Biodegradable Acid-Based Fe2MnO4 Nanoparticles for Water Remediation.

This study demonstrated the synthesis of Fe2MnO4 modified by citric acid, a biodegradable acid, using a simple co-precipitation method. Characterization was performed using qualitative analysis techniques such as Fourier-transformed infrared spectroscopy, scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy, X-ray diffraction, selected-area electron diffraction, N2 adsorption-desorption, and zero-point charge. The prepared nanoparticles had a rough and porous surface, and contained oxygenous (-OH, -COOH, etc.) functional groups. The specific surface area and average pore size distribution were 83 m2/g and 5.17 nm, respectively. Net zero charge on the surface of the prepared nanoparticles was observed at pH 7.5. The prepared nanoparticles were used as an adsorbent to remove methylene blue dye from water under various conditions. Using small amounts of the adsorbent (2.0 g/L), even a high concentration of MB dye (60 mg/L) could be reduced by about ~58%. Exothermic, spontaneous, feasible, and monolayer adsorption was identified based on thermodynamics and isotherm analysis. Reusability testing verified the stability of the adsorbent and found that the reused adsorbent performed well for up to three thermal cycles. Comparative analysis revealed that the modified adsorbent outperformed previously reported adsorbents and unmodified Fe2MnO4 in terms of its partition coefficient and equilibrium adsorption capacity under different experimental conditions.

Origanum vulgare manganese ferrite nanocomposite: An advanced multifunctional hybrid material for dye remediation.

The purpose of the study was to fabricate sustainable and cost-effective material for the thorough cleansing of polluted water. In this context, an economical, phytogenic and multifunctional Origanum vulgare plant-based nanocomposite material, MnFe2O4/OV, was prepared via one-pot synthetic technique. The synthesized nanocomposite with a band gap of 2.02 eV behaved as an efficient nano-photocatalyst for the degradation of both cationic (crystal violet) and anionic (congo red) dyes under direct sunlight irradiation. The material also inhibited the growth of E. coli and S. aureus bacteria and simultaneously adsorbed both cationic and anionic dyes from water through adsorption. A variety of techniques have been used to characterize the nanocomposite, including X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). Additionally, the kinetics of photodegradation of the aforementioned organic dyes has also been investigated. The MnFe2O4/OV exhibited excellent photocatalytic performance, leading to 43% and 72% degradation within 3 h at rate constants of 2.0 × 10-3 min-1 and 6.0 × 10-3 min-1 for crystal violet and congo red, respectively. The crystal violet and congo red were used to testify to the composite's potential for adsorption under the influence of several process variables, including initial solution pH, contact time, temperature, initial dye concentration, and amount of MnFe2O4/OV. The Langmuir maximum adsorption capacity Qmax as in the range 14.06-14.59 mgg-1 for crystal violet and 34.45-23.93 mgg-1 for congo red at pH 7 within 90 min contact time in the temperature range of 30-50 °C. The phenomenon of adsorption was found feasible and endothermic at all the investigated temperatures. Also, E. coli and S. Aureus bacteria have shown growth suppression activity when exposed to MnFe2O4/OV.As a result, the synthesized nanocomposite, MnFe2O4/OV, proved to be an antimicrobial, multifunctional novel nanocomposite, which is in high demand, and could serve as an affordable, and sustainable material for comprehensive water filtration.

Photocatalytic removal of organic dye using green synthesized zinc oxide coupled cadmium tungstate nanocomposite under natural solar light irradiation.

In this work, zinc oxide coupled cadmium tungstate (ZnO-CT) was prepared as a nano-photocatalyst through a green synthesis route using lemon leaf extract and characterized based on diverse microscopic and spectroscopic techniques. To explore the applicabilties of the prepared nanocomposite (NC), its photocatalytic activity has been investigated against Congo red (CR) dye under natural solar light irradiation conditions. ZnO- CT nano-photocatalyst showcases 97% photocatalytic degradation of the CR after 90 min of natural solar light irradiation with quantum yield of 1.16 × 10-8 molecules photon-1. The ZnO-CT NC has shown the enhanced photocatalytic degradation performance against CR when compared to its pristine forms (e.g., ZnO (70%) or CT (44%)). According to the free radical trapping and quenching experiments, the photocatalytic activity of ZnO-CT NC appears to be driven efficiently by superoxide and hydroxyl radicals. The photocatalytic degradation kinetics for CR dye was also studied using the pseudo-first-order, diffusional, and Singh models. The high photocatalytic activity of ZnO-CT NC can be accounted for by the presence of electron-withdrawing functional groups like acids (-COOH) and aldehydes (-CHO) on its surface which helped maintain the prolonged recombination of charge carriers and enhanced stability of ZnO-CT (with moderately low leaching rate of cadmium ions (∼2-5%)).

