Uptake, translocation, and nutrient efficiency of nano-bonechar as a plant growth regulator in hydroponics and soil systems.

The use of nanotechnology in terms of nanoparticles, carbon nanotubes, and quantum dots, when exposed to the plants, helps increase their productivity. It is worth the effort to comprehend the fate of these nanoparticles in plants. Bonechar derived from bones is a rich source of C, P, Ca2+, and Mg2+ nutrients, which can significantly contribute to the growth of the plants. This study focused on the uptake of nano-bonechar (NBC) in the Syngonium podophyllum plant, and its effects on plant growth under hydroponics and soil systems. The compound microscopy and SEM-EDX results confirmed the presence of NBC in the leaves and roots of the plants in hydroponics and soil systems. The FTIR spectra reflected the presence of functional groups of the NBC in the leaves of the Syngonium podophyllum plant. The plant's growth parameters showed an increase in fresh weight, dry weight, shoot length, chlorophyll content, leaf count, total Ca2+, total PO43-, and total organic carbon of plants in both systems. The NBC not just improved plant physiochemical parameters but also built up the soil quality in terms of bioavailable Ca2+, PO43-, water holding capacity, and soil organic matter. It is concluded that the production of carbon-based NBC not only helps manage bone waste but also their efficient uptake in plants significantly improving plant productivity.

Recent advances in visible light driven inactivation of bloom forming blue-green algae using novel nano-composites: Mechanism, efficiency and fabrication approaches.

Over the years, algae have proved to be a water pollutant due to global warming, climate change, and the unregulated addition of organic compounds in water bodies from diffused resources. Harmful algal blooms (HABs) are severely affecting the health of humans and aquatic ecosystems. Among available anti-blooming technologies, semiconductor photocatalysis has come forth as an effective alternative. In the recent past, literature has been modified extensively with a decisive knowledge regarding algal invasion, desired preparation of nanomaterials with enhanced visible light absorption capacity and mechanisms for algal cell denaturation. The motivation behind this review article was to gather algal inactivation data in a systematic way based on various research studies, including the construction of nanoparticles and purposely to test their anti-algal activities under visible irradiation. Additionally, this article mentions variety of starting materials employed for preparation of various nano-powders with focus on their synthesis routes, analytical techniques as well as proposed mechanisms for lost cellular integrity in context of reduced chlorophyll' a' level, cell rapture, cell leakage and damages to other physiological constituents; credited to oxidative damage initiated by reactive oxidation species (ROS). Various floating and recyclable composited catalysts Ag2CO3-N: GO, Ag/AgCl@ZIF-8, Ag2CrO4-g-C3N4-TiO2/mEP proved to be game-changers owing to their enhanced VL absorption, adsorption, stability, separation and reusability. An outlook for the generalized limitations of published reports, cost estimations for practical implementation, issues and challenges faced by nano-photocatalysts and possible opportunities for future studies are also proposed. This review will be able to provide vast insights for coherent fabrication of catalysts, breakthroughs in experimental methodologies and help in elaboration of damage mechanisms.

One-Pot Synthesis of Heterobimetallic Metal-Organic Frameworks (MOFs) for Multifunctional Catalysis.

