Industrial Organic Pollutants Research Articles

Highly Efficient Oil-Water Separation in Different Scenarios through Synergistic Self-Assembly of ZIF-67@PPy Coatings with Unique Wetting Properties.

In recent years, oil pollution and industrial organic pollutants discharge has become a major problem affecting the ecological and human living environment, and the removal of oil in oily wastewater is increasingly urgent, especially for emulsion separation. Therefore, it is crucial to develop efficient oil-water separation membranes with low cost, green sustainability, and ease of operation. Herein, an ingenious spraying hybrid coatings containing ZIF-67 (Zeolitic Imidazolate Framework-67) and polypyrrole (PPy) onto stainless steel mesh (SSM) and polyvinylidene fluoride (PVDF) was proposed. Through solidification and cooperative self-assembly to build rough structures, oil-water separation membranes ZIF-67@PPy SSM and ZIF-67@PPy PVDF have been obtained, which are hydrophilic and oleophilic in air and superoleophobic underwater. Depending on the scenario, on-demand separation of light oil/water mixtures and oil-in-water emulsions can be easily realized. The resulting oil-water separation membranes performed well that the separation efficiency of ZIF-67@PPy SSM can exceed 99.3% for all kinds of light oil/water mixtures, with a water flux of up to 66250 L/(m2·h), and maintains a separation efficiency of 98.5% even after 50 cycles. ZIF-67@PPy PVDF has a separation efficiency of more than 99.4% for various oil-in-water emulsions, and sustains outstanding performance despite undergoing 10 cycles. In addition, ZIF-67@PPy SSM and ZIF-67@PPy PVDF are sustainable in harsh environments, with good mechanical durability and some antimicrobial properties. The coatings prepared in this work that can be used for the separation of light oil/water mixtures and oil-in-water emulsions, and the proposed combination of multiple separation strategies are expected to improve the selectivity, improve efficiency, enhance contamination resistance, and increase accessibility of oil-water separation technologies.

Preparation of Cu-doped MIL-125(Ti)-derived carbon-based composites for the sonodynamic degradation of organic dyes

Sonocatalysis provides a green and sustainable strategy to remove industrial organic pollutants. Toward improving the sonocatalytic performance to remove the organic dyes, a new Cu-C@TiO2 catalyst was prepared via doping the Cu(II) ions into the MIL-125(Ti) and then carbonizing the resultant Cu-MIL-125(Ti) in this study. By the SEM, EDS and BET, the obtained Cu-C@TiO2 was a porous carbon-based hybrid with bimetallic centers, retaining a large amount of organic frameworks to supply adequate specific surface area for the adsorption; By the XPS and UV–vis DRS, the band gap of Cu-C@TiO2 was reduced to significantly broaden the light absorption region and facilitate the separation of electron-hole pairs; By the fluorescence spectra, the graphite-like structure and Cu particles produced on the catalyst surface served as an electron trap to inhibit the recombination of charge carriers. The Cu-C@TiO2 showed an excellent sonocatalytic performance to organic dyes, and under the ultrasound irradiation (35 KHz, 150 W), it could remove more than 95 % of rhodamine B (5.00 mg/L) and methylene blue (5.00 mg/L) within 10 min. By the kinetic analysis, it was found that the dye removal obeyed the first-order kinetic model, and the scavenging studies of free radicals (OH and O2−) verified the Cu-C@TiO2-mediated sonodynamic degradation was in the dye removal. In the end, a Cu-C@TiO2-mediated adsorption/sonodynamic degradation mechanism was proposed to thermodynamically expound the removal process of organic dyes.

