Hydrothermal Process Research Articles

Cost-Effective Synthesis of MXene Cadmium Sulfide (CdS) for Heavy Metal Removal.

Background Environmental contamination resulting from the release of untreated industrial wastewater has emerged as a critical worldwide issue. These effluents frequently have high levels of heavy metals and antibiotics, which are bad for aquatic ecosystems and human health. Oftentimes, conventional wastewater treatment techniques fall short of effectively eliminating these pollutants. Innovative materials that may efficiently absorb or break down contaminants from contaminated water sources are, therefore, desperately needed. Hydrothermally produced MXene cadmium sulfide (CdS) composites have shown great promise as an adsorbent material because of their special qualities, which include high surface area, chemical stability, and customizable surface functions that improve their adsorption capacity for heavy metals and antibiotics alike. Aim The aim of this study is to produce MXene-CdS nanoparticles in a cost-effective method for the simultaneous removal of heavy metals from aqueous contaminants for water pollution control. Methods and materials MXenes were synthesized by selectively etching Ti3AlC2 MAX-phase ceramics using aqueous HF. CdS nanoparticles were synthesized separately and integrated with MXenes via a hydrothermal process. The resulting MXene CdS nanocomposites were characterized using scanning electron microscopy (SEM) for morphology, energy dispersion spectrum (EDS) for elemental composition, X-ray diffraction(XRD) study for phase identification, and removal of heavy metals viaMXene CdS. Results Consistent distribution of CdS nanoparticles on the MXene surface and the creation of MXene CdS nanomembranes with a well-defined shape were observed by SEM analysis. Ti, C, Cd, and S elements, indiciaries of a successful composite formation, were confirmed to be present by EDS. The crystalline structure of both the MXene and CdS phases was confirmed by the distinctive peaks seen in the XRD patterns. MXene-CdS composites facilitate the effective removal of chromium ions from contaminated water. The excellent hydrophilicity of the produced nanomembrane allowed for effective interaction with watery contaminants. Conclusion This study showcases the successful synthesis and characterization of MXene-CdS nanocomposites for environmental remediation, particularly in removing toxic metals like chromium from industrial effluents. SEM analysis confirmed the uniform distribution of CdS nanoparticles on the MXene surface, while elemental composition validated their integration. XRD analysis confirmed the crystalline structures of both components. The nanocomposite exhibited excellent hydrophilicity, enhancing the efficient adsorption of heavy metals. Its large surface area and chemical stability contribute to high adsorption efficiency, making it ideal for wastewater treatment. The scalable synthesis process supports practical applications. This research highlights MXene-CdS nanocomposites as a cost-effective, sustainable solution for water pollution control.

Bio-inspired fabrication of Ag-ZnO nanoparticle decorated Nylon 11 nanofibers: Multifunctional membrane for environmental remediation

Traditional wastewater treatment methods using nanoparticles encounter challenges with catalyst recovery. In this study, we fabricated a Nylon 11 nanofibrous membrane (NFM) via electrospinning and functionalized it with polydopamine to immobilize Ag-ZnO nanoparticles for photocatalytic degradation of organic pollutants. The Nylon 11 NFM was treated with a dopamine tris buffer solution for polydopamine (PDA) coating, which facilitated mussel-inspired attachment of the ZnO nanoparticles. These nanoparticles served as a nucleation site for the biomimetic nucleation of Ag-ZnONPs during the hydrothermal process. The synthesized composite membrane was characterized by various microscopic and spectroscopic techniques. The water contact angle decreased from 135° (Nylon 11 NFM) to 41° (PDA/Nylon 11 NFM) and the filtration efficiency improved 10 folds (from 15.92 Lm-2 hr-1 to 170.60 Lm-2hr-1) at ambient conditions. The Ag-ZnO/PDA/Nylon 11 NFM showed strong antimicrobial activity against different bacterial strains and excellent photocatalytic degradation for methyl orange with a rate constant of 0.0431 min-1, significantly surpassing other configurations. The membrane exhibited excellent stability, reusability and consistent photocatalytic efficiency over multiple cycles. It is easily recoverable from the reaction mixture, and suitable for repeated use, making it a promising candidate for environmental remediation due to its antibacterial properties, photocatalytic activity, enhanced filtration efficiency, and reusability.

