Pharmaceutical Micropollutants Research Articles

Sensory-Motor Perturbations in Larval Zebrafish (Danio rerio) Induced by Exposure to Low Levels of Neuroactive Micropollutants during Development.

Due to increasing numbers of anthropogenic chemicals with unknown neurotoxic properties, there is an increasing need for a paradigm shift toward rapid and higher throughput behavioral bioassays. In this work, we demonstrate application of a purpose-built high throughput multidimensional behavioral test battery on larval stages of Danio rerio (zebrafish) at 5 days post fertilization (dpf). The automated battery comprised of the established spontaneous swimming (SS), simulated predator response (SPR), larval photomotor response (LPR) assays as well as a new thermotaxis (TX) assay. We applied the novel system to characterize environmentally relevant concentrations of emerging pharmaceutical micropollutants including anticonvulsants (gabapentin: 400 ng/L; carbamazepine: 3000 ng/L), inflammatory drugs (ibuprofen: 9800 ng/L), and antidepressants (fluoxetine: 300 ng/L; venlafaxine: 2200 ng/L). The successful integration of the thermal preference assay into a multidimensional behavioral test battery provided means to reveal ibuprofen-induced perturbations of thermal preference behaviors upon exposure during embryogenesis. Moreover, we discovered that photomotor responses in larval stages of fish are also altered by the as yet understudied anticonvulsant gabapentin. Collectively our results demonstrate the utility of high-throughput multidimensional behavioral ecotoxicity test batteries in prioritizing emerging risks associated with neuroactive drugs that can perturb neurodevelopment. Moreover, we showcase the added value of thermotaxis bioassays for preliminary screening of emerging contaminants.

Integrated adsorptive and photocatalytic degradation of pharmaceutical micropollutant, ciprofloxacin employing biochar-ZnO composite photocatalysts

The expensive carbonaceous substrates including graphene, reduced graphene oxide, carbon nanotubes have been coupled with ZnO to improve the properties and photocatalytic performance of carbon based ZnO photocatalysts. To replace these expensive materials, biochar offers as a low-cost alternative to prepare biochar-based photocatalysts. In this study, Calotropis gigantea leaves derived biochar-ZnO (BC-ZnO) composites were synthesized to overcome the ZnO related problems (charge recombination, wider band gap, and poor visible light absorption). Different BC-ZnO (BCZ-1–3) composites were characterized to evaluate their intrinsic properties and composites were employed to degrade ciprofloxacin (CIP). BCZ-3 composite exhibited slower recombination of electron-hole pairs, lower band gap (2.97 eV), and better light absorption in visible region than ZnO. The enhanced adsorptive-photocatalytic degradation efficiency was attained up to 98.5% using BCZ-3 than BC (46.2%) and ZnO (41.4%). The O2∙- and OH• radicals within BCZ-3 are dominant reactive species indulged in CIP photocatalytic degradation. BCZ-3 photocatalyst exhibits 80% degradation of CIP after four regeneration cycles. The maximum adsorption capacity was achieved 54.18 mg g−1 for BCZ-3 than BC (46.20 mg g−1) and ZnO (15.55 mg g−1). The results show that BCZ-X composites can be used as stable, efficient, economical, and sustainable composite for the recovery of pharmaceutical wastewater.

Pharmaceutical Micropollutant Treatment with UV–LED/TiO2 Photocatalysis under Various Lighting and Matrix Conditions

The persistence of pharmaceuticals and personal care products (PPCPs) in water has been a cause for concern for several years. Many studies have successfully used TiO2/UV photocatalysis to remove these compounds from water. In order to optimize these systems for large-scale water treatment, the effects of the reaction matrix, methods to improve energy efficiency, and methods for easy catalyst separation must be considered. The following study examines the photocatalytic degradation of a cocktail of 18 PPCPs using a porous titanium–titanium dioxide membrane and the effect of solution pH on kinetic rate constants. The addition of methanol to the reaction—commonly used as a carrier solvent—had a significant effect on kinetic rate constants even at low concentrations. Solution pH was also found to influence kinetic rate constants. Compounds had higher kinetic rate constants when they were oppositely charged to the membrane at experimental pH as opposed to similarly charged, suggesting that electrostatic forces have a significant effect. The controlled periodic illumination of UV–LEDs was also investigated to increase photonic efficiency. The dual-frequency light cycle used did not cause a decrease in degradation for many compounds, successfully increasing the photonic efficiency without sacrificing performance.

