TiO2 and activated carbon of Argania Spinosa tree nutshells composites for the adsorption photocatalysis removal of pharmaceuticals from aqueous solution

A state-of-the-art review on lignocellulosic biomass-derived activated carbon for adsorption and photocatalytic degradation of pollutants: a property and mechanistic study

A promising water treatment method involves using biomass-derived activated carbon (AC) to remove emerging pollutants from wastewater due to its adsorption capacity, cost-effectiveness, and sustainability. Notwithstanding, the existing literature lacks comprehensive studies that specifically focus on removing contaminants in water by comparing the effectiveness of adsorption and photocatalytic degradation methods. Additionally, there is not much emphasis on analyzing the combined processes of adsorption-photocatalytic degradation utilizing AC. Herein, this paper investigates the intricacies of adsorption-photocatalytic degradation mechanisms and contributing variables in the enhancement of performances using biomass-derived AC. Furthermore, this review paper presents a comprehensive examination of different biomass sources employed in the synthesis of AC. It also discusses the diverse techniques utilized for the fabrication of AC, including physical and chemical activation methods. Finally, the shortcomings and future prospects of biomass-derived AC have been addressed. This study offers significant insights for the development of future biomass-derived AC, with the goal of improving their efficiency and expanding their uses in wastewater treatment.

Elimination of torasemide from aqueous medium: influence of sorption and photocatalytic processes parameters supported by DFT analysis

The sorption and photocatalytic activity of pharmaceutical torasemide using an immobilized TiO2 photocatalyst were investigate. The experimental design included optimization of reaction conditions such as pH and initial pharmaceutical concentration in aqueous solution using the response surface modeling approach, scavenger tests to gain insight into the photocatalysis mechanism, and application of the process to more complex water matrices. TiO2 in the role of sorbent showed a low capacity for torasemide (12.23-29.83 μg/g within 24 h of contact), making this type of removal inefficient on its own. Investigating the sorption process influenced by different process parameters such as pH, temperature, ionic strength, and dosage of TiO2 applied, the low tendency to this kind of material was affirmed by low Kd values (0.70 to 6.78 mL/g) obtained by linear isotherms. Photocatalysis proved to be the better choice for the removal of torasemide from water, with the best kinetics at pH 4 and concentration of 5 mg/L with half-time for degradation of 34.83 min. Computational DFT analysis identified the zwitterionic torasemide structure as predominant under neutral and acidic conditions. It also showed that negatively charged areas around nitrogen-containing fragments probably have the highest potential to promote the TiO2 sorption at low pH conditions, where it is highest, through electrostatic attractions and N-H∙∙∙∙∙OTiO2 hydrogen-bonding contacts.

Valorization and Upcycling of Acid Mine Drainage and Plastic Waste via the Preparation of Magnetic Sorbents for Adsorption of Emerging Contaminants

Plastic waste poses a serious environmental risk, but it can be recycled to produce a variety of nanomaterials for water treatment. In this study, poly(ethylene terephthalate) (PET) waste and acid mine drainage were used in the preparation of magnetic mesoporous carbon (MMC) nanocomposites for the adsorptive removal of pharmaceuticals and personal care products (PPCPs) from water samples. The latter were then characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), and ζ potential. The results of Brunauer-Emmett-Teller isotherms revealed high specific surface areas of 404, 664, and 936 m2/g with corresponding pore sizes 2.51, 2.28, and 2.26 nm for MMC, MMAC-25%, and MMAC-50% adsorbents, respectively. Under optimized conditions, the equilibrium studies were best described by the Langmuir and Freundlich models and kinetics by the pseudo-second-order model. The maximum adsorption capacity for monolayer adsorption from the Langmuir model was 112, 102, and 106 mg/g for acetaminophen, caffeine, and carbamazepine, respectively. The composites could be reused for up to six cycles without losing their adsorption efficiency. Furthermore, prepared adsorbents were used to remove acetaminophen, caffeine, and carbamazepine from wastewater samples, and up to a 95% removal efficiency was attained.