Water quality characteristics and reuse potential using adsorption as a post-treatment option for a full-scale hydrocyclone, coagulation, flocculation, and dissolved air flotation system.

This study established a full-scale hybrid water treatment system combining a hydrocyclone, coagulation, flocculation, and dissolved air flotation unit (HCFD) and evaluated its performance in treating anthropogenically impacted lake water. The HCFD system offered the stable and efficient treatment of fluctuating influent loadings, meeting most of the highest water reclamation quality criteria except for that of organic matter. Adsorption was subsequently examined as a post-treatment process for the HCFD effluent, which has not been examined in many previous studies. As the adsorbent for the post-treatment, pine bark, a locally available agricultural waste feedstock, was modified using H2O2 to maximize its adsorption capacity. The surface modification increased its adsorption capacity for organic matter by 53-112%. The HCFD system in conjunction with the synthesized adsorbent thus demonstrated the ability to meet the highest standards for all water quality parameters, highlighting their synergistic potential for enhancement of water treatment. Liquid chromatography-organic carbon detection and Fourier transform infrared analysis were then employed to determine the mechanisms involved in the removal of specific contaminants using the HCFD system and post-adsorption unit. While the HCFD system successfully eliminated particulate and colloidal matter (e.g., phosphorous and biopolymers with a high molecular weight) using centrifugal and floating separation with the aid of two complementary polymers, the post-adsorption unit effectively adsorbed small-sized dissolved substances (e.g., low molecular weight acids and building blocks) via surface functional groups (-CH, -OH, -CH2, C=O, C=C, and C=O) using van der Waals forces, hydrogen bonding, and π-π or n-π interactions.

Nigella sativa seed based nanocomposite-MnO2/BC: An antibacterial material for photocatalytic degradation, and adsorptive removal of Methylene blue from water.

Antimicrobial Nigella sativa seed-based nanocomposite, MnO2/BC, was synthesized and utilized for the water purification through adsorption, and the photocatalytic degradation. MnO2/BC was prepared by co-precipitation method, and characterized using FT-IR, XRD, SEM, TEM, TGA, and DSC techniques. The composite was investigated for inhibition of bacterial cells growth. FT-IR spectrum indicated the presence of oxygenous groups on the surface; TGA and DSC showed thermal degradation; and XRD, SEM, and TEM investigations indicated amorphous, and porous nature of MnO2/BC having particle size of 190-220 nm. The nanocomposite inhibited the growth of both Gram-positive and Gram-negative bacteria cells in water. The adsorption of Methylene blue from water was investigated in batch method in terms of amount of MnO2/BC, dye concentration, pH, time, and temperature. 1.0 g L-1 of MnO2/BC removed more than 98% of Methylene blue from aqueous solution having concentration of 10 mg L-1 and pH 7.0 at 27 °C. The maximum Langmuir adsorption capacity of MnO2/BC was 185.185 mg g-1 at 45 °C. The adsorption was an endothermic process which obeyed Freundlich isotherm, and pseudo-second order kinetics. Therefore, the Methylene blue binding onto MnO2/BC surface was site-specific partially through the weak hydrogen bonding, and electrostatic interactions. The photocatalytic activity of MnO2/BC has been investigated by degrading the Methylene blue molecules/ions in water under the sunlight and 85% of degradation was achieved during 120 min irradiation. The dye was desorbed at lower pH and regenerated MnO2/BC was used for second cycle of Methylene blue adsorption. The results obtained for this study are much better than the previous Methylene blue adsorption studies with acid washed Black cumin seeds and MnFe2O4/BC for which the capacities were 73.529 mg g-1 and 10.070 mg g-1 at 27 °C, respectively (J. Mol. liq. 2018a, 264, 275-284; J. Clean. Prod. 2018a, 200, 996-1008).

