Tuning of metal oxides photocatalytic performance using Ag nanoparticles integration

Nanomaterials with Excellent Adsorption Characteristics for Sample Pretreatment: A Review

Sample pretreatment in analytical chemistry is critical, and the selection of materials for sample pretreatment is a key factor for high enrichment ability, good practicality, and satisfactory recoveries. In this review, the recent progress of the sample pretreatment methods based on various nanomaterials (i.e., carbon nanomaterials, porous nanomaterials, and magnetic nanomaterials) with excellent adsorption efficiency, selectivity, and reproducibility, as well as their applications, are presented. Due to the unique nanoscale physical–chemical properties, magnetic nanomaterials have been used for the extraction of target analytes by easy-to-handle magnetic separation under a magnetic field, which can avoid cumbersome centrifugation and filtration steps. This review also highlights the preparation process and reaction mechanism of nanomaterials used in the sample pretreatment methods, which have been applied for the extraction organophosphorus pesticides, fluoroquinolone antibiotics, phenoxy carboxylic acids, tetracycline antibiotics, hazardous metal ions, and rosmarinic acid. In addition, the remaining challenges and future directions for nanomaterials used as sorbents in the sample pretreatment are discussed.

Functionalization of MXene-based nanomaterials for the treatment of micropollutants in aquatic system: A review

The increased industrialization and urbanization generate a larger quantity of effluent that is discharged into the environment regularly. Based on the effluent composition produced from various industries, the number of hazardous substances such as heavy metals, hydrocarbons, volatile organic compounds, organic chemicals, microorganisms introduced into the aquatic systems vary. The conventional wastewater treatment systems do not meet the effluent standards before discharge and require a different treatment system before reuse. Adsorption is an eco-friendly technique that uses selective adsorbents to remove hazardous pollutants even at microscale levels. MXene, a 2-Dimensional nanomaterial with resplendent properties like conductivity, hydrophilicity, stability, and functionalized surface characteristics, is found as a potential candidate for pollutant removal systems. This review discusses the fabrication, characterization, and application of MXene based nanoparticles to remove many pollutants in water treatment systems. The improvement in surface properties and adsorption capacity of MXene based NPs, when modified using different modification agents, has also been discussed. Their feasibility in terms of economic and environmental aspects has been evaluated to understand their scope for practical application in large-scale industries. The challenges towards the synthesis and toxicity's importance have been discussed, with the appropriate recommendations.

Improving photocatalytic activity of the ZnS QDs via lanthanide doping and photosensitizing with GO and g-C3N4 for degradation of an azo dye and bisphenol-A under visible light irradiation

In this research, insertion of Gd ions (2 wt%) into the crystalline lattice of the ZnS QDs enhanced the photocatalytic activity of the QDs. In addition, the influence of graphene oxide (GO) and graphitic carbon nitride (g-C₃N₄) was assessed on the photocatalytic activity of the ZnS QDs through degradation of acid red 14 (AR14) and bisphenol-A (BA) under visible light. Higher photocatalytic degradation efficiency (97.1% for AR14 and 67.4% for BA within 180 min) and higher total organic carbon (TOC) removal (67.1% for AR14 and 59.2% for BA within 5 h) was achieved in the presence of ZnS QDs/g-C₃N₄ compared with ZnS QDs/GO nanocomposite. Finally, the Gd-doped ZnS QDs were hybridized with g-C₃N₄ as optimal support to fabricate a potent visible-light-driven photocatalyst for the decomposition of organic contaminants. The maximum photocatalytic degradation of 99.1% and 80.5% were achieved for AR14 and BA, respectively, in the presence of Gd-doped ZnS QDs/g-C₃N₄ nanocomposite. The photosensitization mechanism was suggested for the improved photocatalytic activity of the ZnS QDs/GO, ZnS QDs/g-C₃N₄, and Gd-doped ZnS QDs/g-C₃N₄ nanocomposites under visible light.

Synthesis and characterization of Ag-ion-exchanged zeolite/TiO2 nanocomposites for antibacterial applications and photocatalytic degradation of antibiotics

This paper investigates the synthesis, antibacterial, and photocatalytic properties of silver ion-exchanged natural zeolite/TiO₂ photocatalyst nanocomposite. Zeolite is known to have a porous surface structure, making it an ideal substrate and framework in different nanocomposites. Moreover, natural zeolite has a superior thermal and chemical stability, with hardly any reactivity with chemicals. Finding an effective and low-cost method to remove both antibiotics and bacteria from water resources has become a vital global issue due to the worldwide excessive use of chemicals and antibiotics. This research aims to propose a facile method to synthesize Ag-ion-exchanged zeolite/TiO₂ catalyst for anti-bacterial purposes and photocatalytic removal of atibiotics from wastewaters. TiO₂ particles were deposited on the surface of natural zeolite. Ag ion exchanging was performed via a liquid ion-exchange method using 0.1 M AgNO₃ solution. X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Fourier-transform infrared spectroscopy (FTIR) were used to evaluate the structure of synthesized powders. Antibacterial activities of samples were assessed, using Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922 by disc diffusion method. It was shown that Ag-containing nanocomposite samples have an improved antibacterial performance in both cases. Results showed that the synthesized catalyst has promising potentials in wastewater treatment.

A novel bio-solid phase extractor for preconcentrations of Hg and Sn in food samples

An ecofriendly preconcentration method was developed based on the use of Geobacillus galactosidasius sp. nov immobilized on Amberlite XAD-4 as an adsorbent for the preconcentrations of Hg and Sn. SEM-EDX performed for the investigation of surface functionality and morphology. The detailed investigations of factors such as pH of the solution, flow rate, interfering ions and sample volume have been thanks to the optimization of the pre-concentration system. The optimum pHs were found as 5.0-7.0 for Hg and Sn and also the optimum flow rates were determined as 2 mL min^-1 for recovery of Hg and Sn. Under the best experimental conditions, limits of detections (LOD) were found as 0.53 ng mL^-1 for Hg and 0.27 ng mL^-1 for Sn. RSDs were calculated as 8.2% for Hg and 6.9% for Sn. The process was validated to use certified references (fish samples). ICP-OES was used to measure the levels of Hg and Sn in various real meal patterns after the devised technique was used. Concentrations of Hg and Sn were quantitively measured on gluten-free biscuit, flour, rice, Tuna fish, meat, chicken meat, potato, chocolate, coffee, tap water, energy drink and mineral water samples with low RSD. The developed method emerges as an innovative technology that will eliminate the low cost and toxic effect.