Adsorptive-Photocatalytic Composites of α-Ferrous Oxalate Supported on Activated Carbon for the Removal of Phenol under Visible Irradiation

Adsorptive-photocatalytic composites based on activated carbon (AC) and α-ferrous oxalate dihydrate (α-FOD) were synthesized by an original two-step method and subsequently used for the removal of phenol from aqueous solutions. To obtain the composites, ferrotitaniferous black mineral sands (0.6FeTiO3·0.4Fe2O3) were first dissolved in an oxalic acid solution at ambient pressure, and further treated under hydrothermal conditions to precipitate α-FOD on the AC surface. The ratio of oxalic acid to the mineral sand precursor was tuned to obtain composites with 8.3 and 42.7 wt.% of α-FOD on the AC surface. These materials were characterized by X-ray powder diffraction, scanning electron microscopy, and the nitrogen adsorption-desorption method. The phenol removal efficiency of the composites was determined during 24 h of adsorption under dark conditions, followed by 24 h of adsorption-photocatalysis under visible light irradiation. AC/α-FOD composites with 8.3 and 42.7 wt.% of α-FOD adsorbed 60% and 51% of phenol in 24 h and reached a 90% and 96% removal efficiency after 12 h of irradiation, respectively. Given its higher photocatalytic response, the 42.7 wt.% α-FOD composite was also tested during successive cycles of adsorption and adsorption-photocatalysis. This composite exhibited a reasonable level of cyclability (~99% removal after four alternated dark/irradiated cycles of 24 h and ~68% removal after three simultaneous adsorption-photocatalysis cycles of 24 h). The promising performance of the as-prepared composites opens several opportunities for their application in the effective removal of organic micropollutants from water.

Synergistic adsorption and photocatalysis study of TiO2 and activated carbon composite

The discharge of organic pollutants by the textile and dyeing industries presents an escalating threat to aquatic environments, necessitating the development of effective remediation strategies. This study introduces the utilization of graphite-like structured activated carbon (AC), derived from highland barley straw-a biomass unique to the Plateau regions of China, including Tibet, Qinghai, and Gansu-as a support material for the TiO2 catalyst. TiO2/AC composites with different TiO2 loadings were synthesized by ultrasonic impregnation. The TiO2/AC composites were found to be polycrystalline materials composed of anatase and rutile phases. The TiO2 nanoparticles are well-dispersed over the surface of the AC. The photocatalytic activity of these composites was evaluated through their capacity to degrade a methylene blue (MB) solution upon irradiation. It was observed that the inclusion of TiO2 increases the number of adsorption sites and active sites for methylene blue, with the photocatalytic activity being notably higher at a 3-wt% TiO2 loading, achieving a remarkable 99.6 % degradation efficiency for 100 mg/L MB within 100 min. The experimental kinetic data for the photocatalytic process follow the pseudo-first-order kinetic model. Furthermore, TiO2/AC retains high photocatalytic activity after five reaction cycles. This research provides valuable insights into the application of biomass-derived materials for the purification of water, offering a sustainable solution to both pollution and agricultural waste challenges in Plateau areas of China.

Facile Preparation Method of TiO2/Activated Carbon for Photocatalytic Degradation of Methylene Blue

The development of nanocomposite photocatalysts with high photocatalytic activity, cost-effectiveness, a simple preparation process, and scalability for practical applications is of great interest. In this study, nanocomposites of TiO2 Degussa P25 nanoparticles/activated carbon (TiO2/AC) were prepared at various mass ratios of (4:1), (3:2), (2:3), and (1:4) by a facile process involving manual mechanical pounding, ultrasonic-assisted mixing in an ethanol solution, paper filtration, and mild thermal annealing. The characterization methods included XRD, SEM-EDS, Raman, FTIR, XPS, and UV-Vis spectroscopies. The effects of TiO2/AC mass ratios on the structural, morphological, and photocatalytic properties were systematically studied in comparison with bare TiO2 and bare AC. TiO2 nanoparticles exhibited dominant anatase and minor rutile phases and a crystallite size of approximately 21 nm, while AC had XRD peaks of graphite and carbon and a crystallite size of 49 nm. The composites exhibited tight decoration of TiO2 nanoparticles on micron-/submicron AC particles, and uniform TiO2/AC composites were obtained, as evidenced by the uniform distribution of Ti, O, and C in an EDS mapping. Moreover, Raman spectra show the typical vibration modes of anatase TiO2 (e.g., E1g(1), B1g(1), Eg(3)) and carbon materials with D and G bands. The TiO2/AC with (4:1), (3:2), and (2:3) possessed higher reaction rate constants (k) in photocatalytic degradation of methylene blue (MB) than that of either TiO2 or AC. Among the investigated materials, TiO2/AC = 4:1 achieved the highest photocatalytic activity with a high k of 55.2 × 10-3 min-1 and an MB removal efficiency of 96.6% after 30 min of treatment under UV-Vis irradiation (120 mW/cm2). The enhanced photocatalytic activity for TiO2/AC is due to the synergistic effect of the high adsorption capability of AC and the high photocatalytic activity of TiO2. Furthermore, TiO2/AC promotes the separation of photoexcited electron/hole (e-/h+) pairs to reduce their recombination rate and thus enhance photocatalytic activity. The optimal TiO2/AC composite with a mass ratio of 4/1 is suggested for treating industrial or household wastewater with organic pollutants.