Eco-friendly synthesis and applications of graphene-titanium dioxide nanocomposites for pollutant degradation and energy storage

An innovative, eco-friendly method has been developed to synthesize reduced graphene oxide (rGO) sheets using orange peel extract. Following this, TiO2 nanoparticles are anchored to the rGO sheets through a hydrothermal process, resulting in an rGO/TiO2 nanocomposite (GTO/NC). This study utilized standard characterization techniques to confirm the formation of GTO/NC-1 and GTO/NC-2. Comparative analysis demonstrated that orange peel extract exhibits reducing capabilities compared to other natural reducers. The resulting GTO/NC-1 and GTO/NC-2, specifically GTO/NC-2, enhanced catalytic performance in degrading methyl orange a prevalent organic pollutant in various industrial applications. This nanocomposite achieved a turnover frequency of 0.003 mg MO/mg catalyst/min and displayed remarkable durability, enduring 3.0 cycles with robust first-order rate constants of 0.0193 min−1. Additionally, the electrochemical properties of GTO/NC-1 and GTO/NC-2 as electrode materials were assessed, revealing a specific capacitance of 320.0 Fg−1 at a current density of 1.0 Ag−1 and maintaining about 86.8 % of its initial capacitance after various charge–discharge cycles. These properties highlight the potential of GTO/NC-1 and GTO/NC-2 as both efficient catalysts for environmental remediation and durable materials for energy storage applications, offering substantial benefits for sustainable technology solutions.

Synthesis of isolated ZnO nanorods on introducing g-C3N4 for improved photoelectrocatalytic methanol production by CO2 reduction

The photoelectrocatalytic (PEC) CO2 reduction into fuels has been developed as a prospective approach to resolve the environmental and energy concerns. Herein, a composite catalyst comprising ZnO nanorods dispersed on the g-C3N4 surface (g-C3N4/ZnO) was successfully obtained by simple ZnO seed layer formation and then hydrothermal processes. The synthesized and characterized g-C3N4/ZnO catalytic composite showed 2.8 times enhanced photocurrent density at −1 V applied potential than the bare g-C3N4. The g-C3N4/ZnO catalyst exhibited 2.86 times enhanced the PEC CO2 reduction to methanol than the prepared bare ZnO catalyst. The catalyst’s enhanced the PEC CO2 reduction performance was ascribed to the high surface area, and higher generation and lower recombination of e−/h+ pairs. For the first time, this study showed the enhanced methanol production by the PEC reduction of CO2 over the prepared g-C3N4/ZnO catalytic composite.

Molybdenum Disulfide–Zinc Oxide Mixed Phase Network as Water Purifier

AbstractThe present work reports the development of oxide‐sulfide hybrid by simple hydrothermal process where zinc oxide (ZnO) prepared by simple chemical process is added in situ during the growth of molybdenum disulfide (MoS2) by hydrothermal process. The as prepared sample is characterized by X‐ray diffraction (XRD), field emission scanning electron microscope (FESEM), and energy dispersive X‐ray analysis (EDX). XRD confirms the coexistence of both ZnO and MoS2 in the sample whereas FESEM shows that fractal kind of sulfide structures get developed over ZnO rod. EDX carries the information regarding the stoichiometry of the sample. The sample is proven to be an excellent remover of textile dyes by synergistic effect of photocatalysis and adsorption with almost 100% efficiency following simple first‐order reaction kinetics. When the porous structure of the sample helps the process of adsorption, the charge transfer mechanism has been assumed to be responsible for photocatalytic dye degradation. The latter involves the transferring of electrons or holes between the photocatalyst and the dye molecules, leading to the generation of reactive species that initiate the degradation process. The combined effect of these two processes takes only 30 min to degrade textile dyes like Bengal rose (BR) and methylene blue (MB). Thus, the present work is supposed to serve as milestone in the associated field.

A 2D open framework zinc phosphate and its high proton conductance properties at medium and low temperature

A 2D open-framework zinc phosphate [C3N2H12][Zn2(HPO4)3] (1) was synthesized by solvothermal method. The inorganic anion layer is constructed from Zn2P2O12 cluster units and the interlayer spaces are filled by the diprotonated DAP molecules. The resultant compound had high purity and thermal stability by PXRD and TG analysis. This compound exhibited strongly temperature and humidity dependent proton conductivity, and its highest proton conductivity achieves 2.36 × 10−2 S.cm−1 at 100 %RH and 333 K. Moreover, the important effect of the dense hydrogen bond network in elevating the proton conductivity was explored through comparing the structure and proton conduction behavior between 1 and [C3N2H12][Zn(HPO4)2] (2), which synthesized via the same hydrothermal reaction process, and only a slight difference in the amount of DAP.