A one-pot synthesis of bimetallic metal-organic frameworks (Co/Fe-MOFs) was achieved by treating stoichiometric amounts of Fe and Co salts with 2-aminoterephthalic acid (NH2 -BDC). Monometallic Fe (catalyst A) and Co (catalyst F) were also prepared along with mixed-metal Fe/Co catalysts (B-E) by changing the Fe/Co ratio. For mixed-metal catalysts (B-E) SEM energy-dispersive X-ray (EDX) analysis confirmed the incorporation of both Fe and Co in the catalysts. However, a spindle-shaped morphology, typically known for the Fe-MIL-88B structure and confirmed by PXRD analysis, was only observed for catalysts A-D. To test the catalytic potential of mixed-metal MOFs, reduction of nitroarenes was selected as a benchmark reaction. Incorporation of Co enhanced the activity of the catalysts compared with the parent NH2 -BDC-Fe catalyst. These MOFs were also tested as electrocatalysts for the oxygen evolution reaction (OER) and the best activity was exhibited by mixed-metal Fe/Co-MOF (Fe/Co batch ratio=1). The catalyst provided a current density of 10 mA cm-2 at 410 mV overpotential, which is comparable to the benchmark OER catalyst (i.e., RuO2 ). Moreover, it showed long-term stability in 1 m KOH. In a third catalytic test, dehydrogenation of sodium borohydride showed high activity (turnover frequency=87 min-1 ) and hydrogen generation rate (67 L min-1 g-1 catalyst). This is the first example of the synthesis of bimetallic MOFs as multifunctional catalysts particularly for catalytic reduction of nitroarenes and dehydrogenation reactions.

The mechanism and reaction kinetics of visible light active bismuth oxide deposited on titanium vanadium oxide for aqueous diclofenac photocatalysis.

Non-uniform, non-spherical bismuth oxide deposited on titanium vanadium oxide (3%-BVT1) was successfully synthesized via co-precipitation method and assessed for visible light degradation of aqueous diclofenac. The synthesized photocatalysts were characterized using X-ray diffraction, diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy. Up to 80.7% diclofenac degradation was observed with a significant increment in reaction rate compared to commercially available Degussa P25 (kapp = 0.0013 → 0.0083 min-1) achieved within 3 h treatment time under optimized parameters of diclofenac concentration (10 mg L-1), catalyst loading (0.1 g L-1), and pH (5). The enhanced photocatalysis could be due to electron-hole separation and contribution of powerful oxidative species •OH > O2•- > h+ > > e-. The recyclability experiments indicate that 3%-BVT1 retained its efficiency up to 74.1% over five reaction cycles. Gas chromatography-mass spectrometry analysis indicated the formation of several transformation products during the degradation pathway. The studies of interfering ions depicted mild interference by sulfates, while interference by phosphates and nitrates was negligible during photocatalytic process, i.e., 70, 78.01, and 78.43% for the selected concentrations of 50, 25, and 40 mg L-1 as per their maximum concentrations detected in the natural wastewaters. Thus, 3%-BVT1 is a potential versatile candidate to treat various organic pollutants including pharmaceuticals.

Synthesis of cerium oxide embedded perovskite type bismuth ferrite nanocomposites for sonophotocatalysis of aqueous micropollutant ibuprofen.

Ibuprofen is potentially toxic and carcinogenic for freshwater ecosystems and poses a serious threat to human health by affecting kidney function. The present study focused on the sunlight-controlled degradation of ibuprofen from water using a novel magnetically separable cerium oxide-embedded bismuth ferrite heterostructure. Catalysts were synthesized by solvothermal and co-precipitation methods and characterized by X-ray diffractometry, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-vis optical absorption spectroscopy, and nitrogen adsorption. This study investigated the effect of photocatalysis, sonolysis, sonophotolysis, and sonophotocatalysis on the degradation of ibuprofen in water. Pseudo-first-order and second-order kinetics were applied to evaluate the rate of reaction for ibuprofen degradation. The addition of 5% CeO2 to the BiFeO3 significantly increased the surface area and pore volume of bismuth ferrite, which enhanced their photocatalytic degradation efficiency by 2.28 times in terms of ibuprofen mineralization. Sonolysis treatment alone and in combination with photolysis led to the degradation of ibuprofen, but with the formation of intermediate products. Positive synergy was observed when sonolysis was combined with photocatalysis in terms of the mineralization of ibuprofen and the degradation of intermediates along with their parent compound. It was proposed that, compared to photocatalytic mineralization, the ultrasound-assisted advanced oxidation process resulted in the conversion of ibuprofen to its mineralization products.