Fabrication of CuNPs Using Schiff Base Ligand and Their Catalytic Reduction of Pharmaceutical Drugs, Fluorescence Selective Detection of Cd2+, Antimicrobial, and Antioxidant Activities

Here, we have approached the synthesis of copper nanoparticles (CuNPs) Schiff base (5-trifluoromethoxy-2-(((2chloro-5-(methyl)phenyl)imino)methyl)phenol)). The synthesized CuNPs were characterized by UV-vis spectroscopy, PL, FTIR, powder XRD, and TEM analysis. From the UV-vis absorption spectroscopy, an absorption peak was observed at 585 nm. As a result of the powder XRD and TEM studies, spherical particle sizes ranged between 4 and 10 nm. FT-IR analysis confirmed the presence of functional groups ‒OH, C=C, -C=N-, and C‒H triggers the synthesis of CuNPs. Further, the catalytic property of the CuNPs were revealed by the degradation of pharmaceutical drugs such as Capecitabine (CAP) and Ciprofloxacin (CIP) in 90 min of reaction time in the presence of NaBH4. The reaction kinetics followed pseudo-first-order with k-values (rate constant) 0.248 min-1 and 0.307 min-1. In addition, the synthesized CuNPs have exhibited selective sensing detection of Cd2+ metal ions in different range of concentration (10-100 µM) by spectrofluorometrically with the limit of detection (LOD) is 0.0284 nM and limit of quantification (LOQ) is 0.0586 nM. The CuNPs revealed significant antioxidant activities against DPPH as a common free radical at 50 µg/mL with 71.24% of scavenging activity. The maximum antimicrobial potential and zone of inhibition of P. Aeruginosa is 17.25±0.8 mm and A. niger is 12.1 mm by using CuNPs.

Conversion of locally available materials to biochar and activated carbon for drinking water treatment

For environmental sustainability and to achieve sustainable development goals (SDGs), drinking water treatment must be done at a reasonable cost with minimal environmental impact. Therefore, treating contaminated drinking water requires materials and approaches that are inexpensive, produced locally, and effortlessly. Hence, locally available materials and their derivatives, such as biochar (BC) and activated carbon (AC) were investigated thoroughly. Several researchers and their findings show that the application of locally accessible materials and their derivatives are capable of the adsorptive removal of organic and inorganic contaminants from drinking water. The application of locally available materials such as lignocellulosic materials/waste and its thermo-chemically derived products, including BC and AC were found effective in the treatment of contaminated drinking water. Thus, this review aims to thoroughly examine the latest developments in the use of locally accessible feedstocks for tailoring BC and AC, as well as their features and applications in the treatment of drinking water. We attempted to explain facts related to the potential mechanisms of BC and AC, such as complexation, co-precipitation, electrostatic interaction, and ion exchange to treat water, thereby achieving a risk-free remediation approach to polluted water. Additionally, this research offers guidance on creating efficient household treatment units based on the health risks associated with customized adsorbents and cost-benefit analyses. Lastly, this review work discusses the current obstacles for using locally accessible materials and their thermo-chemically produced by-products to purify drinking water, as well as the necessity for technological interventions.

An eco-friendly cellulose support functionalized with tin titanate nanoparticles for the fast removal of clonazepam drug from the drinking water: adsorption mechanisms

This research studied the performance of tin titanate (SnTiO₃, SnT) and cellulose-based composites for the removal of clonazepam (CZP) drug by physical adsorption. The cellulose was extracted from a plant named tithonia tubaeformis, which is considered as weed in the crop fields of Mexico. The analysis by microscopy revealed that the SnTiO₃ powders are formed by a mixture of coalesced grains and nanotubes with lengths in the range of 97-633 nm. Furthermore, the X-ray diffraction analysis indicated that the SnT powders present a mixture of cassiterite and rutile phases. Experiments for the CZP removal from drinking water were carried out, and several parameters such as initial drug concentration (1-10 mg/L), amount of SnT adsorbent per liter of contaminated solution (10-50 mg/L), and pH (3-10) were varied in order to study their influence on the CZP removal percentage. Essentially, we found that the SnT dosage of 50 mg/L produced the most efficient and fastest CZP removal, since 94.3% of CZP was removed after only 10 min of reaction. Moreover, a piece of cellulose (Cell) was decorated with 50 mg of SnT powder to form the Cell+SnT composite, and this was able to remove a maximum of 80.5% of CZP after 180 min of reaction. If the amount of SnT powder deposited on the Cell+SnT composite is raised up to 100 mg, the composite can remove 95.5% of CZP. The adsorption capacity was also calculated for the SnT powders and Cell+SnT composite and found that it was 6.3 times higher for the SnT powders. Furthermore, the Raman spectra recorded for the Cell+SnT composites demonstrated the presence of surface defects, which acted as adsorption centers for the CZP molecules. The results of this investigation demonstrate that eco-friendly and low-cost floatable composites can be used for the removal of pharmaceutical contaminants, which is an advantage over adsorbent powders.

