Enhanced sonocatalytic degradation of organic dyes from aqueous solutions by novel synthesis of mesoporous Fe3O4-graphene/ZnO@SiO2 nanocomposites

A comparative review on the mitigation of metronidazole residues in aqueous media using various physico-chemical technologies

In the last few decades, pharmaceuticals have emerged as a new class of serious environmental pollutants. The presence of these emerging contaminants even in minimal amounts (micro- to nanograms) has side effects, and they can cause chronic toxicity to health and the environment. Furthermore, the presence of pharmaceutical contaminants in water resources leads to significant antibiotic resistance in bacteria. Hence, the removal of antibiotics from water resources is essential. Thus far, a wide range of methods, including adsorption, photodegradation, oxidation, photolysis, micro-/nanofiltration, and reverse osmosis, has been used to remove pharmaceutical contaminants from water systems. In this article, research related to the processes for the removal of metronidazole antibiotics from water and wastewater, including adsorption (carbon nanotubes (CNTs), magnetic nanocomposites, magnetic molecularly imprinted polymer (MMIP), and metal-organic frameworks), filtration, advanced oxidation processes (photocatalytic process, electrochemical advanced oxidation processes, sonolysis and sonocatalysis) and aqueous two-phase systems (ATPSs), was reviewed. Results reveal that advanced oxidation processes, especially photocatalytic and sonolysis processes, have high potential in removing MNZ (more than 90%).

Hybridization of Polymer-Encapsulated MoS2-ZnO Nanostructures as Organic-Inorganic Polymer Films for Sonocatalytic-Induced Dye Degradation

The development of environmentally friendly technology is vital to effectively address the issues related to environmental deterioration. This work integrates ZnO-decorated MoS2 (MZ) to create a high-performing PVDF-based PVDF/MoS2-ZnO (PMZ) hybrid polymer composite film for sonocatalytic organic pollutant degradation. An efficient synergistic combination of MZ was identified by altering the ratio, and its influence on PVDF was assessed using diverse structural, morphological, and sonocatalytic performances. The PMZ film demonstrated very effective sonocatalytic characteristics by degrading rhodamine B (RhB) dye with a degradation efficiency of 97.23%, whereas PVDF only degraded 17.7%. Combining MoS2 and ZnO reduces electron-hole recombination and increases the sonocatalytic degradation performance. Moreover, an ideal piezoelectric PVDF polymer with MZ enhances polarization to improve redox processes and dye degradation, ultimately increasing the degradation efficiency. The degradation efficiency of RhB was seen to decrease while employing isopropanol (IPA) and p-benzoquinone (BQ) due to the presence of reactive oxygen species. This suggests that the active species •O2- and •OH are primarily responsible for the degradation of RhB utilizing PMZ2 film. The PMZ film exhibited improved reusability without substantially decreasing its catalytic activity. The superior embellishment of ZnO onto MoS2 and effective integration of MZ into the PVDF polymer film results in improved degrading performance.

Sono-assisted photocatalytic degradation of ciprofloxacin in aquatic media using g-C3N4/MOF-based nanocomposite under visible light irradiation

This research study is centered on the sono-assisted photocatalytic degradation of a well-known antibiotic (ciprofloxacin; CIP) in aquatic media using a g-C3N4/NH2-UiO-66 (Zr) catalyst under visible light irradiation. Initially, the catalyst was prepared by a simple method, and its physiochemical features were thoroughly analyzed by XRD, FT-IR, FE-SEM, EDX, EDS-Dot-Mapping, and UV-Vis analytical techniques. After that, the impact of several influential factors affecting the performance of the applied sono-assisted photocatalytic process such as the initial concentration of CIP, solution pH, catalyst dosage, light intensity, and ultrasound power was fully assessed, and the optimal conditions were established. After 75 min of the sono-assisted photocatalytic treatment, the complete degradation of CIP (10 mg/L) was accomplished under the condition as follows: g-C3N4/NH2-UiO-66 (Zr), 0.6 g/L; pH, 5.0, and ultrasound power, light intensity 75 mw/cm2, 200 W/m2. Meanwhile, the photocatalytic degradation of CIP followed the pseudo-first-order kinetic model. In addition, the scavenger experiments demonstrated that OH˚ and O2°- radicals played a key role in the sono-assisted photocatalytic degradation process. It is also acknowledged that the applied catalyst was reused for five consecutive runs with a minor loss observed in its degradation efficiency. In a further experiment, a significant synergistic effect with regard to the degradation of CIP was observed once all three major parameters (visible light, ultrasound waves, and catalyst) were used in combination compared to each used alone. To sum up, it is thought that the integration of g-C3N4/MOF-based catalyst, ultrasound waves, and visible light irradiation could be potentially applied as a promising strategy for the degradation of various pharmaceuticals on account of high degradation performance, simple operation, excellent reusability, and eco-friendly approach.

Ultrasonic treatment of dye chemicals in wastewater: A review

The existence of pollutants, such as toxic organic dye chemicals, in water and wastewater raises concerns as they are inadequately eliminated through conventional water and wastewater treatment methods, including physicochemical and biological processes. Ultrasonic treatment has emerged as an advanced treatment process that has been widely applied to the decomposition of recalcitrant organic contaminants. Ultrasonic treatment has several advantages, including easy operation, sustainability, non-secondary pollutant production, and saving energy. This review examines the elimination of dye chemicals and categorizes them into cationic and anionic dyes based on the existing literature. The objectives include (i) analyzing the primary factors (water quality and ultrasonic conditions) that influence the sonodegradation of dye chemicals and their byproducts during ultrasonication, (ii) assessing the impact of the different sonocatalysts and combined systems (with ozone and ultraviolet) on sonodegradation, and (iii) exploring the characteristics-based removal mechanisms of dyes. In addition, this review proposes areas for future research on ultrasonic treatment of dye chemicals in water and wastewater.