Synthesis of nano calcium silicates from waste calcite and aragonite phases for efficient adsorptive removal of industrial organic pollutants

The present study focuses on the adsorption efficacy of solid-state synthesized calcium silicate for removing congo red dye. Three different sources were used as calcium precursors; one was calcium carbonate, and the other two were natural waste sources, aragonite (P. globosa) and calcite (Eggshells). Structural analysis and functional groups of the samples were carried out by X-ray diffractometer (XRD), and a Fourier Transform Infrared Spectrometer (FTIR). Various well-known models/equations models such as the Liner Straight Line method of Scherrer’s equation (LSLMSE), Sahadat-Scherrer Model (SSM), Monshi-Scherrer model (MSM), Williamson-Hall model (WHM), Size-Strain plot method (SSP), and Halder-Wagner Model (HWM) were applied to compute the crystallite size of the synthesized calcium silicates; the estimated crystallite size range was 8–77 nm. The adsorption efficacy of the synthesized E-CaSiO3, S-CaSiO3, and C-CaSiO3 was assessed under various provisos for eradicating Congo red dye from wastewater. Computed results revealed that the dye removal percentages were approximately 100 % at 120 min and 200 rpm for 0.2 g E-CaSiO3. The point of zero charge evaluation showed that the pH of the adsorbents during maximum dye removal was 7 and was less than the value of pHpzc. Thermodynamics studies confirmed that the adsorption process was spontaneous. The method of adsorption of dye by the adsorbent was more clearly comprehended by Langmuir, Freundlich, and Temkin adsorption isotherm. 151.28 mg/g was the maximum adsorption capacity for S- CaSiO3 depending on the Langmuir isotherm model’s linear form (R2 = 0.924).

Remarkable photodegradation breakdown cost, antimicrobial activity, photocatalytic efficiency, and recycling of SnO2 quantum dots throughout industrial hazardous pollutants treatment

In the conducted research, a one-step hydrothermal synthesis of pure and titanium-doped tin dioxide quantum dots is elaborated upon, with a thorough analysis of their structural, optical, morphological, and photocatalytic properties undertaken using advanced analytical techniques. Through X-ray Diffraction XRD, the crystalline nature and phase purity of the tetragonal structures of SnDs were confirmed, with the crystallite sizes measured at 3.0 nm for SnD1 and 7.66 nm for SnD2, following treatments at 240 °C and 300 °C, respectively. The structural integrity of SnO2 was maintained despite titanium doping. FTIR spectroscopy verified the existence of specific vibrational modes indicative of surface hydroxyl groups. HRTEM images revealed the spherical morphology of particles, with diameters of 3.5 nm for SnD1 and 9.1 nm for SnD2. Optical band gaps, determined through UV-DRS, ranged from 3.33 eV in SnD1 to 3.47 eV in SnDTi2. The photocatalytic degradation of Congo Red dye under xenon lamp irradiation was quantitatively assessed; notably, SnD1 exhibited a 23 % higher rate constant compared to SnD2, attributed to its smaller particle size and a 31 % greater surface area. Doping with 4 % Ti in Sn0.96Ti0.04O2 more than doubled the degradation rate compared to a 6 % Ti doping in Sn0.94Ti0.06O2. Furthermore, the generation of hydroxyl radicals was significantly enhanced, showing an increase of approximately 220 % for SnD1 and 80 % for SnD2. The capability of these nanomaterials to reduce the chemical oxygen demand of industrial organic pollutants to within regulatory limits under solar irradiation was documented, with SnD1 maintaining its photocatalytic efficiency over seven cycles of reuse. In the photocatalytic degradation rate of Congo Red dye, which was 23 % higher for SnD1 compared to SnD2, and the threefold increase in the degradation rate for SnDTi1 compared to SnDTi2. An economic assessment, based on electricity tariffs in Saudi Arabia, highlighted the cost-effectiveness of SnD1, which ranged from 26.93 to 30.36 USD per breakdown cost of the photodegradation process, showing it to be less costly than SnD2. Conversely, SnDTi1 was found to be more economical than SnDTi2, with costs ranging from 26.67 to 33.09 USD. Collectively, the results emphasize the outstanding photocatalytic performance and cost-efficiency of SnDs, reinforcing their potential as sustainable solutions for the treatment of industrial wastewater. Additionally, the antibacterial efficacy of these materials against a range of bacteria, yeast, and fungi was investigated and substantiated.