Synthesis, Structure, and Photocatalytic Activity of TiO2-Montmorillonite Composites

In the present study, TiO2-montmorillonite (MMT) composites were synthesized hydrothermally under variable conditions, including the TiO2/MMT mass ratio, reaction pH, reaction temperature, and dwelling time. These samples were determined by X-ray photoelectron spectrometry (XPS), ultraviolet–visible spectroscopy% (UV-Vis DRS), electrochemical impedance spectroscopy (EIS), transient photocurrent responses, photoluminescence (PL) spectra, electron paramagnetic resonance (EPR), and N2 adsorption–desorption isotherms. The photocatalytic activity was evaluated as the ability to promote the visible-light-driven degradation of 30 mg/L of aqueous methylene blue, which was maximized for the composite with a TiO2 mass ratio of 30 wt% prepared at a pH of 6, a reaction temperature of 160 °C, and a dwelling time of 24 h (denoted as 30%-TM), which achieved a methylene blue removal efficiency of 95.6%, which was 4.9 times higher than that of pure TiO2. The unit cell volume and crystallite size of 30%-TM were 92.43 Å3 and 9.28 nm, respectively, with a relatively uniform distribution of TiO2 particles on the MMT’s surface. In addition, 30%-TM had a large specific surface area, a strong light absorption capacity, and a high Ti3+ content among the studied catalysts. Thus, the present study provides a basis for the synthesis of composites with controlled structures.

Current perspective in metal oxide based photocatalysts for virus disinfection: A review

Nanotechnology holds huge potential for the prevention of various viral outbreaks that have increased at a disquieting rate over the past decades. Metal oxide nanomaterials with oxidative capability are the effective materials that provide platforms as well as tools for the well understanding of the mechanism, its detection, and treatment of various viral diseases like measles, influenza, herpes, ebola, current COVID-19 etc. In this inclusive review, we survey various previous research articles on different notable photoactive transition metal oxides that possess enough potential to act as antiviral agents for the deactivation of harmful viruses. We investigated and highlighted the plausible photocatalytic oxidative mechanism of photoactive transition metal oxides in degrading viral coatings, genomic RNA using suitable free radical generation. The key finding of the present review article including the discovery of a vision on the suitable photocatalytic transition metal oxides that have been proven to be excellent against harmful viruses and consequently combatting deadly CoV-2 in the environment. This review intends to provide conclusive remarks and a realistic outlook on other advanced photocatalytic metal oxides as a potential solution in battling other similar upcoming pandemics.

Nanomaterials: An alternative source for biodegradation of toxic dyes

Environment contamination is a colossal worriment across the world, owing to its detrimental and negative impact on health and ecological systems. Dyes are one of the synthetic organic chemicals that are utilised in a variety of fields, including textiles. As a result, throughout one's production and subsequently in fibre colouring, these are becoming frequent industry-contributed contaminants. Increasing globalisation of international market has presented a problem to textile sector in terms of consistency and production. Textile processors' primary concern, as the highly competitive environment and environmental standards grow more severe is about being mindful of the grade of goods and even non-toxicity of their production processes. There seems to be an immediate necessity to look for methods and technologies which are useful in removing dye colours. Even though each has benefits and weaknesses, many physical, chemical, and biological approaches were explored and used with the application being dependent on the effluent properties, technical feasibility, and cost. Several remediation technologies are already developed, but they seem to be ineffective at removing dyes completely. There is a fast growth of nanoparticles applications in the past few years which has opened up newer, innovating, highly efficient, and low-cost dyes remediation systems. Nanomaterials with large surface areas change surface characteristics and distinctive electron conducting capabilities which make them ideal candidate for the treatment of wastewater that contains dyes. In this review, we have highlighted not only the role of nanotechnology in dye remediation processes but also different types of nanomaterials that can be used for the remediation of dyes.

Phyto-mediated synthesis of nanoparticles and their applications on hydrogen generation on NaBH4, biological activities and photodegradation on azo dyes: Development of machine learning model

This work reports the synthesis of the silver-platinum bimetallic nanoparticles (N@Pt-Ag BNPs) reduced by an ethanolic extract of black seed (Nigella sativa, N) using the green synthesis method, these nanoparticles show a great antibacterial, anticancer, and catalytic activity. The characterization of physicochemical properties of Ag-Pt BNP was carried out using UV-visible spectroscopy (Uv-vis), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Transmission electron microscope (TEM) analysis. The structural morphology shows that the N@Pt-Ag BNPs are spherical particles with a diameter of 5.6 nm. The cytotoxic effects of N@Pt-Ag BNPs were examined by MTT test in human breast cancer, human colon cancer, human pancreatic cancer, L929-Murine fibroblast cells. N@Pt-Ag BNPs have been observed to be much more effective in breast cancer cell lines. The cytotoxic effect of N@Pt-Ag BNPs against healthy L929-murine fibroblast cell lines was not observed. Also, high antibacterial activity on each of the bacteria Escherichia coli (E. coli), Bacillus subtilis (B. subtilis), Methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus aureus (S. aureus), where we note that most strains of E. coli and S. aureus were damaged with a 73% percentage, 67% bacterial inhibition respectively. The results of the catalytic activities of N@Pt-Ag BNPs were obtained by performing the hydrolysis experiments of sodium borohydride (NaBH₄). According to the results obtained, TOF, enthalpy, entropy, and activation energy, values were found to be 2497.14 h^-1, 13.52 kJ/mol, -137.47 J/mol.K, 16.02 kJ/mol, respectively. N@Pt-Ag BNPs were found to be highly effective catalysts for hydrogen production which this was also confirmed by the machine learning model. The photocatalytic activity of N@Pt-Ag BNPs was tested against methylene blue (MB) dye and the highest activity was found as 80%.

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

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

Low-temperature synthesis of hetero-structures of magnetically separable iron oxide@Au-rGO nanocomposite for efficient degradation of organic dye under visible light irradiation

In the present study, Fe₃O₄@Au core-shell nanoparticles decorated on reduce graphene oxide (Fe₃O₄@Au/rGO) nanocomposite were synthesized using the reduction method by sodium citrate, Hummer's method, and hydrothermal method, respectively. The as-prepared nanostructures were characterized by X-ray diffraction (XRD), Energy Dispersive X-ray (EDX), transmission electron microscopy (TEM), scanning electron microscopy (SEM)to assess the surface features, crystallinity and morphological characteristics. These nanostructures were employed for photocatalytic degradation of crystal violet (CV), and amongst them, Fe₃O₄@Au/rGO nanocomposite offered the best results under the visible light irradiation and optimal conditions. The effect of the amount of nano-photocatalyst, initial CV concentration, the initial pH, temperature, stirring speed, and degradation time was evaluated individually. A 100% degradation was obtained after 1 min in the presence of 0.008 g nano-photocatalyst, and also 100% of degradation was achieved after 5 min in the presence of 0.005 g of the prepared nano-photocatalyst. After a few tests, its photocatalytic performance was retained, implying the superior stability of Fe₃O₄@Au/rGO nanocomposite. The kinetic study of photocatalytic degradation also indicated that the fit model for the kinetic reaction was the pseudo-second-order kinetic model. Finally, the photocatalytic degradation of real samples with synthesized nanocomposite showed promising results.

