Inorganic Water Pollutants Research Articles

Elaboration of fibrous structured activated carbon from olive pomace via chemical activation and low-temperature pyrolysis

The objective of this study is to examine the preparation of activated carbon with a fibrous structure obtained from olive pomace through a chemical activation process using phosphoric acid (H3PO4) as the activating agent under air at a lower temperature. According to the findings, the most effective conditions to achieve high-performance activated carbon were 22 vol% of H3PO4, a 2-h chemical activation impregnation residence time at 50 °C, and a 500 °C pyrolysis temperature for 1 h. Structural analysis revealed that activated carbons possess highly developed textural and structural properties, resulting in an iodine value of 923 mg/g and a specific surface of 1400 m2/g. In addition to its microporosity, the produced carbon exhibits a highly developed fibrous structure, providing excellent adsorption properties. To confirm these results, SEM, FT-IR, XRF, XRD, Raman, and TGA techniques were employed. The fibrous carbon produced will expand the use of renewable carbon materials for removing various types of contaminants, including organic and inorganic pollutants in water, and numerous other industrial applications.

Pengolahan Limbah Industri Tahu dengan Tanaman Kenaf (Hibiscus cannabinus L.) untuk Menurunkan Kadar Nitrat (Utilization of Kenaf Plant (Hibiscus cannabinus L.) to Reduce Nitrate Levels in Tofu Industrial Wastewater)

Tofu industry waste is rich in nutrients so it can pollute the environment if there is no processing or remediation of soil contaminated by tofu waste. One technology that can be used is phytoremediation, which uses plants to reduce organic and inorganic pollutants in soil, sediment or water. Kenaf plants (Hibiscus cannabinus L.) have the ability to reduce pollutants so they can be used in the phytoremediation process. This research uses bed evapotranspiration with a batch system to measure the reduction in nitrate levels. The variables used in this research were kenaf plant varieties (KR 12 and KR 15), age (30 days and 45 days) and tofu wastewater concentrations of 50% and 75%. The results of pH observations on day 3 ranged from 7.1 - 7.7. Nitrate analysis observations were carried out every 7 days for 28 days. It is known from research results that kenaf 15 plants aged 45 days have the highest removal efficiency.

First Insight into the Catalytic Activity of Stereolithographically 3D‐Printed Tannin‐Based Carbon Architectures

AbstractThe remediation of polluted water is a major concern for public health and the environment. Catalytic removal of model organic and inorganic pollutants in water using carbon catalysts has shown promising results. In the present work, stereolithographically 3D‐printed bio‐based carbon monoliths with different textural and surface chemistry properties were used as catalysts for oxalic acid oxidation and catalyst supports for bromate reduction in continuous systems. A significant synergistic effect between ozone or dihydrogen and carbon catalyst was evidenced by mineralization of 14–25 % of oxalic acid or reduction of 15–45 % of bromates in the steady state, respectively. The best results were achieved with samples with the highest mesoporous surface area or, in the case of lower surface area, with samples having the strongest basic character. As materials with great potential, optimizing the textural properties of architected carbon monoliths will enable them to compete with other macro‐structured carbon catalysts.

Efficient Removal of Organic and Inorganic Pollutants from Water Using Fe3O4@SiO2@CS@EDTA Nanocomposite: Optimization via Response Surface Methodology (RSM)