Sol-Gel Synthesis of New TiO2 Ball/Activated Carbon Photocatalyst and Its Application for Degradation of Three Hormones: 17α-EthinylEstradiol, Estrone, and β-Estradiol

Many approaches have been investigated to eliminate pharmaceuticals in wastewater treatment plants during the last decades. However, a lack of sustainable and efficient solutions exists for the removal of hormones by advanced oxidation processes. The aim of this study was to synthesize and test new photoactive bio composites for the elimination of these molecules in wastewater effluents. The new materials were obtained from the activated carbon (AC) of Arganian spinosa tree nutshells and titanium tetrachloride by the sol gel method. SEM analysis allowed one to confirm the formation of TiO₂ particles homogeneously dispersed at the surface of AC with a controlled titanium dioxide mass ratio, a specific TiO₂ anatase structure, and a highly specific surface area, evidenced by ATG, XRD, and BET analysis, respectively. The obtained composites were revealed to quantitatively absorb carbamazepine (CBZ), which is used as a referred pharmaceutical, and leading to its total elimination after 40 min under irradiation with the most effective material. TiO₂ high content disfavors CBZ adsorption but improves its degradation. In the presence of the composite, three hormones (17α-ethinylestradiol, estrone, and β-estradiol) are partially adsorbed onto the composite and totally degraded after 60 min under UV light exposure. This study constitutes a promising solution for the efficient treatment of wastewater contaminated by hormones.

Enhanced photocatalytic activity of hydrozincite-TiO2 nanocomposite by copper for removal of pharmaceutical pollutant mefenamic acid in aqueous solution

Nanocomposites based on hydrozincite-TiO₂ and copper-doped HZ-xCu-TiO₂ (x = 0.1; 0.25; 0.35) were synthesized in a single step using the urea method. The samples were characterized by XRD, FTIR, SEM/TEM, and DRS. The study of adsorption capacity and photocatalytic efficiency of these nanocomposites have been tested on a pharmaceutical pollutant, mefenamic acid (MFA). Kinetic study of removal of MFA indicates that this pollutant was adsorbed on the surface of the synthesized phases, according to Langmuir's model. Such adsorption proved to be well adapted in a kinetic pseudo-second-order model with capacity of 13.08 mg/g for HZ-0.25Cu-TiO₂. Subsequently, the kinetics of photocatalytic degradation under UV-visible irradiation was studied according to several parameters, which allowed us to optimize our experimental conditions. The nanocomposite HZ-0.25Cu-TiO₂ showed significant removal efficiency of MFA. Elimination rate reached 100% after 20 min under UV-vis irradiation, and 77% after 7 h under visible light irradiation. Repeatability tests have shown that this nanocomposite is extremely stable after six photocatalytic cycles. By-products of MFA were detected by LC/MS. These photoproducts was produced by three types of reactions of hydroxylation: cyclization and cleavage of the aromatic ring. MFA underwent complete mineralization after 22 h of irradiation in the presence of the HZ-0.25Cu-TiO₂.

Photocatalytic degradation of sulfamethoxazole using TiO2-based materials - Perspectives for the development of a sustainable water treatment technology

Heterogeneous photocatalysis using titanium dioxide-based materials is considered a promising and innovative solution to the water pollution problem. However, due to the limitations concerning the use of the developed materials and the applied photodegradation conditions, the research on photoremediation using TiO₂ often stays behind the lab door. The challenge is to convert the basic research into a successful innovation, leading to the implementation of this process into wastewater treatment. For this purpose, the most active materials and optimal photodegradation conditions must be chosen. This article collects and compares the studies on photocatalytic degradation of an emerging pollutant - sulfamethoxazole, an antibacterial drug - and attempts to find the best approaches to be successfully applied on an industrial scale. Various types of TiO₂-based photocatalysts are compared, including different nanoforms, doped or polymer-based composites, composites with graphene, activated carbon, dyes or natural compounds, as well as possible supporting materials for TiO₂. The paper covers the impact of the irradiation source (natural sunlight, LED, mercury or xenon lamps) and water matrix on the photodegradation process, considering the ecological and economic sustainability of the process. Emphasis is put on the stability, ease of separation and reuse of the photocatalyst, power and safety of the irradiation source, identification of photodegradation intermediates and toxicity assays. The main approaches are critically discussed, main challenges and perspectives for an effective photocatalytic water treatment technology are pointed out.