Multiple phases of yttrium-doped molybdenum trioxide nanorods as efficient dye degrader and bactericidal agents with molecular docking analysis

Contaminants removal is usually becoming an exciting subject of research from water considering their environmental and ecological effects. This work provides pathways to remove organic pollutants from water via nanomaterials and is used as an antibiotic against bacteria like Escherichia coli (E. coli). In this study, molybdenum trioxide (MoO3) and yttrium (Y) doped (2 and 4%) MoO3 nanorods were synthesized by co-precipitation method. Advanced characterization techniques have been introduced to study textural structures, morphological developments, and optical characteristics of produced products. X-ray diffraction studied multiple crystalline structures of prepared samples as hexagonal, orthorhombic, and monoclinic of pure MoO3 with decrease in crystallinity and crystallite size upon Y doping. UV-visible spectroscopy unveiled a redshift (bathochromic effect) in absorption pattern attributed to band gap energy (Eg) decreases. Photoluminescence spectra examined the recombination rate of electrons (e-) and holes (h+) as charge carriers. A sufficient catalytic activity (CA) was observed against methylene blue (MB) dye in an acidic medium (99.74%) and efficient bactericidal action was studied against (E. coli) with zone of inhibition (5.20 mm) for 4% Y-doped MoO3. In addition, in silico docking demonstrated potential inhibitory effect of produced nanomaterials on FabH and FabI enzymes of fatty acid biosynthesis.

In situ preparation of TiO2/f-MWCNT catalyst using Pluronic F127 assisted sol-gel process for sonocatalytic degradation of methylene blue

In this study, titanium dioxide- Pluronics @F127/functionalized -multi walled carbon nanotubes (TiO₂-F127f-/MWCNT) nanocatalysts were prepared, characterized, and used in methylene blue (MB) degradation under ultrasonic conditions. The characterization studies were performed using TEM, SEM, and XRD analyses to reveal the morphological and chemical properties of TiO₂-F127/MWCNT nanocatalysts. To detect the optimum parameters for MB degradation using TiO₂-F127/f-MWCNT nanocatalysts, several experimental parameters were conducted at various conditions such as different temperatures, pH, catalyst amount, hydrogen peroxide (H₂O₂) concentration, and various reaction contents. Transmission electron microscopy (TEM) analyses showed that TiO₂-F127/f-MWCNT nanocatalysts consisted of a homogenous structure and have a 12.23 nm particle size. The crystalline particle size of TiO₂-F127/MWCNT nanocatalysts was found to be 13.31 nm. Scanning electron microscope (SEM) analyses revealed the surface structure of TiO₂-F127/f-MWCNT nanocatalysts turned to be modified after TiO₂ loaded on MWCNT. Under the optimum conditions; pH: 4, MB concentration: 25 mg/L, H₂O₂ concentration: 30 mol/L, reaction time: and catalyst dose: 24 mg/L, chemical oxygen demand (COD) removal efficiency reached a maximum of 92%. To detect the radical effectiveness, three scavenger solvents were tested. Reuse experiments revealed that TiO₂-F127/f-MWCNT nanocatalysts retained 84.2% catalytical activity after 5 cycles. Gas chromatography-mass spectrometry (GC-MS) was successfully used to identify the generated intermediates. In addition, the GC-MS was successfully used to identify produced intermediates. Based on the experimental results, it has been suggested that •OH radicals are the main active species responsible for the degradation reaction in the presence of the TiO₂-F127/f-MWCNT nanocatalysts.

Facile provision of CuO-Kaolin nanocomposite for boosted sonocatalytic removal of Cr(VI) from hydrous media

Nowadays, nanoscale materials have been widely applied in the removal of contaminants from the water system. Reduction of Cr(VI) (as a poisonous species) to Cr(III) (as a slight toxic species) was performed using CuO-Kaolin with ultrasound (US) irradiation. The CuO-Kaolin nanocomposite was synthesized via a facile co-precipitation method. Then X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope and Energy dispersive X-ray spectroscopy analyses were performed to identify the structural features of CuO-Kaolin. The role of influential parameters for the reduction of Cr(VI) was investigated in sonocatalytic advanced oxidation system. About 89.35% of Cr(VI) was removed via US/CuO-Kaolin process after 90 min at optimum conditions (pH = 3, sonocatalyst dosage = 1 g L^-1 and [Cr (VI)]₀ = 20 mg L^-1). This outstanding result was due to the synergistic effect of the increased electron delivery to conduction band on CuO-Kaolin nanocomposite and the increased reactive surface region of nanoparticles by sonication. The presence of H₂O₂ as an amplifier improved the removal efficiency of Cr(VI) from 89.35% to 100% after 20 min. Kinetic experimental results were well described by a pseudo-first-order kinetic model. Desorption experiments showed excellent stability of sonocatalyst during the reaction and maintenance of the catalytic activity up to 10 sequential cycles.

Titanium-based MAX-phase with sonocatalytic activity for degradation of oxytetracycline antibiotic

In light of growing environmental concerns over emerging contaminants in aquatic environments, antibiotics in particular, have prompted the development of a new generation of effective sonocatalytic systems. In this study, a new type of nano-laminated material, Ti₂SnC MAX phase, is prepared, characterized, and evaluated for the sonocatalytic degradation of oxytetracycline (OTC) antibiotic. A variety of identification analyses, including X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectrometry, Brunauer-Emmett-Teller, and diffuse reflectance spectroscopy, were conducted to determine the physicochemical properties of the synthesized catalyst. By optimizing the operating factors, total degradation of OTC occurs within 120 min with 1 g L^-1 catalyst, 10 mg L^-1 OTC, at natural pH of 7.1 and 150 W ultrasonic power. The scavenger studies conclude that the singlet oxygen and superoxide ions are the most active species during the sonocatalytic reaction. Based on the obtained data and GC-MS analysis, a possible sonocatalytic mechanism for the OTC degradation in the presence of Ti₂SnC is proposed. The catalyst reusability within eight consecutive runs reveals the proper stability of Ti₂SnC MAX phase. The results indicate the prospect for MAX phase-based materials to be developed as efficient sonocatalysts in the treatment of antibiotics, suggesting a bright future for the field.

