Simulated Water Samples Research Articles

Adsorption of 2,4-dichlorophenoxyacetic acid and glyphosate from water by Fe3O4-UiO-66-NH2 obtained in a simple green way

In this study, a green adsorbent (Fe3O4-UiO-66-NH2) with the ability of addressing the issues of separation and recovery of UiO-66-NH2 is obtained using a simple co-precipitation method under environmentally benign conditions. Various characterization techniques are utilized for evaluating the properties of the developed adsorbent. The capability of Fe3O4-UiO-66-NH2 towards 2,4-dichlorophenoxyacetic acid (2,4-D) and glyphosate (GP) from solution is explored. The results revealed that the magnetization process did not destroy the crystal structure of UiO-66-NH2, which ensured that Fe3O4-UiO-66-NH2 had good adsorption performance for 2,4-D and GP. The adsorption processes showed a wide pH application range, high salt tolerance, and regeneration performance as well as an excellent adsorption rate. Results from thermodynamic study showed that both processes were spontaneous and endothermic. The unit uptake ability of Fe3O4-UiO-66-NH2 for 2,4-D and GP reached up to 249mg·g-1 and 183mg·g-1 from Langmuir model at 303K, respectively. When solid-liquid ratio was 2g·L-1, Fe3O4-UiO-66-NH2 can reduce the content of 2,4-D or GP with the initial density of 100mg·L-1 below the drinking water requirement limit. In addition, the reusability efficiency of Fe3O4-UiO-66-NH2 towards 2,4-D and GP was found to be 86% and 80% using 5mmol·L-1 NaOH as eluent. Analysis of simulated water samples indicated that Fe3O4-UiO-66-NH2 could achieve the single or simultaneous removal of 2,4-D and GP from wastewater. Summarily, Fe3O4-UiO-66-NH2 as a green adsorbent can serve as an alternative for removing 2,4-D and GP from water body.

Comparison of UV/chloramine disinfection of methylamine water in the absence and presence of bromide: Halonitromethanes formation, toxicity alteration, and reaction mechanisms

UV/chloramine is considered a new potential disinfection process to substitute traditional disinfection methods, and the participation of bromide (Br−) significantly influences halonitromethanes (HNMs) formation during UV/chloramine disinfection. Herein, the formation laws of HNMs from methylamine were explored and compared during UV/chloramine disinfection with and without the existence of Br−. The results indicated that there were similar formation laws of HNMs between the disinfection processes with and without the existence of Br− but different species and productions of HNMs were observed. Furthermore, both the total HNMs productions during UV/chloramine disinfection with and without the existence of Br− were markedly enhanced when increasing chloramine dosage while those were significantly reduced when increasing solution pH from 6.0 to 8.0. Also, it was pointed out that Br− dramatically strengthened the toxicity of HNMs, and the toxicity alteration of HNMs was consistent with the changes in the yields of total HNMs with reaction time. Meanwhile, the reaction mechanisms of HNMs formed from methylamine were speculated during UV/chloramine disinfection with and without the existence of Br−, and Br− presented a non-negligible impact on the formation mechanisms. Finally, the formation laws of HNMs in two real water samples were found to be similar to that in simulated water samples during UV/chloramine disinfection, while different species and yields of HNMs were simultaneously observed. This work illustrated HNMs formation from methylamine and the significant impacts of Br− on HNMs generation during UV/chloramine disinfection.

One-step fluorometric determination of multiple-component dissolved organic matter in aquatic environments

Dissolved organic matter (DOM) is ubiquitous in aqueous environments and is composed of different components that play different but important roles in the migration and the fate of pollutants, emergence of the disinfect byproduct, thus requiring quantitative characterization. However, until now, simultaneous quantification of the main contents in DOM, i.e., saccharides, proteins, and humic substances, has been difficult, impeding us from understanding and predicting the environmental behaviors of typical pollutants. In this work, a fluorescence approach based on the excitation emission matrix (EEM), combined with a new algorithm, denoted matrix reconstruction coupled with prior linear decomposition (MR-PLD), was developed to quantify multiple DOM simultaneously. First, a set of simulated water samples consisting of glucose, tryptones, and humic acid (HA) were analyzed using MR-PLD to validate the feasibility of the method. The DOM components could be reliably determined with a higher accuracy than parallel factor analysis (PARAFAC) and Parallel Factor Framework-Linear Regression (PFFLR), also with a more convenient procedure than conventional PLD. Second, both actual simulated and experimental methods were performed to test the anti-interference performance of MR-PLD, indicating that the quantification of DOM would not be significantly impacted by other fluorophores. Finally, several actual water samples from natural waters and wastewater treatment plants were also analyzed to confirm the robustness of this method in actual aqueous environments. This study provides a new approach to characterize DOM with EEM, contributing to its convenient concentration monitoring and the further exploration of the environmental impacts.

