Decomposition of ibuprofen in water via an electrochemical process with nano-sized carbon black-coated carbon cloth as oxygen-permeable cathode integrated with ultrasound

Ultraviolet light spectroscopic characterization of ibuprofen acid aggregation in deionized water

This work provides a description of the aggregation equilibria of ibuprofen acid in deionized water at temperatures between 20 and 40 °C in the 0.1-20.1 ppm concentration range. For this goal, we have made use of UV-Visible spectroscopy. A calculation algorithm was developed to obtain the aggregate orders and thermodynamic parameters from the experimental absorbance values. Monomeric ibuprofen acid was found to be absent in water solutions. In addition to the dimer, two aggregates formed by 32 and 128 monomeric units were found to co-exist in solution at the highest concentration tested. A critical micelle concentration of 7.8 ppm was estimated for this system. The appearance of the first aggregate occurs when the pH drops below the pKa value, which was determined to be 4.62. At higher ibuprofen concentrations, a sudden jump in the electrical conductivity coincides with the onset of formation of the second aggregate. A varied menu of alternatives is offered with respect to the calibration curve of ibuprofen in water, though the linear calibration of ibuprofen concentration with absorbance might be reasonably performed at 224 nm. Finally, the dissolution rate of the commercial ibuprofen used in this work was found to obey the Noyes-Whitney first order equation.

A Comprehensive Review for Removal of Non-Steroidal Anti-Inflammatory Drugs Attained from Wastewater Observations Using Carbon-Based Anodic Oxidation Process

Non-steroidal anti-inflammatory drugs (NSAIDs) (concentration <µg/L) are globally acknowledged as hazardous emerging pollutants that pass via various routes in the environment and ultimately enter aquatic food chains. In this context, the article reviews the occurrence, transport, fate, and electrochemical removal of some selected NSAIDs (diclofenac (DIC), ketoprofen (KTP), ibuprofen (IBU), and naproxen (NPX)) using carbon-based anodes in the aquatic environment. However, no specific protocol has been developed to date, and various approaches have been adopted for the sampling and elimination processes of NSAIDs from wastewater samples. The mean concentration of selected NSAIDs from different countries varies considerably, ranging between 3992−27,061 µg/L (influent wastewater) and 1208−7943 µg/L (effluent wastewater). An assessment of NSAIDs removal efficiency across different treatment stages in various wastewater treatment plants (WWTPs) has been performed. Overall, NSAIDs removal efficiency in wastewater treatment plants has been reported to be around 4−89%, 8−100%, 16−100%, and 17−98% for DIC, KTP, NPX, and IBU, respectively. A microbiological reactor (MBR) has been proclaimed to be the most reliable treatment technique for NSAIDs removal (complete removal). Chlorination (81−95%) followed by conventional mechanical biological treatment (CMBT) (94−98%) treatment has been demonstrated to be the most efficient in removing NSAIDs. Further, the present review explains that the electrochemical oxidation process is an alternative process for the treatment of NSAIDs using a carbon-based anode. Different carbon-based carbon anodes have been searched for electrochemical removal of selected NSAIDs. However, boron-doped diamond and graphite have presented reliable applications for the complete removal of NSAIDs from wastewater samples or their aqueous solution.

A comprehensive review on MXenes as new nanomaterials for degradation of hazardous pollutants: Deployment as heterogeneous sonocatalysis

MXene-based nanomaterials (MBNs) are two-dimensional materials that exhibit a series of sought after properties, including rich surface chemistry, adjustable bandgap structures, high electrical conductivity, hydrophobicity, thermal stability, and large specific surface area. MBNs have an exemplar performance when applied for the degradation of hazardous pollutants with various advanced oxidation processes such as heterogeneous sonocatalysis. As such, this work focuses on the sonocatalytic degradation of various hazardous pollutants using MXene-based catalysts. First, the general principles of sonocatalysis are examined, followed by an analysis of the main components of the MXene-based sonocatalysts and their application for pollutant degradation. Lastly, ongoing challenges are highlighted with recommendations to address the issues.