Optimization of bandgap reduction in 2-dimensional GO nanosheets and nanocomposites of GO/iron-oxide for electronic device applications.

In this report we have developed different fabrication parameters to tailor the optical bandgap of graphene oxide (GO) nanosheets to make it operational candidate in electronic industry. Here we performed two ways to reduce the bandgap of GO nanosheets. First, we have optimized the oxidation level of GO by reducing amount of oxidizing agent (i.e. KMnO4) to control the sp2/sp3 hybridization ratio for a series of GO nanosheets samples. We noticed the reduction in primary band edge 3.93-3.2 eV while secondary band edge 2.98-2.2 eV of GO nanosheets as the amount of KMnO4 is decreased from 100 to 30%. Second, we have fabricated a series of 2-dimensional nanocomposites sample containing GO/Iron-oxide by using a novel synthesis process wet impregnation method. XRD analysis of synthesized nanocomposites confirmed the presence of both phases,[Formula: see text]-Fe2O3 and Fe3O4 of iron-oxide with prominent plane (001) of GO. Morphological investigation rules out all the possibilities of agglomerations of iron oxide nanoparticles and coagulation of GO nanosheets. Elemental mapping endorsed the homogeneous distribution of iron oxide nanoparticles throughout the GO nanosheets. Raman spectroscopy confirmed the fairly constant ID/IG ratio and FWHM of D and G peaks, thus proving the fact that the synthesis process of nanocomposites has no effect on the degree of oxidation of GO flakes. Red shift in G peak position of all the nanocomposites samples showed the electronic interaction among the constituents of the nanocomposite. Linear decrease in the intensity of PL (Photoluminescence) spectra with the increasing of Iron oxide nanoparticles points towards the increased interaction among the iron oxide nanoparticles and GO flakes. Optical absorption spectroscopy reveals the linear decrease in primary edge of bandgap from 2.8 to 0.99 eV while secondary edge decrease 3.93-2.2 eV as the loading of [Formula: see text]-Fe2O3 nanoparticles is increased from 0 to 5% in GO nanosheets. Among these nanocomposites samples 5%-iron-oxide/95%-GO nanosheet sample may be a good contestant for electronic devices.

Hydrogen peroxide modified and bismuth vanadate decorated titanium dioxide nanocomposite (BiVO4@HMT) for enhanced visible light photocatalytic growth inhibition of harmful cyanobacteria in water.

The persistence of harmful cyanobacterial algal blooms in aquatic ecosystems leads to health damage for various life forms. In this study, a photocatalyst active in the visible light range was prepared by combining BiVO4 with hydrogen peroxide modified titanium dioxide (BiVO4@HMT; for short), using an impregnation method. The catalyst was used to photocatalytically inhibit the growth of cyanobacteria collected from a bloom site. To infer the optimum pH for cyanobacterial growth, the effect of pH was studied. The growth of cyanobacteria was favoured in an alkaline environment at pH values in the range of 8-9.5 when analysed on the 20th day of incubation. Structural and chemical analysis of pristine and composite nano-powders was performed using XRD, SEM, TEM and XPS, confirming the heterojunction formation, while optical and band gap analysis revealed increased visible light absorption and reduced band gap of the composite. A small strawberry seed-like assembly of BiVO4 particles increased the light absorption in the 15%BiVO4@HMT composite and increased the inhibition efficiency up to 2.56 times compared to pristine HMT at an exposure time of 6 h and cell concentration at 0.1 g L-1 with an optimum catalyst dose of 1 g L-1. The amount of chlorophyll 'a' decreased due to the generation of catalytically reactive species, especially holes (h+), which caused oxidative damage to the cell wall, cell membrane and antioxidants in algal cells. This study reports that visible light active nanocatalysts can be used as a promising method for reducing algal blooms in water bodies.

Efficient Recovery of Lithium Cobaltate from Spent Lithium-Ion Batteries for Oxygen Evolution Reaction.