Investigating the role of fibre-matrix interfacial degradation on the ageing process of carbon fibre-reinforced polymer under hydrothermal conditions

The aqueous environment can deteriorate the fibre-matrix interface of carbon fibre-reinforced polymer (CFRP), significantly impairing the non-fibre-dominated mechanical properties. Thus, this study aimed to quantitatively analyse the impact of interfacial degradation on the hydrothermal ageing mechanism and process of the CFRP. Firstly, entire water absorption process of the CFRP under hydrothermal conditions was divided into three stages according to experimental measurement of its water content. Based on this division of stages, a novel water diffusion model was established for the hydrothermally aged CFRP. To measure the mechanical degradation, tensile tests were conducted on unaged, aged, and redried neat epoxy and transversely positioned unidirectional (UD) CFRP specimens. It was found that the transverse tensile strength degradation of UD CFRP was irreversible due to the permanent interfacial debonding between the fibres and matrix, in contrast to the reversible ageing of the epoxy matrix. To further quantify the fibre-matrix interfacial ageing, physically-based models were established for the degraded interfacial strength of CFRP subjected to hydrothermal conditions. After the characterization of the modelling coefficients, the physically-based models can be employed to predict interfacial strength inside the aged CFRP for various ageing durations. The prediction error was only 4.57% for the transverse tensile strength of degraded UD CFRP with various ageing durations from the representative volume element (RVE) simulation with its interfacial strength provided by the physically-based models, validating the effectiveness of the proposed physically-based models for degraded fibre-matrix interface under various ageing conditions.

Hierarchical porous MXene film with diffusion path optimization for supercapacitor

MXenes have immense potential in electrochemical energy storage owing to their outstanding physicochemical properties such as their oxygen-containing groups that impart additional pseudocapacitance to acidic electrolytes. However, during electrode assembly, MXene nanosheets undergo restacking because of hydrogen bonding and van der Waals forces, which causes electrolyte ions to traverse long diffusion pathways between the long and narrow nanosheets. Exploiting the oxidative properties of Ti3C2Tx, a hierarchical porous MXene film with micro-, meso- and macroporous structures was successfully prepared using a simple hydrothermal oxidation and etching process to create micro- and mesoporous structures, followed by ice templating to prepare three-dimensional (3D) linked macroporous structures. Because these hierarchical pores have synergistic effects on electrochemical activity and electrolyte ion diffusion, the film attained a specific capacitance of 539F/g at a current density of 2 A/g when it was used as a supercapacitor electrode, which corresponds to one of the highest values reported for MXene-based electrodes. The film retained 83% of its specific capacitance when the current density was increased to 40 A/g, and exhibited excellent cycling stability. By using this multi-porous MXene design, synergistic improvement in ion diffusion was successfully realized and thus a new strategy to prepare high-performance supercapacitor electrode materials was developed.

Enrichment of Chlorophyta growth via cerium oxide and utilized for hydrogen production via hydrothermal gasification process

Abstract The growing interest in alternative fuels stems from the need to address energy security and economic challenges. Hydrogen fuel is considered a promising solution due to its versatility, efficiency, and potential for zero emissions, as well as continuous technological advancements and increasing policy support. This study intends to enhance Chlorophyta growth by incorporating different volume percentages of cerium oxide (CeO2) as feedstock for hydrogen production through hydrothermal gasification. The research findings indicate that the highest concentration (0.2 vol %) of CeO2 resulted in the maximum growth of 0.63 μ/day, which was utilized for hydrogen extraction. Additionally, the investigation explored the impact of Chlorophyta algae loading (0.05-0.15 g/mL) and processing temperature (500-650°C) on molar fraction, hydrogen yield, gasification efficiency, carbon efficiency, and total hydrogen production. Higher feedstock (0.15 g/mL) and gasification temperature (650°C) were found to improve hydrogen fraction (61.8%), yield (10.2 mol/kg), gasification efficiency (43.8 %), and total hydrogen production (62.5%).

