting the properties above. Interestingly, when the electron sacrifice agent (triethanolamine) was replaced by tetracycline, the CMP-based photocatalyst maintained the capability of photocatalytic hydrogen production (370 μmol·h−1·g−1) and realized efficient photodegradation of tetracycline simultaneously. This work provides a heuristic green dual-function strategy for constructing a sustainable and efficient photocatalytic system for hydrogen evolution with concurrent antibiotic residue degradation.

Unveiling the multifaceted applications of magnetically responsive chitosan capped ZnS QDs for sensing and annihilation of pharmaceutical drugs

The persistence of active pharmaceutical ingredients in water bodies has lead to detrimental impacts on public health as well as deteriorated aquatic resources at breakneck pace. To address this, highly fluorescent chitosan capped ZnS QDs (CZS QDs) were integrated with nickel ferrite nanoparticles (NF NPs) through ultrasonic assisted method to yield a series of magnetically responsive CZS-xNF nanohybrids (x = 5, 10, 15 and 20 wt% of NF). The successful fabrication of nanohybrids were affirmed through various techniques such as Fourier transform infra-red spectroscopy (FT-IR), powder X-ray diffraction (XRD), X-ray photoelectron microscopy (XPS), high resolution transmission electron microscopy (HRTEM), vibrating sample magnetometer (VSM) and diffused reflectance spectroscopy (DRS). The dual applicability of CZS-xNF nanohybrid was witnessed for the detection of pharmaceutical waste by fluorescence sensing and their concomitant annihilation via visible light driven photodegradation reactions. The developed nanohybrid showed exceptional selectivity towards tetracycline antibiotics, with ultra-low limit of detection of 0.53 μM for tetracycline (TC) and 0.30 μM for minocycline (MC), respectively. The fluorescent sensor was also analysed for trace level detection of tetracyclines in real water samples that showed satisfactory recoveries of 90–106%, depicting practical applicability of sensor. Additionally, the excellent photocatalytic features of synthesized nanohybrid prompted their use in photodegradation of TC and MC and a superior photocatalytic performance was achieved in comparison to CZS QDs. The enhanced photocatalytic performance of CZS-xNF nanohybrid can be attributed to type-I charge transfer mechanism, which resulted in efficient charge separation and reduced photo-induced recombination rate of charge carriers. The nanohybrids were recyclable up to four cycles after being utilized in sensing and photocatalysis, thus offering a promising strategy for environmental remediation through synchronized sensing and extirpation of pharmaceutical waste.

Band structure induced photodegradation mechanism of PEI-based carbon quantum dots for tetracycline and toxicity evaluation for these intermediates

Many kinds of carbon quantum dots (CQDs) are already released into the environment, and the factor that determine the photodegradation ability of these CQDs for antibiotics is still unclear. Herein, three PEI-based CQDs (CAPEI, HAPEI and BCNPEI) were prepared by hydrothermal method to clarify the structural factors that determine their photodegradation performance against tetracycline (TC) when exposed to visible light. Experimentally, BCNPEI photodegraded 62 % of TC, while CAPEI and HAPEI photodegraded TC only about 5–8 %. Sizes, functional groups, aromaticity and energy band structures of these CQDs have been analyzed, and the energy band structure has the best linear relationship with the photodegradation properties of CQDs on TC. The conduction band (CB) value of BCNPEI is − 0.623 V and the valence band (VB) value is 2.207 V, which are strong enough to produce hydroxyl radicals (·OH) and superoxide radicals (·O2-) under visible light exposure. And this has been verified with photoactive species capture experiments and ESR experiments. Thus, band structure is the factor that determine the photocatalytic performance of CQDs for TC. Furthermore, a possible photodegradation pathway of TC by CQD was proposed in a study of high-performance liquid chromatography-mass spectrometry (HPLC-MS) results. The photodegradation intermediates of TC were less toxic than TC, suggesting that the photodegradation of TC by CQD can reduce its environmental risk. In this study, valuable insights are provided into the behavior of CQDs exposed to the environment.