An effective fluorescence sensor for herbicide haloxyfop-P-methyl based on cyclic bicyanostilbene imidazole salt

Haloxyfop-P-methyl is a herbicide widely used in agricultural production. However, the lack of facile and on-site detection methods for haloxyfop-P-methyl remains concern. In this work, the first fluorescent sensor for haloxyfop-P-methyl was developed based on a cyclic bicyanostilbene imidazole salt (CBIS). CBIS has been prepared by “1 + 1″ condensation of a bicyanostilbene imidazole derivative with a chiral (1S, 2S)-cyclohexanediamine derivative in 68% yield. It possesses the weak green fluorescence at 514 nm in aqueous media, but the strong blue fluorescence at 493 nm after sensing haloxyfop-P-methyl. This turn-on fluorescence and blue-shift wavelength is only observed for detecting haloxyfop-P-methyl among various pesticides and ions. The limit of detection is as low as 1.41 × 10−8 M. The binding mechanism is clarified as that haloxyfop-P-methyl is encapsulated in the cavity of CBIS. The fluorescence sensing ability of CBIS is applied to detect the haloxyfop-P-methyl in test papers, the real samples of apples and oranges, and simulated water samples, suggesting the good application prospect for facile and on-site sensing haloxyfop-P-methyl in real samples of fruits and foods.

A multifunctional adsorbent based on 2,3-dimercaptosuccinic acid/dopamine-modified magnetic iron oxide nanoparticles for the removal of heavy-metal ions

Overexploitation of nature by humans has led to an increasingly serious issue of heavy-metal water pollution. To reduce the threat of water pollution to humans and the environment, it is imperative to develop or improve the water treatment technology for heavy-metal-containing wastewater. Functionalized Fe3O4 magnetic nanoparticles (Fe3O4 MNPs) have been widely used as effective adsorbents for the removal of heavy-metal ions from water owing to their high efficiency, low cost, selective adsorption ability, and recyclability. In this study, Fe3O4@DA-DMSA magnetic nanoparticles (FDDMs) were prepared by the functionalization of Fe3O4 MNPs with environmentally friendly dopamine (DA) and a heavy-metal detoxifying agent such as 2,3-dimercaptosuccinic acid (DMSA) for the efficient and rapid adsorption of Pb2+, Cu2+, and Cd2+, with maximum adsorption capacities of 187.62, 63.01, and 49.46 mg/g, respectively. FDDMs exhibited the best ability to remove Pb2+ with a maximum adsorption capacity than that of the most reported Fe3O4 MNP-related adsorbents. In actual wastewater and multi-component simulated water samples contaminated with Pb2+, Cu2+, and Cd2+, the as-prepared adsorbent maintained a good removal ability for Pb2+ with low influence by ionic strength and interfering ions, as well as exhibited an excellent selectivity. According to the results of batch experiments and X-ray photoelectron spectroscopy (XPS) analysis of the adsorbent before and after adsorption, the adsorption mechanism of the adsorbent for the removal of heavy-metal ions mainly involves coordination and ion exchange. In addition, the adsorbent exhibited a good regeneration performance. Therefore, FDDMs can be considered as a promising adsorbent for the treatment of heavy-metal wastewater.