H2O2-free catalytic dye degradation at dye/night circumstances using CuS@Au heterostructures decorating on MoS2 nanoflowers

Catalytic remediation of industrial organic pollutants is considered effective mitigation of increasing risks from aqueous contaminations composed of hazardous substances. The need for in-situ environmental remediation is highly demanded to deal with organic contaminations from on-site, instant, and full-time treatment without the need to remove the contaminated sources for ex-situ remediation is highly demanded. In this work, by means of combining the strategies of daytime and dark degradation capabilities of organic dyes, the MoS2/Au@CuS hybrid catalysts resembling semiconductor/metal/semiconductor junction features underline the generation of hydroxyl radicals, and force to speed up the oxidative removal of organic dyes during light-on and light-off conditions in both scenarios. Decorations of CuS on hydrothermally synthesized MoS2/Au nanoflowers are prepared with the in-situ chemical reduction process. We reveal that such circumstance exists when programming the environment in the sequence of light-on/light-off conditions, which actively clicks the generation of H2O2 and strategically accelerates the degradation kinetics, offering an additional opportunity for promoting catalytic degradation of hazardous organic dyes with whole-day feasibility.

Directional self-assembly of octavinyl polyhedral oligomeric silsesquioxane on the surface of melamine sponge: Establishing hydrophobic surfaces to improve oil–water separation performance

The continuous increase in industrial organic pollutants has seriously contaminated the natural environment, posing a threat to natural ecosystems and human survival. The preparation of hydrophobic materials with corrosion resistance is crucial for the efficient treatment of emulsified oil–water mixtures in industrial wastewater.Octavinyl polyhedral oligomeric silsesquioxane-coated melamine foam (OV-POSS@MF), possessing hydrophobic properties, was synthesized through a two-step process: initially, a sulfhydryl layer was built up on the surface of the melamine foam, followed by the subsequent assembly of octavinyl POSS onto the melamine foam's surface via a free radical polymerization reaction between sulfhydryl groups and vinyl moieties. OV-POSS@MF achieves a static water contact angle of 141°, demonstrating its pronounced hydrophobic nature. Moreover, the corrosion resistance, adsorption capacity, oil–water separation efficiency, deformation resistance, and flame retardancy of OV-POSS@MF were thoroughly examined. The results indicate that OV-POSS@MF exhibits strong corrosion resistance and maintains good hydrophobicity even after prolonged exposure to highly acidic and alkaline conditions. Notably, OV-POSS@MF possesses the capability to efficiently and rapidly separate emulsified oil–water mixtures. Furthermore, it retains excellent hydrophobicity even after undergoing up to 100 consecutive compressions or distortions, highlighting its remarkable mechanical resilience. Additionally, OV-POSS@MF demonstrates superior flame retardant properties compared to unmodified melamine foam (MF).

Centrifugally spun superhydrophobic fibrous membranes with core-sheath structure assisted by hyper branched polymer and via click chemistry for high efficiency oil–water separation

Superhydrophobic fibrous membranes have been widely investigated to treat oily wastewater originated from oil spills and industrial organic pollutants. However, the applications of these membranes are usually limited by complex preparation process, high modification cost, and poor durability. In this research, we developed a cost-saving approach to construct the fiber with core-sheath structure by using centrifugal spinning, which was based on the viscosity difference of Polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), hyperbranched unsaturated polyester (HBPU). Subsequently, the hydrophobic long chain was attended on fiber surface through the mercaptan click reaction induced by ultraviolet light, which were assisted by the plenty of double bonds supplied by HBPU. Due to the coarse structure and low surface energy of the treated fibers, the fibrous membranes exhibited super hydrophobic properties for the water contact angle high as 156°. The separation capacity for water-in-oil emulsions were up to 7562.24 L·m−2·h−1 for the flux and separation efficiency were up to 99.27 %. Additionally, the flux and separation efficiency exhibited no significant changes over 50 cycles. Therefore, we provided a unique and straightforward technique for producing superhydrophobic separation fibrous membranes.