Manipulating the d-band center of bimetallic molybdenum vanadate for high performance aqueous zinc-ion battery

Vanadium-based oxides have good application prospects in aqueous zinc ion batteries (AZIBs) due to their structures suitable for zinc ion extraction and intercalation. However, their poor conductivity limits their further development. The d-band center plays a key role in promoting adsorption of ions, which promotes the development of electrode materials. Here, a series of MoV2O8 compounds with oxygen defect (Od-MoV2O8) were synthesized by a simple hydrothermal process and a subsequent vacuum calcination process through strict control of the deoxidation time. Theoretical calculations reveal that the abundant oxygen vacancies in MoV2O8 effectively regulate the d-band center of the zinc ion adsorption site. This precise control of the d-band center enhances the zinc ion adsorption energy of MoV2O8, lowers the migration energy barrier for zinc ions, and ultimately significantly boosts zinc storage performance. The specific capacity is as high as 282.4 mAh/g after 100 cycles at 0.1 A/g, and it also shows excellent performance and outstanding cycle life. In addition, the maximum energy density of Od-MVO-0.5 (MoV2O8 sample deoxidized for 0.5 h) is 343.3 Wh kg−1. Importantly, the mechanism of Zn2+ storage in Od-MoV2O8 was revealed by the combination of in situ and ex situ characterization techniques.

A pH visual sensing platform based on dual-emission chiral carbon dots for discrimination of normal/cancer cells and monitoring food freshness

Accurate detection of pH is important in pathological processes and food freshness. Developing sensors of sensitive response and visualization for pH is highly demanded. In this work, Chiral carbon dots(CCDs) was synthesized via one-pot hydrothermal process using o-phenylenediamine and L-Tryptophan, which displayed circular dichroism (CD) signals at 200–255 nm and 255–300 nm. The CCDs exhibited dual-emission peaks with blue and red emission bands when excited at 360 nm. The ratiometric signals of UV–vis absorption and fluorescence intensity of L-CDs were responsive over the pH range of 2.0 to 11.0 with significant color changes in solution. Fluorescence imaging of live cells displayed different signals related to pH in both the blue and red channels, allowing accurate measurement of the pH of the cellular environment. Furthermore, the pH test paper based on L-CDs enabled monitoring the freshness of shrimp and pork under 365 nm UV light. Therefore, L-CDs provided a multifunctional visual pH sensing platform for environmental monitoring and biosensing.

Hydrothermal processing of primary, waste-activated, and digested sewage sludge: Products characterisation, fate of heavy metals and nutrients, and process integration

Hydrothermal processing of primary, waste-activated, and digested sewage sludge: Products characterisation, fate of heavy metals and nutrients, and process integration

40Ar/39Ar Dating of Hydrothermal Processes in Large Gold Deposits of the Kochkar Anticlinorium (South Urals, Russia)

The age restrictions for productive mineral associations of the two largest gold deposits of the Southern Urals—Svetlinsk and Kochkar, which are located in the East Uralian megazone—are discussed. The 40Ar/39Ar dating method was performed for the first time for potassium-containing hydrothermal minerals (micas and amphiboles) from the ore veins and ore-host alteration, as well as from marbles. The age estimates obtained are in the range of 290–276 Ma; the weighted average value for the Svetlinsk deposit is 276 ± 2 Ma; for the Kochkar field, 284 ± 2 Ma. It is supposed that the studied mineral assemblages of the Svetlinsk and Kochkar deposits were formed in the beginning of the postcollision stage corresponding to the tectonic relaxation regime. Age of hydrothermal mineral formation in the gold fields of the Kochkar anticlinorium are consistent with the time of post-tectonic plutonic activity, which was expressed in the Middle–Southern Urals in large-scale granitization (~300 Ma). The ore-bearing alteration of a femic profile (of the same age for two deposits), which are most likely basificates, are near-synchronous with the granitization.

Facile synthesis of transition metal-selenides@CNTs for electrochemical oxygen evolution reactions

The fabrication of carbon based efficient electrocatalysts for hydrogen production during electrochemical water splitting could be a great achievement to fulfill the future renewable energy demand. In this study, one-step hydrothermal process was used to develop composites of multi-metal selenides with carbon nanotubes (MnSe@CNTs, MnCuSe@CNTs, MnCoNiSe@CNTs) as electrocatalysts for OER during electrolytic water splitting. XRD and SEM with EDS analysis confirm the successful fabrication of proposed catalyst and their crystalline morphology. Among the synthesized functionalized CNTs composites, bimetallic selenide composite gives a better electrocatalytic activity with the reduce overpotential, lower Tafel slope and reduced charge transfer resistance in 1 M KOH. By using this catalyst, water oxidation starts at 1.4 V onset potential with a very low overpotential of 245 mV and the Tafel slope was only 107 mV dec−1. Metal based selenides composites with CNTs introduces a lot of active sites, subsequent nanoparticles of MnSe, MnCuSe, & MnCoNiSe, causes to boost the surface area and electrocatalysis towards oxygen evolution reactions.