Influence of the hydrophobicity of the starch-based coagulant on the coagulation of various pollutants in water and the study of its mechanism

<p indent="0mm">Parts of surface water in China, including some rivers and lakes, show the characteristics of micropollution containing excessive dissolved organic matter, which has become a key factor in restricting the improvement of water quality. Coagulation is one of the most popular technologies in the purification of surface water owing to its low cost and simple operation. However, traditional coagulants, including inorganic and organic synthetic polymer coagulants, usually show a low efficiency in removing organic micropollutants from surface water and pose the risk of secondary pollution. Furthermore, the molecular structures of organic micropollutants contain hydrophilic and a large number of hydrophobic groups. Considering these facts, in this study, starch (St), a natural polymer with the characteristics of environmental friendliness, wide source, and low cost, was used as the raw material and acrylamide and various quaternary ammonium salts containing different lengths of carbon chains were used as modifiers. Accordingly, four modified starch coagulants (CS-DMRCs) with the same charge density and good water solubility but different degrees of hydrophobicity were designed and fabricated using graft copolymerization. Kaolin particles, sodium humate (NaHA), and bovine serum albumin (BSA) were used as the simulated sources of inorganic colloids and different organic pollutants in the micropolluted turbid surface water. The effects of the hydrophobicity of four St-based coagulants on the removal of kaolin particles, NaHA, and BSA from their single, binary, and ternary pollutant aqueous systems were investigated systematically. Based on the apparent coagulation performance, the floc properties, including floc size, compactness, surface morphology, breakage and recovery behaviors, and the zeta potentials of the supernatants after coagulation, the coagulation mechanisms associated with the structural features of the St-based coagulants and treated pollutants were explored and discussed in detail. The St-based coagulants with a higher hydrophobicity showed better coagulation performance owing to the synergistic effects of charge neutralization, bridging flocculation, and hydrophobic association. In addition to these simulated water samples, a real micropolluted turbid surface water sample from the Jiuxiang River of Nanjing was tested and compared with the simulated water samples, further confirming the practicality of the hydrophobically modified cationic St-based coagulants. In summary, CS-DMRCs should have broad prospects in practical applications owing to their easy and simple fabrication and high efficiency in the purification of organic micropolluted turbid surface water.

Efficient electrocatalytic valorization of chlorinated organic water pollutant to ethylene.

Electrochemistry can provide an efficient and sustainable way to treat environmental waters polluted by chlorinated organic compounds. However, the electrochemical valorization of 1,2-dichloroethane (DCA) is currently challenged by the lack of a catalyst that can selectively convert DCA in aqueous solutions into ethylene. Here we report a catalyst comprising cobalt phthalocyanine molecules assembled on multiwalled carbon nanotubes that can electrochemically decompose aqueous DCA with high current and energy efficiencies. Ethylene is produced at high rates with unprecedented ~100% Faradaic efficiency across wide electrode potential and reactant concentration ranges. Kinetic studies and density functional theory calculations reveal that the rate-determining step is the first C-Cl bond breaking, which does not involve protons-a key mechanistic feature that enables cobalt phthalocyanine/carbon nanotube to efficiently catalyse DCA dechlorination and suppress the hydrogen evolution reaction. The nanotubular structure of the catalyst enables us to shape it into a flow-through electrified membrane, which we have used to demonstrate >95% DCA removal from simulated water samples with environmentally relevant DCA and electrolyte concentrations.

What determines accuracy of chemical identification when using microspectroscopy for the analysis of microplastics?

Fourier transform infrared (FTIR) and Raman microspectroscopy are methods applied in microplastics research to determine the chemical identity of microplastics. These techniques enable quantification of microplastic particles across various matrices. Previous work has highlighted the benefits and limitations of each method and found these to be complimentary. Within this work, metadata collected within an interlaboratory method validation study was used to determine which variables most influenced successful chemical identification of un-weathered microplastics in simulated drinking water samples using FTIR and Raman microspectroscopy. No variables tested had a strong correlation with the accuracy of chemical identification (r = ≤0.63). The variables most correlated with accuracy differed between the two methods, and include both physical characteristics of particles (color, morphology, size, polymer type), and instrumental parameters (spectral collection mode, spectral range). Based on these results, we provide technical recommendations to improve capabilities of both methods for measuring microplastics in drinking water and highlight priorities for further research. For FTIR microspectroscopy, recommendations include considering the type of particle in question to inform sample presentation and spectral collection mode for sample analysis. Instrumental parameters should be adjusted for certain particle types when using Raman microspectroscopy. For both instruments, the study highlighted the need for harmonization of spectral reference libraries among research groups, including the use of libraries containing reference materials of both weathered plastic and natural materials that are commonly found in environmental samples.