Structure–Activity Relationships of TiO2 nanoflower-coated Porous Ti Anodes in Electro-catazone process

Electrochemical heterogeneous catalytic ozonation (E-catazone) process is a new advanced oxidation process for the efficient degradation of ozone-resistant pharmaceutical micropollutants (PMPs). The TiO2 nanoflower-coated porous Ti gas diffuser (TiO2-NF@PTGD) anode is crucial to the enhanced PMP degradation, ozone decomposition, and ·OH production in the E-catazone process. However, the relationships and mechanisms between the TiO2-NF@PTGD surface properties and the decontamination ability of E-catazone remain unresolved. Thus, through modulating the TiO2-NF surface properties by varying the hydrothermal preparation conditions of TiO2-NF@PTGD anodes, this study investigated the structure–activity relationships between the anodes and the destruction of the ozone-resistant PMP para-chlorobenzoic acid (p-CBA) by E-catazone. The mechanism was further elucidated by material characterization, interfacial kinetics analysis, and reactive oxygen species (ROS) determination. The results showed that the TiO2-NF@PTGD surface properties, including morphology and surface adsorbed oxygen (Oad), were largely influenced by the hydrothermal conditions (time, NaOH concentration, and temperature) and that Oad, presenting surface active sites, showed a significant positive correlation with the p-CBA degradation efficiency, rate, interfacial kinetic properties, ozone decomposition, and ROS production. At the optimized surface properties of Oad proportion of 29.44% and interfacial kinetic constant of 7.00 × 10−5 M−1 s−1, the complete removal of p-CBA with the highest degradation rate of 6.50 × 10−3 s−1, largest instantaneous ozone demand of 6.56 mg L−1, and largest ·OH exposure of 4.39 × 10−10 M s (5 min) were achieved. This study provides the basic parameters for the scale up preparation of TiO2-NF@PTGD electrodes and E-catazone applications.

Assessing the potential of machine learning methods to study the removal of pharmaceuticals from wastewater using biochar or activated carbon

Pharmaceuticals in wastewater are rapidly becoming new emerging pollutants, affecting humans and the aquatic ecosystem, and can go undetected due to their microscopic nature. Adsorption proves to be a promising technology for the removal of pharmaceuticals from effluent wastewater owning to its low cost, flexibility, and renewability. Adsorbents are porous materials such as silica, clay, resins, and carbon-based materials (e.g., biochars, carbon nanotubes, and activated carbon) often used to remove pharmaceutical micropollutants during adsorption. Among them biochar is an emerging, cost-effective, and eco-friendly sorbent. Modeling methods such as linear correlativity and multilinear regressions, are often employed to explain the adsorption mechanism, however they show limited accuracy and applicability. On the contrary, data driven machine learning (ML) methods is a powerful tool that could be used to study the complex relationship between adsorption performances and biochar properties. This review provides an overview of recent advances in the use of machine learning (ML) methods to explore the field of pharmaceutical adsorption onto biochar. An introduction to different ML algorithms and their advantages and limitations is provided. Furthermore, the challenges and future prospects of ML applications to study the adsorption mechanism is outlined.

Photocatalytic mechanisms and photocatalyst deactivation during the degradation of 5-fluorouracil in water

