Hybrid materials for the removal of emerging pollutants in water: classification, synthesis, and properties

Adsorption and photocatalytic degradation of 2,4-dicholrophenol using surgical mask derived SMAC-Fe2O3 composite; adsorption isotherms, kinetics, thermodynamics

Hybrid material of surgical mask activated carbon (SMAC) and Fe2O3 (SMAC-Fe2O3) composite was prepared by simple co-precipitation method and used as potential material for the remediation of 2,4-dicholrophenol (2,4-DCP). The XRD patterns exhibited the presence of SMAC and Fe2O3, FTIR spectrum showed the FeO-carbon stretching at the wavenumber from 400 to 550 cm-1. UV-Vis DRS results showed the band gap was 1.97 eV and 2.05 eV for SMAC-Fe2O3 and Fe2O3, respectively. The SEM images revealed that the Fe2O3 doped onto the fiber morphology of SMAC. The outcomes of the BET examination exhibited a surface area of 195 m2/g and a pore volume of 0.2062 cm3/g for the SMAC/Fe2O3 composite. The batch mode study shows the maximum adsorption and photocatalytic degradation efficacies which were 97% and 78%, respectively. The experimental data was studied with both linear and nonlinear adsorption isotherm and kinetics models. The nonlinear Langmuir isotherm and pseudo-second-order kinetics (PSOK) models have well fit compared with other models. The Langmuir maximum adsorption capacity (qmax) was found 161.60 mg/g. Thermodynamic analysis shows that the 2,4-DCP adsorption onto SMAC-Fe2O3 was a spontaneous and exothermic process. The PSOK assumes that the adsorption process was chemisorption. The photocatalytic degradation rate constant of 2,4-DCP was calculated using pseudo-first-order kinetics (PFOK) and the rate constant for SMAC-Fe2O3 and Fe2O3 were 0.859 × 10-2 min-1 and 0.616 × 10-2 min-1, correspondingly. In addition, the obtained composite exhibited good reusability after a few cycles. These results confirmed that SMAC-Fe2O3 composite is an effective adsorbent and photocatalyst for removing 2,4-DCP pollutants.

A critical and comprehensive review of the current status of 17β-estradiol hormone remediation through adsorption technology

Even at low concentrations, steroid hormones pose a significant threat to ecosystem health and are classified as micropollutants. Among these, 17β-estradiol (molecular formula: C18H24O2; pKa = 10.46; Log Kow = 4.01; solubility in water = 3.90 mg L-1 at 27 °C; molecular weight: 272.4 g mol-1) is extensively studied as an endocrine disruptor due to its release through natural pathways and widespread use in conventional medicine. 17β-estradiol (E2) is emitted by various sources, such as animal and human excretions, hospital and veterinary clinic effluents, and treatment plants. In aquatic biota, it can cause issues ranging from the feminization of males to inhibiting plant growth. This review aims to identify technologies for remediating E2 in water, revealing that materials like graphene oxides, nanocomposites, and carbonaceous materials are commonly used for adsorption. The pH of the medium, especially in acidic to neutral conditions, affects efficiency, and ambient temperature (298 K) supports the process. The Langmuir and Freundlich models aptly describe isothermal studies, with interactions being of a low-energy, physical nature. Adsorption faces limitations when other ions coexist in the solution. Hybrid treatments exhibit high removal efficiency. To mitigate global E2 pollution, establishing national and international standards with detailed guidelines for advanced treatment systems is crucial. Despite significant advancements in optimizing technologies by the scientific community, there remains a considerable gap in their societal application, primarily due to economic and sustainable factors. Therefore, further studies are necessary, including conducting batch experiments with these adsorbents for large-scale treatment along with economic analyses of the production process.

A state-of-art-review on emerging contaminants: Environmental chemistry, health effect, and modern treatment methods

Pollution problems are increasingly becoming e a priority issue from both scientific and technological points of view. The dispersion and frequency of pollutants in the environment are on the rise, leading to the emergence have been increasing, including of a new class of contaminants that not only impact the environment but also pose risks to people's health. Therefore, developing new methods for identifying and quantifying these pollutants classified as emerging contaminants is imperative. These methods enable regulatory actions that effectively minimize their adverse effects to take steps to regulate and reduce their impact. On the other hand, these new contaminants represent a challenge for current technologies to be adapted to control and remove emerging contaminants and involve innovative, eco-friendly, and sustainable remediation technologies. There is a vast amount of information collected in this review on emerging pollutants, comparing the identification and quantification methods, the technologies applied for their control and remediation, and the policies and regulations necessary for their operation and application. In addition, This review will deal with different aspects of emerging contaminants, their origin, nature, detection, and treatment concerning water and wastewater.

