Photocatalytic Degradation of Pharmaceuticals Carbamazepine, Diclofenac, and Sulfamethoxazole by Semiconductor and Carbon Materials: A Review

Ecological impact of pharmaceutical pollutants and options of river health improvements - A risk analysis-based approach

Pharmaceuticals are one of the emerging pollutants (EPs) in river waters across the world. Due to their toxic effects on aquatic organisms, they have drawn the global attention of the scientific community concerned with river ecosystems. This paper reviews the existing occurrence data for various pharmaceutical pollutants (PPs) reported in river waters in some part of the world and their ecological impacts. Using algae, macroinvertebrates (MI), and fish as biotic indicator groups in water to reflect river health conditions, an attempt has been made to assess the ecological risk due to the presence of PPs in the water environment. After ascertaining the predicted no-effect concentration (PNEC) of PPs for selected groups of aquatic organisms, the risk quotient (RQ) is estimated based on their measured environmental concentration (MEC). When MEC > PNEC and RQ > 1 for any of the biotic indicator, ecologically it is 'high risk' condition. The determination of PNEC uses a minimum assessment factor (AF) of 10 due to uncertainty in data over the no observed effect level (NOEL) or lowest observed effect level (LOEL). Accordingly, MEC 10 times higher than PNEC, (RQ = 10) represents a threshold risk concentration (RCT) beyond which adverse effects may start showing observable manifestations. In the present study, a new classification system of 'high risk' conditions for RQ = 1-10 has been proposed, starting from 'moderately high' to 'severely high'. For RQ > 10, the ecological condition of the river is considered 'impaired'. For river health assessment, in the present study, the whole range of physico-chemical characteristics of river water quality has been divided into three groups based on their ease of measurement and frequency of monitoring. Dissolved oxygen related parameters (DORPs), nutrients (NTs), and EPs. PPs represent EPs in this study. A framework for calculating separate indicator group score (IGS) and the overall river health index (RHI) has been developed to predict indicator group condition (IGC) and river health condition (RHC), respectively. Color-coded hexagonal pictorial forms representing IGC and RHC provide a direct visible perception of the existing aquatic environment and a scientific basis for prioritization of corrective measures in terms of treatment technology selection for river health improvements. The analyses indicate that many rivers across the world are under 'high risk' conditions due to PPs having MEC > PNEC and RQ > 1. Up to RCT, (where RQ = 10), the 'high risk' condition varies from 'moderately high' to 'severely high'. In many instances, RQ is found much more higher than 10, indicating that the ecological condition of river may be considered as 'impaired'. Algae is the most frequently affected group of biotic indicators, followed by MI and fish. A review of treatment methods for selection of appropriate technology to reduce the pollution load, especially PPs from the wastewater streams has been summarized. It appears that constructed wetlands (CWs) are at present the most suitable nature-based solutions, particularly for the developing economies of the world, to reduce the concentrations of PPs within limits to minimize the ecological impacts of pharmaceutical compounds on biotic indicators and restore the river health condition. Some suggestive design guidelines for the CWs have also been presented to initiate the process.

SUNLIGHT-INDUCED decontamination of water from emerging pharmaceutical pollutants using ZnO nanoparticles

A new class of environmental pollutants that have become a significant concern for the entire world's population over the last few decades are pharmaceutical contaminants due to the potential risks they pose to the environment and human health. An investigation on the photocatalytic degradation of four different model pharmaceutical contaminants: Tetracycline (TCT), Sulfamethoxazole (SMX), Chloroquine (CLQ), and Diclofenac (DCF) has been carried out using ZnO nanoparticles as the photocatalyst, and sunlight as the source of energy in a batch photocatalytic reactor. This process resulted in the degradation of about 51% for TCT, 65% for SMX, 61% for CLQ, and 55% for DCF within 30 min of solar irradiation. Complete degradation and COD reduction were achieved after a prolonged irradiation. The slow decay is attributed to the evolution of the intermediate compounds, which were identified using the liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS) method. The possible intermediates formed were identified for each molecule (i.e., TCT having 6 products, SMX, having 4 products, DCF having 8 products and CLQ having 8 products), and the mechanism for each pollutant is proposed. The effect on distinct operational parameters, like catalyst loading, and pH, environmentally relevant parameters such as ionic effect, and multiple contaminants system were investigated. It was found that the anions such as Cl-, SO42-, CO32-, HCO3-, NO3-, F-, Br-, and I-both individually as well as in combination had no effect on the degradation except for SMX. For multiple component systems, when two pollutants are mixed, each pollutant affects the degradation of the other and in the case of CLQ/TCT system, CLQ inhibits the degradation of TCT drastically. The study demonstrates that ZnO is an effective and convenient option for photocatalytic decontamination of water sources contaminated with a variety of pharmaceutical contaminants.

Mechanochemical Degradation of Caffeine and Diclofenac Using Biochar of Fique Bagasse in the Presence of Al: Monitoring by Mass Spectrometry

Much research has been carried out to remove emerging contaminants using diverse materials. Furthermore, studies related to pollutant degradation have increased over the past decade. Mechanochemical degradation can successfully decompose molecules that are persistent in the environment. In this study, the biochar of fique bagasse with mixtures SiO2, Al, Al2O3, and Al-Al2O3 was treated with a mechanochemical technique using a planetary ball mill to investigate the degradation of caffeine and diclofenac. These tests resulted in the transformation of caffeine and diclofenac due to the use of Al employing mechanochemistry. In fact, through the use of liquid chromatography coupled with mass spectrometry, eight and six subproducts were identified for caffeine and diclofenac, respectively. Additionally, analysis of the molecules proposed for caffeine and diclofenac transformation suggested hydroxylation, demethylation, decarboxylation, oxidation reactions, and cleavage of the C-C and C-N bonds in the pollutants studied. The formation of these transformation products could be possible by reductant oxygen species generated from the molecular oxygen in the presence of aluminum and the energy delivered for ball milling. The results obtained show the potential application in the environmental management of mechanochemical treatment in the elimination of emerging contaminants caffeine and diclofenac.