Nigella sativa seed based nanohybrid composite-Fe2O3-SnO2/BC: A novel material for enhanced adsorptive removal of methylene blue from water.

In this work, an advance approach is reported for the water treatment technology using nanohybrid composite Fe2O3-SnO2/BC prepared by incorporation of iron-tin binary oxide into the cellulosic framework of medicinally active Nigella sativa (Black cumin) seed powder. The co-precipitation method was followed to prepare the nanohybrid composite which was subjected to investigate its physiochemical properties using spectroscopic and microscopic techniques. Fourier-transform infrared spectroscopy analysis confirmed the formation of highly functionalized nanocomposite through the hydrogen and electrostatic interactions between the functional groups of seeds and Fe2O3-SnO2. X-ray and selected area electron diffraction pattern revealed the presence of cubic phase of γ-Fe2O3 and tetragonal phase of SnO2 in the composite. The scanning electron microscopic images suggested the porous and relatively smooth surface of the composite, and transmittance electron microscopic images showed the trapping of nano-cubes of Fe2O3-SnO2, having particles size in the range 95-185 nm, into the organic framework of Black cumin seeds, whose zero point charge was found at pH 7.2. The composite was investigated for adsorption of Methylene blue dye from water for which the results revealed that 2.0 gL-1 amount of Fe2O3-SnO2/BC was sufficient to remove more than 95% dye, within 15 min, at 6-9 pH, from its 10 mgL-1 concentration. The thermodynamic studies established spontaneity, feasibility, and endothermic nature of the adsorption process. The adsorption data was satisfactorily described by the Freundlich isotherm which indicated inhomogeneous surface of the composite. Application of Temkin isotherm revealed the same extent of bonding probability and heat of adsorption at 27, 35, and 45 °C. The free energy change calculated from Dubinin-Radushkevich isotherm suggested weak interaction between Methylene blue and Fe2O3-SnO2/BC. The process satisfactorily followed the pseudo-second order kinetics that was controlled by the film diffusion step which indicated interaction of Methylene blue with functional sites of the Fe2O3-SnO2/BC. The Fourier-transform infrared spectroscopy analysis gave the confirmatory evidence for interaction of Methylene blue to Fe2O3-SnO2/BC. The maximum Langmuir adsorption capacity of the Fe2O3-SnO2/BC was found to be 58.82 mgg-1 at 27 °C which is higher than the previously reported adsorbents, MnFe2O4/BC [J. Clean. Prod. 2018. 200, 996-1008], and Fe2O3-ZrO2/BC [J. Clean. Prod. 2019. 223, 849-868]. Therefore, the study showed excellent results for water treatment and can be useful to develop advance water treatment technology.

A metagenome-derived artificial intelligence modeling framework advances the predictive diagnosis and interpretation of petroleum-polluted groundwater.

Groundwater (GW) quality monitoring is vital for sustainable water resource management. The present study introduced a metagenome-derived machine learning (ML) model aimed at enhancing the predictive understanding and diagnostic interpretation of GW pollution associated with petroleum. In this framework, taxonomic and metabolic profiles derived from GW metagenomes were combined for use as the input dataset. By employing strategies that optimized data integration, model selection, and parameter tuning, we achieved a significant increase in diagnostic accuracy for petroleum-polluted GW. Explanatory artificial intelligence techniques identified petroleum degradation pathways and Rhodocyclaceae as strong predictors of a pollution diagnosis. Metagenomic analysis corroborated the presence of gene operons encoding aminobenzoate and xylene biodegradation within the de novo assembled genome of Rhodocyclaceae. Our genome-centric metagenomic analysis thus clarified the ecological interactions associated with microbiomes in breaking down petroleum contaminants, validating the ML-based diagnostic results. This metagenome-derived ML framework not only enhances the predictive diagnosis of petroleum pollution but also offers interpretable insights into the interaction between microbiomes and petroleum. The proposed ML framework demonstrates great promise for use as a science-based strategy for the on-site monitoring and remediation of GW pollution.

