Organic Pollutants In Aquatic Environment Research Articles

Cobalt-loaded carbon nanotubes boosted aerobic ciprofloxacin transformation driven by sulfide: A comprehensive mechanism investigation

Sulfide oxidation under aerobic conditions can produce active oxygen for the transformation of organic pollutants in aquatic environments. However, the catalytic performance of transition metal-supported carbon material on this process is poor understood. This study found that Co-loaded carbon nanotubes (CNTs) was able to realize the efficient aerobic transformation of antibiotic ciprofloxacin (CIP) by sulfide, with the pseudo-first order reaction rate constant improved from 0.013 h−1 without catalyst to 0.44–0.71 h−1 with 100 mg/L Co-loaded CNTs. Singlet oxygen (1O2) was the main active specie playing key roles in the process of CIP aerobic transformation with presence of Co-loaded CNTs. Mechanism studies indicated that the excellent electron transfer ability of Co-loaded CNTs might play an important role to promote the electron transfer and facilitate the formation of intermediate H2O2 and 1O2. Additionally, the Co-loaded CNTs/sulfide system effectively reduced the acute toxicity of organic pollutant, and Co-loaded CNTs showed remarkable cycling stability and negligible leaching. This study gives a better understanding for the Co-loaded CNTs mediated aerobic antibiotics transformation by sulfide, and provide a reference for the application of Co-loaded carbon materials on organics aerobic transformation by sulfide.

Recognition, possible source, and risk assessment of organic pollutants in surface water from the Yongding River Basin by non-target and target screening

Organic pollutants in aquatic environment could have important implications on pollution stress on aquatic organisms and even on the risk of human exposure. Thus, revealing their occurrence in aquatic environment is essential for water quality monitoring and ecological risk purposes. In this study, a comprehensive two-dimensional gas chromatography connected with time-of-flight mass spectrometry (GC × GC-TOF-MS) was applied, to enable non-target and target analysis of pollutants in the Yongding River Basin. Based on the isotopic patterns, accurate masses and standard substances, certain environmental contaminants were tentatively identified which including polycyclic aromatic hydrocarbon (PAHs), organochlorine pesticides (OCPs), phenols, amines, etc. The compounds with the highest concentration were naphthalene (109.0 ng/L), 2,3-benzofuran (51.5 ng/L) and 1,4-dichlorobenzene (35.9 ng/L) in Guishui River. Wastewater treatment plants (WWTPs) discharges were a main source of pollutants in Yongding River Basin, as the types of compounds screened in the downstream river were relatively similar to those from WWTPs. According to the target analysis, a number of pollutants were selected due to the acute toxicity and cumulative discharge from WWTPs and downstream rivers. Three PAHs (naphthalene, Benzo(b)fluoranthene and pyrene) homologues showed moderate risk to fish and H. Azteca in Yongding River Basin, while the rest of the measured chemicals showed low ecological impact across the entire study area based on the risk assessment. The results are helpful for understanding the necessity of high-throughput screening analysis for assessing water quality of rivers and the discharge emissions of pollutants from WWTPs to the river environment.

Algae-derived metal-free boron-doped biochar acts as a catalyst for the activation of peroxymonosulfate toward the degradation of diclofenac