Partial molar volumes of 1–1 electrolytes at high T and P: correlations and predictions

Knowledge of the partial molar volumes of aqueous ions allows accurate calculation of the pressure dependence of equilibrium constants, solubility of minerals, etc., thus being useful for thermodynamic modeling of hydrothermal processes. This study analyzed methods to correlate and predict the values of the partial molar volumes at infinite dilution, V2o, for 1–1 electrolytes and singly charged ions at elevated T and P. Since the precise experimental values of the dielectric constant of water are measured only up to 873 K, we were interested only in non-electrostatic ways to correlate V2o data. First of all, we compiled the V2o values at T > 373 K for the following 1–1 electrolytes: HCl, LiCl, LiI, LiNO3, LiOH, NaF, NaCl, NaBr, NaI, NaNO3, NaOH, NaHCO3, NaClO4, NaH2PO4, NaTr (Tr stands for triflate), KF, KCl, KBr, KI, KNO3, KOH, CsBr, and NH4Cl. Relations, following from the “density” model and from the Fluctuation Solution Theory (FST) were employed to analyze data. It was concluded that at the current state of knowledge of V2o the FST-relations for electrolytes are recommended mainly to reject strongly deviating experimental outliers. However, the “density” model provides a simple and fairly accurate way to describe the compiled set of data with only two parameters for each ion, n and Vhc, values of which were evaluated for the following singly-charged ions: H+, Li+, Na+, K+, Cs+, NH4+, F-, Cl-, Br-, I-, OH–, NO3–, H2PO4-, HCO3–, ClO4-, Tr- (Tr = triflate). Following Mesmer et al. (1988), we consider the fitting parameters Vhc and n to be related to the intrinsic volume of the ion and to the number of water molecules transferred from the bulk water to a hydration shell around the ion, respectively.Although the values of n and Vhc were fitted from data at temperatures from 373 to 673 K and water densities, do, from 0.5 to 1.1 g cm−3, apparently, they predict realistic V2o values at temperatures up to 1600 K and do ranges from 0.2 to 1.6 g cm−3.

Sequential Detection of Hg2+ and TNT Using a Nitrogen‐Doped Polymeric Carbon Dots On–Off–On Fluorescence Sensor

ABSTRACTThis work presents a fluorescence sensor based on nitrogen‐doped carbon dots (N‐CDs) utilized for sequential detection of Hg2+ and TNT. The N‐CDs were produced by a simple and efficient hydrothermal process involving the combination of black bean extract with citric acid (CA) and ethylenediamine (EDA). The resulting N‐CDs exhibit a steady blue fluorescence with a significant quantum yield of 12%. We conducted a thorough investigation into the mechanism by which the fluorescence of NCDs is reduced in the presence of Hg2+. Our analyses, which included Stern–Volmer quenching tests, confirmed the development of a stable complex between N‐CDs and Hg2+. When the NCDs‐Hg2+ complex was exposed to TNT, the fluorescence was selectively restored. This sequential “on–off–on” sensing capacity allows for efficient monitoring of both Hg2+ and TNT, demonstrating good sensitivity and selectivity. The sensor has a low detection limit (LOD) of 3.1 and 46 nM for Hg2+ ions and TNT in a linear range of 0–40 and 0–30 μM, respectively. This study emphasizes the potential application of N‐CDs for detecting heavy metals and explosives at the same time. It highlights their usefulness in sophisticated environmental sensing technologies that are suitable for important applications.

Controllable synthesis of monodisperse hierarchical porous carbon nanorods and their derived superstructures for supercapacitors

Monodisperse hierarchical porous carbon nanorods (HPCNs-1) are synthesized through hydrothermal carbonization and KHCO3 activation using D-xylose, sodium dodecyl sulfate (SDS) and poly (4-styrene sulfonic acid-maleic acid) sodium salt (PSSMA). PSSMA regulates morphology and the accumulation of SDS micelles through inhibition and electrostatic repulsion. SDS serves as a microreactor for hydrothermal processes and a pore-forming agent. KHCO3 generates micropore and ensures a high specific surface area. Additionally, raspberry-like and spindle-like hierarchical porous nanocarbons are obtained with sodium laurate and sodium oleate. Hierarchical porous nanocarbons exhibit controllable morphology, high pore utilization, demonstrating useful electrochemical performance. In a 6 mol·L-1 KOH electrolyte, HPCNs-1 achieves a specific capacitance of 302F·g−1 at a current density of 0.2 A·g−1 with a retention rate of 98 % after 10,000 charge–discharge cycles at 10 A·g−1. In pure 1-butyl-3-methylimidazolium tetrafluoroborate electrolyte, an assembled symmetric supercapacitor with HPCNs-1 demonstrates an energy density of 39.06 W·h·kg−1 at 0.1 A·g−1.