Kinetic, Thermodynamic and Adsorption Isotherm Studies of Detoxification of Eriochrome Black T Dye from Wastewater by Native and Washed Garlic Peel

Eriochrome Black T (EBT) is mutagenic and carcinogenic, and thus its presence in water may result in severe illnesses. This study was aimed at adsorbing EBT from simulated water samples by using a batch adsorption process, onto native (GP) and washed garlic peel (WGP). Surface and structural characterization of native and washed GP was performed using FTIR, SEM, BET, and BJH analysis. The effects of several parameters, affecting the process of adsorption, like pH, temperature, contact time, adsorbent dose, and initial dye concentration, were also examined. Freundlich and Langmuir isotherms were applied to the equilibrium data. Pseudo-first and pseudo-second order models were used to study the adsorption kinetics. The Langmuir isotherm and pseudo-second order model perfectly explained the equilibrium data. ΔG°, ΔH°, ΔS° studies indicated that adsorption of EBT onto GP and WGP was a favorable, spontaneous, and physical process. Maximum dye removal by GP (96%) and WGP (82%) was observed at pH 2. Similarly Maximum adsorption capacities were found to be 99.5 mg/g and 89.4 mg/g for GP and WGP, respectively. It is concluded from these results that garlic peel can be used as a cheaper and more efficient material for the adsorptive removal of EBT from contaminated water samples.

Lignin Microspheres Modified with Magnetite Nanoparticles as a Selenate Highly Porous Adsorbent.

Highly porous lignin-based microspheres, modified by magnetite nanoparticles, were used for the first time for the removal of selenate anions, Se(VI), from spiked and real water samples. The influence of experimental conditions: selenate concentration, adsorbent dosage and contact time on the adsorption capacity was investigated in a batch experimental mode. The FTIR, XRD, SEM techniques were used to analyze the structural and morphological properties of the native and exhausted adsorbent. The maximum adsorption capacity was found to be 69.9 mg/g for Se(VI) anions at pH 6.46 from the simulated water samples. The modified natural polymer was efficient in Se(VI) removal from the real (potable) water samples, originated from six cities in the Republic of Serbia, with an overage efficacy of 20%. The regeneration capacity of 61% in one cycle of desorption (0.5 M NaOH as desorption solution) of bio-based adsorbent was gained in this investigation. The examined material demonstrated a significant affinity for Se(VI) oxyanion, but a low potential for multi-cycle material application; consequently, the loaded sorbent could be proposed to be used as a Se fertilizer.

Effect of Seawater Intrusion on the Formation of Chlorinated and Brominated Trihalomethanes in Coastal Groundwater

Around the world, coastal groundwater is increasingly subject to seawater intrusion (SWI). The quality and characteristics of such waters differ from those of surface and groundwater. In the current study, trihalomethane (THM) formation under varying levels of SWI, natural organic matter (NOM), and chloride-to-bromide (Cl/Br) ratio was evaluated. Different levels of SWI were simulated by mixing deionized water with real seawater (RSW) collected from the Indian Ocean or synthetic seawater (SSW) by varying seawater volumes from 0% to 3%. Humic acid (0 to 5 mg/L) was added to represent NOM at concentrations mimicking natural levels of dissolved organic carbon. The chlorine demand of the simulated water samples was significantly correlated to SWI levels and NOM concentrations. THM concentration in SSW increased from 12.64 µg/L to 105.34 µg/L after 24 h and to 115.8 µg/L after 48 h for an increase from 0% to 3% volume of seawater. For water samples simulated with RSW, maximum THMs after 24 h were 119.2 µg/L, and after 48 h were 126.4 µg/L. An increase in NOM concentration in seawater-intruded water samples resulted in increasing THMs, especially tribromomethane. However, the increment in THMs at higher NOM concentration was lower compared to that at low NOM concentration. Chlorine demand was positively correlated only to tribromomethane. An increase in bromide concentration resulted in lower Cl/Br ratio and a concomitant increase in brominated THMs. The bromine substitution factor corresponding to increasing SWI of 0.25–3% decreased from 2.67 to 1.81 over a reaction time of 24 to 48 h, indicating a shift from TBM dominance to chlorinated THMs.