Efficient pH-universal degradation of antibiotic tetracycline via Co2P decorated Neosinocalamus affinis biochar

Considering the complexity of traditional cobalt phosphide (Co₂P) loaded biochar synthesis research on a simple and efficient synthesis method has practical significance. In this study, after phosphoric acid activation, Neosinocalamus affinis biochar (NAB) and nanoplate Co₃O₄ quickly formed a Co₂P-NAB composite material with high Co₂P crystallinity and was uniformly dispersed on the surface of NAB in a microwave reactor. Co₂P-NAB has an excellent catalytic degradation effect in the activation of peroxymonosulfate (PMS) to degrade tetracycline (TC). The optimal TC degradation efficiency was achieved with the addition of 50 mg L^-1 TC concentration, 0.2 g L^-1 catalysts, 0.406 mM PMS and pH = 6.02. In addition, according to the pseudo-first-order reaction rate constant calculation, the composite of Co₂P-NAB and PMS the synergy efficiency is 81.55 %. Compared with Co₂P-NAB (10.83 %) and PMS (7.62 %) alone, the Co₂P-NAB/PMS system has a significant promotion effect on the degradation of TC molecules. Additionally, the Co₂P-NAB/PMS system had a TC mineralization rate of 68 % in 30 min. Furthermore, after a series of characterization, detection and analysis, and influencing factor experiments, we proposed a potential mechanism for the Co₂P-NAB/PMS reaction system to degrade TC and found that singlet oxygen (¹O₂) plays an essential role in the non-radical degradation process. Finally, according to the liquid chromatography-mass spectrometry (LC-MS) detection of TC degradation intermediates, a possible degradation route was proposed. Therefore, this work uses microwave technology to present a novel and simple synthesis method for transition metal phosphides, which provides potential application value for the treatment of actual wastewater with heterogeneous catalysts.

Graphene-based ZnCr layered double hydroxide nanocomposites as bactericidal agents with high sonophotocatalytic performances for degradation of rifampicin

Herein, ZnCr layered double hydroxide (ZnCr LDH), and its nanocomposites with GO and rGO were synthesized using the co-precipitation method. The samples were characterized using XRD, FT-IR, SEM, TEM, BET, and XPS techniques. The sonophotocatalytic activity of the ZnCr LDH, ZnCr LDH/GO, and ZnCr LDH/rGO was investigated via the degradation of rifampicin (RIF) in the ultrasonic bath under visible light irradiation. The synergy index of more than 1 determined for ZnCr LDH/rGO indicated the positive interaction of sonocatalysis and photocatalysis resulted by hybridizing the LDH nanosheets with rGO. The maximum sonophotocatalytic degradation efficiency of 87.3% was achieved in the presence of ZnCr LDH/rGO nanocomposite with the concentration of 1.5 g L^-1 for degradation of RIF with an initial concentration of 15 mg L^-1 within 60 min sonication under visible light irradiation. The addition of different scavengers indicated that hydroxyl radicals, superoxide anion radicals, and the generated holes played a dominant role in the degradation of the pollutant molecules. A possible degradation mechanism was suggested based on the intermediates. The antibacterial tests confirmed the higher antibacterial activity of ZnCr LDH/GO compared with ZnCr LDH and ZnCr LDH/rGO against Gram-positive Staphylococcus aureus.