Some Useful Plants in Treatment of Ganga Water Pollution and Human Healthcare in India

Long distance of 2510 km long river basin, originating from Bhagirathi from Gangotri glacier in Uttarakhand, The Ganga is the most sacred river of India which is symbolic of purity and moksha and plays a crucial role in the growth of Indian civilization and economy. The river Ganga which is often called “Holy Ganga” or “Mother Ganga” has been exposed to many anthropogenic pollutants for several decades, and due to that it has grasped a serious and evolving problem. Anthropogenic sources include industrial release, domestic wastes, and municipal sewage. Pollution due to religious activities such as religious bathing and idol immersion is also a major concern. According to earlier studies, the 12 municipal towns located along the Ganga river basin leading to Haridwar, discharge nearly 89 million liters of municipal sewage into the river. High amounts of inorganic and organic pollutants are coming from industrial effluents from different industries. These industrial organic and inorganic pollutants are very serious issues for human health as they are carcinogenic and mutagenic to humans which ultimately cause neurological and physiological and other disorders. Like yoga, India can offer numerous plant-based treatments to the world that can benefit the whole on a larger basis. Learning from old-age traditions of Ayurveda, various trees and herbs along the plains of river Ganga are customarily used by many local and rural people in meeting their day-to-day needs and health care. The study highlights some of the potential plant species like Achyranthes aspera, Acorus calamus, Aegle marmelos, Ajuga bracteosa, Arisaema tortuosum, Aristolochia indica, Asparagus racemosus, Ficus religiosa, Gloriosa superba, Helminthostachys zeylanica, Hemidesmus indicus, Tephrosea purpurea, Terminalia chebula, Tinospora cordifolia, Terminalia bellirica and Withania sominifera etc., that can be combinedly used with modern medical science with the vast invaluable knowledge to provide the effective and affordable treatment for various diseases caused by polluted water of Ganga.

Deep mineralization of VOCs in an embedded hybrid structure CoFe2O4/MoS2/PMS wet scrubber system

Peroxymonosulfate (PMS)-based advanced oxidation processes in liquid phase systems can actively degrade toluene. In this work, the catechol structural surfactant was introduced to synthesize the dispersed and homogeneous CoFe2O4 nanospheres and embedded into MoS2 nanoflowers to form magnetically separable heterojunction catalysts. The innovative approach effectively mitigated the traditionally low reduction efficiency of transition metal ions during the heterogeneous activation process. In CoFe2O4/MoS2/PMS system, the toluene removal efficiency remained 95% within 2 h. The contribution of SO4⋅-, ·O2-, ·OH, and 1O2 was revealed by radical quenching experiment and electron paramagnetic resonance spectroscopy. The results illustrated that MoS2 offers ample reduction sites for facilitating PMS activation via Fe3+/Fe2+ redox interactions. Furthermore, an investigation into the toluene degradation pathway within the CoFe2O4/MoS2/PMS system revealed its capability to suppress the formation of toxic byproducts. This ambient-temperature liquid-phase method presented promising route for the removal of industrial volatile organic pollutants.

Harnessing Bio-Immobilized ZnO/CNT/Chitosan Ternary Composite Fabric for Enhanced Photodegradation of a Commercial Reactive Dye.

Growing demand for sustainable wastewater treatment drives interest in advanced photocatalytic materials. Immobilized photocatalysts hold potential for addressing industrial wastewater organic pollutants, offering substantial surface area, agglomeration prevention, and easy removal. In this study, we successfully immobilized ZnO and carbon nanotubes onto a textile substrate through bilateral esterification and explored their effectiveness as a potent photocatalyst for degrading of commercial textile colorant reactive blue 4 (RB-4) colorant. Findings demonstrated significant improvements in photocatalytic performance upon integrating ZnO and CNTs into the fabric, coupled with chitosan immobilization. The immobilization process of ZnO and CNTs onto the substrate was elucidated through a proposed reaction mechanism, while the appearance of carbonyl peaks at 1719.2 cm-1 in the composite fabric further confirmed bilateral esterification. The as-developed immobilized nano-catalyst exhibited remarkable photocatalytic efficiency with an impressive 93.54% color degradation of RB-4. This innovative approach underscores the immense potential of the ternary immobilized (ZnO/fCNT/chitosan) composite fabric for efficient photocatalytic degradation in textile coloration processes. Exploring the early-stage development of immobilized photocatalysts contributes to safer and more eco-friendly practices, addressing pressing environmental challenges effectively.