In this study, plain seaweed biochar (SW) and boron-doped seaweed biochar (BSW) were prepared through a simple pyrolysis process using Undaria pinnatifida (algae biomass) and boric acid. The BSW catalyst was utilized to degrade organic pollutants in aqueous environments by activating peroxymonosulfate (PMS). Surface characterization of the BSW demonstrated successful doping of boron into the biochar materials. BSW600 exhibited greater catalytic activity than SW600, as evidenced by the former's maximum adsorption capacity of diclofenac (DCF) onto BSW600 (qmax = 30.01 mg g−1) and the activation of PMS. Complete degradation of DCF was achieved in 30 min using 100 mg L−1 BSW600, 0.5 mM PMS, and 6.5 initial solution pH as critical parameters. The pseudo-first-order kinetic model accurately described the DCF degradation kinetics. The scavenger experiment displayed that radical and non-radical reactive oxygen species (ROS) formed in the BSW600/PMS system. Furthermore, the generation of ROS in the BSW600/PMS system was confirmed by electron spin resonance spectroscopy (ESR). The percentage contribution of ROS was assessed to be 12.3, 45.0, and 42.7% for HO•, SO4•–, and 1O2, respectively. Additionally, the electron transfer pathway was also confirmed by electrochemical analysis. Moreover, the influence of water matrics on the BSW600/PMS system was demonstrated. The co-existence of anions and humic acid (HA) did not affect the catalytic activity of the BSW600/PMS system. The recyclability of BSW600 was assessed by DCF removal (86.3%) after three cycles. Ecological structure-activity relationships software was used to assess by-product toxicity. This study demonstrates the efficacy of non-metallic heteroatom-doped biochar materials as eco-friendly catalysts in groundwater applications.

Studying the destruction of pollutant in the presence of photocatalysts based on MWCNTs with controlled values of TiO2 nanoparticles

The main goal of the present research is the synthesis of new photocatalysts to reduce the amount of organic pollutants in aquatic environments. For this purpose, the amount of TiO2 nanoparticles in the synthesized samples containing MWCNTs is controlled to synthesize two types of photocatalysts named as MCT#1 and MCT#2. Samples characterizing using XRD reveal that the TiO2 nanoparticles have a combined phase of rutile and anatase. So that in both of photocatalysts, the percentage of anatase phase is higher than rutile. The analysis of the degradation rate demonstrates that intensification level of TiO2 nanoparticles in MCT#2 compared to the MCT#1 leads to enhancement of photocatalytic activity of MCT#2. Design of experiment results shows that the destruction amount of MO is affected by irradiation time and pH. Based on ANOVA study, it is observed that both factors have a significant effect on reducing of MO concentration. Analyzing the results based on Duncan's multiple range test at α = 0.05 confirm that all the studied levels of the main parameters have a logical influence on MO destruction. Meanwhile, it can be deducted that the most and the least of destruction is observed at pH = 7 and pH = 3, respectively.

Preparation of magnetic Fe3O4@PDA/CuS core-shell nanocomposite as a green photocatalyst

To solve the emerging aromatic organic pollutants in aqueous environment, in this study, the efficient recyclable core-shell structured photocatalyst Fe3O4@PDA/CuS was prepared by in situ reduction method. Firstly, Fe3O4 as cores were prepared to provide magnetic recovery. Through the self-polymerization of dopamine (DA), polydopamine (PDA) was coated on Fe3O4 as shells to protect Fe3O4 cores. Then, Cu2+ coordinated with PDA on the surface of Fe3O4@PDA and in situ reduced by Na2S to obtain core-shell structural Fe3O4@PDA/CuS with CuS uniformly growing on the PDA. CuS with a narrow band gap will endow Fe3O4 @PDA/CuS excellent photocatalytic performance for organic dyes degradation. The decomposition rate of methylene blue (MB) reached to 92.1 % within 180 min under visible light irradiation of Fe3O4@PDA/CuS as photocatalyst without any cocatalyst. When pH= 10, the decomposition rate of MB can reach to 92.7 % in 60 min, indicated Fe3O4@PDA/CuS was more suitable for use under alkaline conditions. The capture experiment determined that·OH was the main active substance. This also explained that under alkaline conditions, numerous OH- was conducive to the formation of ·OH, thus accelerated the degradation rate. And the decomposition rate of MB by Fe3O4@PDA/CuS can still reach 83.95 % after reused three times.