Amorphous cobalt oxide decorated halloysite nanotubes for efficient sulfamethoxazole degradation activated by peroxymonosulfate

In this study, a new hollow nanotube material, 30% Co-CHNTs was prepared by the impregnation-chemical reduction-calcination method. This material can be used as a peroxymonosulfate (PMS) activator to catalyse the degradation of sulfamethoxazole (SMX). The best reaction conditions that correspond to the degradation rate of SMX, up to 97.5%, are as follows: the concentration of SMX is 10 mg L^-1, the amount of catalyst is 0.20 g L^-1, the dosage is 1.625 mM, and the solution pH is 6.00. X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma optical emission spectrometry (ICP-OES) show that the calcined composites mainly stimulate an increase in the content of bivalent cobalt in PMS and reduce the leaching of cobalt ions after the reaction. Additionally, the 30% Co-CHNTs + PMS reaction system exhibits a reasonable SMX degradation rate in a natural organic matter solution and excellent stability after three repeated experiments. Furthermore, the possible degradation mechanism in the 30% Co-CHNTs + PMS reaction system was analysed through electron paramagnetic resonance (EPR) and free-radical capture experiments, and it was observed that the non-radical degradation of ¹O₂ plays a leading role in SMX degradation. Finally, according to the nine degradation intermediates detected by liquid chromatography-mass spectrometry (LC-MS), four possible SMX degradation routes were proposed. This study proved that a 30% Co-CHNTs heterogeneous catalyst is easily prepared, inexpensive, and environmentally friendly and has potential application in antibiotic wastewater treatment.

A review on pharmaceuticals removal from waters by single and combined biological, membrane filtration and ultrasound systems

Contaminants of emerging concern (CEC) such as pharmaceuticals commonly found in urban and industrial wastewater are a potential threat to human health and have negative environmental impact. Most wastewater treatment plants cannot efficiently remove these compounds and therefore, many pharmaceuticals end up in aquatic ecosystems, inducing problems such as toxicity and antibiotic-resistance. This review reports the extent of pharmaceutical removal by individual processes such as bioreactors, advanced oxidation processes and membrane filtration systems, all of which are not 100% efficient and can lead to the direct discharge of pharmaceuticals into water bodies. Also, the importance of understanding biotransformation of pharmaceutical compounds during biological and ultrasound treatment, and its impact on treatment efficacy will be reviewed. Different combinations of the processes above, either as an integrated configuration or in series, will be discussed in terms of their degradation efficiency and scale-up capabilities. The trace quantities of pharmaceutical compounds in wastewater and scale-up issues of ultrasound highlight the importance of membrane filtration as a concentration and volume reduction treatment step for wastewater, which could subsequently be treated by ultrasound.

Construction of S-scheme Bi2WO6/g-C3N4 heterostructure nanosheets with enhanced visible-light photocatalytic degradation for ammonium dinitramide

Photocatalysis technology is considered as a promising environmental remediation strategy. Herein, photocatalytic degradation of ammonium dinitramide (ADN, main component of propellant) was investigated over Bi₂WO₆/g-C₃N₄ (BWO/CN) heterostructure nanosheets prepared by a one-step in-situ hydrothermal method. The operating conditions including ADN initial concentration, catalyst dosage, initial pH, temperature and green oxidizer (hydrogen peroxide) were optimized systematically. Under optimal conditions, the photocatalytic degradation rate of ADN over BWO/CN can reach 98.93% after 80 min visible-light irradiation. Besides, the composite has excellent stability for ADN treatment and nitrate ions are the major degradation products. Furthermore, S-scheme heterojunction mechanism was proposed to explain the extremely high REDOX performance of BWO/CN composite.

Removal of ibuprofen by sodium alginate-coated iron-carbon granules combined with the ultrasound and Fenton technologies: influencing factors and degradation intermediates

This study focuses on the preparation of sodium alginate-coated iron-carbon granules (FeCGs) and their capacity to remove ibuprofen (IBU) by combining Fenton and ultrasound technologies. The preferred preparation conditions are as follows: 2% (w/v) sodium alginate, 10% (w/v) iron fillings and biochar, and used CaCl2 as the cross-linking agent. 74.72% of IBU was removed by ultrasound/FeCG under 10 g/L FeCG and 250 W ultrasound power. Fenton/FeCG could remove 92.41% of IBU under 10 g/L FeCG and 2 mM H2O2. Under the above experimental conditions, ultrasound/FeCG has higher reaction speed (9.44 × 10-3 min-1) than Fenton/FeCG (4.95 × 10-3 min-1). However, Fenton/FeCG could remove more TOC than ultrasound/FeCG. During the reaction using the Fenton/FeCG system, 11 degradation intermediates were detected, but only 7 intermediates were produced by the ultrasound/FeCG system. A common single-chain product C5H10O3 formed by IBU degradation was detected in the reaction products during Fenton/FeCG reaction, which benzene ring structure was destroyed; however, the minimum molecular weight of the product detected using the ultrasound/FeCG system was that of C8H10O; the benzene ring structure of IBU is not destroyed. This study provides guidance in the preparation of sodium alginate-coated FeCGs, evaluating the applicability of Fenton/FeCG and ultrasound/FeCG, which was meaningful for organic pollution wastewater treatment.