Live Biomass of Rigidoporus vinctus: A Sustainable Method for Decoloration and Detoxification of Dyes in Water.

In this study, white-rot fungus, Rigidoporus vinctus, collected from an unidentified fallen twig from Pathankot, Punjab, India, was used for biosorption of anionic Congo red and cationic Methylene blue dyes from an aqueous medium. The biosorption efficiency of the live biomass of Rigidoporus vinctus was investigated to optimize biosorbent dosage, process time, concentrations of dyes, and pH of solutions. The results indicated that Rigidoporus vinctus is more efficient than other reported bio-adsorbents for Congo red and Methylene blue dyes. The maximum biosorption activity of Rigidoporus vinctus for Congo red was found at pH 2, and that for Methylene blue was at pH 10, after 24 h of the reaction period. The process followed pseudo-second-order kinetics, which indicated that the interaction of both dyes to the adsorption sites on the surface of Rigidoporus vinctus was responsive to biosorption. The biosorption process could be well explained by the Langmuir isotherm for both dyes. The maximum monolayer biosorption capacity of Rigidoporus vinctus for Congo red and Methylene blue was observed to be 54.0 mg/g and 80.6 mg/g, respectively. The seed germination test was carried out, and it was assessed that the toxicity of dyes was reduced up to significant levels. Based on the present experimental findings, it can be concluded that biosorption using the live biomass of Rigidoporus vinctus can effectively decolorize dye-containing wastewater, thus reducing the hazardous effects of dyes on human beings.

Biomass-derived carbon deposited TiO2 nanotube photocatalysts for enhanced hydrogen production.

In this study, titanium oxide nanotubes (TiO2NTs) were deposited on the surface of activated carbon (AC) by varying the wt% of AC. The physicochemical properties of synthesized TiO2NTs-AC nanocomposites were analysed by various characterization techniques such as XRD, FT-IR, Raman, DRUV-vis, HR-TEM, XPS, PL, and N2 physisorption. The FT-IR, EDX, and XPS analyses proved the existence of interaction between AC and TiO2NTs. This study found that as the content of AC increases, the surface area and pore volume increase while the energy bandgap decreases. The TiO2NTs-AC nanocomposite with 40% AC exhibited a surface area of 291 m2 g-1, pore volume of 0.045 cm3 g-1 and half pore width = 8.4 Å and had a wide band gap energy (3.15 eV). In addition, the photocatalytic application of the prepared nanocomposites for photocatalytic H2 production was investigated. The H2 was produced via photo-reforming in the presence of a sacrificial agent (methanol) under sunlight irradiation. It was found that the prepared TiO2NTs-AC nanocomposite with 40% AC acted as an efficient photocatalyst for aqueous-methanol reforming under various optimization conditions. Approximately 18 000 µmol-1 hydrogen gas was produced via aqueous-methanol reforming under optimized conditions (catalyst dose = 100 mg, temperature = 25 °C, time = 12 hours, vol. of methanol = 20% (v/v), and pH = 7). The reusability of the TiO2NTs-AC nanocomposite was also investigated for 5 consecutive cycles, and the results suggested only a slight decline in efficiency even after the fifth cycle. This study demonstrates the ability of an activated carbon deposited TiO2NT catalyst to produce hydrogen effectively under sunlight.

One-Pot Facile Synthesis of CuO-CdWO4 Nanocomposite for Photocatalytic Hydrogen Production.

Hydrogen (H2) is a well-known renewable energy source that produces water upon its burning, leaving no harmful emissions. Nanotechnology is utilized to increase hydrogen production using sacrificial reagents. It is an interesting task to develop photocatalysts that are effective, reliable, and affordable for producing H2 from methanol and acetic acid. In the present study, CuO, CdWO4, and CuO-CdWO4 nanocomposite heterostructures were prepared using a cost-efficient, enviro-friendly, and facile green chemistry-based approach. The prepared CuO, CdWO4, and CuO-CdWO4 nanocomposites were characterized using X-ray diffraction pattern, Fourier-transform infrared spectroscopy, diffuse reflectance ultraviolet-visible spectroscopy, scanning electron microscopy, transmission electron microscopy, selected area electron diffraction (SAED) pattern, N2 physisorption, photoluminescence, and X-ray photoelectron spectroscopy techniques. The synthesized photocatalysts were utilized for photocatalytic H2 production using aqueous methanol and acetic acid as the sacrificial reagents under visible light irradiation. The influence of different variables, including visible light irradiation time, catalyst dosage, concentration of sacrificial reagents, and reusability of catalysts, was studied. The maximum H2 was observed while using methanol as a sacrificial agent over CuO-CdWO4 nanocomposite. This enhancement was due to the faster charge separation, higher visible light absorption, and synergistic effect between the CuO-CdWO4 nanocomposite and methanol.

