Showing papers by "Joydeep Dutta published in 2021"
TL;DR: This work proposes a novel strategy for the elimination of microplastics using glass fiber substrates to trap low density microplastic particles such as polypropylene (PP) which in parallel support the photocatalyst material.
171 citations
TL;DR: The high removal efficiency and very low levels of iron leaching suggests that ACC-CH-nZVI is a highly efficient and cost-effective catalyst for Fenton-like oxidation of non-biodegradable organic wastes in water.
75 citations
23 Aug 2021
24 citations
TL;DR: In this paper, a thin shell of amorphous tin dioxide (SnOx) was grown on the surface of ZnO to form zinc oxide core-shell nanoparticles that improved the chemical stability of the photocatalyst nanoparticles, as examined at pH 3 and 6.
Abstract: Functional nanocomposites with biopolymers and zinc oxide (ZnO) nanoparticles is an emerging application of photocatalysis in antifouling coatings. The reduced chemical stability of ZnO in the acidic media in which chitosan is soluble affects the performance of chitosan nanocomposites in antifouling applications. In this study, a thin shell of amorphous tin dioxide (SnOx) was grown on the surface of ZnO to form ZnO–SnOx core–shell nanoparticles that improved the chemical stability of the photocatalyst nanoparticles, as examined at pH 3 and 6. The photocatalytic activity of ZnO–SnOx in the degradation of methylene blue (MB) dye under visible light showed a higher efficiency than that of ZnO nanoparticles due to the passivation of electronic defects. Chitosan-based antifouling coatings with varying percentages of ZnO or ZnO–SnOx nanoparticles, with or without the glutaraldehyde (GA) crosslinking of chitosan, were developed and studied. The incorporation of photocatalysts into the chitosan matrix enhanced the thermal stability of the coatings. Through a mesocosm study using running natural seawater, it was found that chitosan/ZnO–SnOx/GA coatings enabled better inhibition of bacterial growth compared to chitosan coatings alone. This study demonstrates the antifouling potential of chitosan nanocomposite coatings containing core–shell nanoparticles as an effective solution for the prevention of biofouling.
21 citations
TL;DR: In this paper, a series of CuZn/MCM-41 catalysts was synthesized by four different routes; one pot hydrothermal synthesis (OPMCM), co-impregnation (COMCM), serial impregnation and copper impregnated on Zn-MCM41 (ZNMCM).
21 citations
TL;DR: In this article, the authors investigated the flow distribution in single flow-through CDI cells and interconnected modules to determine architectural principles that can feasibly reduce the pressure drop with good throughput, thus increasing energy efficiency.
19 citations
TL;DR: In this paper, aloe vera gel was added as a natural antioxidant in chitosan-based composite coating containing ZnO nanoparticles and applied on the surface of freshly harvested pineapple fruits.
Abstract: Rapid postharvest losses and quality deteriorations in pineapple are major challenges to growers and handlers. Chitosan-based coatings on fruit surfaces have gained importance in recent years to enhance postharvest shelf life of the fruits. In this study, aloe vera gel was added as a natural antioxidant in chitosan-based composite coating containing ZnO nanoparticles. The developed formulation was applied on the surface of freshly harvested pineapple fruits. ZnO nanoparticles were used as an antimicrobial agent. Coated pineapple fruits were evaluated for weight loss, total soluble solids, titratable acidity, decay index, maturity index, and sensory attributes, including visual appearance, periodically at 5 day interval during storage. The results showed that the coating of the fruit reduced weight loss by about 5%, and also delayed ripening and oxidative decay compared to the uncoated fruit. Thus, the developed coating formulation is a promising sustainable solution to reduce postharvest losses and to extend shelf life of pineapples.
16 citations
TL;DR: In this paper, the influence of pretreatment conditions and stability of the active sites on the catalytic activity and hysteresis of Pd/SiO2 catalysts was investigated using carbon monoxide (CO) oxidation as a model reaction.
Abstract: Carbon monoxide (CO) oxidation is considered an important reaction in heterogeneous industrial catalysis and has been extensively studied. Pd supported on SiO2 aerogel catalysts exhibit good catalytic activity toward this reaction owing to their CO bond activation capability and thermal stability. Pd/SiO2 catalysts were investigated using carbon monoxide (CO) oxidation as a model reaction. The catalyst becomes active, and the conversion increases after the temperature reaches the ignition temperature (Tig). A normal hysteresis in carbon monoxide (CO) oxidation has been observed, where the catalysts continue to exhibit high catalytic activity (CO conversion remains at 100%) during the extinction even at temperatures lower than Tig. The catalyst was characterized using BET, TEM, XPS, TGA-DSC, and FTIR. In this work, the influence of pretreatment conditions and stability of the active sites on the catalytic activity and hysteresis is presented. The CO oxidation on the Pd/SiO2 catalyst has been attributed to the dissociative adsorption of molecular oxygen and the activation of the C-O bond, followed by diffusion of adsorbates at Tig to form CO2. Whereas, the hysteresis has been explained by the enhanced stability of the active site caused by thermal effects, pretreatment conditions, Pd-SiO2 support interaction, and PdO formation and decomposition.
13 citations
TL;DR: In this paper, Molybdenum disulfide (MoS2) nanostructures have been prepared by a hydrothermal treatment and were decorated with metallic silver (Ag) using the conventional wet incipient impregnation process to form Ag/MoS 2 nano/hetero-junctions.