Photocatalytic oxidation and micropollutants have both attracted extensive attention in the field of wastewater treatment. However, invalidation mechanism of photocatalytic system and target transformation are still a challenge. Here, we used TiO2 supported on nickel foam (TiO2/NF) and 5-fluorouracil (5-FU) as model photocatalyst and pharmaceutical micropollutant to investigate photocatalytic transformation pathways of 5-FU and inhibition mechanisms of its degradation efficiency reduction. Incredibly, removal efficiency of 5-FU dramatically decreased from 80% to 20% after 120 h continuous operation, owning to the competition for hydroxyl radical (•OH) between trans-intermediates and 5-FU, accumulated in the solution. Using HR-MS, the produced intermediates during photocatalytic degradation of 5-FU were revealed to be that mono/polyhydroxylated compounds, short-chain oxides and carboxylation ones were main trans-intermediates. Combining ATR-FTIR, SEM-EDS and validation experiments for factors, it was found that the inhibition of 5-FU degradation should be contributed to the competition for •OH in the bulk or preferential consumption of •OH in TiO2 diffusion layer, by the aforementioned intermediates. The present study provides insights into photocatalytic oxidation of 5-FU and basic information about mechanisms of inhibition on target contaminant removal.

Electrochemical removal of pharmaceutical micropollutants from groundwater

• The drugs removal is quite affected by water matrix characteristics. • EO technology achieved more than 90 % of degradation. • PEO was the most efficient technology; but the energy cost is higher. • Ibuprofen is the most recalcitrant drug studied. • Diclofenac and ketoprofen are the more oxidizable drugs. This study is focused on the evaluation of the performance of electrochemical advanced oxidation processes in the treatment of a mixture of five pharmaceuticals contained in low concentration (1 ppm) in two different actual groundwater matrices with very different ionic conductivities. The five drugs selected were sulfadiazine, naproxen, diclofenac, ketoprofen and ibuprofen. Three types of technologies were compared: photolysis, electrolysis and photo-electrolysis. Results pointed out very important differences between the oxidazability of the five drugs with the three technologies. Also, a strong influence of the water matrix on the efficiency of the process. Although the resulting cell voltages were larger during the electrochemical treatments of the low conductivity groundwater, the removal of drugs was found to be faster and more efficient than that obtained when drugs are contained in the high-conductivity groundwaters. The most recalcitrant drug studied was ibuprofen for all processes evaluated, while diclofenac and ketoprofen were found to be the easiest drugs for being degraded. Differences observed are discussed at the light of the mechanisms proposed in the literature.

Synthesis of non-active electrode (TiO2/GO/Ag) for the photo-electro-Fenton oxidation of micropollutants in wastewater

Heterogeneous photo-electro-Fenton oxidation (hPEF) is known to be a robust technique, which can be employed for promoting organic degradation. This paper describes an environmentally friendly approach with the combination of photocatalysis and electrocatalysis in less acidic pH, aiming to achieve faster mineralization of a pharmaceutical micropollutant without adding any external oxidants. TiO2/GO/loaded Ag non-active electrodes are synthesized for the degradation of bupropion hydrochloride (antidepressant drug). The present work also seeks the parametric modeling and optimization of hPEF process parameters by using R programming. Nonlinear kinetic modeling was performed for the determination of kinetic parameters. The role of selected process parameters on the mineralization of bupropion was also explained in detail. The OH• and O2•− showed their active participation in the degradation process, while Ag and UV-C played an active role in the disinfection of treated wastewater.

A state of the art review on electrochemical technique for the remediation of pharmaceuticals containing wastewater

Pharmaceutical wastewater is a frequent kind of wastewater with high quantities of organic pollutants, although little research has been done in the area. Pharmaceutical wastewaters containing antibiotics and high salinity may impair traditional biological treatment, resulting in the propagation of antibiotic resistance genes. The potential for advanced oxidation processes (AOPs) to break down hazardous substances instead of present techniques that essentially transfer contaminants from wastewater to sludge, a membrane filter, or an adsorbent has attracted interest. Among a variety of AOPs, electrochemical systems are a feasible choice for treating pharmaceutical wastewater. Many electrochemical approaches exist now to remediate rivers polluted by refractory organic contaminants, like pharmaceutical micro-pollutants, which have become a severe environmental problem. The first part of this investigation provides the bibliometric analysis of the title search from 1970 to 2021 for keywords such as wastewater and electrochemical. We have provided information on relations between keywords, countries, and journals based on three fields plot, inter-country co-authorship network analysis, and co-occurrence network visualization. The second part introduces electrochemical water treatment approaches customized to these very distinct discarded flows, containing how processes, electrode materials, and operating conditions influence the results (with selective highlighting cathode reduction and anodic oxidation). This section looks at how electrochemistry may be utilized with typical treatment approaches to improve the integrated system's overall efficiency. We discuss how electrochemical cells might be beneficial and what compromises to consider when putting them into practice. We wrap up our analysis with a discussion of known technical obstacles and suggestions for further research.