Sugarcane Bagasse and Orange Peels as Low-Cost Biosorbents for the Removal of Lead Ions from Contaminated Water Samples

The pollution of water by lead (Pb(II)) constitutes a substantial threat to the environment and subsequently to animals and humans. In this study, the efficacy of sugarcane bagasse (SCB) and orange peels (OPS) have been investigated as potential low-cost biosorbents, individually and in a homogeneous combination for the removal of Pb(II) from simulated and real water samples. Biosorbents were characterised using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) coupled to energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), powder X-ray diffraction (pXRD), a zeta potential analyser, and the Brunauer–Emmett–Teller (BET) method. Batch adsorption studies were explored under several experimental conditions to optimise the removal efficiency of Pb(II) ions from artificially contaminated aqueous solutions. The pH study revealed optimum removal efficiencies of Pb(II) at pH 7, for SCB and OPS. The optimum contact time for SCB and OPS individually and a homogenous mixture was 60, 120, and 120 min, respectively. The study also revealed that the optimum biosorbent dosage was 0.2, 0.17, and 0.2 g for SCB, OPS, and the homogenous combination of SCB and OPS (1:1). Optimum experimental conditions could achieve up to 100% removal efficiencies for 10 and 20 mg/L of Pb(II) using SCB and OPS, respectively. The potential of the homogenised combination of biosorbents demonstrated 100% removal efficiencies for 10 mg/L of Pb(II). The removal of 10 mg/L of Pb(II) in real water samples remained at 100% for biosorbents individually and the homogenised combination. The reusability performance of SCB, OPS, and the homogenised combination of SCB and OPS presented Pb(II) removal efficiencies above 70% for three adsorption–desorption cycles.

A highly selective bifunctional nanosensor based on nanocellulose and 3D polypyrrole decorated with silver-gold bimetallic alloy to simultaneously detect methotrexate and ciprofloxacin

An electrochemical sensing platform for the simultaneous detection of methotrexate (MTX) and Ciprofloxacin (CIF) has been presented using nanocellulose and 3dimensional polypyrrole (NC-3DPPY) hybridized silver-gold bimetallic alloy nanoparticle (Ag-Au). The NC-3DPPY composites and Ag-Au bimetallic alloys were prepared by acid hydrolysis and chemical reduction, respectively. The nanocomposite structure of NC-3DPPY@Ag-Au was prepared through ultrasonication, and the electrochemical performances of the nanocomposites were elucidated by cyclic voltammetry (CV) and square wave voltammetry (SWV). Field emission scanning electron microscopy (FESEM) and High-resolution transmission electron microscopy (HR-TEM) analysis showed that the as-prepared nanocomposites possess a porous structure, and the nanoparticles are interconnected. The thermogravimetric analysis (TGA) results revealed that the NC-3DPPY@Ag-Au nanocomposite has higher thermal stability than NC and NC-3DPPY. The electrocatalytic efficiency of the nanocomposites was evaluated by oxygen evaluation reaction (OER), and the binding interactions between NC-3DPPY@Ag-Au with MTX and CIF were studied using a computational technique. At the optimized values of scan rate, pH, and supporting electrolyte conditions, the fabricated sensor demonstrated a broad linear detection ranges of 5–350 µM and 0.5–50 µM, with a low limit of detection (LOD) of 0.062 and 0.017 µM for MTX and CIF, respectively. The proposed simultaneous electrochemical sensor exhibits high stability, excellent reproducibility and selectivity to detect MTX and CIF in the presence of common interfering species. Our study showed excellent analytical performances for trace level detection of MTX and CIF in simulated blood serum, tablets, and water samples with satisfactory recoveries.

Development of novel Core–shell impregnated polyuronate composite beads for an eco-efficient removal of arsenic

Arsenic (As) can geogenically and anthropogenically contaminate the potable water resources and undoubtedly reduces its availability for human consumption. To circumvent this predicament, present study focuses on the development of a novel biosorbent by impregnating calcium cross-linked polyuronate (alginate) beads (CABs) with bilayer–oleic coated magnetite nanoparticles (CAB@BOFe) for As(V) removal. Initially, the system parameters (i.e., adsorbents dose (0.1– 3.0 g L–1), pH (4.0–13), reaction times (0–180 min) and sorbate concentrations (10–150 µg L–1)) were optimized to establish adsorbent at the lab-scale. CAB@BOFe had higher monolayer (ad)sorption capacity (∼62.5 µg g−1, 120 min) than CABs (∼17.9 µg g−1, 180 min). Electrostatic/Ion-dipole interactions and surface-complexation mechanisms mediated As(V) sorption onto CAB@BOFe mainly obeyed Langmuir isotherm (R2 ∼ 0.9) and well described by intraparticle diffusion process. Furthermore, it demonstrated an excellent arsenate removal performance from the single/multiple anionic contaminants simulated water samples which supported its prospective field applicability.