Combined Structural and Plasmonic Enhancement of Nanometer-Thin Film Photocatalysis for Solar-Driven Wastewater Treatment

Titanium dioxide (TiO2) thin films are commonly used as photocatalytic materials. Here, we enhance the photocatalytic activity of devices based on titanium dioxide (TiO2) by combining nanostructured glass substrates with metallic plasmonic nanostructures. We achieve a three-fold increase of the catalyst's surface area through nanoscale, three-dimensional patterning of periodic, conical grids, which creates a broadband optical absorber. The addition of aluminum and gold activates the structures plasmonically and increases the optical absorption in the TiO2 films to above 70% in the visible and NIR spectral range. We demonstrate the resulting enhancement of the photocatalytic activity with organic dye degradation tests under different light sources. Furthermore, the pharmaceutical drug Carbamazepine, a common water pollutant, is reduced in the aqueous solution by up to 48% in 360 min. Our approach is scalable and potentially enables future solar-driven wastewater treatment.

Response Methodology Optimization and Artificial Neural Network Modeling for the Removal of Sulfamethoxazole Using an Ozone-Electrocoagulation Hybrid Process

Removing antibiotics from water is critical to prevent the emergence and spread of antibiotic resistance, protect ecosystems, and maintain the effectiveness of these vital medications. The combination of ozone and electrocoagulation in wastewater treatment provides enhanced removal of contaminants, improved disinfection efficiency, and increased overall treatment effectiveness. In this work, the removal of sulfamethoxazole (SMX) from an aqueous solution using an ozone-electrocoagulation (O-EC) system was optimized and modeled. The experiments were designed according to the central composite design. The parameters, including current density, reaction time, pH, and ozone dose affecting the SMX removal efficiency of the OEC system, were optimized using a response surface methodology. The results show that the removal process was accurately predicted by the quadric model. The numerical optimization results show that the optimum conditions were a current density of 33.2 A/m², a time of 37.8 min, pH of 8.4, and an ozone dose of 0.7 g/h. Under these conditions, the removal efficiency reached 99.65%. A three-layer artificial neural network (ANN) with logsig-purelin transfer functions was used to model the removal process. The data predicted by the ANN model matched well to the experimental data. The calculation of the relative importance showed that pH was the most influential factor, followed by current density, ozone dose, and time. The kinetics of the SMX removal process followed the first-order kinetic model with a rate constant of 0.12 (min^-1). The removal mechanism involves various processes such as oxidation and reduction on the surface of electrodes, the reaction between ozone and ferrous ions, degradation of SMX molecules, formation of flocs, and adsorption of species on the flocs. The results obtained in this work indicate that the O-EC system is a potential approach for the removal of antibiotics from water.

Quantum and experimental investigation of the application of Crassostrea gasar (mangrove oyster) shell-based CaO nanoparticles as adsorbent and photocatalyst for the removal of procaine penicillin from aqueous solution

The present study was designed to synthesize and characterize calcium oxide nanoparticles (using mangrove oyster shell as a precursor) and apply the synthesized nanoparticles as a photocatalyst to degrade procaine penicillin in an aqueous solution. The photocatalyst exhibited an average band gap of 4.42 eV, showed a maximum wavelength of absorbance in the UV region (i.e., 280 nm), and is a microporous nanoparticle with a particle diameter of 50 nm. The photocatalyzed degradation of the drug was conducted under natural sunlight, and the influence of parameters such as the period of contact, catalyst load, pH, initial drug concentration, and ionic strength was investigated concerning the degradation profile. The results obtained from response surface analysis indicated that an optimum degradation efficiency of about 93% can be obtained at a concentration, pH, and catalyst dosage of 0.125 M, 2, and 0.20 g respectively, at 0.902 desirabilities. The Langmuir-Hinshelwood, modified Freundlich, parabolic diffusion, pseudo-first-/second-order, and zero-, first-, and second-order kinetic parameters were tested to ascertain the best model that best described the experimental data. Consequently, the Langmuir-Hinshelwood, modified Freundlich, and pseudo-second-order models were accepted based on the minimum error and higher R² values. Based on the Langmuir-Hinshelwood rate constants for adsorption and photodegradation as well as the evaluated valence bond potential, the degradation of the drug first proceeded through the mechanism of adsorption and followed by the oxidation of the drug by superoxide (generated from the interaction of electrons that generated by through the absorption of UV radiation). The quantum chemical calculation gave evidence that pointed towards the establishment of strong agreement with experimental data and also showed that the carboxyl functional group in the drug is the target site for adsorption and subsequent degradation.

Literature Review: Evaluation of Drug Removal Techniques in Municipal and Hospital Wastewater

There are several techniques for the removal of pharmaceuticals (drugs) from wastewater; however, strengths and weaknesses have been observed in their elimination processes that limit their applicability. Therefore, we aimed to evaluate the best techniques for the removal of pharmaceuticals from municipal and hospital wastewater. For this, a non-experimental, descriptive, qualitative-quantitative design was used, corresponding to a systematic review without meta-analysis. Based on established inclusion and exclusion criteria, 31 open-access articles were selected from the Scopus, ProQuest, EBSCOhost, and ScienceDirect databases. The results showed that high concentrations of analgesics such as naproxen (1.37 mg/L) and antibiotics such as norfloxacin (0.561 mg/L) are frequently found in wastewater and that techniques such as reverse osmosis, ozonation, and activated sludge have the best removal efficiency, achieving values of 99%. It was concluded that reverse osmosis is one of the most efficient techniques for eliminating ofloxacin, sulfamethoxazole, carbamazepine, and diclofenac from municipal wastewater, with removal rates ranging from 96 to 99.9%, while for hospital wastewater the activated sludge technique proved to be efficient, eliminating analgesics and antibiotics in the range of 41-99%.