N and S co-doped pine needle biochar activated peroxydisulfate for antibiotic degradation

A low-cost nitrogen and sulfur doped biochar (CNS) was prepared by oxygen limiting method using pine needles. In the CNS/PDS system, the degradation rate of tetracycline hydrochloride (TCH) reached 85.6% in 20 min when the pyrolysis temperature was 800 °C. X-ray photoelectron spectroscopy and Raman spectroscopy showed that high-temperature pyrolysis produced more carbonyl and defect, which enhanced the activation efficacy of CNS for PDS. Electron paramagnetic resonance and radical quenching have demonstrated that O2•- and 1O2 played key roles in radical pathway. A novel mechanism for degradation of TCH by electron transfer pathway was proposed by linear sweep voltammetry and electrochemical impedance spectroscopy. CNS served as a transport mediator and the electrons of TCH were continuous transferred to PDS via CNS, which accelerated its oxidation. Moreover, density functional theory demonstrated that pyrrolic N combined with the H atom of PDS to form an N–H structure and generated a PDS-catalyst complex. The projected density of state results showed that pyrrolic N and thiophene S further speeded up the electron transfer process due to their closer proximity to 0 Fermi level. This study provides insight into the reaction mechanism of heteroatom doped biochar for treatment of organic pollutants in aquatic environments.

Zero-Valent Copper-Mediated Peroxymonosulfate Activation for Efficient Degradation of Azo Dye Orange G

Zero-valent metal (ZVMs)-based persulfate activation systems are extensively applied for the elimination of organic pollutants in aqueous environments. In this study, for the first time, zero-valent copper (ZVC) was employed as the peroxymonosulfate (PMS) activator for the efficient degradation of Orange G (OG). The physicochemical properties of ZVC were systematically characterized by FESEM, EDX, TEM, XRD and XPS measurements. Furthermore, the effects of catalyst loading, PMS dosage, OG concentration and inorganic anions on the ZVC/PMS system were, respectively, investigated and explicated. The formation of •OH and SO4•− in the system was verified by quenching experiments and then the possible reaction mechanism was proposed. This work can provide insight into water treatment technology based on ZVMs.

Comparison of modes of action between fish, cell and mitochondrial toxicity based on toxicity correlation, excess toxicity and QSAR for class-based compounds

Mitochondria are significant targets in cells for many environmental chemicals. Mitochondrial damage and dysfunction can lead to apoptosis and death of fish. The objectives of this study were to compare the modes of action (MOAs) between fish, cell and mitochondrial toxicity. To achieve the goal, toxicity correlation, excess toxicity and quantitative structure–activity relationship (QSAR) were investigated between these three toxicity endpoints for a wide range of compounds. Results showed that fish toxicity is well correlated to cytotoxicity, but overall fish toxicity is relatively greater than the cytotoxicity. On the other hand, fish or cell toxicity is poorly related to mitochondrial toxicity, suggesting some compounds share same toxic mechanism but some not. The excess toxicity calculated from toxicity ratio (TR) shows that specifically-acting compounds in cytotoxicity, such as insecticides, fungicides, herbicides, dyes and medications used to treat cancer, depression, heart failure and blood pressure, are active compounds in mitochondrial toxicity. However, the less inert compounds identified in fish and cell toxicity exhibit greatly mitochondrial toxicity. QSAR models reveal that fish or cell toxicity is closely related to the chemical hydrophobicity, ionization, energy of lowest unoccupied molecular orbital, hydrogen bonding potential and stability. These descriptors reflect chemical bio-uptake, reactivity and interaction with target receptors. On the other hand, binomial model reveals that mitochondrial toxicity is closely related to the chemical hydrophobicity and polarizability/dipolarity, indicating bio-uptake and Van der Waals interaction play key roles in mitochondrial toxicity. Theoretical equations have been used to explain the toxicity correlation, excess toxicity and QSAR for fish, cell and mitochondrial toxicity. Above results suggest that cytotoxicity can serve as a surrogate for fish toxicity and be used in the safety evaluation of organic pollutants in aqueous environment, but not mitochondrial toxicity, although some compounds share same modes of action between fish or cell toxicity and mitochondrial toxicity.