Synthesis and adsorption performance of ultra-low silica-to-alumina ratio and hierarchical porous ZSM-5 zeolites prepared from coal gasification fine slag.

Since the human consumption of coal is increasingly growing and coal-based solid wastes are discharged in large quantities, the resource utilization of coal-based solid wastes has been paid more attention. In the present work, for the first time, the coal gasification fine slag is subjected to prepare ZSM-5 zeolites with ultra-low n(SiO2)/n(Al2O3) ratios (less than 20) and hierarchical pore structures. The increase in the concentration of the alkaline extract leads to the decrease of the crystallinity, the irregularity of the microscopic morphology, and the decrease of the specific surface area, resulting in the in-situ generation of mesopores within ZSM-5. Moreover, adsorption experiments demonstrate that ZSM-5-2M exhibits the best methylene blue adsorption performance at the pH of 9 with a removal rate of up to 82.07%, and it also has good adsorption performance in simulated real water samples. Furthermore, the adsorption performance of ZSM-5-2M on the malachite green, Rhodamine B, Congo red, and methyl orange has been investigated and it is found to be very effective for the adsorption of cationic dyes, and its adsorption performance for methylene blue and malachite green is reduced in the presence of anions.

Real-Time On-Site Multielement Analysis of Environmental Waters with a Portable X-ray Fluorescence (pXRF) System

Strict regulations are in place to control the effluents of mining sites and other industries. Heavy metal contamination of aquatic systems caused by leakages is difficult to mitigate as it takes time to detect and localize the leak. Dynamic sampling would drastically reduce the time to locate leakages and allow faster actions to reduce the impact on the environment. The present study introduces a novel portable multielement water analysis system to simultaneously measure Mn, Ni, Cu, Zn, Pb, and U in water samples from natural sources within 15 min from the sampling. The metals are preconcentrated from a 10 mL water sample into a nanoporous filter based on bisphosphonate-modified thermally carbonized porous silicon. The metals can be conveniently analyzed from the filter with a portable XRF analyzer in field conditions. The system was empirically calibrated for a lake water matrix with neutral pH and low alkaline metal concentration. A strong correlation between the XRF intensities and the ICP-MS results was obtained in a concentration range from 50 to 10 000 μg/L. With a DPO-2000C XRF analyzer, the detection limits were 103, 86, 92, 35, 44, and 43 μg/L for Mn, Ni, Cu, Zn, Pb, and U, respectively. The corresponding values with X-MET8000 Expert Geo were 137, 46, 62, 38, 29, and 54. The system was successfully validated with simulated multielement lake water samples and piloted in field conditions. The system provides an efficient way to monitor metals in environmental waters in cases where quick on-site results are needed.

Hydrolysis of norfloxacin in the hyporheic zone: kinetics and pathways.

Understanding the hydrolysis behavior and pathway of norfloxacin (NOR) in the hyporheic zone (HZ) is important for predicting its environmental persistence. Therefore, the effects of different environmental factors on NOR hydrolysis were investigated, and the hydrolysis pathway of NOR in the HZ was determined by DFT calculations and UPLC/TOF-MS. The hydrolysis process of NOR was consistent with the first-order kinetic. The experiment of environmental factors showed that DO was an important factor to affect NOR hydrolysis, and its hydrolysis rate was positively correlated with DO concentration. The superoxide radical (·O2-) was the main active species for NOR hydrolysis. The hydrolysis rates of NOR under neutral and alkaline conditions were higher than that under acidic conditions in both aerobic and anoxic environments. The ions of Ca2+, Mg2+, HCO3-, CO32-, and NO3- in simulated water samples inhibited the hydrolysis of NOR, while Cl- promoted its hydrolysis. In addition, the electronegativity of NOR was determined by DFT calculations, and it was speculated that the active sites of NOR hydrolysis were mainly located in the piperazine ring and quinolone ring. The main hydrolysis pathway of NOR in aerobic environment was piperazine ring cracking and quinolone ring decomposition, and that in anoxic environment was piperazine ring cracking. The results are of great significance to evaluate the environmental fate of NOR in the HZ and provide a theoretical basis for further understanding the degradation and governance of fluoroquinolones in water environment.