Luminescent Hybrid BPA.DA-NVP@Eu2L3 Materials: In Situ Synthesis, Spectroscopic, Thermal, and Mechanical Characterization

A series of homogeneous hybrid BPA.DA-NVP@Eu2L3 materials were obtained through an in situ approach where the luminescent dopant was formed at the molecular level with different contents (0.1; 0.2; 0.5; 1; and 2% by weight). A Europium(III) complex (Eu2L3) with quinoline-2,4-dicarboxylic acid was applied as a luminescence additive while a polymer matrix consisted of a combination of bisphenol A diacrylate (BPA.DA) and N-vinylpyrrolidone (NVP) monomers. Synthesis steps and the final materials were monitored by NMR and Fourier transform infrared spectroscopy (FTIR). The emission, excitation spectra, lifetime, and quantum yield measurements were applied for the determination of the photophysical characteristics. The thermal and mechanical properties of the obtained materials were tested via thermal analysis methods (TG/DTG/DSC and TG-FTIR) in air and nitrogen atmospheres, dynamic mechanical analysis (DMA), and hardness and bending measurements. Generally, even a small addition of the metal complex component causes changes in the thermal, mechanical, and luminescent properties. Hybrid materials with a greater europium complex content are characterized by a lower stiffness and hardness while the heterogeneity and the flexibility of the samples increase. A very small amount of an Eu2L3 admixture (0.1% wt.) in a hybrid material causes an emission in the red spectral range and the luminescence intensity was reached for the BPA-DA-NVP@1%Eu2L3 material. These materials may be potentially used in chemical sensing, security systems, and protective coatings against UV.

Nanomaterials for Removal of Phenolic Derivatives from Water Systems: Progress and Future Outlooks

Environmental pollution remains one of the most challenging problems facing society worldwide. Much of the problem has been caused by human activities and increased usage of various useful chemical agents that inadvertently find their way into the environment. Triclosan (TCS) and related phenolic compounds and derivatives belong to one class of such chemical agents. In this work, we provide a mini review of these emerging pollutants and an outlook on the state-of-the-art in nanostructured adsorbents and photocatalysts, especially nanostructured materials, that are being developed to address the problems associated with these environmental pollutants worldwide. Of note, the unique properties, structures, and compositions of mesoporous nanomaterials for the removal and decontamination of phenolic compounds and derivatives are discussed. These materials have a great ability to scavenge, adsorb, and even photocatalyze the decomposition of these compounds to mitigate/prevent their possible harmful effects on the environment. By designing and synthesizing them using silica and titania, which are easier to produce, effective adsorbents and photocatalysts that can mitigate the problems caused by TCS and its related phenolic derivatives in the environment could be fabricated. These topics, along with the authors' remarks, are also discussed in this review.

Adsorptive and photocatalytic degradation potential of porous polymeric materials for removal of pesticides, pharmaceuticals, and dyes-based emerging contaminants from water

Life on earth is dependent on clean water, which is crucial for survival. Water supplies are getting contaminated due to the growing human population and its associated industrialization, urbanization, and chemically improved agriculture. Currently, a large number of people struggle to find clean drinking water, a problem that is particularly serious in developing countries. To meet the enormous demand of clean water around the world, there is an urgent need of advanced technologies and materials that are affordable, easy to use, thermally efficient, portable, environmentally benign, and chemically durable. The physical, chemical and biological methods are used to eliminate insoluble materials and soluble pollutants from wastewater. In addition to cost, each treatment carries its limitations in terms of effectiveness, productivity, environmental effect, sludge generation, pre-treatment demands, operating difficulties, and the creation of potentially hazardous byproducts. To overcome the problems of traditional methods, porous polymers have distinguished themselves as practical and efficient materials for the treatment of wastewater because of their distinctive characteristics such as large surface area, chemical versatility, biodegradability, and biocompatibility. This study overviews improvement in manufacturing methods and the sustainable usage of porous polymers for wastewater treatment and explicitly discusses the efficiency of advanced porous polymeric materials for the removal of emerging pollutants viz. pesticides, dyes, and pharmaceuticals whereby adsorption and photocatalytic degradation are considered to be among the most promising methods for their effective removal. Porous polymers are considered excellent adsorbents for the mitigation of these pollutants as they are cost-effective and have greater porosities to facilitate penetration and adhesion of pollutants, thus enhance their adsorption functionality. Appropriately functionalized porous polymers can offer the potential to eliminate hazardous chemicals and making water useful for a variety of purposes thus, numerous types of porous polymers have been selected, discussed and compared especially in terms of their efficiencies against specific pollutants. The study also sheds light on numerous challenges faced by porous polymers in the removal of contaminants, their solutions and some associated toxicity issues.