A review of boron removal from aqueous solution using carbon-based materials: An assessment of health risks

Carbon-based compounds have gained attention of researchers for use in boron removal due to their properties, which make them a viable and low cost adsorbent with a high availability, as well as environmental friendliness and high removal efficiency. The removal of boron utilizing carbon-based materials, including activated carbon (AC), graphene oxide (GO), and carbon nanotubes (CNTs), is extensively reviewed in this paper. The effects of the operating conditions, kinetics, isotherm models, and removal methods are also elaborated. The impact of the modification of the lifetime of carbon-based materials has also been explored. Compared to unmodified carbon-based materials, modified materials have a significantly higher boron adsorption capability. It has been observed that adding various elements to carbon-based materials improves their surface area, functional groups, and pore volume. Tartaric acid, one of these doped elements, has been employed to successfully improve the boron removal and adsorption capabilities of materials. An assessment of the health risk posed to humans by boron in treated water utilizing carbon-based materials was performed to better understand the performance of materials in real-world applications. Furthermore, the boron removal effectiveness of carbon-based materials was evaluated, as well as any shortcomings, future perspectives, and gaps in the literature.

Occurrences and removal of pharmaceutical and personal care products from aquatic systems using advanced treatment- A review

Pharmaceuticals, personal care items, steroid hormones, and agrochemicals are among the synthetic and indigenous products that make up micropollutants, also known as emerging contaminants. Pharmaceutical and personal care products (PPPs) are a class of developing micropollutants that can harm living organisms even at low concentrations. Many are detected in surface water and wastewater from the treatment process, with quantities ranging from ng L-1 to gL-1; however, residual PPPs at dangerously high levels have indeed recently been recognized in the ecosystem. Residential sewage treatment plant (STP) dump the largest majority of these pollutants into the environment on a regular basis. As a result of its robust structure, it has a longer lifespan in the environment. This review article discusses how surface water pollutants such pesticides, petroleum hydrocarbons, and perfluorinated compounds affect water quality, as well as the most cost-effective adsorbents for removing these PPPs. The goal of this study is to provide information about the origins of PPP, as well as diagnostic procedures and treatment options. Research on developing contaminants is also aimed at evaluating the efficacy and affordability of adsorption.

Study on particle radiative properties of lignite, hard coal and biomass fly ashes in the infrared wavelength range

Fly ash, which is a by-product of combustion in furnaces or boilers, is used in certain materials as an additive for waste recycling. The optical properties of fly ash and the effects on the heat transfer phenomena of materials used in engineering applications differ and depend on the kind of solid fuel and the combustion conditions. The morphological and the radiative properties of fly ash samples of Turkish lignite, biomass, and hard coal that are burned in different thermal power plants were studied herein. The samples, which were collected from cyclones, were morphologically examined using scanning electron microscopy (SEM) images, and their chemical compositions were analysed by energy dispersive x-ray spectroscopy (EDX). Absorbance measurements were made in the wavelength range from 2.5 to 25 μm, and the discrete dipole approximation (DDA) was applied for a numerical assessment of the radiative properties of the samples. The measured absorbance values of all samples for particle diameters of 25 and 75 μm displayed significant differences in the related wavelength range. The most prominent change was observed in the biomass sample, and the hard coal fly ash had the lowest absorbance values in the related spectrum range. Although the particle shapes of lignite and biomass fly ashes are not same, the changes in the measured absorbance values were similar. The effects of the k index of the complex refractive index (CRI) on the radiative properties were examined for values of 0.01, 0.1, 0.3, 0.5 and 1.0. According to the measured absorption values and the calculated absorption efficiency results, the k index may be between 0.3 and 1.0 at the related wavelength range. It was concluded that the effects of the particle size and absorption index of fly ash on the heat transfer properties are important in the specified wavelength range.

New fabrication of CuFe2O4/PAMAM nanocomposites by an efficient removal performance for organic dyes: Kinetic study

Today, removing pollutants from water sources is essential because of the population increase and the growing need for safe drinking water. Dyes are one of the most critical pollutants from industrial effluents such as paper and textile industries that profoundly affect the environment. There are several ways to remove environmental contaminants. Magnetic nanoparticles have a high ability to adsorb dyes. Of course, increasing the interaction between magnetic nanomaterials and pollutants is also essential, which can be done using porous materials such as dendrimers. In this work, the synthesis of CuFe₂O₄ magnetite nanoparticles within the polyamidoamine dendrimers structure was used as an efficient sorbent to remove both alizarin reds (ARS) and brilliant green (BG) dyes. Moreover, various parameters for dyes removal were studied. The optimum removal conditions were obtained for ARS within 30 min at a sorbent dose of 2 mg per 5 mL for the initial dye concentration of 7.0 ppm in pH 6 at 25 °C, and for BG within 45 min at a sorbent dose of 5 mg per 5 mL for the initial dye concentration of 17.0 ppm in pH 8 at 25 °C. At the optimum values of the above parameters, both dyes' removal efficiency was more than 97%. Also, the obtained results showed that the adsorption isotherm follows the Langmuir model and Temkin model for ARS and BG, respectively. This method was successfully used for the removal of both dyes in water samples.

Arum italicum mediated silver nanoparticles: Synthesis and investigation of some biochemical parameters

The science world advancing day by day contributes to living systems in many areas with the development of nanotechnology. Besides being easily obtained from plants, the advantages it brings increase the importance of nanotechnology. Environmentally friendly, economical, and compatible with plants are just a few of the advantages it brings. Silver metal is one of the most preferred active ingredients in nanoparticle synthesis. Arum italicum is used in the treatment of various diseases in the health sector due to the structures it contains. In our study, nanoparticle synthesis was made by using Ag metal with Arum italicum plant. Then, the antimicrobial, DNA damage prevention and DPPH radical quenching activity of Ag NPs/Ai nanoparticles were investigated. The interaction of the plant with Ag, analysis by X-ray diffraction (XRD), UV visible spectrophotometer (UV-vis), scanning electron microscope and energy dispersive X-ray (SEM-EDX), Fourier-converted infrared spectroscopy (FT-IR) methods has been done. It has been observed that Ag NPs/Ai clusters formed by Arum italicum with Ag have an antibacterial effect against Bacillus subtilis, Bacillus cereus, Enterococcus faecalis, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli pathogens. However, an antifungal effect hasn't been observed against Candida albicans fungus. Pseudomonas aeruginosa bacteria exerted a stronger effect than an antibiotic. It is seen that Ag NPs/Ai has a protective and anti-damage effect against DNA damage. The antioxidant effect of Ag NPs/Ai is remarkable when DPPH radical quenching activity is compared to positive control BHA and BHT.