Fabrication of Mn/P co-doped hollow tubular carbon nitride by a one-step hydrothermal–calcination method for the photocatalytic degradation of organic pollutants

Efficient photocatalytic degradation of trace organic pollutants in aqueous environment by a hollow tubular carbon nitride co-doped with manganese and phosphorus under visible light.

Photocatalytic Hydrogen Production from Urine Using Sr-Doped TiO2 Photocatalyst with Subsequent Phosphorus Recovery via Struvite Crystallization

Currently, the discharge of wastewater and utilization of phosphorus (P) in human activities cause some environmental problems, such as high organic pollutants in aquatic environments which results in dirty water sources, and a shortage of phosphate rock reserves due to the high demand of P. Therefore, fuel energy and struvite crystallization from waste sources can be considered interesting alternatives. In this work, the modified catalyst for hydrogen production, along with solving environmental problems, was examined. The strontium (Sr) doped-titanium dioxide (TiO2) nanoparticles were synthesized by wetness impregnation method. The synthesized catalyst was characterized using UV-vis spectroscopy (UV-vis), photoluminescence (PL), X-ray diffraction (XRD), photoluminescence (PL), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS). The Sr-doped TiO2 catalysts had been utilized as the photocatalyst for the hydrogen production from synthetic human urine (a representative of waste source). The doping content of Sr in TiO2 varied from 0.5, 1, 2, and 4%, and the photocatalytic performances were compared with pristine TiO2 nanoparticles. The results showed that 1% Sr-doped TiO2 had the highest photocatalytic activity for hydrogen production and decreased the amount of chemical oxygen demand (COD) in the synthetic human urine. Subsequently, P could be recovered from the treated human urine in the form of struvite.

A nanocubicle-like 3D adsorbent fabricated by in situ growth of 2D heterostructures for removal of aromatic contaminants in water

Focusing on the emergence of organic pollutants in aqueous environments, attempts to assemble two-dimensional (2D) materials into three-dimensional (3D) structures are expected to improve their pollution control performance. However, most 3D heterostructural nanomaterials are constructed by mechanical mixing methods, which result in structures that are randomly arranged and prone to collapse. Two typical 2D carbon materials, reduced graphene oxide (rGO) and covalent triazine frameworks (CTFs), have exhibited excellent effects in the fields of contaminant adsorption and photocatalysis, respectively. However, their regular packing structure could not provide an interconnected pore network suitable for the diffusion or adsorption of pollutants. In this study, a series of heterostructures named rGCs were fabricated by direct growth of 2D CTFs with different ratios on the surface of rGO layers. The rGCs were designed to remove trace concentrations of naphthalene (NAP) and benzophenone (BP) from water, which can be regenerated under sunlight. rGC-20, in which nanocubicle-like 3D heterostructures were successfully constructed, not only adsorbed NAP and BP with superb normalized adsorption capacities (5000–5300 μmol/g) but also could be regenerated with an exceptional percentage recovery of 90–95% in the 4th cycle. The microenvironment created in nanocubicle-like 3D heterostructures enhances the adsorption of pollutants, the excitation of electrons and utilization of radicals, which further promotes the adsorption and photocatalysis of rGCs. This work provides a promising adsorbent with outstanding adsorption-regeneration ability for aromatic contaminant removal from water. Data availabilityThe main data that support the findings of this study are available from the article and its Supplementary Information. Extra data are available from the corresponding author on request.