Recent advances on PFAS degradation via thermal and nonthermal methods

Per- and polyfluoroalkyl substances (PFAS) are a set of synthetic chemicals which contain several carbon-fluorine (C-F) bonds and have been in production for the past eight decades. PFAS have been used in several industrial and consumer products including nonstick pans, food packaging, firefighting foams, and carpeting. PFAS require proper investigations worldwide due to their omnipresence in the biotic environment and the resulting pollution to drinking water sources. These harmful chemicals have been associated with adverse health effects such as liver damage, cancer, low fertility, hormone subjugation, and thyroid illness. In addition, these fluorinated compounds show high chemical, thermal, biological, hydrolytic, photochemical, and oxidative stability. Therefore, effective treatment processes are required for the removal and degradation of PFAS from wastewater, drinking water, and groundwater. Previous review papers have provided excellent summaries on PFAS treatment technologies, but the focus has been on the elimination efficiency without providing mechanistic understanding of removal/degradation pathways. The present review summarizes a comprehensive examination of various thermal and non-thermal PFAS destruction technologies. It includes sonochemical/ultrasound degradation, microwave hydrothermal treatment, subcritical or supercritical treatment, electrical discharge plasma technology, thermal destruction methods/incinerations, low/high-temperature thermal desorption process, vapor energy generator (VEG) technology and mechanochemical destruction. The background, degradation mechanisms/pathways, and advances of each remediation process are discussed in detail in this review.

In-vitro toxicity assessment of a textile dye Eriochrome Black T and its nano-photocatalytic degradation through an innovative approach using Mf-NGr-CNTs-SnO2 heterostructures

The present study aimed to assess the in-vitro toxicity of a popular azodye, Eriochrome Black T (EBT) which may be an environmental hazard causing water pollution if released by textile industries as waste effluents to nearby water ponds. We explored the toxic potential of EBT at 200, 400 and 800 μg/ml concentrations, which were selected based on quantification of EBT present in the pond water near carpet industries. We investigated the permeability of EBT across the organ barriers and found it to be 6.48 ± 0.44% at the highest concentration. EBT also showed up to 26.46 ± 0.533% hemolytic potential on human RBCs. MTT assay revealed toxicity of up to 64.9 ± 10.12%. A dose-dependent increase in intracellular ROS levels and Caspase 3/7 activity was observed and confocal microscopy also demonstrated a similar trend of cellular apoptosis indicating ROS mediated induction of apoptosis as a mechanism of EBT induced cytotoxicity. After establishing the toxicity of EBT, an innovative nano-photocatalytic approach for dye remediation was applied by using as synthesized Mf-NGr-CNTs-SnO₂ heterostructures. This catalyst showed dye degradation potential of up to 82% in 2 h in the presence of sun light. The degraded dye products were tested to have up to 30% reduced cellular toxicity as compared to the parent compound. This work successfully establishes the toxicity of EBT along with devising an innovative approach towards dye degradation where the catalyst is adhered on melamine foam and not being mixed in the effluents directly, thereby, reducing the possibility of catalyst being leached out into the river water.

Mitigation of hazards and risks of emerging pollutants through innovative treatment techniques of post methanated distillery effluent - A review

Distillery wastewater has high biological and chemical oxygen demand and requires additional treatment before it can be safely discharged into receiving water. It is usually processed through a biomethanation digester and the end product is the post-methanated distillery effluent (PMDE). Research have shown that PMDE released by molasses-based distilleries is a hazardous effluent that can cause harm to the biota and the environment; it contains elevated amount of total dissolved solids (TDS), total suspended solids (TSS) and excess levels of persistent organic compounds (POPs), heavy metals, phenolic compounds, and salts. The practice of wastewater reuse for irrigation in many water scarce countries necessitates the proper treatment of PMDE before it is discharged into receiving water. Convention methods have been in practice for decades, but innovative technologies are needed to enhance the efficiency of PMDE treatment. Advance physical treatment such as membrane separation technology using graphene, ion-exchange and ultrafiltration membranes; chemical treatment such as advanced oxidation methods, electrocoagulation and photocatalytic technologies; biological treatment such as microbial and enzymatic treatment; and hybrid treatment such as microbial-fuel cell (MFC), genetically modified organisms (GMO) and constructed wetland technologies, are promising new methods to improve the quality of PMDE. This review provides insight into current accomplishments evaluates their suitability and discusses future developments in the detoxification of PMDE. The consolidated knowledge will help to develop a better management for the safe disposal and the reuse of PMDE wastewater.

Synthesis of various dimensional metal organic frameworks (MOFs) and their hybrid composites for emerging applications - A review

Metal organic frameworks (MOFs) represent the organic and inorganic hybrid porous materials. MOFs are low dense and highly porous materials which in turn provide large surface area that can accumulate and store numerous molecules within the pores. The pore size may also act as a mesh to separate molecules. The porous nature of MOFs is beneficial for altering the intrinsic properties of the materials. Over the past decade, different types of hybrid MOFs have been reported in combination with polymers, carbon materials, metal nanoparticles, metal oxides, and biomolecules for various applications. MOFs have also been used in the fabrication of electronic devices, sensors, energy storage, gas separation, supercapacitors, drug delivery and environmental clean-up. In this review, the unique structural orientation, exceptional properties and recent applications of MOFs have been discussed in the first section along with their porosity, stability and other influencing factors. In addition, various methods and techniques involved in the synthesis and designing of MOFs such as solvothermal, electrochemical, mechanochemical, ultrasonication and microwave methods are highlighted. In order to understand the scientific feasibility of MOFs in developing new products, various strategies have been applied to obtain different dimensional MOFs (0D, 1D, 2D and 3D) and their composite materials are also been conferred. Finally, the future prospects of MOFs, remaining challenges, research gaps and possible solutions that need to be addressed by advanced experimental design, computational models, simulation techniques and theoretical concepts have been deliberated.

Polydopamine-Modified Cellulose Nanofibril Composite Aerogel: An Effective Dye Adsorbent

In this study, a new cellulose nanofibril (CNF) composite aerogel was fabricated using a green and facile mussel-inspired coating strategy. First, the CNF hydrogel was crosslinked by calcium ion followed by immersion in dopamine solution. Second, the surface of CNF was modified using polydopamine (PDA) to obtain PDA@CNF (PCNF) composite aerogel. The PCNF composite aerogels had large surface areas (368.15 m²/g) and low bulk density (27.2 mg/cm³). The composite aerogel exhibited improved mechanical properties, which were almost three times compared with those of CNF aerogel. Moreover, PCNF composite aerogel had good resilience under a wet state. The PDA functional layer remarkably enhanced the adsorption capacities of the composite aerogel for methylene blue (MB). The maximum adsorption of MB was 208 mg/g at an initial dye concentration of 50 mg/L. The adsorption isotherm and kinetic behaviors of the composite aerogel were consistent with Langmuir and pseudo-second-order models. In addition, the PCNF composite aerogels had a high adsorption capacity over a wide pH range. The reuse experiment showed that the removal efficiency of the composite aerogel remained higher than 85% after five cycles. Therefore, PCNF composite aerogels may have potential application in wastewater treatment due to its environmental sustainability and low energy consumption.