Determination of exposure to major iodide ion uptake inhibitors through drinking waters

Goiter, abnormal enlargement of the thyroid gland, is a significant worldwide public health problem. Iodine deficiency is known as the most common cause. Iodine is actively transported as iodide ion (I^-) using Sodium Iodide Symporter (NIS) and sufficient blocking of I^- transportation prevents the synthesis of thyroid hormones. The transportation can be blocked by some polyatomic anions known as I^- uptake inhibitors. Perchlorate (ClO₄^-), thiocyanate (SCN^-) and nitrate (NO₃^-) are reported as the major I^- uptake inhibitors and exposure could be through various routes. Drinking water is an important exposure route. Since water is essential to sustain life, drinking water safety is very important for the protection of public health. However, as a result of natural and human-based processes, water can be contaminated and contamination of drinking water is a global food safety problem due to causing significant health and environmental problemsIn that context, this study aims to determine exposure levels to I^- uptake inhibitors that arise from drinking waters at five different districts in Antalya, Turkey. Collected water samples contained NO₃^- and ClO₄^- in the range of 0.86-47.42 mg/L and <LOQ-0.11 mg/L, respectively. SCN^- levels were <LOQ in all samples. Daily exposure was calculated for different age groups of 2-65+ years using contaminant levels, water consumption and body weight data. Mean NO₃^- and ClO₄^- exposure levels were in the range of 115.89-375.06 and 0.07-0.22 μg/kg bw/d, respectively. Exposure levels were decreased with increasing age and the highest exposure levels were calculated for children due to their lower body weight. Although no risk was determined for the I^- uptake inhibitors in tested locations based on the guideline values recommended by EPA and WHO, there has been a need for more exposure assessment studies in the areas where the high prevalence of goiter is observed all over the world.

Spectral and structure characterization of Ferula assafoetida fabricated silver nanoparticles and evaluation of its cytotoxic, and photocatalytic competence

This study aims to develop an eco-friendly method for rapidly synthesizing silver nanoparticles (AgNPs) using Asafoetida ethanol extracts and to validate AgNPs synthesis using UV-vis spectroscopy (absorption spectrum), FTIR (functional groups), XRD (crystallinity), FE-SEM (size of the particles) and SEM-EDAX (Purity). Furthermore, to evaluate the anti-proliferative effect of Ag NPs against grown cultured L6 cell lines, studies have shown that AgNPs biosynthesis inhibits cancer cell growth compared to control cell lines. UV-vis absorption verified the existence of Ag NPs, and the spectrum was observed at 480 nm. Functional groups are present in the synthesized Ag NPs were shifted on 528.48 cm^-1 confirmed using an FT-IR spectrum. Consequently, anti-cancer efficacy observed the IC₅₀ value of As Ag NPs against L6 cells was 1.0 μg/mL for 48 h. Finally, using a halogen lamp, studies explored the photocatalytic degradation of AgNPs against the methylene blue radioactive dye and achieved a 96 percent degradation rate in 90 min. Asafoetida mediated silver nanoparticles show grater photodegradation for methylene blue dye, which is present in textile industries, when exposed to solar light, and it has a wide range of potential applications in wastewater treatment. As a whole, biosynthesized silver nanoparticles showed excellent cytotoxic, antioxidant, and photocatalytic dye degradation effects.

Synthesis, Characterization, Photocatalysis, and Antibacterial Study of WO3, MXene and WO3/MXene Nanocomposite

Tungsten oxide (WO₃), MXene, and an WO₃/MXene nanocomposite were synthesized to study their photocatalytic and biological applications. Tungsten oxide was synthesized by an easy and cost-effective hydrothermal method, and its composite with MXene was prepared through the sonication method. The synthesized tungsten oxide, MXene, and its composite were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR), energy-dispersive X-ray analysis (EDX), and Brunauer–Emmett–Teller (BET) for their structural, morphological, spectral, elemental and surface area analysis, respectively. The crystallite size of WO₃ calculated from XRD was ~10 nm, the particle size of WO₃ was 130 nm, and the average thickness of MXene layers was 175 nm, which was calculated from FESEM. The photocatalytic activity of as-synthesized samples was carried out for the degradation of methylene blue under solar radiation, MXene, the WO₃/MXene composite, and WO₃ exhibited 54%, 89%, and 99% photocatalytic degradation, respectively. WO₃ showed maximal degradation ability; by adding WO₃ to MXene, the degradation ability of MXene was enhanced. Studies on antibacterial activity demonstrated that these samples are good antibacterial agents against positive strains, and their antibacterial activity against negative strains depends upon their concentration. Against positive strains, the WO₃/MXene composite’s inhibition zone was at 7 mm, while it became 9 mm upon increasing the concentration. This study proves that WO₃, MXene, and the WO₃/MXene nanocomposite could be used in biological and environmental applications.

Orange peel extract influenced partial transformation of SnO2 to SnO in green 3D-ZnO/SnO2 system for chlorophenol degradation

In recent times, visible light enhancement has become much more considered due to the enlightening properties of nanocomposite systems. This has potential applications for wastewater treatment due to the blemish of toxic organic chemicals from industrial sectors. Therefore, this work is focused on novel 3D ZnO/SnO₂ nanocomposites synthesized by the green method (orange peel extracts supported combined chemical processes) utilized for the removal of chlorophenol effluent. The orange peel extract has been incorporated as one of the major components to synthesize an effective nanocomposite. Also, the pure materials were synthesized along with these nanocomposites and tested under various instrumental techniques. The characterized results showed that the composites prepared with orange peel extract exhibited hexagonal 3D ZnO nanospheres with 3D tetragonal structured SnO₂ nanocubes. Elemental analysis showed that the partial amount of SnO₂ has transformed to SnO due to the reducing ability of orange peel extract. Also, the existing different (Zn²⁺, Sn⁴⁺, and Sn²⁺) states helped in delaying the transfer of electron-hole recombination to obtain photocatalytic chlorophenol degradation. Further, the prevailing line dislocation can compromise more vacancy and interact with more electrons. The high surface area, least crystallite size, and lower bandgap inspired to enhance the visible light activity. Simultaneously, the pure form of nanomaterial has poor light absorption under visible light. This study achieves the photocatalytic degradation of 77.5% against chlorophenol using a green 3D composite system.