Cobalt doped iron oxychloride as efficient heterogeneous Fenton catalyst for degradation of paracetamol and phenacetin

Cobalt doped iron oxychloride (Co-FeOCl) was synthesized and employed as catalyst in Fenton degradation of paracetamol (APAP) and phenacetin (PNCT) for the first time. The catalytic performance was evaluated by means of various parameters including catalyst load, hydrogen peroxide (H₂O₂) dose and pH value. The high removal of APAP (87.5%) and PNCT (76.0%) was obtained under conditions of 0.2 g/L Co-FeOCl and 0.5 mM H₂O₂ at pH 7.0, with calculated pseudo-first order kinetic constants of 0.031 min^-1 for APAP and 0.023 min^-1 for PNCT. Particularly, quenching tests and in situ electron spin resonance (ESR) tests were employed for the identification of the reactive oxygen species (ROS) in system. Hydroxyl radical (·OH) and superoxide radical (O₂^-·) were the primary ROS in Co-FeOCl/H₂O₂ system. A possible mechanism for H₂O₂ activation by Co-FeOCl catalyst was proposed as well. Finally, the formation of typical disinfection by-products (DBPs) decreased slightly in Co-FeOCl/H₂O₂ pre-oxidation. However, stability and reusability of Co-FeOCl were deactivated in the consecutive three cycles.

Electrochemical degradation of ibuprofen using an activated-carbon-based continuous-flow three-dimensional electrode reactor (3DER)

We developed a continuous-flow three-dimensional electrode reactor (3DER) to remove ibuprofen (IBP) from water. The effects of the operating parameters on the 3DER performance were investigated. The 3DER was constructed by filling a conventional two-dimensional electrode reactor with granular activated carbon, which acted as particle electrodes. The IBP removal efficiency of the 3DER was 98% in 4 h, which was 2.5 times higher than the removal efficiency for the two-dimensional electrode reactor. IBP removal kinetics tests indicated that the current density (1-20 mA/cm²) correlated better than the other operating parameters with the first-order rate constant (k). The flow rate affected the IBP removal kinetics to a small degree. Chloride and sulfate supporting electrolyte concentrations between 17 and 100 mM affected the IBP removal kinetics in opposite ways. Increasing the chloride concentration increased k, but increasing the sulfate concentration decreased k. Radical quenching experiments indicated that much more IBP degradation occurred through both indirect and direct oxidation mechanisms in the 3DER than in the two-dimensional electrode reactor. The particle electrodes caused hydroxyl radicals to form when the 3DER treatment was started, but the particle electrodes later acted as third electrodes and favored direct oxidation of IBP.

Mechanistic insight into ultrasound-induced enhancement of electrochemical oxidation of ofloxacin: Multi-response optimization and cost analysis