Mixed-Matrix Membrane Adsorbers for the Simultaneous Removal of Different Pharmaceutical Micropollutants from Water

Mixed-Matrix Membrane Adsorbers for the Simultaneous Removal of Different Pharmaceutical Micropollutants from Water

Advanced bio-oxidation of fungal mixed cultures immobilized on rotating biological contactors for the removal of pharmaceutical micropollutants in a real hospital wastewater

Hospital wastewater represents an important source of pharmaceutical active compounds (PhACs) as contaminants of emerging concern for urban wastewater treatment plants. This work evaluates a fungal biological treatment of a hospital effluent before discharging in the municipal sewer system. This treatment was performed in rotating biological contactors (RBCs) covered with wooden planks in order to promote the attachment of the fungal biomass. These bioreactors, initially inoculated with Trametes versicolor as white rot fungi, have created biofilms of a diversified population of fungal (wood-decaying fungi belonging to Basidiomycota and Ascomycetes) and bacterial (Beta-proteobacteria, Firmicutes, and Acidobacteria) microorganisms. The mixed fungal/bacterial community achieved a stable performance in terms of carbon, nitrogen, and phosphorous reductions for 75 days of continuous operation. Moreover, a remarkable removal of pharmaceutical micropollutants was accomplished especially for antibiotics (98.4 ± 0.7, 83 ± 8% and 76 ± 10 for azithromycin, metronidazole and sulfamethoxazole, respectively). Previous studies have proven a high efficiency of fungi for the removal of microcontaminants as a result of advanced bio-oxidation processes mediated by oxidizing hydroxyl radicals. This study evidences the development of a stable fungal-bacterial mixed culture over wooden-modified RBCs for in-situ removal of pharmaceutical compounds of hospital wastewater under non-sterile conditions and non-strict temperature control, avoiding periodical fungal inoculation due to destabilization and displacement of fungal cultures by indigenous wastewater bacteria.

Point of need simultaneous biosensing of pharmaceutical micropollutants with binder free conjugation of manganese stannate micro-rods on reduced graphene oxide in real-time analysis

BackgroundThe usage and intake of various pain killers and antibiotics are widespread in this modern world with the increased population. These uptakes of medications could not be stopped, while developing modern techniques to ensure their presence can be done to be aware of the drugs engaged. A simultaneous electrochemical sensing of acetaminophen (ACAP) and ciprofloxacin (CIP) was done using manganese stannate anchored over reduced graphene oxide nanosheets (Mn2 SnO4 /rGO) on glassy carbon electrode (GCE). MethodsMn2 SnO4 was prepared via hydrothermal method and then reduced graphene oxide was integrated with Mn2 SnO4 with a simple ultrasonication method. Mn2 SnO4 /rGO was characterized to analyze the structural and chemical properties with XRD, and Raman. FT-IR was done to investigate the functional group presence in Mn2 SnO4 /rGO. XPS and EDAX analysis initiated for the investigation of elemental presence. Moreover, the morphological representation of Mn2 SnO4 /rGO was confirmed by FE-SEM and TEM images. The resistance of Mn2 SnO4 /rGO/GCE was studied with electrochemical impedance spectroscopy. The simultaneous electrochemical sensing of ACAP and CIP with Mn2 SnO4 /rGO/GCE as the working electrode was done utilizing cyclic voltammetry and differential pulse voltammetry technique to know the electrochemical properties. Significant findingsThe Mn2 SnO4 /rGO has achieved a rod like morphology which was anchored and tangled over sheet like rGO. XRD results exhibit a cubic structure of Mn2 SnO4 /rGO which is compared with the crystal structure as a polyhedral structure. All the recognized elements present in Mn2 SnO4 /rGO was confirmed with XPS and EDAX analysis. Mn2 SnO4 /rGO/GCE experienced excellent electron mediating behavior with higher potent for the simultaneous oxidation of ACAP and CIP. The oxidation peak current had linear dependency over the concentrations of ACAP and CIP, ranging from 0.049 to 890 μM for simultaneous addition. While, the linear range was from 0.049 to 880 μM for ACAP continuous addition (CIP-constant) and 0.049 to 850 μM when CIP added (ACAP-constant) linearly. The novelty of the present work is the limit of detection for individual detection was 0.013 μM (ACAP) and 0.022 μM (CIP) while for simultaneous detection attained about 0.0139 μM ACAP and CIP 0.023 μM which is lesser when compared with the other reports. Moreover, the real-time analysis was carried in several real samples as biological fluids, pharmaceutical and environmental samples using DPV. Designing a novel material with low cost effectiveness enriched with excellent characters is more influential in electrochemical studies.