Tectonic–Hydrothermal Processes and their Relationship with the Petroleum Potential of the Bazhenov-Abalak Complex of Western Siberia

Abstract —The main types of reservoir rocks have been identified within the Bazhenov-Abalak complex. To assess the geological resources of hydrocarbons, it is proposed to formally divide the entire set of lithological rock types comprising the Bazhenov-Abalak complex into two main varieties: fluid seals and reservoirs. We argue that it is possibile to distinguish between potentially productive and productive rocks, represented by siliceous and carbonate varieties, according to logging data. A possible mechanism for the formation of reservoir rocks within the Bazhenov-Abalak complex as a result of the tectonic-hydrothermal impact on these deposits has been reconstructed. An original methodology for identifying perspective zones of various categories of hydrocarbon accumulation in the Bazhenov-Abalak complex through integrating seismic data and tectonophysical modeling carried out on their basis has been proposed. For example, an assessment of the predicted geological resources of hydrocarbons contained in the Bazhenov-Abalak complex within the limits of 3D seismic exploration of the Yem-Yegovskaya area has been carried out. The necessity of assessing the prospects for oil content and calculating the predicted geological resources of hydrocarbons in the whole Bazhenov-Abalak complex, and not only in the Bazhenov Formation, is substantiated, based on a single mechanism of formation of reservoir rocks of tectonic-hydrothermal origin in them.

Hydrothermally synthesis of a green SnS-Carbon microplate adsorbent for the removal of mercury ion from water samples

Mercury ion (Hg2+) finds a broad industrial application and due to its significant toxicity to both humans and aquatic life, development of highly effective adsorbents for its removal holds considerable importance. This study introduces a green adsorbent consisting of tin sulfide (SnS)‑carbon microplates synthesized through a straightforward one-step hydrothermal process followed by its application for the removal of Hg2+ from water samples. The synthesized adsorbent is characterized using Fourier Transform Infrared Spectrophotometry (FT-IR), Field Emission Scanning Electron Microscopy (FESEM), Energy-Dispersive X-ray spectroscopy (EDX), Thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) and X-Ray diffraction analysis (XRD). Through the optimization of crucial parameters and with thanks to the effective interaction between S atoms (soft base) of SnS-C adsorbent and Hg2+ (soft acid), an impressive Hg2+ removal percentage of approximately 99.0 % is achieved for 100 mg L−1 Hg2+. Interpreting of isotherm models indicate that Hg2+ adsorption conforms to the Langmuir isotherm with a maximum adsorption capacity of 238.1 mg/g. Finally, the SnS-Carbon microplate adsorbent exhibits notable advantages, including a green and convenient synthesis route (achieved through a one-step hydrothermal method) and high efficiency, making it a potent adsorbent for the decontamination of Hg2+ from water samples.

HYDROTHERMAL SYNTHESIS OF NITROGEN-DOPED CQDS OF RUBUS NIVEUS LEAVES FOR FLUORESCENT pH SENSING AND PHOTOCATALYTIC APPLICATIONS

The development of a fluorescent pH sensor and the treatment of wastewater with nanoparticles are both critical topics. The variation in pH impacts the morphology and subsequent properties of the nanoparticles, which are used for their utilization in various fields and the second one gives a better treatment approach for industrial waste entities. The present study examines the effects of these variables on the biologically produced nitrogen-doped carbon quantum dots (NCQDs). Hydrothermal process was performed for the synthesis of the same by using Rubus-niveus leaf extract as a precursor. The UV-Vis spectroscopy analysis shows absorption spectra in the wide range of 200 nm to 800 nm and shows prominent peaks at 236 nm and 392 nm, respectively. Further, the direct energy band gap of 3.65eV was analysed for NCQDs. The SEM image shows flower-shaped particles, and FT-IR analysis indicates the existence of amide, CHO, N-H, and C-N functional groups. XRD pattern showed that the surface morphology of NCQDs is amorphous in nature. A good response was found in the variation of fluorescence intensity with the pH values, confirming the possibility of NCQDs serving as pH sensors. Rhodamine-B (Rh-B) dye's reaction kinetics was revealed for the purpose of analyzing the potential of NCQDs for the degradation of commercial dyes and found to be followed by pseudo-first order kinetics with the correlation coefficient of 0.80.