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.

Ciprofloxacin removal by ultrasound-enhanced carbon nanotubes/permanganate process: In situ generation of free reactive manganese species via electron transfer

Recently, free reactive manganese species (RMnS) generated via permanganate catalytic oxidation technology has been applied to contaminants abatement and sludge dewatering. This study proposed a novel free RMnS generation method in ultrasound enhanced carbon nanotube (CNTs)/permanganate process (UCP) for organics removal. Taking ciprofloxacin as a target contaminant, the removal efficiency in the UCP process (9.78 s^-1) was remarkably higher than that of the permanganate (0.71 s^-1) and CNTs/permanganate (2.57 s^-1) processes. CNTs could enrich manganese compounds and ciprofloxacin, and act as an electronic platform for the electronic transfer from ciprofloxacin to manganese compounds for free RMnS generation, which was revealed by DFT calculation and spectrum analysis. Meanwhile, ultrasound further regulated the generation of RMnS as it could transform the inactive solid Mn(IV) into free RMnS. In the UCP process, non-free radical modes including RMnS oxidation (49.8%) and electron transfer (23.5%) were the dominant processes for ciprofloxacin removal in the UCP process, and hydroxyl radical oxidation (13.2%), CNTs adsorption (5.5%), and PM oxidation (8.0%) also contributed to ciprofloxacin removal. Interestingly, CNTs could be well reused in the UCP process as more than 88.75% of ciprofloxacin was removed after five times reuse of CNTs. The UCP process provides a novel strategy for rapid contaminants removal in water treatment via continuous generation of free RMnS.

Remediation of malachite green in wastewater by ZIF-8@Fe/Ni nanoparticles based on adsorption and reduction

Dye-contaminated wastewater resulting from rapid industrialization and urbanization is a global problem. In this study, a ZIF-8@Fe/Ni sample was synthesized for the removal of malachite green (MG), removing more than 99% of an initial MG concentration of 50 mg L^-1 within 120 min with a 318 K adsorption capacity of 151.520 mg g^-1. To understand the dye removal mechanism based on adsorption and reduction, ZIF-8@Fe/Ni was characterized by various techniques. XRD showed that the ZIF-8@Fe/Ni composite had a characteristic peak attributable to Fe/Ni around 44.8°, where the presence of Fe/Ni did not affect the structure of ZIF-8. SEM confirmed that ZIF-8@Fe/Ni was successfully prepared, while XRD and FTIR revealed that the structure of ZIF-8@Fe/Ni remained stable following the introduction of Fe/Ni. XPS showed that while Fe/Ni nanoparticles existed in ZIF-8-Fe/Ni, partial oxidation also occurred. GC-MS demonstrated the creation of two major MG degradation products, (4-aminophenyl) (phenyl) methanone and 4-aminophenol. While the overall adsorption process of MG to ZIF-8@Fe/Ni conformed to pseudo-second-order kinetics, degradation followed pseudo-first-order reduction kinetics. When applied to the remediation of wastewater, ZIF-8@Fe/Ni removed 92% of MG. Overall, this study demonstrated that ZIF-8@Fe/Ni could be a promising material for the treatment of wastewater.

Boosted sono-oxidative catalytic degradation of Brilliant green dye by magnetic MgFe2O4 catalyst: Degradation mechanism, assessment of bio-toxicity and cost analysis

The magnetic MgFe₂O₄ nanoparticles (NPs) were fabricated via a facile co-precipitation technique and was comprehensively characterized by XRD, FTIR, SEM, EDX and VSM. The prepared NPs were used as catalyst in presence of ultrasound (US) irradiation to activate persulfate (PS) for generation of sulfate radicals (SO₄^·-) for boosted degradation of toxic Brilliant Green (BG) dye. Preliminary experiments revealed that highest BG dye degradation efficiency of 91.63% was achieved at MgFe₂O₄ catalyst dose of 1.0 g/L, PS dose of 300 mg/L, and initial dye concentration of 70 ppm within 15 min of US irradiation. However, only US, US in presence of PS oxidation and US in presence of MgFe₂O₄ catalyst have shown 20.2%, 83.6% and 45.0% of BG dye removal, respectively. Furthermore, response surface methodology (RSM) based central composite design (CCD) was executed to investigate the effect of interaction between independent variables such as MgFe₂O₄ catalyst dose (0.5-1.5 g/L), PS dose (150-350 mg/L), initial BG dye concentration (50-150 ppm) and US irradiation time (4-12 min). The RSM based quadratic model was used to predict the experimental data, and the prediction accuracy was confirmed by analysis of variance (R² = 0.98). The established RSM model has predicted the optimum experimental conditions as MgFe₂O₄ catalyst dose of 0.75 g/L, PS dose of 300 mg/L, initial dye concentration of 75 ppm and sonication time of 10 min. Subsequently, the treatment cost analysis was performed for all thirty experimental runs of CCD, and the RSM predicted response was found to be evidently optimum as this has delivered best economic condition (140 $/kg of BG removed) with respect to relative dye removal (%). COD removal and residual sulfate analysis have demonstrated satisfactory reduction of COD (90.31%) as well as sulfate ions (42.87 ppm) in the dye solution after treatment. Results of degradation pathway analysis portrayed the transformation of BG molecule (M/Z ratio 385) into simpler fractions with M/Z ratio of 193, 161, 73, and 61. Moreover, the toxicity analysis revealed that sono-catalytically activated PS system has efficiently reduced the toxicity level of BG dye from 93.9% to 5.13%.