In this paper, a hybrid advanced oxidation process of sonoelectrochemical, in which ultrasound and electrochemical are applied simultaneously, has been used for the degradation of ofloxacin (bio-recalcitrant pharmaceutical pollutant). Response surface methodology based central composite design was applied to understand the parametric effects of ultrasonic power, current density, initial pH, and electrolyte dose. Enhanced ofloxacin degradation was obtained using sonoelectrochemical (≈95%) process in comparison to the electrochemical (≈60.6%) and sonolysis alone (≈7.2%) after 120 min treatment time. Multi-response optimization was used so as to maximize COD removal (70.12%) and minimize specific energy consumption (11.92 kWh (g COD removed)^-1)at the optimized parametric condition of pH = 6.3 (natural pH), ultrasonic power = 54 W, current density = 213 A m^-2, and Na₂SO₄ electrolyte dose = 2.0 g L^-1. It was revealed that ^•OH radicals contribute major to the ofloxacin degradation reaction among the other oxidizing agents. Degradation of the ofloxacin followed pseudo-first-order kinetics with a higher reaction rate, which confirmed the synergistic effect of 34% between ultrasound and electrochemical approaches. The degradation pathway of ofloxacin removal was elucidated at optimum condition by the temporal evolution of the intermediate compounds and final products using gas chromatography coupled with mass spectroscopy (GC-MS), liquid chromatography-mass spectroscopy (LC-MS), high-resolution mass spectroscopy (HR-MS), and Fourier transform infrared spectroscopy (FTIR). Atomic force microscopy (AFM) and field emission scanning electron microscope (FE-SEM) coupled with energy dispersed X-ray (EDX) were used to determine the morphology of electrodes. Operational cost analysis was done based on the reactor employed in the present study.

Comparison of the behavior of ZVI/carbon composites from both commercial origin and from spent Li-ion batteries and mill scale for the removal of ibuprofen in water

Zero valent iron/carbon composites were successfully synthesized from commercial iron oxide and graphite (ZVI/C) and also by using graphite obtained from spent Li-ion batteries and iron oxide from mill scale (ZVI/C-X) as a new approach for the valorization of these waste. The composites were synthesized through carbothermic reactions and tested as catalysts for the degradation of ibuprofen from water by Fenton reaction. The optimal conditions for synthesizing ZVI/C composites were a temperature of 1000 °C maintained for 2 h. The structural, and textural features of ZVI/C with different ZVI mass ratios were characterized by different techniques. ZVI/C composites with higher ZVI mass ratios showed higher degradation rates for the removal of ibuprofen both in presence and absence of H₂O₂. Moreover, ZVI/C-X composite, obtained from industrial waste, showed activity even after four consecutive cycles of use with very low concentration of iron ions in solution after reaction (4.8 mg L^-1 after 4 h), which supports the high stability and low Fe-lixiviation of ZVI/C-X composite. The results of this study prove the possibility of synthesizing composites using graphite from spent Li-ion batteries and iron oxide from mill scale, and their potential for the degradation of ibuprofen in water, with comparable activities to those obtained from commercial feedstocks.

Photocatalytic degradation of gemifloxacin antibiotic using Zn-Co-LDH@biochar nanocomposite

The aim of the present study was to investigate the photocatalytic performance of biochar (BC)-incorporated Zn-Co-layered double hydroxide (LDH) nanostructures in gemifloxacin (GMF) degradation as a model pharmaceutical pollutant. The as-prepared Zn-Co-LDH@BC showed high photocatalytic efficiency due to the enhanced separation of photo-generated charge carriers using cobalt hydroxide as well as inhibiting the agglomeration of LDH nanostructures by incorporation of BC. According to the results, 92.7% of GMF was degraded through photocatalysis in the presence of Zn-Co-LDH catalyst. The photocatalytic performance of BC-incorporated Zn-Co-LDH was highly dependent on the solute concentration and photocatalyst dosage. The addition of ethanol caused more inhibiting effect than that of benzoquinone (BQ), indicating the major role of ^•OH in decomposition of GMF compared to the negligible role of O₂^•-. A greater enhancement in the photocatalytic degradation of GMF was obtained when the photoreactor containing Zn-Co-LDH@BC nanostructures was oxygenated. Less than 10% drop in the removal efficiency of GMF was observed within five successive operational runs. The results of chemical oxygen demand (COD) analysis indicated the COD removal efficiency of about 80% within 200 min, indicating the acceptable mineralization of GMF. The reaction pathways were also proposed for the photocatalytic conversion of GMF under UV light irradiation.