Application of nanofibrous protein for the purification of contaminated water as a next generational sorption technology: a review

Globally, wastes from agricultural and industrial activities cause water pollution. Pollutants such as microbes, pesticides, and heavy metals in contaminated water bodies beyond their threshold limits result in several diseases like mutagenicity, cancer, gastrointestinal problems, and skin or dermal issues when bioaccumulated via ingestion and dermal contacts. Several technologies have been used in modern times to treat wastes or pollutants such as membrane purification technologies and ionic exchange methods. However, these methods have been recounted to be capital intensive, non-eco-friendly, and need deep technical know-how to operate thus, contributing to their inefficiencies and non-efficacies. This review work evaluated the application of Nanofibrils-protein for the purification of contaminated water. Findings from the study indicated that Nanofibrils protein is economically viable, green, and sustainable when used for water pollutant management or removal because they have outstanding recyclability of wastes without resulting in a secondary phase-pollutant. It is recommended to use residues from dairy industries, agriculture, cattle guano, and wastes from a kitchen in conjunction with nanomaterials to develop nanofibrils protein which has been recounted for the effective removal of micro and micropollutants from wastewater and water. The commercialization of nanofibrils protein for the purification of wastewater and water against pollutants has been tied to novel methods in nanoengineering technology, which depends strongly on the environmental impact in the aqueous ecosystem. So, there is a need to establish a legal framework for the establishment of a nano-based material for the effective purification of water against pollutants.

Hierarchy of hybrid materials. Part-II: The place of organics-on-inorganics in it, their composition and applications

Hybrid materials or hybrids incorporating organic and inorganic constituents are emerging as a very potent and promising class of materials due to the diverse but complementary nature of their properties. This complementarity leads to a perfect synergy of properties of the desired materials and products as well as to an extensive range of their application areas. Recently, we have overviewed and classified hybrid materials describing inorganics-in-organics in Part-I (Saveleva, et al., Front. Chem., 2019, 7, 179). Here, we extend that work in Part-II describing organics-on-inorganics, i.e., inorganic materials modified by organic moieties, their structure and functionalities. Inorganic constituents comprise of colloids/nanoparticles and flat surfaces/matrices comprise of metallic (noble metal, metal oxide, metal-organic framework, magnetic nanoparticles, alloy) and non-metallic (minerals, clays, carbons, and ceramics) materials; while organic additives can include molecules (polymers, fluorescence dyes, surfactants), biomolecules (proteins, carbohydtrates, antibodies and nucleic acids) and even higher-level organisms such as cells, bacteria, and microorganisms. Similarly to what was described in Part-I, we look at similar and dissimilar properties of organic-inorganic materials summarizing those bringing complementarity and composition. A broad range of applications of these hybrid materials is also presented whose development is spurred by engaging different scientific research communities.