Synthesis of Ta2O5 by introducing graphene quantum dot with excellent photocatalytic performance for degradation of tetracycline

Wide band gap, weak adsorption ability, poor electronic conductivity and insufficient charge transportation limit the applications of Ta2O5 in photodegradation of antibiotics. The paper reports synthesis of Ta2O5 photocatalyst by introducing glycine-functionalized graphene quantum dot (GGQD). The introduction of GGQD effectively prevents the hydrolysis of Ta(V) and finally leads to the formation of small Ta2O5 nanorods. The modification of graphene sheets on the Ta2O5 surface enhances the adsorption towards tetracycline. The presence of Ta4+ self-doped oxygen vacancy narrows the band gap of Ta2O5, optimizes the band position and creates new defect energy level. These improve the light absorption capacity to visible light and promotes the photogenerated charge transfer. The graphene as electron trap suppresses the recombination of photogenerated charge carriers. The graphene as light sensitizer expands the absorption to visible light. The synergy of these multiple structure engineering realizes an excellent photocatalytic performance of Ta2O5 for solar-light driven tetracycline photodegradation. The photodegradation efficiency of 60 min solar-light irradiation is 6.6 times higher, apparent kinetic constant is 19.3 times higher and photocurrent density is 13.4 times over Ta2O5. The study also paves an avenue for construction of metal nanomaterials with desirable photoelectric properties in catalysis, energy storage and conversion and sensing.

Novel MIL-88B(Fe)/ZnTi-LDH high-low junctions for adsorption and photodegradation of tetracycline: Characteristics, performance, and mechanisms

In this paper, a high-efficient MIL-88B(Fe)/ZnTi-LDH high-low junction photocatalyst was successfully prepared by a simple method for the photodegradation of tetracycline (TC). The combination of MIL-88B(Fe) and ZnTi-LDH created an internal electric field and high-low junction, facilitated the separation of carriers, and thus enhanced photocatalytic activity. The optimized MZ-30% sample showed the highest photocatalytic degradation of TC about 93.51%. The photocatalytic kinetic removal rate of MZ-30% reached 0.0941 min−1, 31.36 times of MIL-88B(Fe) (0.003 min−1) and 1.7 times of ZnTi-LDH (0.0550 min−1). Furthermore, MZ-30% possessed the highest adsorption capacity for TC (543.89 mg/L). The effects of co-existing ions, initial pH, water source, and humic acid (HA) on TC degradation were examined. The main active substances of MIL-88B(Fe)/ZnTi-LDH in photocatalytic reaction were 1O2, h+, and ·O2- confirming by reactive species elimination experiment and electron spin resonance (ESR) tests. The molecular structure and toxicity of intermediates were investigated by a high-performance liquid chromatography-mass spectrometer (HPLC-MS) and Toxicity Estimation Software Tool (T.E.S.T), and the possible degradation pathway of TC was revealed. The results highlight that MIL-88B(Fe)/ZnTi-LDH high-low junction composite is a desirable photocatalyst for removing antibiotics and other emerging contaminants in water.

Carbon nanotubes as electron mediators for CNTs/CdS/MoS2 high efficient photodegradation of tetracycline under visible light

The ternary nanocomposites of CNTs/CdS/MoS2 was synthesized by a simple two-step hydrothermal method and characterized accordingly. In situ growth of CdS on the surface of CNTs decreased the size of CdS particles and increased its dispersibility. Moreover, CdS took advantage of the good conductivity of CNTs to accelerate the conduction of photogenerated holes and reduced the recombination efficiency of charge carriers. MoS2 grew in situ on the surface of CdS, and the interface between them formed a close contact heterostructure. The built-in electric field formed at the interface between the two forced the photogenerated electrons of CdS and the holes of MoS2 to recombine here. This property not only changed the path of photogenerated electrons and holes, but also made the surface of MoS2 becoming the active center of reduction reaction. The hybrid structure of CNTs/CdS/MoS2 in-situ composite significantly improved the photocatalytic performance. When CNTs/CdS/MoS2 was used as photocatalyst, the degradation rate of tetracycline was 96.7% under 100 min of visible irradiation, and the data was still above 95% after 5 cycles indicate. This indicated that the ternary complex has good photocatalytic performance and stability. The successful preparation of CNTs/CdS/MoS2 provides an economically feasible approach for the degradation of tetracycline.