Urchin-like fluorinated covalent organic frameworks decorated fabric for effective self-cleaning and versatile oil/water separation

Oil contamination and industrial organic pollutants emission have been a serious problem affecting the ecological and residential environment. Membrane-based separation shows great application prospect due to its low-cost, environmental-friendly and easy operation. Therefore, the development of efficient oil-water separation membranes is highly desirable. Herein, a fabric filter with superwettability was prepared by coating urchin-like fluorinated covalent organic frameworks (COFs) on fabric, which was well utilized in filtering immiscible oil-water mixture and surfactant-stabilized water-in-oil emulsion driven only by gravity for the first time. The as-prepared COF fabric filter (defined as fabric@u-FCOF) possessed many outstanding properties, including superhydrophobicity with the water contact angle of approximately 151.6°, satisfactory resistance for alkaline, acidic and saline environments, as well as superior mechanical durability under harsh conditions. Because of the super-micropore of fabric@u-FCOF and the nanopore in the COF coating, the obtained fabric@u-FCOF exhibited excellent performances in terms of separation efficiency and permeability, in which the oil flux was up to 16964 L·m−1·h−2 and separation efficiency for the mixed o-dichlorobenzene/water was higher than 99.4%. In addition, the fabric@u-FCOF also showed excellent self-cleaning performance due to the micro/nano hierarchical structure of its surface. These excellent properties make it an ideal candidate for applications of oil/water separation and water purification.

Special Issue on “Resource Recovery and Harmless Treatment Processes for Industrial Organic Pollutants”

Industrial transformation has brought about huge changes to the human society in many different aspects [...]

A green and facile one-step hydration method based on ZIF-8-PDA to prepare melamine composite sponges with excellent hydrophobicity for oil-water separation

Frequent crude oil spills and illegal discharges of industrial organic pollutants cause serious damage to the ecological environment and considerable loss of valuable resources. Therefore, there is an urgent need to develop efficient strategies to separate and recover oils or reagents from sewage. Herein, a green, facile and rapid one-step hydration method was applied to obtain the composite sponge (ZIF-8-PDA@MS) that monodispersed zeolitic imidazolate framework-8 nanoparticles with high porosity and large specific surface area were firmly loaded onto the melamine sponge by ligand exchange and the self-assembly of dopamine. The water contact angle of ZIF-8-PDA@MS with multiscale hierarchical porous structure could reach 162°, which remained stable over a long period of time and a wide pH range. ZIF-8-PDA@MS displayed excellent adsorption capacities (up to 85.45–168.95 g⋅g−1), and could be reused at least 40 times. Besides, ZIF-8-PDA@MS exhibited remarkable photothermal effect. Simultaneously, Silver nanoparticle-immobilized composite sponges were also prepared via in-situ reduction of silver ions to inhibit bacterial contamination. The composite sponge developed in this work can be used not only for the treatment of industrial sewage, but also for the emergency response of large-scale marine oil spill accidents, which has inestimable practical value for water decontamination.

In-situ construction of Zr-based metal-organic framework core-shell heterostructure for photocatalytic degradation of organic pollutants.

Photocatalysis is an eco-friendly promising approach to the degradation of textile dyes. The majority of reported studies involved remediation of dyes with an initial concentration ≤50mg/L, which was away from the existing values in textile wastewater. Herein, a simple solvothermal route was utilized to synthesize CoFe2O4@UiO-66 core-shell heterojunction photocatalyst for the first time. The photocatalytic performance of the as-synthesized catalysts was assessed through the photodegradation of methylene blue (MB) and methyl orange (MO) dyes at an initial concentration (100mg/L). Under simulated solar irradiation, improved photocatalytic performance was accomplished by as-obtained CoFe2O4@UiO-66 heterojunction compared to bare UiO-66 and CoFe2O4. The overall removal efficiency of dyes (100mg/L) over CoFe2O4@UiO-66 (50mg/L) reached >60% within 180min. The optical and photoelectrochemical measurements showed an enhanced visible light absorption capacity as well as effective interfacial charge separation and transfer over CoFe2O4@UiO-66, emphasizing the successful construction of heterojunction. The degradation mechanism was further explored, which revealed the contribution of holes (h+), superoxide (•O2 -), and hydroxyl (•OH) radicals in the degradation process, however, h+ were the predominant reactive species. This work might open up new insights for designing MOF-based core-shell heterostructured photocatalysts for the remediation of industrial organic pollutants.