Engineered pine nut shell derived activated carbons for improved removal of recalcitrant pharmaceuticals in urban wastewater treatment

Novel powdered activated carbons (PACs) from pine cones and pine nut shells (PNSs) were tested for the competitive adsorption of pharmaceutical compounds (PhCs) in spiked (100 µg/L) secondary effluent and mixed liquor from an urban wastewater treatment plant. Steam activated PNS77, with hierarchical pore structure and 1463 m²/g of BET area, outperformed the commercial benchmark (WP220, mineral origin) for PhCs and dissolved organic matter (DOM) control. PNS77 attained the highest adsorption capacity and rate in synthetic and real wastewaters. Competitive adsorption isotherms revealed the detrimental effect of direct site competing DOM on PhC removal. The PhCs' adsorbability increased with their hydrophobicity, regardless of the water matrix. Kinetic data allowed inferring that indirect competition due to pore constriction/blockage appeared to occur only in mixed liquor. Adsorption isotherm data modelling for ng/L range revealed 80 % removal of carbamazepine and diclofenac would be achieved dosing 8-15 mg/L PNS77 to secondary effluent, while for mixed liquor the dose must be doubled to balance the increased competition. Hydrophilic sulfamethoxazole required a higher dose (34-44 mg/L), lower in the mixed liquor. PNS77 hierarchical pore network and basic surface chemistry minimized DOM direct site competition, requiring lower doses in practical applications for wastewater treatment.

Removal of Emerging Contaminants from Water Using Cyclodextrin-Based Polymers and Advanced Oxidation Processes: The Case of Carbamazepine

Using a water-insoluble β-cyclodextrin-epichlorohydrin copolymer (β-EPI) as an adsorbent to remove carbamazepine (CBZ), an anti-epileptic drug often found both in hospital and urban wastewater, has been validated. The effect of several physicochemical parameters on CBZ retention onto β-EPI, such as contact time, adsorbent dosage, CBZ initial concentration, pH, salts, and temperature, was assessed. The adsorption process occurs in a very short time, less than 20 min, and depends on CBZ concentration and β-EPI amount used. Changes in pH and salt presence, regardless of the type of cation or anion used, do not significantly affect the system’s efficiency. Desorption experiments were also performed, and methanol has proven to be the best CBZ extraction medium; it was also found that the polymer can be recovered and reused for at least five cycles, which makes it cheap and environmentally friendly. Advanced oxidation processes were also tested for CBZ removal by synthesizing a β-EPI polymer bearing titanium dioxide for adsorption and consecutive photocatalytic degradation of the retained pollutant directly onto the material; the effect of TiO2 amount in the polymer on CBZ oxidation was evaluated. These experiments highlighted the system’s effectiveness, and it was also observed that the H2O2 presence in the solution enhanced the CBZ photodegradation.

Ag@ZIF-8/g-C3N4 Z-scheme photocatalyst for the enhanced removal of multiple classes of antibiotics by integrated adsorption and photocatalytic degradation under visible light irradiation

By combining the plasmon resonance of Ag nanoparticles and orientation effects of ZIF-8, as well as the visible-light activity of g-C₃N₄, we constructed a direct Z-scheme heterojunction with a co-existing Ag⁺/Ag⁰ system by an in situ coprecipitation method. The presence of Ag⁺/Ag⁰ on the surface of ZIF-8 was confirmed by the exchange of Ag⁺ and Zn²⁺ ions. This promoted the reduction of the band gap of ZIF-8, according to X-ray diffraction (XRD) and X-ray photoelectron spectroscopy. The results reveal that the 12 wt% Ag@ZIF-8/g-C₃N₄ nanocomposite presented the best adsorptive–photocatalytic activity for the degradation of multi-residue antibiotics under visible light irradiation for 60 min. Its degradation efficiency reached 90%, and its average apparent reaction rate constant was 10.27 times that of pure g-C₃N₄. In the radical scavenger experiments, ˙O₂⁻ and ˙OH were shown to be important in the process of photocatalytic degradation. In addition, we proposed a possible direct Z-scheme photocatalytic mechanism, that is, an internal electric field was formed to compensate the mediators between the interfaces of Ag@ZIF-8 and g-C₃N₄. This improvement can be attributed to the direct Z-scheme heterojunction system fabricated between Ag@ZIF-8 and g-C₃N₄. This can accelerate photogenerated electron–hole separation and the redox capability of Ag@ZIF-8/g-C₃N₄. The integration of the adsorption and photocatalytic degradation of various antibiotics is a promising approach. ZIF-8 has been widely used in the integrated adsorptive–photocatalytic removal of various antibiotics due to its large surface area, high orientation adsorption capacity. Therefore, this study provides new insights into the design of enhanced redox capacity for the efficient degradation of multiple antibiotics under visible-light irradiation.

By combining the plasmon resonance of Ag nanoparticles and orientation effects of ZIF-8, as well as the visible-light activity of g-C₃N₄, we constructed a direct Z-scheme heterojunction with a co-existing Ag⁺/Ag⁰ system by an in situ coprecipitation method.

Light-Activated Hydroxyapatite Photocatalysts: New Environmentally-Friendly Materials to Mitigate Pollutants

This review focuses on a reasoned search for articles to treat contaminated water using hydroxyapatite (HAp)-based compounds. In addition, the fundamentals of heterogeneous photocatalysis were considered, combined with parameters that affect the pollutants’ degradation using hydroxyapatite-based photocatalyst design and strategies of this photocatalyst, and the challenges of and perspectives on the development of these materials. Many critical applications have been analyzed to degrade dyes, drugs, and pesticides using HAp-based photocatalysts. This systematic review highlights the recent state-of-the-art advances that enable new paths and good-quality preparations of HAp-derived photocatalysts for photocatalysis.