AbstractThe elimination of pollution from wastewater holds significant value, especially when targeting colored and heavy metals originating from industrial activities. This study aims to optimize the degradation of both organic and inorganic pollutants in water by utilizing Fe3O4@SiO2@CS@EDTA (NCM@EDTA) core‐shell nanocomposite adsorbents. The NCM@EDTA adsorbents were synthesized in a step‐by‐step process and characterized using various techniques. Field emission scanning electron microscopy (FESEM) revealed an increase in average size to 137 nm, and transmission electron microscopy (TEM) confirmed the presence of a core‐shell structure. Additional characterization techniques included XRD, XPS, FT‐IR, EDX, BET analysis, and VSM, establishing the presence of functional groups, elemental analysis, and magnetic properties. Optimization of pollutant removal was conducted using response surface methodology (RSM), considering factors such as NCM@EDTA amount, reaction time, and temperature. Under optimized conditions, significant removal efficiency for Congo red, Safranin, and Cu2+ – representing cationic, anionic, and inorganic pollutants – was observed. The adequacy of the models was evaluated using p‐Value, F‐value, adjusted R2, and correlation coefficient (R2) for every pollutant, indicating a strong agreement between experimental data and predicted values. Additionally, the process of adsorbent recycling was studied, revealing that the internal structure remains unchanged throughout the removal and recovery process.

Potassium ferrate enhanced active manganese oxide filter material to remove BPA: Influence of NH4+、Mn2+

Active manganese oxide (MnOx) filter media can remove NH4+ and Mn2+ with high efficiency, but the removal of Bisphenol A (BPA) in water has the problem of poor stability, and the interaction between BPA and other inorganic pollutants in water is not clear. In order to improve the ability of continuous removal of BPA, this study used potassium ferrate (PF) to strengthen MnOx filter media to remove BPA from water, and investigated the effects of NH4+ and Mn2+ on the removal of BPA. The results showed that the removal efficiency of BPA increased from 73 % to 100 % by adding 0.1 mol/L PF, and the removal efficiency increased with the increase of PF concentration. A certain concentration of NH4+ and Mn2+ increased the removal efficiency of BPA by reacting with high-valent Fe to produce more active substances. The continuous removal of bisphenol A showed that the MnOx filter media had good stability, but the removal efficiency was only 48 % after 11 consecutive BPA removal tests, and the removal efficiency could be maintained above 70 % after adding PF. Combined with the results of free radical quenching, electron paramagnetic resonance (EPR) and methylphenyl sulfoxide (PMSO) experiments, it was confirmed that the active substances in the system included ·OH, 1O2, and high-valent Fe and Mn, but the main contribution to the BPA removal was Mn(Ⅲ). The results of X-ray photoelectron spectroscopy (XPS) also demonstrated that the addition of PF generated new active substances on the surface of the filter media, which increased the removal rate of BPA.

Asymmetric response of transition metal cationic orbitals to applied electric field

Understanding the quantum mechanical mechanisms underlying atomic/ionic interfacial processes and phenomena, particularly their dependence on the electronic orbital rearrangement of atoms/ions in an external electric field, remains a significant challenge. This study investigated the asymmetric response of transition metal (TM) cationic orbitals when subjected to an applied electric field. Quantum mechanical calculations were employed to quantify the newly formed hybrid orbitals and evaluate the corresponding orbital energies of the TM cations. Analysis of the quantitative contribution of asymmetric orbital hybridization to TM–surface interactions showed a significant change in orbital energy and increased effective charges of TM cations at the charged surface. This asymmetric response, induced by a negative external electric field generated from the structural charges of clay minerals (e.g., montmorillonite), repels electrons from the outer-shell orbital. This repulsion consequently increases the electron binding energy of the inner-shell orbitals, leading to new surface reactions, polarization-enhanced induction force, and polarization-induced covalent bonding between the TM cations and the charged surface. Our theoretical predictions regarding TM–clay mineral interactions are consistent with the experimental observations of TM cation adsorption. This finding has significant implications for the adsorptive removal of TM cations from wastewaters and for enhancing the catalytic efficiency of TM–surface catalysts. The unique physical and chemical characteristics exhibited by TMs at charged particle surfaces, resulting from their asymmetric response, can play pivotal roles in environmental and chemical engineering.