Recyclable and Magnetically Functionalized Metal-Organic Framework Catalyst: IL/Fe3O4@HKUST-1 for the Cycloaddition Reaction of CO2 with Epoxides

A recyclable and magnetic nanocomposite catalyst (IL/Fe₃O₄@HKUST-1) was synthesized via grafting ionic liquid (IL) [AEMIm]BF₄ into magnetically functionalized metal-organic framework Fe₃O₄@HKUST-1 in a water-ethanol media. The properties of IL/Fe₃O₄@HKUST-1 were fully characterized by powder X-ray diffraction, electron microscopy, Fourier-transform infrared spectroscopy, nitrogen adsorption-desorption, density-functional theory, and a magnetic property measurement system. IL/Fe₃O₄@HKUST-1 showed high activity in the solvent-free cycloaddition of CO₂ with epoxides under mild conditions. Furthermore, the catalyst can be easily separated from the reaction mixture, and the recycled catalyst maintained high performance for several cycles. The synergistic effect of the Lewis acid and base sites in IL/Fe₃O₄@HKUST-1 contributes to its greater reactivity than individual IL or HKUST-1.

Design and performance of a novel direct Z-scheme NiGa2O4/CeO2 nanocomposite with enhanced sonocatalytic activity

A novel direct Z-scheme NiGa₂O₄/CeO₂ nanocomposite was designed and prepared via simple sol-hydrothermal and calcination methods, and its sonocatalytic activity was tested by studying the degradation of a model antimicrobial agent, malachite green (MG), under ultrasonic irradiation. Near complete (96.2%) degradation of MG (at 10 mg/L) could be achieved by the NiGa₂O₄/CeO₂ nanocomposite (at 1.0 g/L) after ultrasonic irradiation (40 kHz, 300 W) for 60 min at 25 °C. Under the same conditions, only 51.2 and 72.0% of the MG degraded in the presence of NiGa₂O₄ and CeO₂ (at 1.0 g/L), respectively. These results demonstrate that the direct Z-scheme NiGa₂O₄/CeO₂ nanocomposite has excellent sonocatalytic activity, which is attributed to the matching band-gaps between NiGa₂O₄ and CeO₂. The sonocatalytic activity of NiGa₂O₄/CeO₂ nanocomposite decreased by 17% after four cycles of reuse, which is indicative of relatively good reusability. Scavenging experiments revealed that sonocatalytic degradation of MG results from the combined action of hydroxyl radicals (OH) and holes (h⁺), with the latter having a greater contribution. The pathways and mechanism of MG degradation were proposed based on the degradation intermediates detected. The results demonstrate that the prepared direct Z-scheme NiGa₂O₄/CeO₂ nanocomposite worked as designed and exhibited high and stable sonocatalytic activity during MG degradation, and could thus serve as a promising candidate in sonocatalytic treatment of other organic pollutants in wastewaters. The findings also provide new insights on the mechanism of sonocatalytic degradation and the design of efficient Z-scheme sonocatalysts.

A low-cost solvent-free method to synthesize α-Fe2O3 nanoparticles with applications to degrade methyl orange in photo-fenton system

Hematite nanoparticles (α-Fe₂O₃ NPs) were successfully synthesized by a low-cost solvent-free reaction using Ferrous sulfate waste (FeSO₄·7H₂O) and pyrite (FeS₂) as raw materials and employed for the decolorization of Methyl Orange by the photo-Fenton system. The properties of α-Fe₂O₃ NPs before and after photo-Fenton reaction were characterized by X-ray powder diffraction (XRD), Field emission scanning electron microscopy (FESEM), Fourier transform infrared (FT-IR) spectrum and X-ray photoelectron spectroscopy (XPS), and the optical properties of α-Fe₂O₃ NPs were analyzed by UV-vis diffuse reflectance spectra (UV-vis DRS) and Photoluminescence (PL) spectra. The analytic results showed that the as-formed samples having an average diameter of ~50 nm exhibit pure phase hematite with sphere structure. Besides, little differences were found by comparing the characterization data of the particles before and after the photo-Fenton reaction, indicating that the photo-Fenton reaction was carried out in solution rather than on the surface of α-Fe₂O₃ NPs. A 2⁴ central composite design (CCD) coupled with response surface methodology (RSM) was applied to evaluate and optimize the important variables. A significant quadratic model (P-value<0.0001, R² = 0.9664) was derived using an analysis of variance (ANOVA), which was adequate to perform the process variables optimization. The optimal process conditions were performed to be 395 nm of the light wavelength, pH 3.0, 5 mmol/L H₂O₂ and 1 g/L α-Fe₂O₃, and the decolorization efficiency of methyl orange was 99.55% at 4 min.

Sonochemical synthesis and structural characterization of an organic-inorganic nanohybrid based on a copper-dithiocarbamate complex and PMo12O403- polyanion as a novel sonocatalyst

A new organic-inorganic nanohybrid compound, ([Cu{(HOCH₂CH₂)₂NCS₂}₂]₃[PMo₁₂O₄₀] (1)), has been prepared by sonochemical technique using copper(II) dithiocarbamate complex and a Keggin-type polyoxomolybdate in this research. FT-IR, XRD, FE-SEM, TEM, EDX, UV-Vis, TGA, BET, and single crystal XRD analyses were applied to describe the properties of the composition of the nanohybrid. Compound (1) is composed of [PMo₁₂O₄₀]^3- building blocks and [Cu{(HOCH₂CH₂)₂NCS₂}₂]¹⁺ cationic moieties, and electrostatic forces and substantial hydrogen-bonding interactions were applied to pack them; and consequently, a three dimensional supramolecular framework was made based on single-crystal X-ray diffraction patterns. FE-SEM and TEM images approved the morphology of the nanohybrid sample to be extremely penetrable. Very good sonocatalytic performance is shown by this supramolecular nanohybrid in the degradation of Rhodamine B (RhB), which is a cationic organic dye. The results showed complete degradation of cationic RhB (25 mg/L) within 70 min with the rate constant of 0.039min^-1 in the presence of nanohybrid (1) and H₂O₂ (4 mmol/L). Also, sonocatalytic activity of the nanohybrid (1) was higher than H₃PMo₁₂O₄₀, showing that the combining Cu(DEDTC)₂ complex with H₃PMo₁₂O₄₀ could be an excellent choice to improve its sonocatalytic activity. The used nanohybrid (1) can be recycled after easily removing from the reaction media by centrifuging, and there was no considerable loss of catalytic activity and retention of the structure.