Design of biomass-based composite photocatalysts for wastewater treatment: a review over the past decade and future prospects

This investigation applied a systematic review approach on publications covering primary data during 2012-2022 with a focus on photocatalytic degradation of pollutants in aqueous solution by composite materials synthesized with biomass and, at least, TiO₂ and/or ZnO semiconductors to form biomass-based composite photocatalysts (BCPs). After applying a set of eligibility criteria, 107 studies including 832 observations/entries were analyzed. The average removal efficiency and degradation kinetic rate reported for all model pollutants and BCPs were 77.5 ± 21.5% and 0.064 ± 0.174 min^-1, respectively. Principal component analysis (PCA) was applied to analyze BCPs synthesis methods, experimental conditions, and BCPs' characteristics correlated with the removal efficiency and photodegradation kinetics. The relevance of adsorption processes on the pollutants' removal efficiency was highlighted by PCA applied to all categories of pollutants (PCA_pol). The PCA applied to textile dyes (PCA_dyes) and pharmaceutical compounds (PCA_pharma) also indicate the influence of variables related to the composite synthesis (i.e., thermal treatment and time spent on BCPs synthesis) and photocatalytic experimental parameters (catalyst concentration, pollutant concentration, and irradiation time) on the degradation kinetic accomplished by BCPs. Furthermore, the multivariate analysis (PCA_pol) revealed that the specific surface area and the narrow band gap are key characteristics for BCPs to serve as a competitive photocatalyst. The effect of scavengers on pollutants' degradation and the recyclability of BCPs are also discussed, as necessary aspects for scalability trends. Further investigations are recommended to compare the performance of BCPs and commercial catalysts, as well as to assess the costs to treat real wastewater.

Investigation of the Oxidative Stress Response of a Green Synthesis Nanoparticle (RP-Ag/ACNPs) in Zebrafish

Silver nanoparticles (AgNPs) are prominent nanomaterials that are efficiently used in different industries including medical products, water treatment, and cosmetics. However, AgNPs are known to cause adverse effects on the ecosystem and human health. In this study, aqueous extract of Rumex patientia (RP) was used as a reducing and stabilizing agent in AgNP biosynthesis. The obtained activated carbon (AC) from Chenopodium album (CA) plant was combined with RP-AgNPs to synthesize RP-Ag/AC NPs. Next, the effects of these green synthesis RP-Ag/AC NPs on zebrafish (Danio rerio) embryos and larvae were investigated. First, we characterized the RP-Ag/AC NPs by using X-ray diffraction (XRD) and transmission electron microscopy (TEM) and determined LC₅₀ value as 217.23 mg/L at 96 h. Next, the alterations in survival rate, hatching rate, and morphology of the larvae at 96 h were monitored. The survival rates decreased in a dose-dependent manner. Morphological defects such as yolk sac edema, pericardial edema, spinal curvature, and tail malformation in the NP-treated larvae were observed. RP-Ag/AC NPs stimulated the production of neuronal NOS (nNOS) and 8-OHdG in zebrafish brain tissues in a dose-dependent manner and enhanced neutrophil degeneration and necrosis at concentrations of 50 and 100 mg/L. Thus, the obtained data suggest that the green synthesis process is not sufficient to reduce the effect of oxidative stress caused by AgNPs on oxidative signaling.

Electrochemical sensing system for the analysis of emerging contaminants in aquatic environment: A review

This survey distinguishes understudied spaces of arising impurity research in wastewaters and the habitat, and suggests bearing for future checking. Thinking about the impeding effect of toxins on human wellbeing and biological system, their discovery in various media including water is fundamental. This review sums up and assesses the latest advances in the electrochemical detecting of emerging contaminants (ECs). This survey is expected to add to the advancement in electrochemical applications towards the ECs. Different electrochemical insightful procedures like Amperometry, Voltammetry has been examined in this overview. The improvement of cutting edge nanomaterial-based electrochemical sensors and biosensors for the discovery of drug compounds has accumulated monstrous consideration because of their benefits, like high affectability and selectivity, continuous observing, and convenience has been reviewed in this survey. This survey likewise features the diverse electrochemical treatment procedures accessible for the removal of ECs.