Owing to technological advancements and the ever-increasing population, the search for renewable energy resources has increased. One such attempt at finding effective renewable energy is recycling of lithium-ion batteries and using the recycled material as an electrocatalyst for the oxygen evolution reaction (OER) step in water splitting reactions. In electrocatalysis, the OER plays a crucial role and several electrocatalysts have been investigated to improve the efficiency of O2 gas evolution. Present research involves the use of citric acid coupled with lemon peel extracts for efficient recovery of lithium cobaltate from waste lithium-ion batteries and subsequent use of the recovered cathode material for OER in water splitting. Optimum recovery was achieved at 90 °C within 3 h of treatment with 1.5 M citric acid and 1.5% extract volume. The consequent electrode materials were calcined at 600, 700 and 800 °C and compared to the untreated waste material calcined at 600 °C for OER activity. The treated material recovered and calcined at 600 °C was the best among all of the samples for OER activity. Its average particle size was estimated to be within the 20-100 nm range and required a low overpotential of 0.55 V vs. RHE for the current density to reach 10 mA/cm2 with a Tafel value of 128 mV/dec.

Facile Synthesis of g-C3N4/MoO3 Nanohybrid for Efficient Removal of Aqueous Diclofenac Sodium.

Graphitic carbon nitride modified by molybdenum trioxide (g-C3N4/MoO3) as a nanohybrid was synthesized by co-precipitation method. Here, g-C3N4/MoO3 nanohybrid was used for the first time as an adsorbent for the pharmaceutical drug, diclofenac, (an aqueous micropollutant) from water to mitigate its possible environmental toxic effects. Compared to pristine components, the nanohybrid exhibited better adsorptive removal of diclofenac. Adsorption was enhanced with increment in MoO3 content from 1 to 3 wt %; however further increment in MoO3 content resulted in lower adsorption capacity due to agglomeration of MoO3 particles over g-C3N4. 162 mg g-1 adsorption capacity was achieved for 300 mg L-1 diclofenac in solution with 1 g L-1 adsorbent at pH = 6. Adsorption of diclofenac over g-C3N4 /MoO3 followed pseudo 2nd order kinetics. Temkin, Langmuir, Dubinin Radushkevich and Freundlich isotherm models were applied on the experimental results concluding that diclofenac adsorption over g-C3N4/MoO3 followed the Langmuir isotherm. The adsorption mechanism could be explained by the π-π interaction between aromatic rings of diclofenac and g-C3N4/MoO3 (3%) nanohybrid, which is also evident by the FTIR results. This study presents the facile fabrication of a 2nd generation adsorbent for the treatment of diclofenac contaminated water that may as well help achieve the removal of other micropollutants form water.

A facile synthesis of bismuth oxychloride-graphene oxide composite for visible light photocatalysis of aqueous diclofenac sodium.

In this study, bismuth oxychloride/graphene oxide (BiOCl-GO) composite was fabricated by facile one pot hydrothermal method. The pure BiOCl and BiOCl-GO composite was characterized by X-ray diffraction, Transmission electron microscopy X-ray photoelectron spectroscopy and UV-Vis diffuse reflectance spectroscopy. The synthesized composite was then assessed for photocatalytic degradation of diclofenac sodium (DCF) in visible as well as direct solar light and UV irradiation. Results indicated that the photocatalytic removal efficiency of DCF was significantly affected by dose of catalysts, pH value and source of light. The results reveled that degradation efficiency of BiOCl-GO for DCF reduced from 100 to 34.4% with the increases in DCF initial concentration from 5 mg L-1 to 25 mg L-1. The solar light degradation of DCF using BiOCl-GO was achieved with apparent rate constant 0.0037 min-1. The effect of scavengers study revealed that superoxide ions and holes were mainly responsible for DCF degradation. The regeneration study indicates that BiOCl-GO composite can be successfully recycled up to the five cycles. The study revealed the effectiveness of one pot hydrothermal method for the fabrication of BiOCl-GO composite.