Sono-coprecipitation synthesis of ZnO/CuO nanophotocatalyst for removal of parathion from wastewater

Semiconductor photocatalysis is an effective method used to degrade organophosphorus compounds. Here, the potential of a commonly mixed oxide semiconductor, ZnO/CuO, has been examined to degrade methyl parathion. Sono-coprecipitation method was used to provide ZnO/CuO nanocomposites, and it was applied to photocatalytic and sono-photocatalytic degradation of methyl parathion under solar light irradiation. Powder x-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), the Brunauer-Emmett-Teller (BET) surface area, field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM) were used to characterize the synthesized samples. The optimal experimental conditions such as ZnO/CuO photocatalyst 90:10 M ratios, the initial concentration of 20 mg/L parathion, 1 g/L photocatalyst loading, no compressed air sparging, pH of 8, and ultrasonic power (60 W and 80 kHz) were used to degrade the parathion effectively. The parathion was fully (100% removal) degraded after 60 min sono-photoirradiation in the optimal experimental conditions. A real water sample was used to examine the ability of the ZnO/CuO photocatalyst 90:10 to remove the parathion in the water-soluble ions. Graphical abstract.

MIL-101(Cr)–cobalt ferrite magnetic nanocomposite: synthesis, characterization and applications for the sonocatalytic degradation of organic dye pollutants

In this study, for the first time, a novel magnetically recyclable MIL-101(Cr)/CoFe₂O₄ nanocomposite was prepared via a facile solvothermal method. The morphology, structural, magnetic and optical properties of the nanocomposite were characterized via field emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM), energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), UV-visible spectroscopy (UV-visible) and BET surface area analysis. Furthermore, the sonocatalytic activity of the MIL-101(Cr)-based magnetic nanocomposite was explored for the degradation of organic dye pollutants such as Rhodamine B (RhB) and methyl orange (MO) under ultrasound irradiation in the presence of H₂O₂. Under optimized conditions, the degradation efficiency reached 96% for RhB and 88% for MO. The sonocatalytic activity of MIL-101(Cr)/CoFe₂O₄ was almost 12 and 4 times higher than that of the raw MIL-101(Cr) and pure CoFe₂O₄, respectively. The improved sonocatalytic performance of the as-prepared binary nanocomposite can be attributed to the relatively high specific surface area of MIL-101(Cr) and magnetic property of CoFe₂O₄, as well as the fast generation and separation of charge carriers (electrons and holes) in MIL-101(Cr) and CoFe₂O₄. In addition, the trapping tests demonstrated that ·OH radicals are the main active species in the dye degradation process. Moreover, the most influencing factors on the sonocatalytic activity such as the H₂O₂ amount, initial dye concentration and catalyst dosage were investigated. Finally, the nanocomposite was magnetically separated and reused without any observable change in its structure and performance even after four consecutive runs.

A magnetically separable MIL-101(Cr)/CoFe₂O₄ binary nanocomposite was prepared via a hydrothermal route and applied as a sonocatalyst for the efficient degradation of organic dyes.

Co nanoparticle-embedded N,O-codoped porous carbon nanospheres as an efficient peroxymonosulfate activator: singlet oxygen dominated catalytic degradation of organic pollutants

A mesoporous N,O-doped carbon@Co composite with good magnetism for efficient catalytic elimination of organic pollutants via peroxymonosulfate activation.

Fabrication of a novel magnetic CdS nanorod/NiFe2O4/NaX zeolite nanocomposite with enhanced sonocatalytic performance in the degradation of organic dyes

Herein, magnetically separable CdS nanorods (NRs)/NiFe₂O₄/NaX zeolite ternary nanocomposite was fabricated and applied for the enhanced sonocatalytic degradation of organic dyes.

Synthesis and characterization of a novel manganese ferrite–metal organic framework MIL-101(Cr) nanocomposite as an efficient and magnetically recyclable sonocatalyst

A magnetic MnFe₂O₄/MIL-101(Cr) nanocomposite was synthesized and applied as a novel sonocatalyst for enhanced degradation of organic dye pollutants.

Synergistic catalytic effect between ultrasound waves and pyrimidine-2,4-diamine-functionalized magnetic nanoparticles: Applied for synthesis of 1,4-dihydropyridine pharmaceutical derivatives

A convenient strategy for synthesis of the various derivatives of 1,4-dihydropyridine (1,4-DHP), as one of the most important pharmaceutical compounds, is presented in this study. For this purpose, firstly, magnetic iron oxide nanoparticles (Fe₃O₄ NPs) were fabricated and suitably coated by silica network (SiO₂) and trimethoxy vinylsilane (TMVS). Then, their surfaces were well functionalized with pyrimidine-2,4-diamine (PDA) as the main active sites for catalyzing the synthesis reactions. In this regard, the performance of three different methods including reflux, microwave (MW) and ultrasound wave (USW) irradiations have been comparatively monitored via studying various analyses on the fabricated nanocatalyst (Fe₃O₄/SiO₂-PDA). Concisely, high efficiency of the USW irradiation (in an ultrasound cleaning bath with a frequency of 50 kHz and power of 250 W/L) has been well proven through the investigation of the main factors such as excellent surface-functionalization, core/shell structure conservation, particle uniformity, close size distribution of the particles, and great inhibition of the particle aggregation. Then, the effectiveness of the USW irradiation as a promising co-catalyst agent has been clearly demonstrated in the 1,4-DHP synthesis reactions. It has been concluded that the USW could provide more appropriate conditions for activation of the catalytic sites of Fe₃O₄/SiO₂-PDA NPs. However, high reaction yields (89%) have been obtained in the short reaction times (10 min) due to the substantial synergistic effect between the presented nanocatalyst and USW.