CoFe2O4 nanoparticles decorated onto graphene oxide and graphitic carbon nitride layers as a separable catalyst for ultrasound-assisted photocatalytic degradation of Bisphenol-A

The advanced oxidation process (AOP) through ultrasound-assisted photocatalytic degradation has attracted much attention in removing emerging contaminants. Herein, CoFe₂O₄-GO and CoFe₂O₄-g-C₃N₄ nanocomposites were synthesized using the ultrasound-assisted co-precipitation method. TEM, XRD, XPS, EDS, SEM, and FT-IR techniques characterized the structural, morphological, and chemical properties of the synthesized nanocomposites. The analyses showed that CoFe₂O₄ structure was nano-sized and distributed more homogeneously in graphene oxide (GO) layers with oxygenated functional groups than graphitic carbon nitride (g-C₃N₄). While the efficiency of composite catalysts, as photocatalysts, for degradation of bisphenol-A (BPA) was low in the visible region in the presence of persulfate, their catalytic efficacy was higher with sonolytic activation. The addition of persulfate as an oxidant remarkably enhanced the target pollutant degradation and TOC removal of BPA solution. Both composite catalysts showed 100 % BPA removal with the synergistic effect of visible region photocatalytic oxidation and sonocatalytic oxidation in the presence of persulfate at pH 6.8. In ultrasound-assisted photocatalytic oxidation of BPA, the highest mineralization efficiencies were obtained at 2 h treatment time, pH 6.8, 16 mM PS, catalyst dosages of 0.1 g/L CoFe₂O₄-GO, and 0.4 g/L CoFe₂O₄-g-C₃N₄ as 62 % and 55 %, respectively. An effective catalyst was obtained by reducing e^-/h⁺ recombination and charge transfer resistance by decorating the GO layers with CoFe₂O₄.

Boosting Output Performance of Triboelectric Nanogenerator via Mutual Coupling Effects Enabled Photon-Carriers and Plasmon

Boosting the output performance of triboelectric nanogenerators via some unique methods is always a meaningful way to speed up their commercialization. However, the available approach to boost performance is mainly restricted to one physics effect based and the basic research of boosting performance via mutual coupling effects is little research. Herein, a new strategy is creatively proposed based on charge traps from mutual coupling effects, generated from g-C3 N4 /MXene-Au composites, to further promote the output performance of triboelectric nanogenerator. It is found that photon-generated carriers coupling surface plasmon effect enables composites filled into tribo-material with visible light is an excellent value in boosting performance. The charge traps from mutual coupling effects for boosting performance are analyzed theoretically and verified by experiments. The output power of boosting-triboelectric nanogenerator (TENG) achieves a sixfold enhancement (20 mW) of normal TENG with polydimethylsiloxane (PDMS) in ambient conditions. This work provides a profound understanding of the working mechanism of mutual coupling effects boosting the performance of TENG and an effective way for promoting TENG output.

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

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

Removal of metal ions using a new magnetic chitosan nano-bio-adsorbent; A powerful approach in water treatment

In this study, a magnetic chitosan/Al₂O₃/Fe₃O₄ (M-Cs) nanocomposite was developed by ethylenediaminetetraacetic acid (EDTA) functionalization to enhance its adsorption behavior for the removal of Cd(II), Cu(II) and Zn(II) metal ions from aqueous solution. The results revealed that the EDTA functionalization of M-Cs increased its adsorption capacity ~9.1, ~5.6 and ~14.3 times toward Cu, Cd and Zn ions. The maximum adsorption capacity followed the order of Cd(II) > Cu(II) > Zn(II) and the maximum adsorption efficiency was achieved at pH of 5.3 with the removal percentage of 99.98, 93.69 and 83.81 %, respectively, for the removal of Cu, Cd and Zn ions. The metal ions adsorption kinetic obeyed pseudo-second-order equation and the Langmuir isothermal was found the most fitted model for their adsorption isothermal experimental data. In addition, the thermodynamic study illustrated that the adsorption process was exothermic and spontaneous in nature.

Determination of Salicylic Acid Using a Highly Sensitive and New Electroanalytical Sensor

Background:

A drug sensor (salicylic acid, in this case) was designed and made up of this research. The senor was made by modification of paste electrode (MPE) with CuO-SWCNTs and 1-hexyl-3-methylimidazolium chloride (HMICl). The MPE/CuO-SWCNTs/HMICl showed catalytic activity for the oxidation signal of salicylic acid in phosphate buffer solution.

Methods:

Electrochemical methods were used as a powerful strategy for the determination of salicylic acid in pharmaceutical samples. Aiming at this goal, carbon paste electrode was amplified with conductive materials and used as a working electrode.

Results:

The MPE/CuO-SWCNTs/HMICl was used for the determination of salicylic acid in the concentration range of 1.0 nM – 230 µM using differential pulse voltammetric (DPV) method. At pH=7.0, as optimum condition, the MPE/CuOSWCNTs/HMICl displayed a high-quality ability for the determination of salicylic acid in urine, pharmaceutical serum, and water samples.

Conclusion:

The MPE/CuO-SWCNTs/HMICl was successfully used as a new and high performance working electrode for the determination of salicylic acid at a nanomolar level and in real samples.

A review on recent trends in the removal of emerging contaminants from aquatic environment using low-cost adsorbents

Emerging contaminants (ECs), a class of contaminants with low concentrations but significant harm, have received a lot of attention in recent times. ECs comprises of various chemicals that enter the environment every day. In today's modern lifestyle, we use many chemical-based products. These persist in wastewater and ultimately enter the water bodies, causing serious problems to the human and aquatic ecosystem. This is because the conventional wastewater treatment methods are inefficient in identifying and removing such contaminants. Aiming for a long-term, effective solution to this issue, Adsorption was proposed. Although several adsorbents are already present in the market, which have proved beneficial in removing such ECs, not all are affordable. This article reviews replacing costly adsorbents with agriculture-based biomass that are abundant, inexpensive, and biodegradable and possess excellent adsorption capacity. The objectives of this article is to look at adsorption as a viable treatment option for emerging pollutants, as well as sophisticated and cost-effective emerging contaminants treatment options.