Degradation of toxic agrochemicals and pharmaceutical pollutants: Effective and alternative approaches toward photocatalysis

Emerging concern regarding the remediation of environmental pollution has expanded tremendously in recent years. Pharmaceutical industries and agricultural sectors release an enormous amount of residues containing toxic pollutants at trace levels which poses a serious impact on the environment and human health. To cope with the effect of hazardous and toxic contaminants, numerous methodologies have been developed for the treatment of effluents released from the agrochemical and pharmaceutical industries. Amongst them, photocatalysis has gained much more attention for the degradation of pollutants due to its low cost, higher capability, green and eco-friendly approaches. Photocatalysts are the substrate that plays a key role in pollutant removal through photocatalysis by accelerating the necessary chemical reactions using a light source. In this review, the recent progress on photocatalysis and its fundamental mechanism in agrochemicals and pharmaceutical pollutant degradation was summarized. This review concisely discusses the incorporation of various metal oxides and nanomaterials into semiconductors for the effective degradation of contaminants. The current status and future research on different sectors and the difficulties in the photocatalytic removal of agrochemical and pharmaceutical pollutants are also reviewed in detail.

Effects of nitrogen/bismuth-doping on the photocatalyst composite of carbon dots/titanium dioxide nanoparticles (CDs/TNP) for enhanced visible light-driven removal of diclofenac

The present work demonstrates the coupling of titanium dioxide, TiO₂ nanoparticles (TNP) with N-doped, Bi-doped, and N-Bi co-doped rice husk-derived carbon dots (CDs) via a facile dispersion method, forming respective photocatalyst composites of CDs/TNP, N-CDs/TNP, Bi-CDs/TNP and N-Bi-CDs/TNP. Characterization analyzes verified the successful incorporation of respective CDs samples into TNP, forming photocatalyst composite with narrowed band gap and quenched photoluminescence intensity. Photocatalytic activity of TNP and the respective composites was investigated for photodegradation of diclofenac (DCF) under both simulated sunlight and natural sunlight irradiation. The as-prepared N-Bi-CDs/TNP composite showed the best photocatalytic performance among all composites, able to completely degrade 5 ppm of DCF within 60 min and 180 min under both types of visible light irradiation, respectively. The N-Bi-CDs/TNP composite also showed a TOC removal efficiency up to 87.63%. N-Bi-CDs, worked as photosensitizer and electron reservoir, contributed to the outstanding photocatalytic activity of N-Bi-CDs/TNP, whereby the recombination was prolonged and light absorption was shifted towards the visible light region. Furthermore, the composite of N-Bi-CDs/TNP also demonstrated good stability and reusability over repeated degradation cycles. The photodegradation of DCF resulted into several intermediates, which were identified from LC-MS analysis. The present work could provide an insight on the application of heteroatoms doped and co-doped carbon dots in semiconductor oxide as high performance photocatalysts.

Nanophotocatalysis for the Removal of Pharmaceutical Residues from Water Bodies: State of Art and Recent Trends

Background:

The occurrence of pharmaceuticals in surface and drinking water is ubiquitous and is a major concern of researchers. These compounds cause a destructive impact on aquatic and terrestrial life forms, and the removal of these compounds from the environment is a challenging issue. Existent conventional wastewater treatment processes are generally inefficacious because of their low degradation efficiency and inadequate techniques associated with the disposal of adsorbed pollutants during comparatively effective methods like the adsorption process.

Remediation Method:

Semiconductor-mediated photocatalysis is an attractive technology for the efficient removal of pharmaceutical compounds. Among various semiconductors, TiO2 and ZnObased photocatalysts gained much interest during the last years because of their efficiency in decomposing and mineralizing the lethal organic pollutants with the utilization of UV-visible light. Incessant efforts are being undertaken for tuning the physicochemical, optical, and electronic properties of these photocatalysts to strengthen their overall photocatalytic performance with good recycling efficiency.

Results:

This review attempts to showcase the recent progress in the rational design and fabrication of nanosized TiO2 and ZnO photocatalysts for the removal of pollutants derived from the pharmaceutical industry and hospital wastes.

Conclusion:

Photocatalysis involving TiO2 and ZnO provides a positive impact on pollution management and could be successfully applied to remove pharmaceuticals from wastewater streams. Structure modifications, the introduction of heteroatoms, and the integration of polymers with these nano photocatalysts offer leapfrogging opportunities for broader applications in the field of photocatalysis.

Wastewater irrigation in India: Current status, impacts and response options

Wastewater generated from urban agglomerations in India is estimated to be 26.4 km³ annually and 28% of it is treated. This has a potential to irrigate about 2.1 million-ha agricultural land, contribute 4 million Mg of plant nutrients, generate 2.8 million person-days of employment and reduce green house gas (GHG) emission by 73.7 million Mg CO₂-e. Farmers in peri-urban areas depend largely on raw and partially treated wastewater for livelihood via raising high value crops such as vegetable, fodders and fruits. Both controlled and uncontrolled disposal of waste waters leads to progressive and irreversible contamination of soils, surface and ground waters with pathogens, heavy metals and organic micro-contaminants and consequently their bio-transfer through the chain: sewage-soil-vegetation-animal-humans. This has led to the development of a considerable assortment of regulatory measures and guidelines aimed at reducing or eliminating wastewater related health risks. Because conventional treatment technologies are cost prohibitive, alternate methods based on biological and land treatment systems are being advocated. Since soils are the most logical sinks for wastewater, efforts are to optimise rates and methods of water application, quantify the sink capacity of soils to immobilise contaminants and protect the quality of produce. Reuse of diluted or undiluted wastewaters improves crop productivity by 10-36% though production sustainability depends on soil type, climatic conditions, crop grown, irrigation techniques and socio-political factors. Disposal of wastewater in tree plantations and constructed wetlands with consequent removal of toxic metals/compounds using hyper-accumulators/accumulators plants provide for a possible alternative. Ignoring the associated risks, using pisciculture for sewage disposal is quite popular in high rainfall areas. With growing water scarcities, it is utmost important to recognise wastewaters as a valuable resource and formulate appropriate policy initiatives considering the health and livelihood issues of the per-urban farmers and consumers of food as well as risks to environment.