Accelerated photocatalytic degradation of iohexol over Co3O4/g-C3N4/Bi2O2CO3 of p-n/n-n dual heterojunction under simulated sunlight by persulfate

A novel Co3O4/g-C3N4/Bi2O2CO3 (BCCN) photocatalyst with p-n/n-n heterojunction was synthesized through a solvent-thermal method. The degradation efficiency of 20 mg/L iohexol reached 94 % in 60 min (kapp =0.0417 min−1) in BCCN/light/PS system, which was 2.8 and 6.5 times higher than systems of BCCN/light (kapp =0.0150 min−1) and BCCN/PS (kapp =0.0064 min−1). The g-C3N4 addition lowered conduction band of the prepared material to produce superoxide radicals, activate persulfate and further prevent the recombination of photoelectrons and holes. Superoxide radicals and singlet oxygens were dominant radicals for iohexol degradation. Besides, persulfate could act as electron acceptor to enhance efficiency of electron transfer. The interaction between sulfate, superoxide and hydroxyl radicals improved singlet oxygens production. Furthermore, theoretical calculation and liquid chromatography mass spectrometry were performed to analyze degradation pathway of iohexol in the system. Ultimately, the BCCN/light/PS system can provide a new method to degrade organic pollutants in aquatic environments.

Contrasting effects of microplastics on sorption of diazepam and phenanthrene in soil

Microplastics have attracted extensive attention regarding their role in the cycling of organic pollutants in aquatic environments. However, the influence of microplastics on the sorption of organic pollutants in soil is unclear. Herein, we investigated the sorption of polar diazepam and nonpolar phenanthrene to two soils (Inceptisol and Oxisol). Batch sorption experiments were used to evaluate the effect of polyethylene (PE), polypropylene (PP), and polystyrene (PS) microplastics at addition rates of 0.1%, 1%, and 10% (w/w). The addition of microplastics significantly decreased the overall sorption of diazepam at 10%, and increased the sorption of phenanthrene at 1%, while the effects were negligible at other addition rates. Decreased sorption of diazepam was attributed to its lower sorption affinity to microplastics than to soil. Microplastics, even at 0.1%, substantially decreased the relative distribution of phenanthrene in soil, particularly for PE in the Oxisol with lower foc. The sorption affinity of phenanthrene followed the order PE > soil organic carbon (SOC) > PP > PS, suggesting that PE can be a significant sink of phenanthrene in contaminated soils. Overall, microplastics can change the sorption of diazepam and phenanthrene to soil and therefore affect their mobility and environmental risk in soil ecosystems.

A sandwich temperature control membrane inlet mass spectrometer for dissolved gases and volatile organic compounds in aqueous solution

A sandwich temperature control membrane inlet system based on a miniature mass spectrometer is presented that demonstrates improved analytical performance for the measurement of dissolved gases and volatile organic compounds (VOCs) in aqueous solution. Aqueous solution is directly brought to the monolayer flat membrane interface at a constant flow rate. A heating resistor and a thermocouple are fixed on the side of the membrane and aqueous solution respectively. This new strategy allows for a temperature compensation method, affording an improvement of sensitivity and a reduction of response time compared with the conventional heating solution temperature control strategy. Furthermore, a static heating mode is applied to effectively remove the memory effect. Automatic sampling and measurement are achieved by using the membrane inlet system with silicone sheeting of 50 μm thickness. The vacuum is below 3 × 10−5 Torr, which can make the instrument work normally. A good linear response is observed for benzene in the range of 0.1 ppm–10 ppm and the detection limit is 50 ppb. The analytical capacity of this system is demonstrated by the on-line analysis of VOCs in aqueous solution, in which the dominant ions are detected rapidly. The results indicate that the sandwich temperature control membrane inlet mass spectrometer (STC-MIMS) has a potential application for on-line analyzing organic pollution in aquatic environments.