Development and Characterization of Bioadsorbents Derived from Different Agricultural Wastes for Water Reclamation: A Review

The presence of dangerous pollutants in different water sources has restricted the availability of this natural resource. Thus, the development of new low-cost and environmentally-friendly technologies is currently required to ensure access to clean water. Various approaches to the recovery of contaminated water have been considered, including the generation of biomaterials with adsorption capacity for dangerous compounds. Research on bioadsorbents has boomed in recent years, as they constitute one of the most sustainable options for water treatment thanks to their abundance and high cellulose content. Thanks to the vast amount of information published to date, the present review addresses the current status of different biosorbents and the principal processes and characterization methods involved, focusing on base biomaterials such as fruits and vegetables, grains and seeds, and herbage and forage. In comparison to other reviews, this work reports more than 60 adsorbents obtained from agricultural wastes. The removal efficiencies and/or maximum adsorption capacities for heavy metals, industrial contaminants, nutrients and pharmaceuticals are presented as well. In addition to the valuable information provided in the literature investigation, challenges and perspectives concerning the implementation of bioadsorbents are discussed in order to comprehensively guide selection of the most suitable biomaterials according to the target contaminant and the available biowastes.

A Review on the Removal of Carbamazepine from Aqueous Solution by Using Activated Carbon and Biochar

Carbamazepine (CBZ), one of the most used pharmaceuticals worldwide and a Contaminant of Emerging Concern, represents a potential risk for the environment and human health. Wastewater treatment plants (WWTPs) are a significant source of CBZ to the environment, polluting the whole water cycle. In this review, the CBZ presence and fate in the urban water cycle are addressed, with a focus on adsorption as a possible solution for its removal. Specifically, the scientific literature on CBZ removal by activated carbon and its possible substitute Biochar, is comprehensively scanned and summed up, in view of increasing the circularity in water treatments. CBZ adsorption onto activated carbon and biochar is analyzed considering several aspects, such as physicochemical characteristics of the adsorbents, operational conditions of the adsorption processes and adsorption kinetics and isotherms models. WWTPs usually show almost no removal of CBZ (even negative), whereas removal is witnessed in drinking water treatment plants through advanced treatments (even >90%). Among these, adsorption is considered one of the preferable methods, being economical and easier to operate. Adsorption capacity of CBZ is influenced by the characteristics of the adsorbent precursors, pyrolysis temperature and modification or activation processes. Among operational conditions, pH shows low influence on the process, as CBZ has no charge in most pH ranges. Differently, increasing temperature and rotational speed favor the adsorption of CBZ. The presence of other micro-contaminants and organic matter decreases the CBZ adsorption due to competition effects. These results, however, concern mainly laboratory-scale studies, hence, full-scale investigations are recommended to take into account the complexity of the real conditions.

Fe-TiO2/AC and Co-TiO2/AC Composites: Novel Photocatalysts Prepared from Waste Streams for the Efficient Removal and Photocatalytic Degradation of Cibacron Yellow F-4G Dye

Fe-TiO2/AC and Co-TiO2/AC composites were prepared from activated carbon (AC) derived from residues of peanut hulls and TiO2 photocatalyst, electrochemically prepared from titanium scrap, and doped with Fe and Co, respectively. The adsorption capacity and photocatalytic activity of the Fe-TiO2/AC and Co-TiO2/AC composites were studied for removing and degrading Cibacron Yellow F-4G (CYF-4G) from wastewater. Doped ACs were characterized by thermogravimetry (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), a new X-ray absorption technique (XRA), and elemental analysis (EA). Interesting relationships were found between SEM, XRA, and TGA data and the doped amount of catalyst on ACs. Optimal dye adsorption was found at a pH of 2.0. The CYF-4G adsorption kinetics are followed according to the pseudo-second order model. The experimental data revealed that the Langmuir model fits better than the Freundlich and Temkin models. A decrease in adsorption capacity was observed when the catalyst dope percentage increased. A removal and degradation efficiency of the dye close to 100% was achieved around 120 min. A synergistic adsorption and photocatalytic degradation effect of the Fe-TiO2/AC and Co-TiO2/AC composites could be observed when adsorption experiments were conducted under simulated visible radiation.