COVID-19 drugs in aquatic systems: a review

The outbreak of the human coronavirus disease 2019 (COVID-19) has induced an unprecedented increase in the use of several old and repurposed therapeutic drugs such as veterinary medicines, e.g. ivermectin, nonsteroidal anti-inflammatory drugs, protein and peptide therapeutics, disease-modifying anti-rheumatic drugs and antimalarial drugs, antiretrovirals, analgesics, and supporting agents, e.g. azithromycin and corticosteroids. Excretion of drugs and their metabolites in stools and urine release these drugs into wastewater, and ultimately into surface waters and groundwater systems. Here, we review the sources, behaviour, environmental fate, risks, and remediation of those drugs. We discuss drug transformation in aquatic environments and in wastewater treatment systems. Degradation mechanisms and metabolite toxicity are poorly known. Potential risks include endocrine disruption, acute and chronic toxicity, disruption of ecosystem functions and trophic interactions in aquatic organisms, and the emergence of antimicrobial resistance.

Microbial Electrochemical Fluidized Bed Reactor: A Promising Solution for Removing Pollutants From Pharmaceutical Industrial Wastewater

The capacity of electroactive bacteria to exchange electrons with electroconductive materials has been explored during the last two decades as part of a new field called electromicrobiology. Such microbial metabolism has been validated to enhance the bioremediation of wastewater pollutants. In contrast with standard materials like rods, plates, or felts made of graphite, we have explored the use of an alternative strategy using a fluid-like electrode as part of a microbial electrochemical fluidized bed reactor (ME-FBR). After verifying the low adsorption capacity of the pharmaceutical pollutants on the fluid-bed electrode [7.92 ± 0.05% carbamazepine (CBZ) and 9.42 ± 0.09% sulfamethoxazole (SMX)], our system showed a remarkable capacity to outperform classical solutions for removing pollutants (more than 80%) from the pharmaceutical industry like CBZ and SMX. Moreover, the ME-FBR performance revealed the impact of selecting an anode potential by efficiently removing both pollutants at + 200 mV. The high TOC removal efficiency also demonstrated that electrostimulation of electroactive bacteria in ME-FBR could overcome the expected microbial inhibition due to the presence of CBZ and SMX. Cyclic voltammograms revealed the successful electron transfer between microbial biofilm and the fluid-like electrode bed throughout the polarization tests. Finally, Vibrio fischeri-based ecotoxicity showed a 70% reduction after treating wastewater with a fluid-like anode (+ 400 mV), revealing the promising performance of this bioelectrochemical approach.

Solar Light-Induced Methylene Blue Removal over TiO2/AC Composites and Photocatalytic Regeneration

TiO₂-containing photocatalysts, which combine TiO₂ with carbon-based materials, are promising materials for wastewater treatment due to synergistic photodegradation and adsorption phenomena. In this work, TiO₂/AC composites were produced by the in situ immobilization of TiO₂ nanoparticles over activated carbon (AC) derived from spent coffee grains, using different TiO₂/AC proportions. The TiO₂/AC composites were tested as adsorbents (dark) and as photocatalysts in a combined adsorption+photocatalytic process (solar irradiation) for methylene blue (MB) removal from ultrapure water, and from a secondary effluent (SecEf) of an urban wastewater treatment plant. All the materials were characterized by XRD (X-ray powder diffraction), N₂ adsorption–desorption isotherms at −196 °C, SEM (scanning electron microscopy), UV-Vis diffuse reflectance, FTIR (Fourier-transform infrared spectroscopy), TPD (temperature programmed desorption), XPS (X-ray photoelectron spectroscopy) and TGA (thermogravimetric analysis). The TiAC60 (60% C) composite presented the lowest band gap (1.84 eV), while, for TiAC29 (29% C), the value was close to that of bare TiO₂ (3.18 vs. 3.17 eV). Regardless of the material, the solar irradiation improved the percentage of MB discolouration when compared to adsorption in dark conditions. In the case of simultaneous adsorption+photocatalytic assays performed in ultrapure water, TiAC29 presented the fastest MB removal. Nevertheless, both TiAC29 and TiAC60 led to excellent MB removal percentages (96.1–98.1%). UV-induced photoregeneration was a promising strategy to recover the adsorption capacity of the materials, especially for TiAC60 and AC (>95%). When the assays were performed in SecEf, all the materials promoted discolouration percentages close to those obtained in ultrapure water. The bulk water parameters revealed that TiAC60 allowed the removal of a higher amount of MB, associated with the overall improvement of the SecEf quality.

Visible-Light Active Sulfur-Doped Titania Nanoparticles Immobilized on a Silica Matrix: Synthesis, Characterization and Photocatalytic Degradation of Pollutants

The photocatalytic oxidation (PCO) of pollutants using TiO2-based materials can significantly improve indoor air quality (IAQ), which in turn, has a significant impact on human health and life expectancy. TiO2-based nanoparticles (NPs) are widely used as part of building materials to function as photocatalysts in PCO. In this work, a series of sulfur-doped TiO2 NPs immobilized on a silica matrix were synthesized by combining a sol-gel process with ball milling. The samples were structurally characterized by X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), Fourier-transform infrared spectroscopy (FT-IR) and N2 adsorption-desorption isotherms. Furthermore, the morphological characteristics were determined by dynamic light scattering (DLS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The photocatalytic activity of the as prepared S-doped TiO2/SiO2 NPs in the degradation of liquid and air pollutants under visible-light irradiation was investigated. Our results show that sulfur is an effective dopant for activating TiO2/SiO2 photocatalysts under visible-light irradiation. Silica constitutes a "safe-by-design" approach and inhibits the aggregation of NPs during synthesis. The most efficient photocatalyst afforded 79% removal of methyl orange (5 h), 26% removal of acetaldehyde (1 h) and 12% oxidation of NO (1 h).