Quantitative structure-activity relationship models for predicting singlet oxygen reaction rate constants of dissociating organic compounds

As singlet oxygen (1O2) is ubiquitous in the environment, 1O2-involved oxidation may play an important role in the transformation and fate of organic pollutants. Accordingly, the reaction rate constants (k1O2) of organic compounds with 1O2 are important to determine the environmental fate and persistence assessment of organic pollutants. However, currently there are limited k1O2 data available, especially for organic chemicals with different charged (deprotonated/protonated) forms. Herein three quantitative structure-activity relationship (QSAR) models (one comprehensive model and two models for neutral and deprotonated molecules) were created for predicting aqueous k1O2 values for diversely dissociating molecules. The models include larger datasets (180 chemicals) and have wider applicability domain than previous ones. Molecular structural characteristics (only half-wave potential is present in both models) determining the 1O2 reaction rate of neutral and deprotonated molecules vary greatly. The comparison results of predicting k1O2 values of organic compounds at certain pH conditions show that the combination of the QSAR models for neutral and deprotonated molecules has advantages over the comprehensive QSAR model. This work is the first study to predict k1O2 for a wide variety of neutral and deprotonated molecules and provides an important tool for assessing the fate of organic pollutants in aquatic environments.

A review on hybrid techniques for the degradation of organic pollutants in aqueous environment.

The creation of the modern world requires many industrial sectors, however, sustainability needs to be considered while developing industries. In particular, organic pollutants generated by many of these industries contaminate the environment leading to health and other issues. Advanced oxidation processes (AOPs) have been introduced to remove organic pollutants present in wastewater. Sonolytic degradation of organic pollutants is considered as one of the AOPs, however, this process has its limitations. In order to overcome the limitations, hybrid techniques involving ultrasound and other AOPs have been developed. That is, ultrasound combined with heterogeneous AOPs (ultrasound/metal ions, ultrasound/metal oxides, and ultrasound/photocatalysis) and homogeneous AOPs (ultrasound/ozone, ultrasound/H2O2, and ultrasound/persulfate) for the degradation/mineralization of organic pollutants. This review highlights the advantages of using hybrid techniques involving ultrasound for the degradation of organic pollutants in aqueous solutions.

Photoelectro-Fenton system including electromagnetic induction electrodeless lamp and black carbon poly tetra fluoro ethylene air-diffusion cathode: Degradation kinetics, intermediates and pathway for azo dye

The role of illumination and cathode is important to improve the efficiency of photoelectro-Fenton (PEF) system. In this study, cathodes with black carbon-poly tetra fluoro ethylene (BC-PTFE) for increase the concentration of hydrogen peroxide in PEF. A new PEF system using EIEL and BC-PTFE air-diffusion cathode was established. The electrode performance was tested and the influence factors, degradation kinetics, intermediates, pathway and mechanism of the model compound methyl orange (MO) were studied. The capacities of concentration decays and total organic carbon (TOC) removals were compared between different electrochemical advanced oxidation processes. The experimental conditions were optimized for a current density of 20 mA cm−2 with 0.5 mM Fe2+ and 100 mg L−1 MO at 20 °C and pH 3.0 in an 8 L reservoir. The higher MO concentration was, the smaller pseudo-first-order kinetic constants of concentration decays and TOC removals were. Intermediate products were identified by gas chromatography-mass spectrometry and ion-exclusion high performance liquid chromatograph in EIEL-PEF. Combined with frontier electron density, the degradation pathway was deduced as follows: destruction of azo bond, substitution of •OH, dehydrogenation and oxidation, opening-ring and mineralization. In EIEL-PEF, the concentration of oxalic acid and oxamic acid reached the maximum value 9.2 and 1.5 mg L−1 at 60 and 90 min, respectively. The photolysis of N-intermediates produced NH4+-N was released in more proportion than NO3−-N and oxamic acid-N. The study indicated that PEF system has the potential to remove organic pollutants in aquatic environments.