Ultrasonication for removal of organic micropollutants from water

This review collects the most theoretical and experimental data about the fundaments of ultrasonic cavitation and its application in the domain of water and drinking water treatment. It is describing the most important mechanism of acoustic cavitation based on "Hot spot theory" which is based on free radicals, especially hydroxyl radicals. The experimental examples are focused on organic micropollutants removal from wastewater and drinking water. There are many organic pollutants resistant to classical treatment flows in wastewater and drinking water treatment plants which means there must be updated with new technologies like Advanced Oxidation Processes (AOPs). Ultrasonication and advanced ultrasonication is one of these new approaches. Ultrasonication was the base of a new chemistry domain - sonochemistry and its development led to new and modern degradation methods of natural and industrial organic pollutants: natural organic matter, phenols, organochlorinated compounds, surfactants, etc. with high mineralization degree. Some examples are described below.

Defect assisted Reactive Oxygen Species generation for photocatalytic degradation of methylene blue by nano-structured zinc oxide synthesized in CTAB medium

Herein, we report facile, room temperature synthesis of undoped zinc oxide semiconductor nanoparticles and their efficient photocatalytic property towards methylene blue dye degradation. Synthesis of zinc oxide nanoparticles was carried out by facile, eco-friendly and cost-effective, CTAB-assisted method using various aliphatic amines (methyl amine, dimethyl amine and n-butyl amine) as bases. The phase purity, structure, crystallinity, morphology and optical properties of the materials obtained with different aliphatic amines were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–Vis and photoluminescence spectroscopy investigations. It was proved that the different aliphatic amines used manipulates both photodegradation properties and morphology of the undoped ZnO materials. The nanomaterial synthesized with n-butyl amine showed the highest catalytic degradation due to high absorption (∼40%) in visible region. The presence of oxygen and zinc vacancies were confirmed from the two emission bands under UV excitation in photoluminescence (PL) studies. Visible light-driven photocatalytic activity of the prepared ZnO nanorods was evaluated by measuring the photodegradation of widely used industrial organic pollutants methylene blue, showed good efficiency of the catalytic samples. In this present study, we propose a mechanism involving e-h pair generation through bandgap and ROS generation assisted aptly by the presence of defects, facilitating the photo-catalytic activity towards dye degradation.

Proposing two-dimensional covalent organic frameworks material for the capture of phenol molecules from wastewaters

Industrial wastewater organic pollutants such as phenol can be treated through adsorption on active surfaces. Herein, the adsorption mechanism and dynamic behaviors of phenol molecules onto covalent organic frameworks (COFs) with well-defined supramolecular structures are investigated via molecular dynamics and well-tempered metadynamics simulations under various external electric fields. The Lenard–Jones interaction is predominant during the adsorption process, while NH and OH groups in COFs and phenol, respectively, can increase the adsorption due to the electrostatic interaction. Besides, the adsorption affinity of phenol on COFs is weakened by increasing the electric field strength. In addition, the free energy values for the complexes with and without the external electric field at their global minima reached at about −264.68, −248.33, and −290.13 (for 1, 0.5, and 0 V nm−1) kJ mol−1, respectively. The obtained results confirmed the COFs as prominent adsorbents for loading phenol and its removal from the water-contaminated environment.