CuO-ZnO-CdWO4: a sustainable and environmentally benign photocatalytic system for water cleansing.

Currently, there is a major problem of water contaminations, especially of dyes, all over the world. A new technique is being developed daily for the treatment of contaminated water. In many ways, a photocatalytic degradation of a dye by a mixed metal oxide photocatalyst is counted as the best technique for water treatment. This paper also addresses the preparation and photocatalytic application of newly developed mixed metal oxide nanocomposite, CuO-ZnO-CdWO4. A novel mixed metal oxide CuO-ZnO-CdWO4 nanocomposite has been synthesized by a green route using Brassica Rapa leaves extract. The application of CuO-ZnO-CdWO4 as a photocatalyst in wastewater treatment has been thoroughly discussed. Several spectroscopic and microscopic techniques were used to characterize the prepared nanocomposite. The photocatalytic activity of CuO-ZnO-CdWO4 nanocomposite with a band gap of 3.13 eV was observed under the artificial visible light and sunlight for the degradation of Congo red dye. The results under sunlight show the 1.45 times greater removal efficiency than under the artificial visible light. Pseudo-first-order, diffusion, and Singh kinetics models were used to describe the kinetics of dye degradation. Pseudo-first-order model was found to be best fitted model for present study. The performance of CuO-ZnO-CdWO4 was estimated by significant parameters such as quantum yield, figure of merit, turnover number, and mean turnover frequency. The value these parameters were calculated as 1.70 × 10-8 molecules photon-1, 1.77 × 10-4, 2.98 × 108 s-1, and 3.31 × 10-4 s-1, respectively. These parameters revealed high potential of CuO-ZnO-CdWO4 for Congo red dye degradation.

Facile green synthesis of ZnO-CdWO4 nanoparticles and their potential as adsorbents to remove organic dye.

In this work, ZnO-CdWO4 nanoparticles have been synthesized by the ecofriendly green method with lemon leaf extract to favorably anchor functional groups on their surface. The prepared ZnO-CdWO4 nanoparticles are used as adsorbent to treat Congo red (CR) dye after characterization through FT-IR, UV-Vis, TEM, SEM-EDX, and HRTEM techniques. The equilibrium partition coefficient and adsorption capacity values for CR by ZnO-CdWO4 are estimated as 21.4 mg g-1 µM-1 and 5 mg g-1, respectively (at an initial dye concentration of 10 mg L-1). The adsorption process is found as exothermic and spontaneous, as determined by the ΔG°, ΔS°, and ΔH° values. The Boyd plot has been used as a confirmatory tool to fit the adsorption kinetics data along with intraparticle diffusion and pseudo-second-order models. Based on this research, ZnO-CdWO4 nanoparticles are validated as an effective adsorbent for CR dye in aqueous solutions.

Qualitative analysis of acid washed black cumin seeds for decolorization of water through removal of highly intense dye methylene blue.

Dyes in water change the colour, taste and odour of water, are highly visible, and can be toxic and cancerous for the coloured water consumption human beings. Basic dyes particularly, methylene blue, MB has high colour intensity, shows intense colour even at low concentration, and are very toxic due to their complex structure. Instead of adsorption, removal of MB from water using various traditional treatment methods is costly and less effective. The use of bioadsorbent provides easy and low cost technique for removal of MB. For searching the adequate technique of dye removal, adsorption efficiency and mechanism of bioadsorbent can be analyzed. To this, MB removal efficiency of seeds of medicinal plant, black cumin seeds were analyzed. The data are supplied in the article.