Screening and Seasonal Behavior of Analgesics, Non-steroidal Anti-inflammatory Drugs, and Antibiotics in Two Urban Wastewater Treatment Plants

Pharmaceutical active compounds (PhACs) belonging to analgesics, antibiotics, and non-steroidal anti-inflammatory drugs (NSAIDs) therapeutic classes were monitored in wastewater influents and effluents from two Portuguese urban wastewater treatment plants (UWWTPs) for 24 months. Both facilities were chosen due to their effluents are discharged in highly touristic and sensitive areas, Tagus river and Ria Formosa coastal lagoon, respectively. Target PhACs, acetaminophen, diclofenac, ibuprofen, naproxen, sulfadiazine, and sulfamethoxazole were measured using solid-phase extraction (SPE) coupled to liquid chromatography tandem mass spectrometry (LC-MS/MS). PhACs occurrence in the influents was higher than 98%, with acetaminophen presenting the highest concentrations, with values between 16.3 µg/L and 124 µg/L. In the effluents, distinct behavior was observed with diclofenac and sulfamethoxazole showing recalcitrant characteristics, whereas acetaminophen, ibuprofen, and naproxen showed removal efficiencies above 95%. Acetaminophen and ibuprofen amount in influents showed consistently higher concentration levels in autumn (in Beirolas and Faro Nw UWWTPs) and winter (only in Beirolas UWWTP) seasons. These seasonal trends were observed to a greater extent in Beirolas UWWTP than in Faro Nw UWWTP. This study enabled the comprehensive definition of a behavior pattern for these target contaminants, contributing to better characterization and build-up a library of PhACs occurrence. It also allowed a robust seasonal profiling of the target compounds due to the high number of samples analyzed by each season and a longer monitoring campaign, making the obtained results more significant.

Toxicity of CuS/CdS semiconductor nanocomposites to liver cells and mice liver

Semiconductor nanomaterials not only bring great convenience to peoples lives but also become a potential hazard to human health. The purpose of this study was to evaluate the toxicity of CuS/CdS nanocomposites in hepatocytes and mice liver. The CuS/CdS semiconductor nanocomposites were synthesized by a biomimetic synthesis - ion exchange strategy. Nanosize was confirmed by high-resolution transmission electron microscopy and dynamic light scattering. The composition and physical properties were measured by powder X-ray diffraction, Fourier transform infrared spectra, atomic absorption spectroscopy, thermogravimetry-differential scanning calorimetry and zeta potential analysis. The results revealed that CuS/CdS nanocomposites had 8.7 nm diameter and negative potential. Ion exchange time could adjust the ratio of CuS and CdS in nanocomposites. The toxicological study revealed that CuS/CdS nanocomposites could be internalized into liver cells, inhibited endogenous defense system (e.g. GSH and SOD), induced the accumulation of oxidation products (e.g. ROS, GSSG and MDA), and caused hepatocyte apoptosis. The in vivo experiments in Balb/c mice showed that the experimental dose (4 mg/kg) didn't cause observable changes in mice behavior, physical activity and pathological characteristics, but the continuous accumulation of Cd²⁺ in the liver and kidney might be responsible for its long-term toxicity.

Synthesis of Oxygen Deficient TiO2 for Improved Photocatalytic Efficiency in Solar Radiation

The photocatalytic activities of TiO2 have been limited mainly to absorbing in the ultraviolet spectrum which accounts for only 5% of solar radiation. High energy band gap and electron recombination in TiO2 nanoparticles are responsible for its limitations as a photocatalyst. An oxygen deficient surface can be artificially created on the titanium oxide by zero valent nano iron through the donation of its excess electrons. A visible light active TiO2 nanoparticle was synthesized in the current investigation through simple chemical reduction using sodium boro-hydride. The physical and textural properties of the synthesized oxygen deficient TiO2 photocatalyst was measured using scanning/ transmission electron microscopy while FTIR, XRD and nitrogen sorption methods (BET) were employed for its further characterizations. Photochemical decoloration of orange II sodium dye solution in the presence of the synthesized TiO2 was measured using an UV spectrophotometer. The resulting oxygen deficient TiO2 has a lower energy band-gap, smaller pore sizes, and enhanced photo-catalytic properties. The decoloration (88%) of orange (II) sodium salt solution (pH 2) under simulated solar light was possible at 20 min. This study highlights the effect of surface oxygen defects, crystal size and energy band-gap on the photo-catalytical property of TiO2 nanoparticles as impacted by nano zero valent iron. It opens a new window in the exploitation of instability in the dopant ions for creation of a visible light active TiO2 photocatalyst.

Mitigation of emerging pollutants and pathogens in decentralized wastewater treatment processes: A review

Emerging pollutants (such as micropollutants, microplastics) and pathogens present in wastewater are of rising concern because their release can affect the natural environment and drinking water resources. In this decade, with increasing numbers of small-scale decentralized wastewater systems globally, the status of emerging pollutant and pathogen mitigation in the decentralized wastewater treatment processes has received more attention. This state-of-the-art review aims to discuss the mitigation efficiencies and mechanisms of micropollutants, microplastics, and pathogens in single-stage and hybrid decentralized wastewater treatment processes. The reviewed results revealed that hybrid wastewater treatment facilities could display better performance compared to stand-alone facilities. This is because the multiple treatment steps could offer various microenvironments, allowing incorporating several mitigation mechanisms (such as sorption, degradation, filtration, etc.) to remove complicated emerging pollutants and pathogens. The factors (such as system operation conditions, environmental conditions, wastewater matrix) influencing the removals of emerging pollutants from wastewater in these systems have been further identified. Nevertheless, it was found that very limited research work focused on synergised or conflicted effects of operation conditions on various emerging pollutants naturally present in the wastewater. Meanwhile, effective, reliable, and rapid analysis of the emerging pollutants and pathogens in the complicated wastewater matrix is still a major challenge.