Photothermal catalytic degradation of textile dyes by laccase immobilized on Fe3O4@SiO2 nanoparticles

Efficient and convenient degradation of industrial organic pollutants are of great importance for green chemical schemes and cost-effectiveness. This work introduced the immobilization of laccase on Fe3O4@SiO2 nanoparticles (Fe3O4@SiO2-laccase) for photothermal catalytic degradation of textile dyes. The Fe3O4@SiO2-laccase presented excellent reusability, improved thermal and pH stabilities, and remarkable organic compounds, inhibitors and metal ions tolerance. Batch experiments indicate that the maximum loading amount and activity recovery for laccase were about 10.5 mg/g and 109.7%, respectively. Meanwhile, the immobilized laccase was employed for photothermal catalytic degradation of textile dyes. The degradation assays revealed that the initial removal efficiencies were 99.6%, 99.5%, 94.6%, 94.2%, 89.4% and 79.3% for high concentrations of malachite green (MG), brilliant green (BG), reactive blue 19 (RB19), azophloxine, procion red MX-5B and alizarin red in 30–60 min illumination, respectively. Even after 10 recycling cycles, the photothermal catalytic degradation rates of the textile dyes were observed at 98.7%, 99.3%, 88.8%, 79.0%, 78.7% and 64.4%, respectively. The outstanding photothermal catalytic performances demonstrated that the Fe3O4@SiO2-laccase has a technical application in wastewater treatment.

Efficient and recyclable AuNPs/aminoclay nanocomposite catalyst for the reduction of organic dyes

Industrial dye effluents and organic pollutants pose serious environmental threats for which efficient catalytic adsorbents have been indispensable in treating them. In the present work, the synthesis of gold nanoparticles (AuNPs) dispersed over aminopropyl-functionalized magnesium phyllosilicate (AMP) composites (AuNPs/AMP NC) is reported, involving the organic-inorganic hybrid structure with the strategy of AuNP formation over AMP clay. The AuNPs decorated AMP hybrid nanocomposite was characterised by XRD, FTIR, TGA, UV-Visible, SEM-EDAX, and TEM techniques. The presence of a surface plasmon resonance (SPR) absorption band at 520 nm in UV-Visible spectra revealed the formation of AuNPs over AMP support, which was supported by XRD results. The average particle size of AuNPs with spherical morphology was in the range of 3 nm, respectively. The catalytic performance of the AuNPs/AMP NC was studied through the reduction of malachite green (MG), phenol red (PR), rhodamine B (RhB), rhodamine 6 G (Rh6G), and Congo red (CR) in the presence of NaBH4, respectively. The progress of reductive dye degradation was monitored via UV–Vis spectrophotometry. The kinetic data was analysed and apparent rate constants were determined for the respective dyes. The reduction efficiency of the nanocatalyst over MG, PR, RhB, Rh6G, and CR, in the presence of NaBH4 was determined as > 98%, respectively. Such prolific nanocomposite catalysts could be employed as an alternative to toxic dye and organic component degradation in environmental treatment.

P-Nitrophenol contaminated soil remediation in a spray-type coaxial cylindrical dielectric barrier discharge plasma system.

In the present work, plasma remediation of p-nitrophenol (PNP) contaminated soil was performed in a novel spray-type coaxial cylindrical dielectric barrier discharge (DBD) system at ambient temperature. This system is capable of generating large-size nonthermal plasma (NTP) and improving the diffusion and transfer of chemical active species around the dispersed soil particles. Several key parameters including plasma treatment time, discharge voltage, soil granular size, the entry speed of soil, PNP initial concentration, gas variety, and gas flow rate were investigated in terms of PNP degradation and energy efficiencies. Under the optimized experimental conditions, 54.2% of PNP was degraded after only 50 s discharge treatment, indicating that the spray-type coaxial cylindrical DBD system can degrade organic pollutants in soil more quickly compared to other plasma systems due to its efficient transfer of reactive oxygen and nitrogen species (RONS) into the contaminated soil. The possible PNP degradation pathways were proposed based on intermediates identification results and the role of reactive species analysis. The toxicological assessment of the PNP decomposition products was conducted by quantitative structure-activity relationship (QASR) analysis. This work is expected to provide a potential plasma technology for rapid and efficient processing of industrial organic pollutants contamination soil.