Photocatalytic degradation of Penicillin G in aqueous solutions: Kinetic, degradation pathway, and microbioassays assessment

The photocatalytic degradation of pharmaceutical micropollutants of Penicillin G (PG) was investigated in a photoreactor at a laboratory scale. The impact of type of catalyst, pH, and initial concentration of PG were studied. Maximum removal efficiency was obtained at pH = 6.8, [ZnO]0 = 0.8 g L−1, and [PG]0 = 5 mg L−1 and reaction time of 150 min. The addition of persulfate sodium (PPS) enhanced the efficiency of the photocatalytic reaction. The efficiency of photolysis process in the presence of PPS was significantly improved to 72.72% compared to the classical photocatalysis system (56.71%). Optimum concentration of PPS to completely degraded PG was found to be 500 mg L−1. The QuEChERS extraction, GC-MS/MS method, and concentration technique showed favorable performance identification of the possible mechanism of PG degradation pathway. Toxicity of PG and its by-products were evaluated using microbioassays assessment based on nine selected bacterial strains. Results confirmed the effectiveness of the implemented system and its safe use via the bacteria Bacillus subtilis, which has illustrated significant activity. Due to the high efficiency, facility benefits, and low-cost of the suggested process, the process can be considered for the degradation of various pharmaceutical contaminants in pharmaceutical industry treatment under the optimal conditions.

CNT Microtubes with Entrapped Fe3O4 Nanoparticles Remove Micropollutants through a Heterogeneous Electro‐Fenton Process at Neutral pH

AbstractCatalyst‐coated carbon electrodes require two preparation stages: electrode assembly using carbon and polymeric binders and subsequent catalyst immobilization on the porous carbons electrode. Such conventional coating methods require several steps, which is time‐, chemical‐, and energy‐consuming. Also, polymeric binders can impair the porosity and block catalytic sites of final electrodes. This study introduces a novel one‐pot synthesis method in which Fe3O4 nanoparticles are entrapped within a multi‐walled carbon nanotube network, the latter being templated with microtubular geometry. Such carbon microtubes (CMT) represent a standalone geometry, serving as a binder‐free electrode for an energy‐efficient heterogeneous electro‐Fenton (HEF) process. Fe3O4‐containing CMTs remove carbamazepine (CBZ), a frequently detected pharmaceutical micropollutant in water bodies. While almost all literature reports degradation at acidic conditions requiring the use of acid, this material system functions at pH 7 ± 0.3 with lengthy reusability. The remarkable mineralization of the total oxidized CBZ emerges from the confinement of oxidation by‐products in CMTs’ 3D framework, where unselective radicals are formed once the electro‐generated H2O2 reacts with embedded Fe3O4. Additionally, the 3D network prevents the entrapped catalysts from leaching in acidic environments because of the increased local pH during electrolysis.

A novel process for the covalent immobilization of laccases on silica gel and its application for the elimination of pharmaceutical micropollutants.