The degradation pathways of carbamazepine in advanced oxidation process: A mini review coupled with DFT calculation

Degradation pathway is important for the study of carbamazepine (CBZ) removal in advanced oxidation processes (AOPs). Generally, degradation pathways are speculated based on intermediate identification and basic chemical rules. However, this semiempirical strategy is sometimes time-consuming and baseless. To improve the situation, a mini meta-analysis was first conducted for the degradation pathways of CBZ in AOPs. Then, the rationality of the pathways was analyzed by Density Functional Theory (DFT) calculation. Results show that the degradation pathways of CBZ in various AOPs has high similarity, and the reactive sites predicted by Fukui function fitted well with the data retrieved from literatures. In addition, molecule configuration of degradation intermediates was found to play a very important roles on degradation pathway. The study reveals that computational chemistry is a useful tool for degradation pathway speculation in AOPs.

Pharmaceutical and Personal Care Products in Different Matrices: Occurrence, Pathways, and Treatment Processes

The procedures for analyzing pharmaceuticals and personal care products (PPCPs) are typically tedious and expensive and thus, it is necessary to synthesize all available information from previously conducted research. An extensive collection of PPCP data from the published literature was compiled to determine the occurrence, pathways, and the effectiveness of current treatment technologies for the removal of PPCPs in water and wastewater. Approximately 90% of the compiled published papers originated from Asia, Europe, and the North American regions. The incomplete removal of PPCPs in different water and wastewater treatment processes was widely reported, thus resulting in the occurrence of PPCP compounds in various environmental compartments. Caffeine, carbamazepine, diclofenac, ibuprofen, triclosan, and triclocarban were among the most commonly reported compounds detected in water and solid matrices. Trace concentrations of PPCPs were also detected on plants and animal tissues, indicating the bioaccumulative properties of some PPCP compounds. A significant lack of studies regarding the presence of PPCPs in animal and plant samples was identified in the review. Furthermore, there were still knowledge gaps on the ecotoxicity, sub-lethal effects, and effective treatment processes for PPCPs. The knowledge gaps identified in this study can be used to devise a more effective research paradigm and guidelines for PPCP management.

Graphene-Based Composites as Catalysts for the Degradation of Pharmaceuticals

The incessant release of pharmaceuticals into the aquatic environment continues to be a subject of increasing concern. This is because of the growing demand for potable water sources and the potential health hazards which these pollutants pose to aquatic animals and humans. The inability of conventional water treatment systems to remove these compounds creates the need for new treatment systems in order to deal with these class of compounds. This review focuses on advanced oxidation processes that employ graphene-based composites as catalysts for the degradation of pharmaceuticals. These composites have been identified to possess enhanced catalytic activity due to increased surface area and reduced charge carrier recombination. The techniques employed in synthesizing these composites have been explored and five different advanced oxidation processes-direct degradation process, chemical oxidation process, photocatalysis, electrocatalyis processes and sonocatalytic/sono-photocatalytic processes-have been studied in terms of their enhanced catalytic activity. Finally, a comparative analysis of the processes that employ graphene-based composites was done in terms of process efficiency, reaction rate, mineralization efficiency and time required to achieve 90% degradation.

C-,N- and S-Doped TiO2 Photocatalysts: A Review

This article presents an overview of the reports on the doping of TiO2 with carbon, nitrogen, and sulfur, including single, co-, and tri-doping. A comparison of the properties of the photocatalysts synthesized from various precursors of TiO2 and C, N, or S dopants is summarized. Selected methods of synthesis of the non-metal doped TiO2 are also described. Furthermore, the influence of the preparation conditions on the doping mode (interstitial or substitutional) with reference to various types of the modified TiO2 is summarized. The mechanisms of photocatalysis for the different modes of the non-metal doping are also discussed. Moreover, selected applications of the non-metal doped TiO2 photocatalysts are shown, including the removal of organic compounds from water/wastewater, air purification, production of hydrogen, lithium storage, inactivation of bacteria, or carbon dioxide reduction.

Investigation of the interfacial behavior of organics on sulfide semiconductor surfaces by quantum chemical calculations and molecular dynamics simulations

The presence of organic pollutants in the world is harmful to our existence and the environment.

Photocatalytic study of nanocomposite membrane modified by CeF3 catalyst for pharmaceutical wastewater treatment

Cerium fluoride (CeF₃) nanoparticles (NPs) were synthesized and applied in polysulfone (PS) membrane fabricated by phase inversion method. The produced nanocomposite membranes (PS/CeF₃) with different contents of CeF3 NPS (0.25%, 0.5%, 0.75% and 1% w/w) were used to treat pharmaceutical wastewaters. The membranes were characterized by FESEM, EDX, XRD, FTIR, porosity, and water contact angle analyses. Evaluation of the characteristics and performance of the nanocomposite membranes confirmed that utilizing photocatalytic CeF₃ NPs in membrane structure could effectively decompose organic contaminants in pharmaceutical wastewaters. It also improves the hydrophilicity and antifouling ability of membrane during filtration especially, in the presence of UV irradiation. The permeate flux of the PS membrane increased from 35.1 to 63.77 l/m²h by embedding 0.75% of CeF₃ NPs in membrane structure due to the porosity enhancement from 71.36-78.42% and the decrease in contact angle from 62.9º to 53.73º. Moreover, the flux decline of PS/CeF₃-0.75% membrane under UV irradiation was from 63.6 to 46.1 l/m²h that considerably lower than that of the neat PS membrane (from 34.7 to 4.9). On the other hand, the degradation efficiency of PS/CeF₃-0.75% membrane was more than 97%, and COD removed was more than 65% while they were 75% and 31%, respectively for the nascent PS membrane. Therefore, applying the appropriate amount of CeF₃ NPs in PS membranes not only greatly increased the permeate flux but also significantly enhanced the degradation efficiency and COD removal. This indicates that nanocomposite membranes can be confidently applied for pharmaceutical wastewater treatment UV irradiation.