Machine Learning Assisted Metal Oxide‐Bismuth Oxy Halide Nanocomposite for Electrochemical Sensing of Heavy Metals in Aqueous Media

AbstractHeavy metal in excess quantity is one of the major inorganic pollutants in water. It causes several hazards to human life and ecosystem. It exists in traces in most of the commonly available drinking water sources from lakes, ponds, wells, etc., However, their presence in treated water is relatively significant. As the treated water is primarily used for agricultural purposes, it is necessary to monitor and measure their concentration. This requires sensing of metals in aqueous medium with good sensitivity and stability. Recently, nanosensors coupled with electrochemical transducer is preferred for analyzing heavy metal in aqueous solutions. In this work, Silver oxide‐bismuth oxy bromide coated with nafion is proposed as an electrochemical sensor for detection of heavy metal ions in aqueous solution. Cyclic voltammetry (CV) behavior of the proposed electrode is observed in different electrolytes. Further, Differential Pulse Voltammetry (DPV) study shows that current increases with trace nickel and copper metal ions of different concentration. Further, machine learning (ML) algorithms such as Naïve Bayes, ANN, SVM and decision trees are employed for nickel ions to train the cyclic voltammetry data and evaluate its performance. Naïve Bayes algorithm provides the best accuracy of 93.2% among all the models.

Ultrasonic-assisted adsorption of heavy copper and lead metal ions by g-C3N4, application of g-C3N4@MNPs (M: Pb, Cu) in the catalytic photoreduction of organic pollutants

In this paper, the prepared g-C3N4 was used firstly as an adsorbent of copper and lead ions by using both ultrasonic and classical methods in order to improve the adsorption of bigger metal amounts in a very good dispersion. This adsorption study was performed in-depth by evaluating the influence of contact time, the metal concentration, and the pH effect. The adsorption mechanism follows the Langmuir isotherm and the pseudo-second-order model which confirm its chemisorption type. The maximal adsorbed quantities obtained were 285.7 mg/g and 238.09 mg/g for Cu2+ and Pb2+ respectively which represent a high performance. Once the adsorption was done, the obtained nanocomposite g-C3N4@CuNPs and g-C3N4@PbNPs were used in the photocatalytic reduction of anionic and cationic dye in a simple and binary system which constitutes a recovery and recycling of heavy metals. All materials were characterized by several analyses in order to investigate the structural, thermal, textural, and morphological properties. Each nanocomposite showed an affinity for a specific material according to its surface charge. Finally, the rate constants towards methylene blue dye reached a high level up to 1.2881 min−1 and 0.6406 min−1 for the g-C3N4@CuNPs and g-C3N4@PbNPs respectively, implying a large efficiency against both organic and inorganic water pollutants.

Advancements in Adsorption Techniques for Sustainable Water Purification: A Focus on Lead Removal

The long-term sustainability of the global water supply, with a paramount emphasis on cleanliness and safety, stands as a formidable challenge in our modern era. In response to this pressing issue, adsorption techniques have emerged as pivotal and widely recognized solutions for the removal of hazardous pollutants, with a particular emphasis on lead adsorption from wastewater. This comprehensive review explores the relentless advancements made in the adsorption domain, highlighting innovations using separation and purification techniques that surpass traditional metal oxide-based adsorbents. Of particular note is the growing exploration of alternative materials, such as starch, chitosan, nanoscale structures like zeolites and metal-organic frameworks, magnetic materials, and carbon-based substances for the development of inorganic adsorbents. These materials, with their remarkable capacity for nanoscale structural adjustment, possess extraordinary capabilities for effective contaminant removal, facilitating swift water purification. The literature survey for this review was conducted using the Google Scholar engine, with “adsorbents for lead remediation” as the starting keywords, resulting in approximately 6000 papers. The search was refined to focus on the last three years and specifically targeted review papers which are most relevant to lead remediation. More than 100 papers were analysed to investigate various techniques, surface modifications, and adsorbent materials for managing inorganic pollutants in water. This review also illuminates research limitations, with a specific focus on starch-based adsorbents in lead remediation. As we progress towards practical commercial applications, this review identifies challenges associated with the development of inorganic adsorbents and provides invaluable insights into future prospects. Surface modification emerges as a promising path, with the potential to substantially enhance adsorption capacity, potentially doubling or even quadrupling it. Moreover, the adsorbents demonstrate impressive regenerative capabilities, maintaining up to 90% regeneration efficiency after multiple cycles. In conclusion, starch-based adsorbents show considerable potential as effective agents for lead purification from aquatic environments. Nevertheless, the need for further research persists, emphasizing the optimization of the adsorption process and exploring the long-term stability of starch-based adsorbents in real-world scenarios.