Natural, low-cost adsorbents for toxic Pb(II) ion sequestration from (waste)water: A state-of-the-art review

Pb(II) ions is an inorganic pollutant that is present in the environment. Its presence affects both human health and ecosystem. Economically, amongst many wastewater treatment approaches, adsorption is both cheap and environmentally friendly for removing Pb(II) ion from contaminated water. In this state of the art review, about 227 research and review based publications on adsorption-based studies between 1989 and 2021, which have used various materials as adsorbents of Pb (II) ions, were selected and reviewed for more evaluation. A number of adsorbents which have been reported in these literatures for the adsorption of Pb(II) ion are agrobased, modified agrobased, clay minerals, modified/nanocomposite clay minerals, silica-based, zeolite-based and chitosan-based adsorbents, respectively. The adsorption potential of the adsorbents is exhibited under optimum experimental conditions. The unmodified and modified agro based adsorbents were shown to exhibit the greatest Pb(II) adsorption capacity, with great potential for further exploration, compared to the others afore-listed. The effects of operating parameters such as pH, initial metal ion concentration, adsorbent dose and reaction time are discussed. Furthermore, in order to comprehend the nature of adsorption process between the adsorbent and contaminant (Pb(II)), thermodynamic analyses of adsorption systems are intensively described. All these discussions revealed the applicability of adsorption process for toxic Pb(II) ions removal with respect to wastewater treatment techniques. The review concludes by commenting on the various adsorbents' adsorption capacity and proposes some studies that should also be considered in future works.

Recent Advantages of Mediator Based Chemically Modified Electrodes; Powerful Approach in Electroanalytical Chemistry

Background:

Modified electrodes have advanced from the initial studies aimed at understanding electron transfer in films to applications in areas such as energy production and analytical chemistry. This review emphasizes the major classes of modified electrodes with mediators that are being explored for improving analytical methodology. Chemically modified electrodes (CMEs) have been widely used to counter the problems of poor sensitivity and selectivity faced in bare electrodes. We have briefly reviewed the organometallic and organic mediators that have been extensively employed to engineer adapted electrode surfaces for the detection of different compounds. Also, the characteristics of the materials that improve the electrocatalytic activity of the modified surfaces are discussed.

Objective:

Improvement and promotion of pragmatic CMEs have generated a diversity of novel and probable strong detection prospects for electroanalysis. While the capability of handling the chemical nature of the electrode/solution interface accurately and creatively increases , it is predictable that different mediators-based CMEs could be developed with electrocatalytic activity and completely new applications be advanced.

Graphene derivatives in bioplastic: A comprehensive review of properties and future perspectives

The research and technological advancements observed in the latest years in the nanotechnology field translated into significant application developments in various areas. This is particularly true for the renewable polymers area, where the nano-reinforcement of biobased materials leads to an increase in their technique and economic competitiveness. The efforts were predominantly focused on materials development and energy consumption minimization. However, attention must also be given to the widespread commercialization and the full characterization of any particular potential toxicological and environmental impact. Some of the most important nanomaterials used in recent years as fillers in the bioplastic industry are graphene-based materials (GBMs). GBMs have high surface area and biocompatibility and have interesting characterizations such as strangeness and flexibility. In this paper, the current state of the art for these GBMs in the bioplastics area, their challenges, and the strategies to overcome them are analyzed.

Zn0.94Mn0.06O for adsorption and photo-degradation of methyl orange dye under visible irradiation: Kinetics and isotherms study

Three photocatalyst-adsorbents consist of Zn_0.97Mn_0.03O, Zn_0.94Mn_0.06O, and Zn_0.92Mn_0.08O were synthesized by hydrothermal method and calcined at 800 °C. The structural and optical properties of the sample Zn_0.94Mn_0.06O were characterized by using XRD; TEM; SEM; EDS; DLS; and DRS. The surface of the sample Zn_0.94Mn_0.06O consists of nano-particles (<100 nm) and nano-holes (18.4 nm), also the band-gap of it was obtained 2.89 eV. Adsorption and photo-degradation of methyl orange (MO) dye was investigated in darkness and under visible light irradiation (200 W tungsten). The sample Zn_0.94Mn_0.06O showed the most decolorization efficiency in the shortest time, so that 0.15 g of it adsorbed and destroyed the MO dye molecules (99 ± 1 %) in 40 s under irradiation. The most adsorption capacity of Zn_0.94Mn_0.06O was obtained 30.06 mg/g and the mechanism of the dye adsorption was investigated by using BET analysis and zeta potential. Also the adsorption isotherm and kinetics were calculated for describing the adsorption of MO onto the Zn_0.94Mn_0.06O.

Sustainable multilayer biomass carbon and polymer hybrid column as potential antibacterial water filter

Stipulation of fresh water for domestic use without any microbial, organic and inorganic contaminants is of high need. Sustainable, efficient, cost-effective and robust water purification technologies is of high need and it can be achieved using nanomaterials and their composite. Nanostructured graphene has unique properties like high surface to volume ratio, higher absorbability, reusability with minimal chemical alterations, and low cytotoxicity. From the validation of these properties, we have developed PLLA-Ag@graphene sandwich structures as an effective adsorbate for water purification application. As the real water bodies have lot of bacterial contaminants, the material is also designed as efficient adsorbate with antibacterial efficacy. In view of achieving these objectives, we have synthesized PLLA fibre mats by electrospinning method, followed by PLLA-Graphene and Ag decorated PLLA-graphene mats. The crystallite size for graphite and Ag@graphene was calculated as 30.82 nm and 43.79 nm, respectively. Furthermore, the UV analysis of Ag@graphene shows two peaks corresponding to graphene and Ag NP at 285 nm and 407 nm respectively. The layers were assembled in the order of polymeric fibre, as-fired biomass graphite, Ag@graphene for methodical filtration process. The filtration efficacy of the filtrate was tested using sewage water and the results shows higher contamination removal percentage of 87 % with TDS values in the drinking water standards after filtration. The antibacterial efficacy results also evidence of the potentialities of the hybrid system towards water purification application.

Properties and Recent Advantages of N,N’-dialkylimidazolium-ion Liquids Application in Electrochemistry

:

N,Nʹ-dialkylimidazolium-ion liquids is one of the important ionic liquids with a wide range of application as conductive electrolyte and in electrochemistry. The modified electrodes create a new view in fabrication of electroanalytical sensors. Many modifiers have beeen suggested for modification of electroanalytical sensor since many years ago. Over these years, ionic liquids and especially room temperature ionic liquids have attracted more attention due to their wide range of electrochemical windows and high electrical conductivity. N,Nʹ-dialkylimidazolium-ion liquids are one of the main important ionic liquids suggested for modification of bare electrodes and especially carbon paste electrodes. Although many review articles have reported onthe use of ionic liquids in electrochemical sensors, no review article has been specifically introduced so far on the review of the advantages of N,Nʹ-dialkylimidazolium ionic liquid. Therefore, in this review paper we focused on the introduction of recent advantages of N,Nʹ-dialkyl imidazolium ionic liquid in electrochemistry.