Novel plantain peel activated carbon-supported zinc oxide nanocomposites (PPAC-ZnO-NC) for adsorption of chloroquine synthetic pharmaceutical used for COVID-19 treatment

Chloroquine has been reported as an effective drug for the treatment of COVID-19 and with the rise in its administration and continued use, metabolites of chloroquine invariably find their way into the environment. There are many concerns recently on the presence of pharmaceuticals in the aquatic environment, hence the need for environmental remediation via effective adsorbent. Plantain peel activated carbon-supported zinc oxide (PPAC-ZnO) nanocomposite was prepared and characterized using physicochemical and spectroscopic techniques. The rate of uptake of chloroquine by PPAC-ZnO nanocomposite was investigated by batch technique under different operational parameters. PPAC-ZnO nanocomposite was characterized by various physicochemical techniques by SBET = 606.07 m2g-1, pH(pzc) = 4.98 surface area by Saer's method = 273.4 m2g-1. The carboxylic, phenols, lactone, and basic sites were determined by the Boehm method. Chloroquine uptake was confirmed by FTIR and SEM before and after adsorption. Change in morphology after adsorption was revealed by scanning electron microscopy (SEM). X-ray diffraction (XRD) showed the crystallinity of PPAC-ZnO nanocomposite. The batch adsorption experiment results showed that adsorption capacity increased with an increase in temperature. The maximum chloroquine sorption was 78.89% at a concentration of 10 ppm and a temperature of 313 K. Equilibrium sorption fitted well to Langmuir and Temkin isotherms with a high correlation coefficient (R 2) of 0.99. Pseudo-second-order best described the kinetic data and adsorption mechanism was pore diffusion dependent. Thermodynamics parameters (ΔG =  - 25.65 to - 28.79 kJmol-1; ΔH = 22.06 kJmol-1 and ΔS = 157.69 Jmol-1) demonstrated feasibility, spontaneity, and endothermic behavior of the process with degrees of randomness. The activation energy for adsorption was less than 40 kJmol-1 suggesting a physisorption mechanism. This study results revealed that PPAC-ZnO nanocomposites are a sustainable and effective adsorbent for the removal of pharmaceutical waste.

Photoactivation and photoregeneration of TiO2/PAC mixture applied in suspension in water treatments: approach to a real application

The process TiO₂/PAC/UV-vis has been under study and compared with the isolated treatments of adsorption and photocatalysis determining possible synergies between adsorption and photocatalysis of target antibiotics: amoxicillin, enrofloxacin, sulfadiazine, and trimethoprim. The characterization of the TiO2/PAC mixture was carried out via FESEM and FTIR. Moreover, a kinetic study has been performed. The effect of UV-vis radiation and the type of matrix was analyzed in TiO₂/PAC/UV-vis process. The performance of this treatment has been monitored during three cycles, evaluating also the regeneration of TiO₂/PAC mixture by UV-vis light. TiO₂/PAC/UV-vis process allowed the removal of the antibiotics in the range 90-100% (an average removal of 93% of the initial concentration) after 60 min of treatment. However, only amoxicillin showed a significant synergy applying TiO₂/PAC/UV-vis process. Regarding matrix effect, no influence of the matrix type (ultrapure water or treated wastewater) was observed. Since PAC tends to be deactivated gradually, the TiO₂/PAC/UV-vis process performance decreases after each cycle in a 15% average. Finally, regeneration via UV-vis light started to be effective after a total of 4 h of regeneration.

Study of the photoinduced transformations of sertraline in aqueous media

In the present study, the photoinduced degradation of the antidepressant drug sertraline under artificial solar radiation was examined. Photolysis was studied under different experimental conditions to explore its photolytic fate in the aqueous environment. Photolytic degradation kinetics were carried out in ultrapure water, wastewater effluent, as well as in the presence of dissolved organic matter (humic acids), bicarbonate and nitrate ions which enabled their assessment on sertraline photo-transformation. The reaction of sertraline with photoactive compounds accelerated sertraline transformation in comparison with direct photolysis. Moreover, TiO₂-mediated photocatalytic degradation of sertraline was investigated, and focus was placed on the identification of by-products. As expected, photocatalysis was extremely effective for sertraline degradation. Photocatalytic degradation proceeded through the formation of forty-four transformation products identified by HPLC-HRMS and after 240 min of irradiation total mineralization was achieved. Microtox bioassay (Vibrio fischeri) was employed to assess the ecotoxicity of the photocatalysis-treated solutions and results have indicated that sertraline photo-transformation proceeds through the formation of toxic compounds.