Facile fabrication and application of highly efficient reduced graphene oxide (rGO)-wrapped 3D foam for the removal of organic and inorganic water pollutants.

The pace of water contamination is increasing daily due to expanding industrialisation. Finding a feasible solution for effectively remediating various organic and inorganic pollutants from large water bodies remains challenging. However, a nano-engineered advanced hybrid material could provide a practical solution for the efficient removal of such pollutants. This work has reported the development of a highly efficient and reusable absorbent comprising a porous polyurethane (PU) and reduced graphene oxide (rGO) nanosheets (rGOPU) for the removal of different organic oils (industrial oil, engine oil and mustard oil), dyes (MB, MO, RB, EY and MV) and heavy metals (Pb(II), Cr(VI), Cd(II), Co(II) and As(V)). The structure, morphology and properties of the rGOPU hybrid absorbents were analysed by using Raman spectroscopy, field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Brunner-Emitte-Teller (BET) analysis. The rGOPU possessed both superhydrophobicity and superoleophilicity with water and oil contact angles of about 164° and 0°, respectively. The prepared rGOPU has demonstrated an excellent oil-water separation ability (up to 99%), heavy metals removal efficiency (more than 75%), toxic dye adsorption (more than 55%), excellent recyclability (> 500 times for oils), extraordinary mechanical stability (90% compressible for > 1000 cycles) and high recoverability. This work presents the first demonstration of rGOPU's multifunctional absorbent capacity in large-scale wastewater treatment for effectively removing a wide variety of organic and inorganic contaminants.

Applications of Transition Metal Oxides and Chalcogenides and their Composites in Water Treatment: a review

High population growth, industrialization, precipitous urban settlement, and poor government policies in some circles have increased resource consumption and various environmental activities that promote water pollution. Diverse materials such as nanomaterials, quantum dots, carbonaceous materials, and quaternary-metallic oxides have been very successful in removing benign pollutants from contaminated water bodies. Lately, transition metal oxides (TMOs) and transition metal chalcogenides (TMCs), and their composites have attracted favorable research interest in environmental applications due to their flexible elemental composition, manipulatable bandgaps, earth abundance, optoelectrical properties, visible light activity, and catalytic stability. This review explores the applications of these binary, ternary, quaternary, and heterostructure TMOs and TMCs for a broad range of biological, organic, and inorganic pollutants in water and wastewater treatment. The most popular water treatment strategies used include photocatalysis, adsorption, antimicrobial, persulfate/peroxymonosulfate activation, and the Fenton-like process. The mechanisms of catalysis for these processes were briefly highlighted. Lastly, the conclusion and prospects of the use of the TMOs and TMCs in water and wastewater treatment were discussed.

Revisiting the mechanisms of nitrite ions and ammonia removal from aqueous solutions: photolysis versus photocatalysis.