Modeling of azo dyes adsorption on magnetic NiFe2O4/RGO nanocomposite using response surface methodology

BACKGROUND

Azo group dyes are the largest group of synthetics dyes that widely used in industries, especially in textile industry. The presence of these organic compounds in wastewaters and their discharge into environment without efficient treatment may cause adverse effect on human, living and aquatic environment. The purpose of this study was to optimize the adsorption of azo dye of Direct Red 81 (anionic dye) and Basic Blue 41 (cationic dye) from aqueous solution onto magnetic NiFe₂O₄/RGO nanocomposite.

METHODS

In this study the response surface methodology (RSM) based on the central composite design (CCD), was used to optimization and modeling of adsorption process DR81 and BB41 dye on NiFe₂O₄/RGO. in order to investigating the effect of the operating parameters on the adsorption efficiency DR81 and BB41, four influential factors were chosen that includes of pH (3-9), contact time (5-25 min), adsorbent amount (0.02-0.05 g) and initial dye concentration (40-200 mg/L). A total of 30 experiments were performed for each dye in this study. The concentration of dye in solution was measured by spectrophotometer. The structure of synthesized adsorbent was investigated using Scanning Electron Microscope (SEM), X-ray diffraction (XRD), Fourier transform irradiation (FTIR), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM).

RESULTS

Analysis of variance (ANOVA) showed that regression model for both dye adsorption with value of P value <0.001 is significant statistically. The correlation coefficient (R²) for DR81 (R² = 0.9968) and BB41 (R² = 0.9948) indicated which there is a good agreement between predicted values and the results of the experiments and the model also well predict the adsorption efficiency. Furthermore, the factors of pH, dye concentration and adsorbent dose, have the greatest effect on adsorption, respectively, while contact time have the lowest effect on adsorption of both dyes. The adsorption behavior of the DR81 and BB41 onto NiFe₂O₄/RGO was best described by the Langmuir and Freundlich isotherm, respectively. The optimum conditions for maximum removal of DR81 (96.41%) was found to be at pH 3, contact time 19.68 min, adsorbent dose 0.02 g and initial dye concentration 40 mg/L. However, the optimum conditions for maximum removal of BB41 (97.87%) was found to be at pH 9 contact time 18.16 min, adsorbent dose 0.02 g and initial dye concentration 40 mg/L.

CONCLUSION

The present study shows that magnetic NiFe₂O₄/RGO nanocomposite have much potential as a powerful adsorbent for the rapid adsorption of anionic (DR81) and cationic dyes (BB41) from aqueous solution.

Enhanced sonocatalytic performance of ZnTi nano-layered double hydroxide by substitution of Cu (II) cations

In this research, a series of CuZnTi-LDHs with different Cu²⁺/Zn²⁺ molar ratio were synthesized by co-precipitation method with the purpose of improving the sonocatalytic performance of ZnTi-LDH. All the LDH samples were synthesized by a facile co-precipitation process. The as-prepared LDHs were characterized by Powder X-ray diffraction (XRD), Field emission-scanning electron microscopy (FESEM), Transition electron microscopy (TEM), Brunauer-Emmelt-Teller (BET) analysis, and UV-visible diffuse reflectance spectroscopy (DRS) analysis. The results showed that Cu²⁺ substitution can significantly enhance the sonocatalytic properties of ZnTi-LDH. The Methylene blue degradation percentage over ZnTi-LDH reached 30% in 90 min, whilst this percentage reaches 71% over CuZnTi-LDH (1:1). The role of the Cu²⁺ incorporation on the observed enhancement in sonocatalytic performance was revealed by investigating the effect of radical scavengers on degradation efficiency and DRS spectra of ZnTi-LDH and CuZnTi-LDH (1:1). Benzoquinone (BQ), ammonium oxalate and tert-Bu lead to 22.5%, 53.5% and 74.6% decrease in degradation percentage by CuZnTi-LDH (1:1). However, the degradation efficiency showed 16.6%, 3.3% and 63.3% reduction in the presence of BQ, ammonium oxalate and tert-Bu respectively, in dye degradation by ZnTi-LDH. DRS spectra demonstrated that the band gap of the LDH decreases by Cu²⁺ substitution. The effect of operational parameters on sonodegradation was investigated as well. The kinetics of sonodegradation reaction obeyed the first order reaction kinetics with R² of 0.95.

A review on carbon-based materials for heterogeneous sonocatalysis: Fundamentals, properties and applications

Contamination of water resources by refractory organic pollutants is of great environmental and health concern because these compounds are not degraded in the conventional wastewater treatment plants. In recent years, sonocatalytic treatment has been considered as a promising advanced oxidation technique for the acceptable degradation and mineralization of the recalcitrant organic compounds. For this purpose, various sonocatalysts have been utilized in order to accelerate the degradation process. The present review paper provides a summary of published studies on the sonocatalytic degradation of various organic pollutants based on the application of carbon-based catalysts, including carbon nanotubes (CNTs), graphene (GR), graphene oxide (GO), reduced graphene oxide (rGO), activated carbon (AC), biochar (BC), graphitic carbon nitride (g-C₃N₄), carbon doped materials, buckminsterfullerene (C60) and mesoporous carbon. The mechanism of sonocatalytic degradation of different organic compounds by the carbon-based sonocatalysts has been well assessed based on the literature. Moreover, the details of experimental conditions such as sonocatalyst dosage, solute concentration, ultrasound power, applied frequency, initial pH and reaction time related to each study have also been discussed in this review. Finally, concluding remarks as well as future challenges in this research field regarding new areas of study are also discussed and recommended.

Preparation of a novel Z-scheme KTaO3/FeVO4/Bi2O3 nanocomposite for efficient sonocatalytic degradation of ceftriaxone sodium

In this work, a novel Z-scheme sonocatalyst, KTaO₃/FeVO₄/Bi₂O₃, is prepared via ultrasonic-assisted isoelectric point method. The prepared samples are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectroscopy. The catalytic activity of Z-scheme KTaO₃/FeVO₄/Bi₂O₃ sonocatalyst is studied in degradation of ceftriaxone sodium under ultrasonic irradiation. In addition, the influences of ultrasonic irradiation time, scavengers and sonocatalyst used times on sonocatalytic degradation of ceftriaxone sodium are examined. Under the experimental conditions of 150 min ultrasonic irradiation time, 1.00 g/L KTaO₃/FeVO₄/Bi₂O₃ addition amount and 10.00 mg/L ceftriaxone sodium concentration, the sonocatalytic degradation ratio of ceftriaxone sodium achieves 81.30%. Finally, the possible sonocatalytic degradation mechanism of ceftriaxone sodium caused by Z-scheme KTaO₃/FeVO₄/Bi₂O₃ sonocatalyst is proposed. The enhanced sonocatalytic activity may be attributed to the fact that the FeVO₄ as a special conductive channel provides a strong driving force to transfer electrons through valence state changes of iron and vanadium, which accelerates electron transfer from conduction band (CB) of Bi₂O₃ to valence band (VB) of KTaO₃. Perhaps, the KTaO₃/FeVO₄/Bi₂O₃ composite is an excellent Z-scheme sonocatalyst which can be used to effectively degrade the organic pollutants in wastewater under ultrasonic irradiation.