Synthesis using natural functionalization of activated carbon from pumpkin peels for decolourization of aqueous methylene blue.

In this study, a novel approach was applied for modification and functionalization of pumpkin peels (PP) derived carbon using natural beetroot extract. PP waste biomass was carbonized at 250 (AC250), 350 (AC350), 450 (AC450) and 550 °C (AC550) and used as adsorbent for the scavenging of methylene blue (MB). The adsorption results revealed that AC250 was the most efficient material. Thereafter, AC250 was further modified with different acids and natural beetroot extract to enhance the adsorption efficiency for MB removal. Modified and functionalized carbon materials were characterized to determine the functional groups, crystalline nature and surface morphology of adsorbents using Fourier Transformed Infra-Red spectroscopy, X-ray Diffraction and Scanning Electron Microscopy. The pore size distribution measurements by non-local density functional theory (NLDFT) revealed the presence of large number of mesopores in the beetroot activated carbon (BAC) with the BET specific surface area of 3.6 m2.g-1. The adsorption studies exhibited the highest adsorption (198.15 mg.g-1) for MB using 0.5 g.L-1 of adsorbent mass at 200 mg.L-1 MB concentration and 50 °C within 180 min. Reaction kinetics analysis of the experimental data revealed that adsorption followed pseudo second order kinetic model where BAC250 showed highest reaction rate constant value of 0.0095 and correlation coefficient value of 0.9992. The equilibrium data were tested by using Freundlich and Langmuir isotherm models. For both isotherms, the characteristic parameters were determined and the adsorption behaviour was found to fit well with the Langmuir isotherm model indicating monolayer adsorption of MB.

Development of plant-microbe phytoremediation system for petroleum hydrocarbon degradation: An insight from alkb gene expression and phytotoxicity analysis.

Aim of present work was to assess in-planta association potential of isolated endophytic bacterial strain Pseudomonas sp. (J10) (KY608252) with two cultivars of Lolium perenne L. (small & jumbo) and Arabidopsis thaliana L. for total petroleum hydrocarbon (TPH) degradation, alkane monooxygenase (alkb) gene expression and phytotoxicity analysis. A plant-microbe phytoremediation system was established to investigate the bacteria's ability to colonize the plant body and quantification of alkb gene to help withstand TPH stress in soil as well as in hydroponics. A real-time PCR method was developed to analyze bacterial colonization and survival within the plant body. Analysis revealed that J10 efficiently colonized all the tested plant species and expressed alkb gene under hydrocarbon stress ranging between 3.7 × 102-3.9 × 106 in A. thaliana and L. perenne (small), respectively. The colonization was more pronounced in soil as compared to hydroponic system. J10 inoculation reduced phytotoxicity and suggested that inoculation had a positive effect on plant growth under stress conditions as compared to control. L. perenne (small) showed significant TPH removal efficiency (45.6%) followed by L. perenne jumbo (24.5%) and A. thaliana (6.2%). In hydroponics, L. perenne (small) degraded about 28.2% TPH followed by L. perenne (jumbo) as 24.4%. Potential of the indigenously isolated plant endophytes may be exploited further for phytoremediation efficiency and industrial applications.

Diesel degrading bacterial endophytes with plant growth promoting potential isolated from a petroleum storage facility.