Heavy Metal Removal from Aqueous Effluents by TiO2 and ZnO Nanomaterials

The presence of heavy metals in wastewater, such as Ni, Pb, Cd, V, Cr, and Cu, is a serious environmental problem. This kind of inorganic pollutant is not biodegradable for several years, and its harmful effect is cumulative. Recently, semiconductor nanomaterials based on metal oxides have gained interest due to their efficiency in the removal of heavy metals from contaminated water, by inducing photocatalytic ion reduction when they absorb light of the appropriate wavelength. The most commonly applied semiconductor oxides for these purposes are titanium oxide (TiO2), zinc oxide (ZnO), and binary nanomaterials composed of both types of oxides. The main purpose of this work is to critically analyse the existent literature concerning this topic focusing specially in the most important factors affecting the adsorption or photocatalytic capacities of this type of nanomaterials. In particular, photocatalytic activity is altered by various factors, such as proportion of polymorphs, synthesis method, surface area, concentration of defects and particle size, among others. After a survey of the actual literature, it was found that, although these metal oxides have low absorption capacity for visible light, it is possible to obtain an acceptable heavy metal reduction performance by sensitization with dyes, doping with metallic or nonmetallic atoms, introduction of defects, or the coupling of two or more semiconductors.

Recent advances in carbon-based nanomaterials for the treatment of toxic inorganic pollutants in wastewater

Wastewater contains inorganic pollutants, generated by industrial and domestic sources, such as heavy metals, antibiotics, and chemical pesticides, and these pollutants cause many environmental problems.

Mesoporous Silica Modified with 2-Phenylimidazo[1,2-a] pyridine-3-carbaldehyde as an Effective Adsorbent for Cu(II) from Aqueous Solutions: A Combined Experimental and Theoretical Study

In this study, we will present an efficient and selective adsorbent for the removal of Cu(II) ions from aqueous solutions. The silica-based adsorbent is functionalized by 2-phenylimidazo[1,2-a] pyridine-3-carbaldehyde (SiN-imd-py) and the characterization was carried out by applying various techniques including FT-IR, SEM, TGA and elemental analysis. The SiN-imd-py adsorbent shows a good selectivity and high adsorption capacity towards Cu(II) and reached 100 mg/g at pH = 6 and T = 25 °C. This adsorption capacity is important compared to other similar adsorbents which are currently published. The adsorption mechanism, thermodynamics, reusability and the effect of different experimental conditions, such as contact time, pH and temperature, on the adsorption process, were also investigated. In addition, a theoretical study was carried out to understand the adsorption mechanism and the active sites of the adsorbent, as well as the stability of the complex formed and the nature of the bonds.

Mechanisms of NO2 Detection in Hybrid Structures Containing Reduced Graphene Oxide: A Review

The sensitive detection of harmful gases, in particular nitrogen dioxide, is very important for our health and environment protection. Therefore, many papers on sensor materials used for NO₂ detection have been published in recent years. Materials based on graphene and reduced graphene oxide deserve special attention, as they exhibit excellent sensor properties compared to the other materials. In this paper, we present the most recent advances in rGO hybrid materials developed for NO₂ detection. We discuss their properties and, in particular, the mechanism of their interaction with NO₂. We also present current problems occuring in this field.

Molybdenum Modified Sol–Gel Synthesized TiO2 for the Photocatalytic Degradation of Carbamazepine under UV Irradiation

Pharmaceutical CEC compounds are a potential threat to man, animals, and the environment. In this study, a sol–gel-derived TiO2 (SynTiO2) was produced and subsequently sonochemically doped with a 1.5 wt% Mo to obtain the final product (Mo (1.5 wt%)/SynTiO2). The as-prepared materials were characterized for phase structure, surface, and optical properties by XRD, TEM, N2 adsorption–desorption BET isotherm at 77 K, and PSD by BJH applications, FTIR, XPS, and UV-Vis measurements in DRS mode. Estimated average crystallite size, particle size, surface area, pore-volume, pore size, and energy bandgap were 16.10 nm, 24.55 nm, 43.30 m2/g, 0.07 cm3/g, 6.23 nm, and 3.05 eV, respectively, for Mo/SynTiO2. The same structural parameters were also estimated for the unmodified SynTiO2 with respective values of 14.24 nm, 16.02 nm, 133.87 m2/g, 0.08 cm3/g, 2.32 nm, and 3.3 eV. Structurally improved (Mo (1.5 wt%)/SynTiO2) achieved ≈100% carbamazepine (CBZ) degradation after 240 min UV irradiation under natural (unmodified) pH conditions. Effects of initial pH, catalyst dosage, initial pollutant concentration, chemical scavengers, contaminant ions, hydrogen peroxide (H2O2), and humic acid (HA) were also investigated and discussed. The chemical scavenger test was used to propose involved photocatalytic degradation process mechanism of CBZ.