In the present work, pharmaceutical micropollutant degradation by laccase immobilized on silica through an innovative process is proposed. The influence of different parameters on the immobilization conditions was evaluated by a 23 full factorial design, and parameters leading to the highest activity were identified. Under these conditions, laccase activity reached 14 ± 2 U g-1 of silica with a protein immobilization yield of 35%. The biocatalyst characterization did not show any change in pH and thermal stabilities but enhanced the long-term storage of laccases. Immobilized T. versicolor laccases were then tested to remove four pharmaceutical micropollutants (amoxicillin, ciprofloxacin, carbamazepine, and sulfamethoxazole) in the presence of redox mediators (syringaldehyde, p-coumaric acid, and ABTS). High removal yields (50-100% according to the pollutant) were obtained within 4 h of treatment due to the synergistic effect of laccase-mediator biotransformation and adsorption on the support. Overall, the pharmaceuticals' removal efficiency was highly influenced by their physicochemical properties; however, the presence of redox mediators impacted not only the oxidation mechanism but also the interactions between the biocatalyst and micropollutants. Finally, the reusability of the biocatalyst was proved during 7 degradation cycles.

Removal of Pharmaceutical Micropollutants with Integrated Biochar and Marine Microalgae.

Using microalgae to remove pharmaceuticals and personal care products (PPCPs) micropollutants (MPs) have attracted considerable interest. However, high concentrations of persistent PPCPs can reduce the performance of microalgae in remediating PPCPs. Three persistent PPCPs, namely, carbamazepine (CBZ), sulfamethazine (SMT) and tramadol (TRA), were treated with a combination of Chaetoceros muelleri and biochar in a photobioreactor during this study. Two reactors were run. The first reactor comprised Chaetoceros muelleri, as the control, and the second reactor comprised Chaetoceros muelleri and biochar. The second reactor showed a better performance in removing PPCPs. Through the response surface methodology, 68.9% (0.330 mg L−1) of CBZ, 64.8% (0.311 mg L−1) of SMT and 69.3% (0.332 mg L−1) of TRA were removed at the initial concentrations of MPs (0.48 mg L−1) and contact time of 8.1 days. An artificial neural network was used in optimising elimination efficiency for each MP. The rational mean squared errors and high R2 values showed that the removal of PPCPs was optimised. Moreover, the effects of PPCPs concentration (0–100 mg L−1) on Chaetoceros muelleri were studied. Low PPCP concentrations (<40 mg L−1) increased the amounts of chlorophyll and proteins in the microalgae. However, cell viability, chlorophyll and protein contents dramatically decreased with increasing PPCPs concentrations (>40 mg L−1).

Removal performance and optimisation of pharmaceutical micropollutants from synthetic domestic wastewater by hybrid treatment

Occurrence of pharmaceutical micropollutants in aquatic environments has been one amongst serious environmental problems. During this study, two reactors, including a sequencing batch reactor (SBR) + powdered composite adsorbent (CA) (first reactor, SBR + CA) and a sequencing batch reactor (second reactor, SBR), were designed to treat synthetic wastewater. Powdered CA was added with a dosage of 4.8 g L−1 to the first reactor. Tap water was contaminated with chemical oxygen demand (COD), ammonia and three pharmaceuticals, namely, atenolol (ATN), ciprofloxacin (CIP) and diazepam (DIA) to produce synthetic wastewater. The SBR + CA illustrated a better performance during synthetic municipal wastewater treatment. Up to 138.6 mg L−1 (92.4%) of COD and up to 114.2 mg L−1 (95.2%) of ammonia were removed by the first reactor. Moreover, optimisation of pharmaceuticals removal was conducted through response surface methodology (RSM) and artificial neural network (ANN). Based on the RSM, the best elimination of ATN (90.2%, 2.26 mg L−1), CIP (94.0%, 2.35 mg L−1) and DIA (95.5%, 2.39 mg L−1) was detected at the optimum initial concentration of MPs (2.51 mg L−1) and the contact time (15.8 h). In addition, ANN represented a high R2 value (>0.99) and a rational mean squared error (<1.0) during the optimisation of micropollutants removal by both reactors. Moreover, adsorption isotherm study showed that the Freundlich isotherm could justify the abatement of micropollutants by using CA better than the Langmuir isotherm.