A comprehensive review on MXenes as new nanomaterials for degradation of hazardous pollutants: Deployment as heterogeneous sonocatalysis

MXene-based nanomaterials (MBNs) are two-dimensional materials that exhibit a series of sought after properties, including rich surface chemistry, adjustable bandgap structures, high electrical conductivity, hydrophobicity, thermal stability, and large specific surface area. MBNs have an exemplar performance when applied for the degradation of hazardous pollutants with various advanced oxidation processes such as heterogeneous sonocatalysis. As such, this work focuses on the sonocatalytic degradation of various hazardous pollutants using MXene-based catalysts. First, the general principles of sonocatalysis are examined, followed by an analysis of the main components of the MXene-based sonocatalysts and their application for pollutant degradation. Lastly, ongoing challenges are highlighted with recommendations to address the issues.

Efficient and fast degradation of 4-nitrophenol and detection of Fe(III) ions by Poria cocos extract stabilized silver nanoparticles

In this study, a simple and environment-friendly method has been successfully applied for the production of silver nanoparticles (AgNPs) using Poria cocos extract. The reaction time of 60 min, the temperature of 90 °C, and silver ion concentration of 2.0 mM were identified as the best condition for the PC-AgNPs fabrication. The XRD analysis confirmed a highly crystalline face-centered cubic structure of the biosynthesized material. The PC-AgNPs were presented separately in a spherical shape with an average crystal size of 20 nm, as endorsed by the TEM and FE-SEM measurements. The presence and crucial role of biomolecules in stabilizing the nanoparticles were elucidated by FTIR, EDX, and DLS techniques. The prepared biogenic nanoparticles were further applied for the reduction of 4-nitrophenol (4-NP) and colorimetric detection of Fe³⁺ ions. The study results proved that PC-AgNPs exhibited superior catalytic activity and reusability in the conversion of 4-NP by NaBH₄. The complete reduction of 4-NP could be achieved in 10 min with the pseudo-first-order rate constant of 0.466 min^-1, and no significant performance loss was found when the material was reused five times. The colorimetric probe based on PC-AgNPs displayed outstanding sensitivity and selectivity towards Fe³⁺ ions with a detection limit of 1.5 μM in a linear range of 0-250 μM. Additionally, the applicability of the developed assay was explored for testing Fe³⁺ ions in tap water. PC-AgNPs have a great potential for further applications as a promising catalyst for reducing nitrophenols and biosensors for the routine monitoring of Fe³⁺ in water.

Fabrication of Electrochemical Sensor for Epinine Determination Amplified with MgO/CNTs Nanocomposite and Ionic Liquid

Background:

Catecholamines are a large group of pharmacological and biological compounds that are widely used in biological systems. These compounds are prepared both naturally and synthetically with many key roles in the human body and its activities. Therefore, many researchers focused on the identification and determination of catecholamines in biological samples.

Methods:

MgO/SWCNTs were synthesized through the chemical precipitation method. In addition, cyclic voltammetry, differential pulse voltammetry, and chronoamperometric methods were used for the electro-oxidation reaction study of epinine at the surface of the modified electrode.

Results:

Carbon paste electrode (CPE) modified with MgO/SWCNTs nanocomposite and 1-butyl- 3-methylimidazolium methanesulfonate (BMMS) was used as an electrochemical sensor for the determination of epinine. The results showed a linear dynamic range of 5.0 nM-250 μM with a detection limit of 0.1 nM for epinine determination using MgO/SWCNTs/BMMS/CPE as a sensor.

Conclusion:

In the present study, a highly sensitive electrochemical sensor was designed and fabricated as an analytical tool for the determination of epinine. MgO/SWCNTs/BMMS/CPE was successfully used for the determination of epinine in water and dextrose saline with an acceptable recovery range of 98.7%-102.72%.

Graphene-based materials for metronidazole degradation: A comprehensive review

Due to its cytotoxic effect, metronidazole (MNZ) is a drug commonly used to treat bacterial, protozoal, and microaerophilic bacterial infections. After consumption, it undergoes a series of metamorphic reactions that lead to the degradation of oxidized, acetylated, and hydrolyzed metabolites in the environment. To eliminate such pollutants, due to their high potential, adsorption and photocatalysis extensive processes are used in which graphene can be used to improve efficiency. This review analyses the use of graphene as an absorbent and catalyst with a focus on absorption and photocatalytic degradation of MNZ by graphene-based materials (GBMs). The parameters affecting the adsorption, and photocatalytic degradation of MNZ are investigated and discussed. Besides, the basic mechanisms occurring in these processes are summarized and analyzed. This work provides a theoretical framework that can direct future research in the field of MNZ removal from aqueous solutions.

Promising Cr-Doped ZnO Nanorods for Photocatalytic Degradation Facing Pollution

Chromium (Cr)-doped zinc oxide (ZnO) nanorods with wurtzite hexagonal structure were prepared through a thermal decomposition technique. The concentration effect of the Cr doping on the structural, morphological, and optical properties of the ZnO nanorods was established by correlating various measurements: transmission electron microscopy (TEM), photoluminescence (PL), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and several UV-visible studies. The obtained nanorods were investigated as photocatalysts for the photodegradation process of methyl orange (MO), under UV-vis light illumination. Different weights and time intervals were studied. A 99.8% photodegradation of MO was obtained after 100 min in the presence of 1 wt.% Cr III acetate hydroxide and zinc acetate dehydrate “ZnO-Cr1”. The kinetic rate constant of the reaction was found to be equal to 4.451 × 10−2 min−1 via a pseudo-first order rate model. Scavenger radicals demonstrated the domination of OH• radicals by those of O2•− superoxide species during the photodegradation. The interstitial oxygen site Oi is proposed to play a key role in the generation of holes in the valence band under visible irradiation. The ZnO-Cr1 photocatalyst displayed good cycling stability and reusability.

Sequestration of toxic Pb(II) ions using ultrasonic modified agro waste: Adsorption mechanism and modelling study

Treating the effluents from industries by using biological and agricultural wastes is an emerging field of research. In this study, three different biosorbents are prepared from tamarind seeds such as; raw, sulphuric acid-modified and ultrasonic-assisted surface-modified tamarind seed powder has been utilized to expel the Pb (II) ions from synthetic solution. The surface characteristics of the newly synthesized raw and surface modified agro-waste biomass were studied by FTIR and SEM. An experimental study was carried out to investigate the effect of different parameters on adsorption of Pb(II) ions using raw, sulphuric acid-modified and ultrasonic-assisted surface-modified tamarind seeds. The maximum Pb(II) ions adsorption was found at pH - 6.0, temperature - 303 K, biosorbent dosage - 3.5 g/L and contact time - 60 min for raw tamarind seeds and 30 min for sulphuric acid-modified and ultrasonic-assisted surface-modified tamarind seeds. The adsorption mechanism was described by Langmuir isotherm and pseudo-first order kinetic model. Among the three biosorbents, ultrasonic-assisted surface-modified tamarind seeds show higher adsorption capacity (18.86 mg/g) of Pb(II) ions removal from the synthetic solution. The thermodynamic study declared that the present Pb(II) ions adsorption onto the prepared biosorbents was spontaneous, exothermic and followed physical adsorption process. Results have shown that tamarind seed was found to be the best adsorbent in the expulsion of Pb(II) ions from the wastewater environment.