Silkworm cocoon derived N, O-codoped hierarchical porous carbon with ultrahigh specific surface area for efficient capture of methylene blue with exceptionally high uptake: kinetics, isotherm, and thermodynamics

Dyes are typical water contaminants that seriously affect water quality. In this study, silkworm cocoon derived N, O-codoped hierarchical porous carbon was successively developed via a facile pre-carbonization and chemical activation method, and characterized thoroughly by SEM, TEM, HRTEM, XRD, Raman, N₂ adsorption and XPS. The as-prepared N, O-HPC showed a well-developed porous structure with an ultra-high specific surface area of 2270.19 m² g^-1, which proved to be a high-efficiency adsorbent. Batch adsorption experiments demonstrated that MB adsorption was highly dependent on contact time, initial MB concentration, temperature and initial solution pH. However, no remarkable effects of humic acid and ionic strength were observed. In the kinetic studies, the good applicability of a pseudo-second-order kinetic model was demonstrated. The adsorption isotherm study showed that a Langmuir isotherm model can describe the experimental data much more suitably with a maximum monolayer adsorption capacity value of 2104.29 mg g^-1, which is among the highest in previously reported adsorbents and ascribed to multiple adsorption mechanisms including pore filling, π-π stacking interaction and electrostatic interaction between MB and N, O-HPC. Thermodynamic analyses suggested that MB adsorption onto N, O-HPC was spontaneous and endothermic. Furthermore, the as prepared adsorbent showed highly efficient adsorption for MB in tap water and synergistic adsorption performance toward MB and MO. Therefore, N, O-HPC derived from silkworm cocoon could be considered as an efficient, novel and advantageous material for wastewater remediation.

Biosynthesized silver nanoparticles using Bacillus amyloliquefaciens; Application for cytotoxicity effect on A549 cell line and photocatalytic degradation of p-nitrophenol

The present study reports the biosynthesis of silver nanoparticles (AgNPs) using Bacillus amyloliquefaciens MSR5. The cellfree supernatant of B. amyloliquefaciens acted as a stabilizing agent for the synthesis of AgNPs. The synthesized AgNPs were characterized using UV-vis spectrophotometer, PXRD, FTIR, SEM-EDX, DLS, and TEM. TEM image showed the spherical shape of the biosynthesized AgNPs and it was found to be 20-40 nm in range. In this study, the AgNPs were prepared by ultrasonic irradiation. The stability of the AgNPs was found to be -33.4 mV using zeta potential. The catalytic 4-nitrophenol (4-NP) degradation by AgNPs was examined under solar irradiation and furthermore, the effects of several degradation parameters were studied. The biosynthesized AgNPs exhibited a strong chemocatalytic action with a comprehensive degradation (98%) of 4-NP to 4-aminophenol (4-AP) using NaBH₄ within 15 min. In addition, MTT assay was performed to evaluate the cytotoxicity of the biosynthesized AgNPs (10 - 200 μg). The results have shown that the AgNPs exhibited significant activity on A549 cells, which was dosedependent. The study elucidates the AgNPs synthesized using cellfree culture supernatant can be used for the elimination of hazardous pollutants from wastewater.

A sono-photocatalyst for humic acid removal from water: Operational parameters, kinetics and mechanism

As a precursor of disinfection byproducts, humic acid (HA) has adverse effects on aquatic environments and human health. Currently, many advanced oxidation processes (AOPs) have been proposed to remove HA from drinking water, one of which is photocatalysis. However, the long reaction time required for degradation and drawbacks of the photocatalysts limit the large-scale application of photocatalysis. Therefore, two principal objectives were achieved in this work. First regarding the technology, we combined photocatalysis with ultrasonic waves to remove HA. Second regarding the photocatalyst, quaternary Fe₃O₄/TiO₂-N-GO (FTNG) sono-photocatalysts with different amounts of Fe₃O₄ were first synthesized using a simple hydrothermal method. Characterizations were performed to confirm the successful synthesis of the sono-photocatalyst and to determine some of its properties. The influence of different experimental factors such as Fe₃O₄ content, ultrasonic power, catalyst dosage and initial HA concentration were studied. The first-order kinetic and second-order kinetic equations were used to simulate the experimental data. The results showed that FTNG-0.2 with 0.2 g of Fe₃O₄, which was added upon preparation, showed the highest sono-photocatalytic ability. In our experimental setup, greater than 99% removal efficiency (UV₂₅₄) and 94% mineralization rate (TOC) were achieved within 90 min at the optimum conditions (60 W ultrasound power and 1.0 g/L catalyst dosage for 30 mg/L HA). Compared with the pseudo-first-order kinetic model, pseudo-second-order model fitted better with the experimental data and it had higher R² values of 0.92, 0.98 and 0.98 for 30, 40 and 50 mg/L of HA, respectively. According to the scavenging tests and the ESR analysis, both of the OH and O₂^- were produced in the reaction, however, O₂^- radicals were assumed to be the dominating reactive species for the HA degradation. Moreover, after five repetitive experiments, the removal efficiency of HA can still reach 88.5%, indicating high stability of FTNG-0.2 sono-photocatalyst. The mechanism of degradation of HA by FTNG-0.2 in sono-photocatalytic system was mentioned based on several factors including the ultrasonic cavitation effect, Fenton-like reactions, photocatalytic reactions, etc. In fact, this was the first study to treat HA through sono-photocatalytic process, which showed great potential in drinking water treatment.