Three-dimensional (3D) thermal controlled polymer for simplified dispersive liquid-liquid microextraction in phthalic acid easters detection of straw

In this paper, a three-dimensional (3D) polyfunctional group and thermal controlled polymer p(POSS-co-DMAEMA) was prepared based on the chemical structure of the phthalic acid easters (PAEs) and applied as an extractant for dispersive liquid–liquid microextraction (DLLME) in combination with HPLC-UV. The polymer with good biocompatibility can be dispersed and aggregated by shaking and heating based on the thermal controlled properties without the assistance of instruments, which shortened the DLLME process as low as 5 min. The feasibility of the developed method was verified using 5 PAEs as targets in simulated water samples, which showed good precision (RSD%, 1.3–10.0, n = 3) and low detection limit (0.19–0.52 ng mL−1) under the optimal extraction conditions. This proposed method was successfully applied in analyzing four straws and good spiked recoveries over the range of 91.60–128.00% were obtained. Furthermore, molecular docking was employed to explore the molecular interactions and calculate binding energies between the polymer and organic pollutants, ensuring the synthesized polymer has a strong extraction ability for PAEs. The satisfied extraction efficiency can be attributed to the fact that the p(POSS-co-DMAEMA) is water-soluble at room temperature but hydrophobic at high temperature, and the high extraction ability can be achieved by the strong intermolecular forces between the polymer and PAEs. The experimental results suggest that the proposed method holds good promise for the trace analysis of PAEs.

Conversion of waste bottle PET to magnetic microparticles adsorbent for dye-simulated wastewater treatment

Mass production and consequent accumulation of plastic wastes in the environment urges the development of technologies for the efficient plastic wastes utilization and valorization to materials and products to support circular economy. Here, we report a novel conversion of PET plastic to a magnetic microparticles adsorbent prepared by co-precipitation of Fe3O4 nanoparticles with oligomeric products of PET aminolysis. The obtained adsorbent represents highly water-dispersible oligo(terephthalamide) particles of several tens μm size embedding magnetic nanoparticles randomly distributed in the organic matrix. The PET-derived magnetic adsorbent was used for the rapid and facile magnetic separation of an anionic dye (Congo Red, CR) from dye simulated water samples. The adsorbent containing plenty of amine groups showed superb adsorption capacity for CR of ca. 780 mg/g which is pH dependent and optimal at pH 6.5. Furthermore, the microparticular, non-aggregative state of the adsorbent coupled with its magnetic functionality provided rapid saturation of the adsorbent with dye by ca. 70% of the equilibrium adsorption capacity within 5 min and possibility of instantaneous removal from solution by a magnet. The proposed here material design addresses simultaneously the problem of plastic wastes utilization and preparation of cost-effective and efficient adsorbents for environmental cleaning purposes.

Effective removal of Pb(II) and Ni(II) ions by Bacillus cereus and Bacillus pumilus: An experimental and mechanistic approach

Herein, we report a bacteria-based strategy as an efficient, reasonable, benign, and promising methodology for remediating heavy metals fed waterbodies. The contemporary study deals with isolating, screening, and characterizing heavy metal resistive bacteria from metal-rich sites. The transcriptome analysis reveals the identity of the isolated species as Bacillus pumilus and Bacillus cereus. Batch studies put forth the bioremoval results in designed conditions of different pH, concentration, dose, and time. The mechanistic actions are drawn using complementary techniques such as Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). The theory of surface adsorption of lead (Pb(II)) and nickel (Ni(II)) is further fostered by the application of adsorption isotherms. The conducted studies establish the bacterial morphological stratagems and multifarious biochemical approaches for countering metallic ions of Pb(II) and Ni(II). The exhibition of significant removal results by the isolated bacterial strains in simulated water samples with remarkable proliferation rates has opened up its favorability for industrial platforms.