Thirteen (13) endophytic bacterial strains were isolated from Echinochloa crus-galli (Cockspur grass) and Cynodon dactylon (Bermuda grass) growing in an oil-contaminated site at a petroleum storage and transportation facility. Of the 13 strains assessed for their potential to degrade monoaromatic compounds (phenol, toluene, and xylene) and diesel and for their plant growth promoting (PGP) ability (phosphate solubilization, siderophores and 1-aminocyclopropane-1-carboxylate (ACC) deaminase production), isolate J10 (identified as Pseudomonas sp. by 16S rRNA gene sequencing) was found to the best diesel biodegrader with the best PGP traits. The Monod model used for Pseudomonas sp. J10 growth kinetics on diesel fuel as the sole carbon source showed that the maximum specific bacterial growth rate was 0.0644 h- 1 and the half velocity constant (K s ) was estimated as 4570 mg L- 1. The overall growth yield coefficient and apparent growth yield were determined to be 0.271 g h- 1 and 0.127 g cells/g substrate, respectively. Pseudomonas sp. J10 removed 69% diesel in four days as determined by gas chromatographic (GC) analysis. These findings could assist in developing an endophyte assisted efficient diesel biodegradation system using Pseudomonas sp. J10 isolated from Echinochloa crus-galli.

Facile synthesis of g-C3N4(0.94)/CeO2(0.05)/Fe3O4(0.01) nanosheets for DFT supported visible photocatalysis of 2-Chlorophenol.

Visible light active g-C3N4(0.94)/CeO2(0.05)/Fe3O4(0.01) ternary composite nanosheets were fabricated by facile co-precipitation routes. The density functional theory (DFT) computations investigated changes in geometry and electronic character of g-C3N4 with CeO2 and Fe3O4 addition. Chemical and surface characterizations were explored with XRD, XPS, SEM, TEM, PL, DRS and Raman measurements. DRS and PL spectroscopy evidenced the energy band gap tailoring from 2.68 eV for bulk g-C3N4 and 2.92 eV for CeO2 to 2.45 eV for the ternary nanocomposite. Efficient electron/hole pair separation, increase in red-ox species and high exploitation of solar spectrum due to band gap tailoring lead to higher degradation efficiency of g-C3N4(0.94)/CeO2(0.05)/Fe3O4(0.01). Superior sun light photocatalytic breakdown of 2-Chlorophenol was observed with g-C3N4 having CeO2 loading up to 5 wt%. In case of ternary nanocomposites deposition of 1 wt% Fe3O4 over g-C3N4/CeO2 binary composite not only showed increment in visible light catalysis as predicted by the DFT studies, but also facilitated magnetic recovery. The g-C3N4(0.94)/CeO2(0.05)/Fe3O4(0.01) nanosheets showed complete mineralization of 25 mg.L-1 2-CP(aq) within 180 min exposure to visible portion of sun light and retained its high activity for 3 consecutive reuse cycles. The free radical scavenging showed superoxide ions and holes played a significant role compared to hydroxyl free radicals while chromatographic studies helped establish the 2-CP degradation mechanism. The kinetics investigations revealed 2.55 and 4.04 times increased rate of reactions compared to pristine Fe3O4 and CeO2, showing highest rate constant value of 18.2 × 10-3 min-1 for the ternary nanocomposite. We present very persuasive results that can be beneficial for exploration of further potential of g-C3N4(0.94)/CeO2(0.05)/Fe3O4(0.01) in advance wastewater treatment systems.

Butterfly cluster like lamellar BiOBr/TiO2 nanocomposite for enhanced sunlight photocatalytic mineralization of aqueous ciprofloxacin.

The present study for the first time reports facile in-situ room temperature synthesis of butterfly cluster like lamellar BiOBr deposited over TiO2 nanoparticles for photocatalytic breakdown of ciprofloxacin (CIP). The butterfly cluster arrangement of BiOBr resulted in an increase in surface area from 124.6 to 160.797 m2·g-1 and subsequently increased incident light absorption by the composite photocatalyst. The XRD indicated the existence of TiO2 as spherical ≈10-15 nm diameter particles with [101] preferential growth planes of anatase phase while the lamellar BiOBr showing growth along [110] and [102] preferential planes that were also confirmed by the HR-TEM images. DRS data implicated 2.76 eV as the energy band gap of the synthesized nanocomposite while PL spectroscopic analysis predicted it to be 2.81 eV. XPS measurements examined the chemical oxidation states of the constituents among the nanocomposite samples. The lameller structure of BiOBr in 15%BiOBr/TiO2 acts as a manifold promoting both visible light (λ > 420 nm) and direct sunlight catalytic degradation of 25 mg·L-1 aqueous CIP up to 92.5% and 100%, respectively within 150 min. The rate constant values suggested that the visible light photocatalysis of CIP with 15%BiOBr/TiO2 was 5.2 and 9.4 times faster compared to pristine TiO2 and BiOBr, respectively. The free radical scavenging study demonstrated that although photogenerated superoxide ions and holes contribute to the overall photocatalytic activity, yet, hydroxyl radicals predominantly control the CIP oxidation. The synthesized nanocomposite was re-used up to five cycles and retained 82.98% efficiency even after 5th use cycle showing a decline of only 12%. The catalyst stability and easy recovery adds to its reusability and value of the photocatalytic process.