Assessing the applicability of a new carob waste-derived powdered activated carbon to control pharmaceutical compounds in wastewater treatment

This paper assesses the applicability of a new carob waste-derived powdered activated carbon (PAC) obtained by steam activation for pharmaceutical compounds (PhCs) removal in urban wastewater treatment plants (WWTPs) with activated sludge (AS) secondary treatment. The new carob-derived PAC presents chemical and textural properties similar to a high-performing commercial PAC produced from vegetable source by physical activation. The adsorption isotherms of three target PhCs, carbamazepine, diclofenac and sulfamethoxazole, spiked (at around 100 μg/L) in mixed liquor (ML) and in clarified-ML from the AS-bioreactor of a WWTP show: (i) minor reduction of PAC capacity with real MLs compared to clarified MLs; (ii) the higher the PhC hydrophobicity, the higher the PAC adsorption capacity in both water matrices; (iii) hydrophobic interactions probably overweight electrostatic interactions between the PhCs and the slightly positively charged PAC in these real water matrices with background organics and inorganics. The PhC adsorption results with ML and clarified-ML are used to calibrate the IAST-based tracer model (TRM) and predict the new PAC performance when added to AS-bioreactor vs. in post-secondary treatment, at the PhC naturally-occurring trace concentrations. The modelling projections show (i) one needs higher PAC doses than those reported in the literature, particularly in post-treatment, and (ii) the benefits of PAC dosing to the bioreactor, with only a slightly higher PAC dose being needed when compared to its post-secondary dosing and minimising the capital investment.

Core-Shell Molecularly Imprinted Polymers on Magnetic Yeast for the Removal of Sulfamethoxazole from Water

In this work, magnetic yeast (MY) was produced through an in situ one-step method. Then, MY was used as the core and the antibiotic sulfamethoxazole (SMX) as the template to produce highly selective magnetic yeast-molecularly imprinted polymers (MY@MIPs). The physicochemical properties of MY@MIPs were assessed by Fourier-transform infrared spectroscopy (FT-IR), a vibrating sample magnetometer (VSM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), specific surface area (S_BET) determination, and scanning electron microscopy (SEM). Batch adsorption experiments were carried out to compare MY@MIPs with MY and MY@NIPs (magnetic yeast-molecularly imprinted polymers without template), with MY@MIPs showing a better performance in the removal of SMX from water. Adsorption of SMX onto MY@MIPs was described by the pseudo-second-order kinetic model and the Langmuir isotherm, with maximum adsorption capacities of 77 and 24 mg g^-1 from ultrapure and wastewater, respectively. Furthermore, MY@MIPs displayed a highly selective adsorption toward SMX in the presence of other pharmaceuticals, namely diclofenac (DCF) and carbamazepine (CBZ). Finally, regeneration experiments showed that SMX adsorption decreased 21 and 34% after the first and second regeneration cycles, respectively. This work demonstrates that MY@MIPs are promising sorbent materials for the selective removal of SMX from wastewater.

Titanium Dioxide Nanoparticles: Prospects and Applications in Medicine

Metallic and metal oxide nanoparticles (NPs), including titanium dioxide NPs, among polymeric NPs, liposomes, micelles, quantum dots, dendrimers, or fullerenes, are becoming more and more important due to their potential use in novel medical therapies. Titanium dioxide (titanium(IV) oxide, titania, TiO₂) is an inorganic compound that owes its recent rise in scientific interest to photoactivity. After the illumination in aqueous media with UV light, TiO₂ produces an array of reactive oxygen species (ROS). The capability to produce ROS and thus induce cell death has found application in the photodynamic therapy (PDT) for the treatment of a wide range of maladies, from psoriasis to cancer. Titanium dioxide NPs were studied as photosensitizing agents in the treatment of malignant tumors as well as in photodynamic inactivation of antibiotic-resistant bacteria. Both TiO₂ NPs themselves, as well as their composites and combinations with other molecules or biomolecules, can be successfully used as photosensitizers in PDT. Moreover, various organic compounds can be grafted on TiO₂ nanoparticles, leading to hybrid materials. These nanostructures can reveal increased light absorption, allowing their further use in targeted therapy in medicine. In order to improve efficient anticancer and antimicrobial therapies, many approaches utilizing titanium dioxide were tested. Results of selected studies presenting the scope of potential uses are discussed in this review.

TiO2 nanoparticles and C-Nanofibers modified magnetic Fe3O4 nanospheres (TiO2@Fe3O4@C-NF): A multifunctional hybrid material for magnetic solid-phase extraction of ibuprofen and photocatalytic degradation of drug molecules and azo dye

Accurate sensitive analysis of drug ingredient substances in biological, pharmaceutical and environmental samples and removal of drug ingredient substances in environmental samples owngreat importance for sustaining viability. The realization of these processes using a single material offers significant advantages in terms of cost, time and ease of use. In this study, TiO₂ nanoparticles and C-Nanofibers modified magnetic Fe₃O₄ nanospheres (TiO₂@Fe₃O₄@C-NFs) synthesized as a multifunctional material employing a simple hydrothermal synthesis method. This innovative material was exploited in the magnetic solid-phase extraction (MSPE) method for the preconcentration of ibuprofen and photocatalytic degradation of antibiotics, non-steroidal anti-inflammatory drugs (NSAIDs), and azo dye. To our knowledge, no studies have been previously conducted using the same material as magnetic solid-phase extraction adsorbent and magnetically separable photocatalyst. The characterization of TiO₂@Fe₃O₄@C-NFs was carried out by XRD, FE-SEM, EDX and Raman techniques. The main analytical parameters affecting MSPE performance of ibuprofen such as pH, sorbent amount eluent type and volume and sample volume were optimized. The optimum values of the method were determined at the following parameters: pH 4.0, adsorbent amount 150 mg and eluent 2 mL of acetone. Ibuprofen analysis after MSPE was carried out using a high-performance liquid chromatography diode array detection system (HPLC-DAD). The photocatalytic degradation efficiencies of TiO₂@Fe₃O₄@C-NF hybrid material for probe-analytes reached 80-100% and the complete degradation attained within the range of 8-125 min under UV irradiation. Simple preparation, practical isolation from solutions, high efficiency, reproducibility, and sustainability are the main advantages of the TiO₂@Fe₃O₄@C-NFs for MSPE and photocatalytic degradation applications.