Kinetics, equilibrium and thermodynamic investigations of methylene blue dye removal using Casuarina equisetifolia pines

Casuarina equisetifolia pines are degradable biopolymeric substance with dye-sequestering property was utilized as biosorbent to expel a cationic dye; methylene blue dye from simulated wastewater. The prepared adsorbent material was characterized for their structural, morphological and elemental features to understand their suitability in augmenting in dye-wastewater remediation. The results infer that 0.5 g/L biosorbent was proficient in removing 100 mg/L methylene blue (pH 7.0 ± 0.2) when agitated at 150 rpm for 120 min. Isothermal behavior were evaluated using non-linear isotherm models like Temkin, Langmuir and Freundlich models while the rate-limiting steps were found using kinetic models. Temkin isotherm and pseudo-first order model explained the removal mechanism among the models evaluated, which infers that the biosorption followed physisorption with the maximum adsorption capacity of 41.35 mg/g. Thermodynamic behavior of methylene blue removal by C. equisetifolia pines powder described the feasibility of biosorption as well as the type of heat involved. Equilibrium sorption capacities, rate constants and correlation coefficients explains that MB dye removal by C. equisetifolia pines is presumably physisorption, spontaneous and endothermic in nature.

Adsorptive removal of Pb(II) ions onto surface modified adsorbents derived from Cassia fistula seeds: Optimization and modelling study

Cassia fistula seeds has been utilized for the abstraction of Pb(II) ions from the aqueous environment. Raw Cassia fistula seeds (RCF) and three different surface modified (physically treated - PMCF and chemically treated - HMCF and SMCF) adsorbent material were taken for investigation. The adsorption properties of these materials and their contact amongst the Pb(II) ion and sorbent materials were characterized by FTIR and SEM analysis. The parameters influencing the adsorption capacity of varied adsorbents were evaluated: maximum solution pH for Pb(II) is 5.0; interactive time is 30 min; dosage is 8.0 g/L for RCF, 4.0 g/L for HMCF, 2.5 g/L for PMCF and 1.0 g/L for SMCF. The modelling study reveals that Freundlich isotherm and Pseudo first order kinetics fits well and the utmost adsorption measurements for the varied adsorbents were found to be 13.22, 28.28, 48.66 and 129.3 mg/g, respectively.

Analysis on the removal of emerging contaminant from aqueous solution using biochar derived from soap nut seeds

For clearing pollutants and emerging contaminants like ciprofloxacin-500mg from wastewaters generated from pharmaceutical industries, soapnut seeds biochar was synthesized and used as an adsorbent for the effective removal process. Tubular furnace operated under nitrogen gas environment was used to synthesize biochar. The batch analysis were carried out successfully to study the removal mechanism and the removal efficiency of the chosen pollutant. The soapnut seeds biochar showed excellent adsorption of ciprofloxacin at pH 6 and temperature 303 K when the dosage was 0.07 g. The Langmuir removal capacity of 33.44 mg/g was received and the Freundlich model provided the best-fits. The ciprofloxacin-500mg adsorption process correlated well with the pseudo-second-order kinetics equation, and the intraparticle diffusion mechanism mainly controlled the process. The characterization of biochar concluded that O-H groups, CO groups, COO^-groups and C-F groups, and π-π interactions, pore-filling effect, and cation exchange interactions played a role in the adsorption process. Therefore, the findings of the present work revealed that soapnut seeds biochar would be an excellent low-cost adsorbent for the removal of ciprofloxacin-500mg from wastewater.

Visible light driven exotic p (CuO) - n (TiO2) heterojunction for the photodegradation of 4-chlorophenol and antibacterial activity

The treatment of industrial waste and harmful bacteria is an important topic due to the release of toxins from the industrial pollutants that damage the water resources. These harmful sources frighten the life of every organism which was later developed as the carcinogenic and mutagenic agents. Therefore, the current study focuses on the breakdown or degradation of 4-chlorophenol and the antibacterial activity against Escherichia coli (E. coli). As a well-known catalyst, pure titanium-di-oxide (TiO₂) had not shown the photocatalytic activity in the visible light region. Hence, band position of TiO₂ need to be shifted to bring out the absorption in the visible light region. For this purpose, the n-type TiO₂ nanocrystalline material's band gap got varied by adding different ratios of p-type CuO. The result had appeared in the formation of p (CuO) - n (TiO₂) junction synthesized from sol-gel followed by chemical precipitation methods. The optical band gap value was determined by Kubelka-Munk (K-M) plot through UV-Vis diffusive reflectance spectroscopy (DRS). Further, the comprehensive mechanism and the results of photocatalytic and antibacterial activities were discussed in detail. These investigations are made for tuning the TiO₂ catalyst towards improving or eliminating the existing various environmental damages.

Effective water/wastewater treatment methodologies for toxic pollutants removal: Processes and applications towards sustainable development

Release of pollutants due to inflating anthropogenic activities has a conspicuous effect on the environment. As water is uniquely vulnerable to pollution, water pollution control has received a considerable attention among the most critical environmental challenges. Diverse sources such as heavy metals, dyes, pathogenic and organic compounds lead to deterioration in water quality. Demand for the pollutant free water has created a greater concern in water treatment technologies. The pollutants can be mitigated through physical, chemical and biological methodologies thereby alleviating the health and environmental effects caused. Diverse technologies for wastewater treatment with an accentuation on pre-treatment of feedstock and post treatment are concisely summed up. Pollutants present in the water can be removed by processes some of which include filtration, reverse osmosis, degasification, sedimentation, flocculation, precipitation and adsorption. Membrane separation and adsorption methodologies utilized to control water pollution and are found to be more effective than conventional methods and established recovery processes. This audit relatively features different methodologies that show remarkable power of eliminating pollutants from wastewater. This review describes recent research development on wastewater treatment and its respective benefits/applications in field scale were discussed. Finally, the difficulties in the enhancement of treatment methodologies for pragmatic commercial application are recognized and the future viewpoints are introduced.