Stabilized fabrication of anatase-TiO2/FeS2 (pyrite) semiconductor composite nanocrystals for enhanced solar light-mediated photocatalytic degradation of methylene blue.

A novel visible light active TiO2/FeS2 semiconductor photocatalyst was synthesized by a simple wet chemical process. X-ray diffraction (XRD) was used to analyze the anatase TiO2 and pyrite structures in FeS2/TiO2 nanocrystals. Scanning electron microscopy (SEM) confirmed the spherical morphology of composite nanocrystals. X-ray photoelectron spectroscopy (XPS) identified the Fe2+, S1-, Ti4+, and O2- oxidation states of relevant species. Energy dispersive X-ray (EDX) analysis was performed for compositional analysis. The measured band gap of the TiO2/FeS2 nanocomposite system was 2.67 eV, which is smaller than un-doped TiO2 (3.10 eV) and larger than FeS2 (1.94 eV). The photocatalytic activity of TiO2/FeS2 was significantly higher than pure FeS2 for degrading methylene blue (MB) under solar light irradiation due to the increase in visible light absorption, reduction in band gap energy, and better election-hole pair separation. The photocatalytic degradation of MB was investigated under the influence of solution pH, dye concentrations, and varied catalyst dosage. The optimum degradation (100%) of MB was observed in 180 min and the photocatalysis of MB reduced as the dye concentrations in the solution increased from 15 to 75 mg L-1. These results prove that the TiO2/FeS2 nanocomposite has the stability, recycling, and adaptability for its practical application as a visible light photocatalyst for wastewater treatment. TiO2/FeS2 showed increased degradation of the organic pollutant; which is confirmed by the increased rate of chemical reaction following pseudo first-order reaction kinetics with the highest rate constant value of 0.0408 m-1 having highest R 2 value of 0.9981.

Fe3O4/SiO2/TiO2 nanoparticles for photocatalytic degradation of 2-chlorophenol in simulated wastewater.

Photocatalysis has emerged as an advance and environmental-friendly process for breakdown of organic contaminants in wastewater. This work reports facile synthesis and characterization of stable magnetic core-shell-shell Fe3O4/SiO2/TiO2 nanoparticles and their effectiveness for photocatalysis. The surface morphology, crystal structure, and chemical properties of the photocatalyst were characterized by using scanning electron microscope (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD), and nitrogen physisorption. Stability of synthesized nanoparticles in aqueous medium was tested by leaching test. The photocatalytic degradation of 2-chlorophenol was investigated and reaction parameters for best catalyst performance were optimized. Catalyst dose of 0.5 g/L under optimized conditions produced complete degradation of 25 mg/L 2-chlorophenol (2-CP) within 130 min of 100-W ultraviolet (UV) irradiation while 97.2 % degradation of 50 mg/L 2-CP was achieved within 3 h. The rate of photocatalytic degradation was determined by considering pseudo first-order kinetics and Hugul's kinetic equations. The Hugul's kinetics was found to provide a better interpretation of the experimental results than the generally adopted pseudo first-order reaction kinetics.