Characteristics and Behavior of Different Catalysts Used for Water Decontamination in Photooxidation and Ozonation Processes

The objective of this study was to summarize the results obtained in a wide research project carried out for more than 15 years on the catalytic activity of different catalysts (activated carbon, metal–carbon xerogels/aerogels, iron-doped silica xerogels, ruthenium metal complexes, reduced graphene oxide-metal oxide composites, and zeolites) in the photooxidation (by using UV or solar radiation) and ozonation of water pollutants, including herbicides, naphthalenesulfonic acids, sodium para-chlorobenzoate, nitroimidazoles, tetracyclines, parabens, sulfamethazine, sodium diatrizoate, cytarabine, and surfactants. All catalysts were synthesized and then texturally, chemically, and electronically characterized using numerous experimental techniques, including N2 and CO2 adsorption, mercury porosimetry, thermogravimetric analysis, X-ray diffraction, Fourier-transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, diffuse reflectance UV–vis spectroscopy, photoluminescence analysis, and transmission electron microscopy. The behavior of these materials as photocatalysts and ozonation catalysts was related to their characteristics, and the catalytic mechanisms in these advanced oxidation processes were explored. Investigations were conducted into the effects on pollutant degradation, total organic carbon reduction, and water toxicity of operational variables and the presence of different chemical species in ultrapure, surface, ground, and wastewaters. Finally, a review is provided of the most recent and relevant published studies on photocatalysis and catalyzed ozonation in water treatments using similar catalysts to those examined in our project.

Hydrogen Production through Glycerol Photoreforming on TiO2/Mesoporous Carbon: Influence of the Synthetic Method

This article explores the effect of the synthetic method of titanium dioxide (TiO₂)/C composites (physical mixture and the water-assisted/unassisted sol-gel method) on their photocatalytic activity for hydrogen production through glycerol photoreforming. The article demonstrates that, apart from a high surface area of carbon and the previous activation of its surface to favor titania incorporation, the appropriate control of titania formation is crucial. In this sense, even though the amount of incorporated titania was limited by the saturation of carbon surface groups (in our case, ca. 10 wt.% TiO₂), the sol-gel process without water addition seemed to be the best method, ensuring the formation of small homogeneously-distributed anatase crystals on mesoporous carbon. In this way, a ca. 110-fold increase in catalyst activity compared to Evonik P25 (expressed as hydrogen micromole per grams of titania) was achieved.

Adsorption and Photocatalytic Study of Phenol Using Composites of Activated Carbon Prepared from Onion Leaves (Allium fistulosum) and Metallic Oxides (ZnO and TiO2)

The aim of this study was to evaluate and compare the adsorption and photocatalytic activity of activated carbon-based photocatalysts. Titanium dioxide (TiO2) and zinc oxide (ZnO) were chosen as semiconductors to prepare composites with activated carbon by the wet impregnation method. Activated carbon was prepared using as starting material onion leaves (Allium fistulosum) and as activating agent phosphoric acid (H3PO4). Photooxidation and batch adsorption of phenol was studied to compare the efficiency of the materials prepared. The results showed that the composite AC–TiO2 has a greater photocatalytic activity and a better adsorption capacity compared to AC–ZnO composite.

Zebrafish toxicity assessment of the photocatalysis-biodegradation of diclofenac using composites of TiO2 and activated carbon from Argania spinosa tree nutshells and Pseudomonas aeruginosa

The occurrence and persistence of pharmaceutical products (PPs) in the environment have recently been well-documented and are a major concern for public health. Their incidence in aquatic ecosystems is the result of their direct release without any prior treatment or insufficient wastewater treatment. Therefore, an efficient and safe posttreatment process for removing PPs must be developed. In this study, we focused on the ability of photocatalysis or combined photocatalysis and biodegradation to effectively and safely remove diclofenac (DCF) and its by-products from water. The heterogeneous photocatalysis system was based on bio-sourced activated carbon obtained from Argania spinosa tree nutshells and Degussa P25 titanium dioxide (ACP-TiO₂), and biodegradation involved Pseudomonas aeruginosa. Toxicity tests were conducted with zebrafish embryos to evaluate the applicability of the treatment processes. The results showed that photocatalytic treatment with 0.1 mg/L of ACP-TiO₂ 9% for 7.5 h is sufficient to eliminate DCF (50 mg L^-1) and its by-products from water. Low levels of malformation (< 20%) were detected in zebrafish embryos treated with photocatalyzed DCF solutions at 1, 5, and 7 mg L^-1 after 4 days of exposure. After 3 h of incubation, P. aeruginosa was found to reduce the toxicity of DCF (10 mg L^-1) photocatalyzed for 2 and 4 h. Additional studies should be conducted to elucidate the biodegradation mechanism.