Stone cutting industry waste-supported zinc oxide nanostructures for ultrasonic assisted decomposition of an anti-inflammatory non-steroidal pharmaceutical compound

Powdered stone waste (PSW) obtained from a stone cutting industrial unit was applied as support for the immobilization of nano-sized ZnO to be utilized as an effective catalyst for the catalytic conversion of acetaminophen (ACE) under ultrasonication. The incorporation of ZnO nanostructures into PSW structure enhanced the specific surface area and pore volume of the as-prepared nanocompound. The change in the value of zero point of charge (pH_zpc) of the PSW after being covered also demonstrated the good immobilization and distribution of ZnO nanostructures on the surface of PSW. The sonocatalysis of ACE over ZnO/PSW followed pseudo-first order kinetic (reaction rate of 2.27 × 10^-2 1/min). The highest degradation efficiency of 98.1% was attained when the ZnO/PSW-contained sono-reactor was irradiated by UVC light. The presence of t-butanol led to the lowest degradation efficiency (57.7%), indicating that the sonocatalytic conversion of ACE was hydroxyl radical (OH)-dependent. Although the mineralization efficiency of ACE by the process was not excellent, bio-toxicity assessment on the effluent revealed decreasing the inhibition percent from 50.8 to 16.7% within reaction time of 240 min.

A review on carbon-based materials for heterogeneous sonocatalysis: Fundamentals, properties and applications

Contamination of water resources by refractory organic pollutants is of great environmental and health concern because these compounds are not degraded in the conventional wastewater treatment plants. In recent years, sonocatalytic treatment has been considered as a promising advanced oxidation technique for the acceptable degradation and mineralization of the recalcitrant organic compounds. For this purpose, various sonocatalysts have been utilized in order to accelerate the degradation process. The present review paper provides a summary of published studies on the sonocatalytic degradation of various organic pollutants based on the application of carbon-based catalysts, including carbon nanotubes (CNTs), graphene (GR), graphene oxide (GO), reduced graphene oxide (rGO), activated carbon (AC), biochar (BC), graphitic carbon nitride (g-C₃N₄), carbon doped materials, buckminsterfullerene (C60) and mesoporous carbon. The mechanism of sonocatalytic degradation of different organic compounds by the carbon-based sonocatalysts has been well assessed based on the literature. Moreover, the details of experimental conditions such as sonocatalyst dosage, solute concentration, ultrasound power, applied frequency, initial pH and reaction time related to each study have also been discussed in this review. Finally, concluding remarks as well as future challenges in this research field regarding new areas of study are also discussed and recommended.

Template-free microspheres decorated with Cu-Fe-NLDH for catalytic removal of gentamicin in heterogeneous electro-Fenton process

Nano-layered double hydroxide (NLDH) decorated with Fe and Cu was applied as a novel heterogeneous catalyst for catalytic degradation of gentamicin by the electro-Fenton (EF) process. The EF process was equipped with graphite plate under aeration to electrochemically generate hydrogen peroxide in the solution. The characterization analyses confirmed the suitable structure of as-synthesized Cu-Fe-NLDH to be acted as catalyst for treating the target pollutant. The comparative study showed the highest removal efficiency of 91.3% when the Cu-Fe-NLDH-equipped EF process was applied in comparison with the Fenton (50%) and the electro-oxidation alone (25.6%). The acidic pHs favored the degradation of gentamicin. Increasing the current resulted in the enhanced degradation of gentamicin, while the excessive electrolyte concentration (0.1 mol/L) and catalyst dosage (1.5 g/L) led to the tangible drop in the reactor performance. At a specified reaction time, the injection of O₃ gas enhanced the efficiency of the Cu-Fe-NLDH-equipped EF process. The presence of ethanol led to more suppressing effect than benzoquinone, indicating the dominant role of OH radical in the degradation of gentamicin compared with other free radical species such as O₂^- radical. Only 10% drop in the degradation efficiency of gentamicin was observed within 10 operational runs. The mineralization efficiency of about 77% was achieved after 300 min in terms of chemical oxygen demand (COD) removal. The intermediate byproducts generated during the destructive removal of gentamicin were also identified.