Nitrite ions and ammonia are widespread forms of inorganic water pollutants. Nevertheless, the mechanisms of their photolytic and photocatalytic reactions under UV-A irradiation are still fully undisclosed, particularly, at different pH values under aerobic and inert atmospheres. Herein, we have studied the photolytic decomposition of nitrite ions under different conditions using 365nm UV-A LED as a light source instead of mercury lamps that emit photons in the UV-B region and generate a lot of heat. The results indicated that the rate of nitrite disproportionation in the dark at pH ≤ 3.0 is remarkably high relative to the rate of the photolytic decomposition. At pH ˃ 3, the photolytic reaction is negligible and nitrite ions showed considerable stability. In contrast, the photocatalytic oxidation of nitrite ions over TiO2 photocatalysts, namely, TiO2P25, TiO2UV100, and TiO2 anatase/brookite mixture proceeds at pH ˃ 3.0. TiO2 P25 exhibited the highest photocatalytic activity at pH 5. Interestingly, the photolytic simultaneous removal of nitrite ions and ammonia was possible at pH 9.0 in the absence of oxygen (Ar atmosphere). A 42.69 ± 0.66%, 27.75 ± 1.7%, and 32.74 ± 0.59% of nitrogen calculated based on nitrite, ammonia, and both of them, respectively, can be removed after 6h of UV-A irradiation. The selectivity of N2 evolution was 77.6%. The nitrogen removal rate was significantly reduced in the presence of TiO2 photocatalyst evincing that TiO2 photocatalysis is applicable for nitrite ions oxidation, whereas the photolytic process is better suited for the simultaneous removal of nitrite ions and ammonia.

Carbon nano-structures and functionalized associates: Adsorptive detoxification of organic and inorganic water pollutants

• An overview of carbon-assisted materials for removal of different organic and inorganic pollutants. • Review of the key factors that affect adsorption performance. • Specific mechanism of interactions for different carbonaceous adsorbents. • Analysis of parameters and kinetics of adsorption. • The current hurdles and future insights to give overview on carbon-assisted materials for remediation of environmental pollutants. Deterioration of water quality is a desperate threat worldwide. Industrial development regularly added a vast amount of organic and inorganic contaminants to water. Therefore, eradicating these contaminants is highly essential for the well-being of biotic components. Adsorption-assisted technologies are among the most benign and principally used due to their higher efficiencies at lower costs and independence of complex technological supports. Carbon nanomaterials, such as activated carbons, carbon nanotubes, graphene-based materials, and carbon dots have been broadly adopted as adsorbents because of their outstanding surface characteristics. Researchers worked a lot on activation procedures and chemicals to achieve an ultrahigh surface area (above 3000 m 2 /g) to increase the adsorption efficiency. Further, cross-linked carbon nanotubes exhibited much-selected adsorption to organics. Carbon dots, a new type of carbon-based nanomaterials emerged as excellent adsorbents when introduced into the polymers matrix and provided promising platforms for the removal of metal ions. Also, graphene oxide and other oxidized forms of carbon being rich in functional groups are reported to exhibit excellent adsorption capacities as high as 2564 mg/g at 25 °C for basic and cationic compounds. Here, we reviewed the various types of pollutants found in aquatic biota with some basics on fundamentals and mechanistic features of adsorption, adsorption efficiency regulating factors. The article emphasized the performances of carbon nanomaterials and associated nanocomposites for the adsorption of various pollutants. The review also addresses the essential issues for the technical development and commercial application of carbon-assisted materials as nano adsorbents for water decontamination.

Photocatalytic Efficiency of Titanium Dioxide for Dyes and Heavy Metals Removal from Wastewater

The hazardous toxicity of dye materials, even in low concentrations, harms ecological systems. It releases a large number of contaminants into the water, resulting as waste water. Dyes prevent the process of photosynthesis by obstructing light passage, lowers the oxygen levels dissolved in the water. Also, a good number of the dyes and heavy metals are carcinogenic and mutagenic to human beings. Heterogeneous photocatalysis is a promising technology for removing organic, inorganic, and microbial pollutants from water and wastewater. It is preferable to other conventional wastewater treatment approaches due to its benefit, such as low cost, environmental friendliness, ability to proceed at ambient temperature and pressure conditions, and to completely degrade pollutants into environmentally safe products with suitable measures. The titanium oxide (TiO2) is one of the most promising material that has gained enormous importance in the field of energy and environmental applications. The unique physicochemical properties of TiO2 make it one of the best candidates among existing photocatalysts. This review provides an overview of strategies employed to augment its catalytic performance as well as the impact of different operational parameters on the removal proficiency of various organic and inorganic pollutants in water and wastewater treatment. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Photocatalytic activity of CuO nanoparticles for organic and inorganic pollutants removal in wastewater remediation