Quartz crystal microbalance-based method to study adsorption of endocrine disruptor compounds on zeolite

ABSTRACT Endocrine disrupting chemicals (EDCs) can be present as trace-level organic pollutants in aquatic environments and are difficult to measure and remove. In this study, a method was developed using a modified quartz crystal microbalance (QCM) to investigate the adsorption of EDCs by zeolite filter. Bisphenol A (BPA), oestrone (E1), oestradiol (E2), and sulfamethoxazole (SMZ) were selected as four representative endocrine disruptors in a water environment and their adsorption on zeolite was measured by QCM in real-time. The adsorption results were well described by a pseudo-first-order kinetic model and by a Sips isotherms model. The adsorption of the four adsorbents is related to their molecular structure, molecular polarity, and chargeability. The removal rate of EDCs by zeolite for different initial concentrations appeared to plateau, with the removal rates of the four selected EDCs all above 80% except for the maximum initial concentration. Changes of pH and ionic strength had no effect on the adsorption capacity of the four EDCs, with a removal rate of about 90%. However, the response time at pH 5.50 was about 300 s faster than that at pH 8.50 and the addition of electrolyte shortened the mass response time of several organic compounds on QCM.

Biorenewable triblock copolymers consisting of l-lactide and \u03b5-caprolactone for removing organic pollutants from water: a lifecycle neutral solution

BackgroundCurrent methods of removing organic pollutants from water are becoming ineffective as the world population increases. In this study, a series of biorenewable triblock copolymers with hydrophobic poly(ε-caprolactone) block and hydrophilic poly(l-lactide) blocks were synthesized and tested as agents to remove environmental pollutants from an aqueous solution. The percent of pollutant removed and equilibrium inclusion constants were calculated for the polymers. These values were compared to previously known removal agents for their effectiveness.ResultsTriblock copolymer samples removed over 70% of the polycyclic aromatic hydrocarbon (PAH) phenanthrene from an aqueous solution, with selectivity for the adsorption of phenanthrene over other PAHs tested. The inclusion constant was 7.4 × 105 M−1 and adsorption capacity was 5.8 × 10−7 mol phenanthrene/g polymer. Rose Bengal was used to further probe the nature of interactions between the copolymers and a small molecule guest. Solid samples of the block-poly(l-lactide)–block-poly(ε-caprolactone)–block-poly(l-lactide) (PLLA–PCL–PLLA) systems were found to rapidly remove over 90% of Rose Bengal from aqueous solution, resulting in a complete disappearance of the characteristic pink color. Solutions of the copolymers in dichloromethane also removed Rose Bengal from water with a similar level of efficiency. Large inclusion constant values were obtained, ranging from 1.0 × 105 to 7.9 × 105 M−1, and the average adsorption capacity value of 6.2 × 10−7 mol/g polymer was determined. Aged polymer samples exhibited different adsorption characteristics and mechanistic theories for the removal of Rose Bengal were determined.ConclusionThe triblock copolymer consisting of l-lactide and ε-caprolactone was effective in removing various organic pollutants in aqueous environments. It is a biorenewable material which leads to minimal waste production during its lifecycle. These polymers were in general more effective in removing organic pollutants than commercially available pollution removal systems.

Hydrothermal synthesis of type II ZnIn2S4/BiPO4 heterojunction photocatalyst with dandelion-like microflower structure for enhanced photocatalytic degradation of tetracycline under simulated solar light

In this work, the type II ZnIn2S4/BiPO4 heterojunction solar -light driven photocatalysts were synthesized via a facile hydrothermal method, which possessed the unique dandelion-like microflower heterostructure. Among all the ZnIn2S4/BiPO4 with different mass ratios, 70 wt% ZnIn2S4/BiPO4 heterojunction displayed the highest photocatalytic activity, which can degrade 84% tetracycline (TC, 40 mg/L) in 90 min and the rate constant is 0.02017 min−1. It is about 1.89 and 3.14 times that of ZnIn2S4 and BiPO4, respectively. The enhanced photocatalytic activity mainly derives from the formed type II heterojunction between ZnIn2S4 and BiPO4, thereby effectively improving the separation efficiency of electron-hole pairs during the photocatalytic reaction. On the basis of the results of active species capturing and ESR experiments, •OH and •O2− were proven two predominant species in the photocatalytic system. This work is expected to provide a design opportunity to construct highly efficient BiPO4-based type II heterojunction photocatalysts for photocatalytic applications of degradation on organic pollutants in aqueous environment.