Unveiling the activating mechanism of tea residue for boosting the biological decolorization performance of refractory dye

Conventional microbial treatments are challenged by new synthetic refractory dyes. In this work, tea residue was found serving as an effective activator to boost the decolorization performance of anthraquinone dye (reactive blue 19, RB19) by a new bacterial flora DDMY2. The unfermented West Lake Longjing tea residue showed the best enhancement performance. Seventeen main kinds of components in tea residue had been selected to take separate and orthogonal experiments on decolorization of RB19 by DDMY2. Results suggested epigallocatechin gallate (EGCG) in tea residue played important roles in boosting the treatment performance. Illumina MiSeq sequencing results confirmed that EGCG and tea residue pose similar impact on the change of DDMY2 community structure. Some functional bacterial genera unclassified_o_Pseudomonadales, Stenotrophomonas and Bordetella were enriched during the treatment of RB19 by EGCG and tea residue. These evidences suggested EGCG might be the key active component in tea residue that responsible for the enhancement effect on decolorization performance. These results revealed the activating mechanism of tea residue from the perspective of composition.

Sonocatalytic degradation of tetracycline antibiotic using zinc oxide nanostructures loaded on nano-cellulose from waste straw as nanosonocatalyst

The aim of the present investigation was the combination of ZnO nanostructures with nano-cellulose (NC) for the efficient degradation of tetracycline (TC) antibiotic under ultrasonic irradiation. The removal efficiency of 12.8% was obtained by the sole use of ultrasound (US), while the removal efficiency increased up to 70% by the US/ZnO treatment process. Due to the integration of ZnO nanostructures with NC, the removal efficiency of 87.6% was obtained within 45 min. The removal efficiency substantially decreased in the presence of tert-butyl alcohol (more than 25% reduction), indicating that ^radOH-mediation oxidation is responsible for the degradation of TC molecules. Peroxymonosulfate (PMS) led to the most enhancing effect on the removal of TC among percarbonate, persulfate and periodate ions. The addition of PMS caused the degradation efficiency of 96.4% within the short contact time of 15 min. The bio-toxicity examination on the basis of inhibition test conducted on activated sludge revealed diminishing the oxygen consumption inhibition percent [I_OUR (%)] from 33.6 to 22.1% during the US/ZnO/NC process. Consequently, the utilization of the US/ZnO/NC process can convert TC molecules to less toxic compounds. However, longer reaction time is required for complete conversion into non-toxic substances.

Sonocatalytic degradation of butylparaben in aqueous phase over Pd/C nanoparticles

In the present work, the sonocatalytic degradation of butylparaben was investigated using Pd immobilized on carbon black as the sonocatalyst. The presence of 25 mg/L 10Pd/C significantly increased the removal rate of butylparaben and the observed kinetic constant increased from 0.0126 to 0.071 min^-1, while the synergy index between sonolysis and adsorption was 70.7%. The BP degradation followed pseudo-first-order kinetics with the apparent kinetic constant decreased from 0.071 to 0.030 min^-1 when the initial concentration of butylparaben increased from 0.5 to 2 mg/L. The process was being favored slightly under alkaline conditions. The presence of organic matter (20 mg/L humic acid) reduced the apparent kinetic constant more than two times. The addition of chlorides up to 250 mg/L did not significantly reduce the rate of reaction, while the presence of 250 mg/L bicarbonates reduced the observed kinetic constant from 0.071 to 0.0472 min^-1. The prepared catalyst retains the efficiency after five subsequent experiments since the apparent kinetic constant was only slightly decreased from 0.071 to 0.059 min^-1.