Enhanced visible-light photocatalysis of clofibric acid using graphitic carbon nitride modified by cerium oxide nanoparticles

Recently, the emerging pharmaceutical micropollutants have become an environmental concern. Herein, we report an efficient elimination of clofibric acid (CA) using visible light-driven g-C3N4/CeO2 prepared by hydrothermal method. Among the catalysts with different compound ratios, g-C3N4/CeO2-3 (1.2 g g-C3N4 with 3 mmol Ce(NO3)3∙6H2O) exhibited the best photocatalytic performance. The effect of catalyst dosage was investigated and the optimal value was determined as 0.5 g L–1. The effect of initial pH (pH0) showed CA elimination decreased with increasing pH0. The underlying mechanism for CA oxidation was proposed based on synthetical analysis of photoluminescence emission spectra, transient photocurrent responses, electron paramagnetic resonance, chemical quenching experiments and band edge potential of g-C3N4 and CeO2. Photogenerated hole was primarily responsible for CA elimination while singlet oxygen played an auxiliary role. The products of CA oxidation were detected using liquid chromatography mass spectrometry (LC-MS) method and a possible pathway was put forward. Various organics were used as target contaminants to assess photocatalytic performance of g-C3N4/CeO2 heterojunction under acidic and alkaline pH conditions. The analysis of relationship between the oxidation peak potential (EOP) and the reaction rate constant indicated that photocatalysis using as prepared g-C3N4/CeO2-3 heterojunction is apt to oxidize contaminants with electron withdrawing group under acid condition.

Removal of Synthetic Estrogen from Water by Adsorption on Modified Bentonites

Natural bentonite is an adsorbent that can be easily modified as a low-cost material effective for the removal of persistent pharmaceutical micropollutants from water bodies. In this study, the modification of untreated bentonite by sodium is addressed to obtain Na-bent, which was further modified with L-Tryptophan (L-Trp) as well as with FeCl2.4H2O to produce Trp-Na-bent and Fe-Na-bent, respectively. The nonmodified and modified bentonite samples were tested for the adsorption of the pharmaceutical micropollutant 17α-ethinylestradiol (EE2) present in water bodies, a synthetic estrogen with very high toxicity. The structure of bentonite, before and after modification, was characterized using Fourier transform infrared, X-ray diffraction, Brunauer-Emmett-Teller, and thermal analysis (thermogravimetric analysis and differential scanning calorimetry) techniques. The influence of various experimental parameters on the adsorbent/adsorbate interaction was investigated. Equilibrium and kinetic studies of EE2 micropollutant adsorption were performed varying the initial adsorbate concentration, mass of bentonite, and contact time. The maximum adsorption for an initial concentration of 10 mg/L of EE2 was 4.20 mg/g, reaching the equilibrium after 2 h. The equilibrium data were fitted with Langmuir, Freundlich, and Dual-mode model equations. Adsorption kinetic data were analyzed using the pseudo-first order, pseudo-second order, and intraparticle diffusion models. The pseudo-second order model was the one that better described the kinetic data. The highest value of the equilibrium rate constant was obtained for Trp-Na-bent, followed by Fe-Na-bent. The results obtained show that the Trp-Na-bent complex exhibits a promising performance for the adsorption of EE2.

Pharmaceuticals removal by immobilized laccase on polyvinylidene fluoride nanocomposite with multi-walled carbon nanotubes

The presence of pharmaceutical micropollutants in water and wastewater is considered a serious environmental issue. To eliminate these pollutants, biodegradation of pharmaceuticals using enzymes such as laccase, is proposed as a green method. In this study, immobilized laccase was used for the removal of two model pharmaceutical compounds, carbamazepine and diclofenac. Polyvinylidene fluoride (PVDF) membrane modified with multi-walled carbon nanotubes (MWCNTs) were synthesized as a tailor-made support for enzyme immobilization. Covalently immobilized laccase from Trametes hirsuta exhibited remarkable activity and activity recovery of 4.47 U/cm2 and 38.31%, respectively. The results also indicated improvement in the operational and thermal stability of the immobilized laccase compared to free laccase. Finally, by using immobilized laccase in a mini-membrane reactor, removal efficiencies of 27% in 48 h and 95% in 4 h were obtained for carbamazepine and diclofenac, respectively. The findings suggest that immobilized laccase on PVDF/MWCNT membranes is a promising catalyst for large-scale water and wastewater treatment which is also compatible with existing treatment facilities.