Heterogeneous photocatalysis is a promising technology for eradicating organic, inorganic, and microbial pollutants in water and wastewater remediation. It is a more preferable method to other conventional wastewater treatment approaches on account of its low cost, environmental benignity, ability to proceed at ambient temperature and pressure conditions, and capability to completely degrade pollutants under appropriate conditions into environmentally safe products. In heterogeneous photocatalysis, pollutant removal is mainly induced by in-situ generated reactive radicals and their subsequent attack when energetic radiation impinges on the semiconductor catalyst. As such, for the effective and economical removal of wastewater pollutants, the employed catalyst should have high photonic efficiency, less toxic, abundant, chemically and photochemically stableand visible light active. Copper (II) oxide (CuO) is one among such promising compounds and its photocatalytic performance has been hampered primarily by rapid recombination and slow mobility of photogenerated charge carriers. So, this review provides an overview of the strategies adopted to mitigate the aforementioned drawbacks and also other operational parameters to boost its catalytic activity towards the elimination of toxic organic and inorganic metal ion contaminants in an aqueous media.

Comparison of different phytoremediation strategies for acid mine drainage (AMD)

Acid Mine Drainage (AMD) is a severe environmental problem that results from mining industry activities around the world. Water pollution from acid mine drainage not only damages the quality of water and soil but also affects a sustainable environment such as plants and animals in a mining area. Mining water typically has acid with highly toxic heavy metal concentrations. Remediation is one of the technologies that can be used to reduce heavy metal pollutant water from mine drainage water. There were many researches about remediation in the past, but phytoremediation has attracted various researchers’ attention. Phytoremediation is a remediation pollutants method using a plant as a media that has the advantages of being efficient, economical, and eco-friendly. The most significant important aspect for the successful phytoremediation method is a selection of the plant species. Aquatic plants have a high level of efficiency in reducing organic and inorganic pollutants in water. The efficiency of aquatic plants can be improved with innovative approaches. This review focuses on the comparison characteristic of aquatic plants in the phytoremediation method to reduce heavy metals in pollutant water. Comparison served to support innovations to improve efficiency phytoremediation application research challenge for acid mine drainage issues in the near future.

Zirconium Based MOFs and Their Potential Use in Water Remediation: Current Achievements and Possibilities

Water pollution and scarcity are two of the most serious problems humanity is currently facing. Therefore, it is important to develop effective and inexpensive technologies and treatments to remove key pollutants from water. Zr based Metal-Organic Frameworks (MOFs) are new materials with the potential to remove organic and inorganic pollutants. However, it is important to critically analyze their performance in laboratory trials to evaluate their scalability potential for wastewater treatment. This document presents a critical review of the most recent studies and advances regarding Zr based MOFs, specifically the UiO-66 and Ui-O67 MOFs and analogous materials. We found that, although these materials are effective at removing inorganic and organic pollutants in water, there are still available research opportunities and knowledge gaps that need to be addressed. There is a need to further understand the mechanisms involved in the removal process to be able to develop more effective materials and/or to determine the best operating conditions during its implementation. Variations in removal efficiencies between the same MOFs also call for a more detailed description of the synthesis, as well as a better characterization of the material. This is because small variations in the characteristics of MOFs lead to non-homogeneous results, making accurate predictions of their removal capacity more difficult to determine. Finally, there is a need to better understand the stability of Zr based MOFs, as well as their removal capacity and reusability in wastewater with competitive ions, at standard pH and temperature operating conditions.