Performance and microbial community of an electric biological integration reactor (EBIR) for treatment of wastewater containing ibuprofen

Electric biological integration reactor (EBIR) was designed and built for the treatment of wastewater containing ibuprofen. This study evaluates the removal performance of EBIR by comparison with biological aerated filter (BAF), while also discussing the optimal operational parameters of EBIR within the context of the response surface methodology. The results indicate that EBIR exhibits higher average removal rates of ibuprofen, chemical oxygen demand (COD) and NH₄⁺-N, i.e. 93.48%, 86.72% and 85.19%, representing an increase by 61.59%, 14.57% and 10.49%, respectively, compared with BAF. The optimal conditions for EBIR were 12.73 A/m² current density (CD), 3.5 h hydraulic retention time and 0.08 mg/L influent ibuprofen concentration. In addition, microbial community structures were detected using an Illumina Miseq PE300 system, which were different at the phylum, class, and genus levels between EBIR and BAF. The microbial communities of EBIR, including mainly Trichococcus, Aeromonas, Saprospiraceae_uncultured, Thiobacillus, Aeromonas Flavobacterium, Sphingopyxis, Candidate_division_TM7_norank, Acinetobacter and physicochemical properties indirectly confirmed the excellent removal performance at 12.73 A/m² CD.

Implementation of martite nanoparticles prepared through planetary ball milling as a heterogeneous activator of oxone for degradation of tetracycline antibiotic: Ultrasound and peroxy-enhancement

The aim of the present study was to employ martite nanoparticles synthesized through planetary ball milling instead of conventional sources of iron for the activation of Oxone in order to decompose tetracycline (TC) antibiotic in the aquatic phase. Accordingly, martite nanoparticles-activated Oxone exhibited a remarkable improvement in degrading TC molecules up to 87%. The results indicated an increased decomposition rate of TC with increasing Oxone concentration, martite nanoparticles dosage, and initial pH. In the absence of ultrasound, the decomposition rate of TC was 0.0481 min^-1 within 30 min, while the implementation of ultrasound at 320 W and addition of hydrogen peroxide at 40 mM led to increase in the decomposition rate up to 0.0770 and 0.0907 min^-1, respectively. The presence of carbonate and even persulfate ions suppressed the decomposition rate. Inversely, the addition of chloride and carbon tetrachloride enhanced the reactor performance in terms of TC degradation. Within four consecutive experimental runs, only 10.8% was dropped in the decomposition rate, indicating the appropriate reusability potential of martite nanoparticles. The results confirmed the appropriate ability of the treatment process in degrading and mineralizing the target pollutant but a longer exposure time is required for an efficient mineralization.

Implementation of continuously electro-generated Fe3O4 nanoparticles for activation of persulfate to decompose amoxicillin antibiotic in aquatic media: UV254 and ultrasound intensification

In the present investigation, the treatment of amoxicillin (AMX)-polluted water by the activated persulfate (PS) was considered. As a novel research, continuously electro-generated magnetite (Fe₃O₄) nanoparticles (CEMNPs) were utilized as the activator of PS in an electrochemical medium. The PS/CEMNPs displayed a remarkable enhancement in the decomposition of AMX molecules up to 72.6% compared with lonely PS (24.8%) and CEMNPs (13.4%). On the basis of pseudo-first order reaction rate constants, the synergy percent of about 70% was achieved due to the combination of PS with CEMNPs. The adverse influence of free radical-scavenging compounds on the efficiency of the PS/CEMNPs process was in the following order: carbonate < chloride < tert-butyl alcohol < ethanol. Overall, these results proved the main role of free radical species in degrading AMX. The implementation of ultrasound (US) enhanced the performance of the PS/CEMNPs process. Nevertheless, the highest degradation efficiency of about 94% was achieved when UV₂₅₄ lamp was joined the PS/CEMNPs system. Under UV₂₅₄ and US irradiation, the results showed significant potential of the PS/CEMNPs process for degrading AMX antibiotic and generating low toxic effluent based on the activated sludge inhibition test. However, more time is needed to achieve the acceptable mineralization.