Adsorption equilibrium, kinetics and thermodynamics of Rhodamine B dye from aqueous solution using Iraqi Porcellanite rocks

Industrial wastewater and other polluted water need to be treated to make it possible to discharge into rivers and reuse them. Adsorption takes the importance of ways to remove organic and inorganic pollutants in water. The search for materials that are locally available and cheap to use as adsorbent surfaces. The Iraqiporcellanite powder can be used to remove the dye of Rhodamine B in batch method. The effect of various experimental parameters such as contact time, temperature, solution pH, weight of adsorbent initial dye concentration, ionic strength were investigated. The adsorption studies included both equilibrium adsorption isotherms and kinetics. The applicability of Langmuir and Freundlich equations was investigated at different temperature, and the Freundlich isotherm exhibited the best fit with experimental data. The thermodynamic parameters indicated that the adsorption was a spontaneous process (ΔG was negative), the negative value of ΔH indicate endothermic and ΔS was positive value (random), the kinetic data well described by Pseudo-second order kinetic model with intra particle diffusion as one of the rate limitring steps.

Ultrasonic assisted anchoring of Yb2O3 nanorods on In2S3 nanoflowers for norfloxacin degradation and Cr(VI) reduction in water: Kinetics and degradation pathway

The design and fabrication of environmentally benign, visible light-responsive heterojunction photocatalysts remain a viable route towards sustainable exploitation of photocatalysis for water treatment. In this contribution, binary nanostructures consisting of varying ratios of In2S3 and Yb2O3 (In2S3/Yb2O3) were obtained via a two-step method involving hydrothermal synthesis and ultrasonic treatment. The prepared materials were characterised extensively to reveal information about their morphology, optical properties, phase composition, chemical states and electrochemical properties. Subsequently, the nanocomposite photocatalysts were investigated for their dual role of photooxidation of the emerging pollutant; norfloxacin (NFX) and photoreduction of the toxic heavy metal; Cr(VI) in spiked water samples. The photocatalytic activity of the nanocomposites was found to be dependent on the photocatalyst composition (ratio of In2S3:Yb2O3) and dose, contact time and initial concentration of the pollutant. Under optimised conditions, Cr(VI) reduction efficiency reached 96.4% in just 45 min of visible light irradiation and the degradation rate is 28.84 times and 3.90 times higher than that of Yb2O3 and In2S3, respectively. Equally, over 95.0% NFX degradation was achieved in 50 min, under optimal conditions. The enhanced activity is credited to efficient visible light absorption, remarkable charge separation and transfer, leading to increased lifetime of the photogenerated charge carriers. Moreover, the possible degradation route for NFX was crafted based GC-MS analysis. Finally, the photostability and recyclability of the composite photocatalyst was probed and a plausible charge transfer mechanism was proposed. This work demonstrates the effectiveness of the ultrasonication method for preparing binary nanostructures and the versatility of the photocatalysts towards detoxification of both organic and inorganic pollutants in water.

Graphene Family Nanomaterials (GFN)-TiO2 for the Photocatalytic Removal of Water and Air Pollutants: Synthesis, Characterization, and Applications.

Given the industrial revolutions and resource scarcity, the development of green technologies which aims to conserve resources and reduce the negative impacts of technology on the environment has become a critical issue of concern. One example is heterogeneous photocatalytic degradation. Titanium dioxide (TiO2) has been intensively researched given its low toxicity and photocatalytic effects under ultraviolet (UV) light irradiation. The advantages conferred by the physical and electrochemical properties of graphene family nanomaterials (GFN) have contributed to the combination of GFN and TiO2 as well as the current variety of GFN-TiO2 catalysts that have exhibited improved characteristics such as greater electron transfer and narrower bandgaps for more potential applications, including those under visible light irradiation. In this review, points of view on the intrinsic properties of TiO2, GFNs (pristine graphene, graphene oxide (GO), reduced GO, and graphene quantum dots (GQDs)), and GFN-TiO2 are presented. This review also explains practical synthesis techniques along with perspective characteristics of these TiO2- and/or graphene-based materials. The enhancement of the photocatalytic activity by using GFN-TiO2 and its improved photocatalytic reactions for the treatment of organic, inorganic, and biological pollutants in water and air phases are reported. It is expected that this review can provide insights into the key to optimizing the photocatalytic activity of GFN-TiO2 and possible directions for future development in these fields.