Abstract: Molybdenum disulfide (MoS2) nanostructures have been prepared by a hydrothermal treatment and were decorated with metallic silver (Ag) using the conventional wet incipient impregnation process to form Ag/MoS2 nano/hetero-junctions. The physiochemical functionalities were characterized using X-ray diffraction, Fourier transfer infrared spectroscopy, Raman spectroscopy, field emission scanning electron microscopy, energy dispersive spectroscopy and transmission electron microscopy. UV–Vis (ultraviolet–visible) spectroscopy shows an improved light absorption in visible region for Ag/MoS2 nano/hetero-junctions due to the surface plasmon resonance absorption. Photoluminescence (PL) studies suggest efficient photoexcited charge separation to occur in Ag/MoS2 nano/hetero-junctions due to an internal electric field formed across Schottky interface. The nonlinear responses of as-prepared samples to intense laser fields were examined using standard single-beam Z-scan technique under a 532 nm CW second-harmonic Nd:YAG laser irradiation wherein demonstrated reverse saturable absorption behaviors and self-defocusing responses due to negative lens effects were observed. The third-order nonlinear refractive index and absorption coefficient for Ag/MoS2 nano/hetero-junctions were found to be 6.5 × 10-7 cm2/W and 3.5 × 10-4 cm/W, respectively, showing 1.44 and 1.5 times enhancement than in MoS2 nanostructures.
12 citations
12 citations
15 Jan 2021
TL;DR: In this paper, a dynamic Langmuir (DL) model is extended to a linear-state-space DL model (LDL), which can incorporate general structural and operational modes, including membrane CDI and constant-current operation.
Abstract: While black-box models such as neural networks have been powerful in many applications, direct physical modeling (white box) remains crucial in many fields where experimental data are difficult or time-consuming to obtain. Here, we demonstrate with an example from desalination by capacitive deionization (CDI), how an existing physical model could be strengthened by combining a general modeling framework with physical insights (gray box). Thus, a dynamic Langmuir (DL) model is extended to a linear-state-space DL model (LDL). Results obtained show the new LDL model could incorporate general structural and operational modes, including membrane CDI and constant-current operation. The formulation removes the need for direct measurements of detailed device properties without adding model complexity, and MATLAB code for automatically implementing the model is provided in the Supplementary Information. We conclude the new LDL model is widely applicable, offering great flexibility in calibration data, and enabling prediction over general operating modes.
TL;DR: In this paper, the optical and high-temperature stability performances of six different solar selective reflector (SSR) materials were studied in the cavity wall of a cavity receiver in determining the receiver efficiency.
TL;DR: In this article, a new high-temperature absorber material was proposed by combining Ti2AlC MAX phase material and iron-cobalt-chromite spinel coating/paint.
Abstract: Enhancing the operating temperature of concentrating solar power systems is a promising way to obtain higher system efficiency and thus enhance their competitiveness. One major barrier is the unavailability of suitable solar absorber materials for operation at higher temperatures. In this work, we report on a new high-temperature absorber material by combining Ti2AlC MAX phase material and iron-cobalt-chromite spinel coating/paint. This durable material solution exhibits excellent performance, passing the thermal stability test in an open-air environment at a temperature of 1250 °C for 400 h and at 1300 °C for 200 h. The results show that the black spinel coating can offer a stable high solar absorptivity in the range of 0.877-0.894 throughout the 600 h test under high temperatures. These solar absorptivity values are even 1.6-3.3% higher than that for the sintered SiC ceramic that is a widely used solar absorber material. Divergence of solar absorptivity during these relatively long testing periods is less than 1.1%, indicating remarkable stability of the absorber material. Furthermore, considering the simple application process of the coating/painting utilizing a brush followed by curing at relatively low temperatures (room temperature, 95 and 260 °C in sequence), this absorber material shows the potential for large-scale, high-temperature solar thermal applications.
TL;DR: In this paper, a lower-energy alternative in which glass is mechanically activated in a ball mill and leached with nitric acid was tested, which resulted in 78% lead extraction during leaching at 95°C.
Abstract: Glass waste dumps from crystal glass production is an health issue due to the occurrence of antimony, arsenic, cadmium and lead in crystal glass. Recovery of those elements could both decrease pollution and recycle metals in the circular economy. Pyrometallurgy is a potential recovery method, yet limited by high energy consumption. Here we tested a lower-energy alternative in which glass is mechanically activated in a ball mill and leached with nitric acid. Results show that mechanical activation destabilised the glass structure and resulted in 78% lead extraction during leaching at 95 °C. Temperature had the most significant effect on extraction, whereas acid concentration, from 0.5 to 3 M, and leaching time, from 0.5 to 12 h, had insignificant effects. In each experiment, 75% of the final extracted amount was achieved within 30 min. The study demonstrates potential for lead extraction from glass waste at lower acid concentration, shorter leaching time and lower temperature, of 95 °C, than traditional pyrometallurgical extraction, typically operating at 1100 °C.
DOI•
22 Nov 2021
TL;DR: In this article, a review mainly discusses photocatalysis, antifouling activity, and formulation of coatings using metal and metal oxide nanomaterials (nanoparticles, nanowires, nanorods).
Abstract: Biofouling is a major concern to the maritime industry. Biofouling increases fuel consumption, accelerates corrosion, clogs membranes and pipes, and reduces the buoyancy of marine installations, such as ships, platforms, and nets. While traditionally marine installations are protected by toxic biocidal coatings, due to recent environmental concerns and legislation, novel nanomaterial-based anti-fouling coatings are being developed. Hybrid nanocomposites of organic-inorganic materials give a possibility to combine the characteristics of both groups of material generating opportunities to prevent biofouling. The development of bio-inspired surface designs, progress in polymer science and advances in nanotechnology is significantly contributing to the development of eco-friendly marine coatings containing photocatalytic nanomaterials. The review mainly discusses photocatalysis, antifouling activity, and formulation of coatings using metal and metal oxide nanomaterials (nanoparticles, nanowires, nanorods). Additionally, applications of nanocomposite coatings for inhibition of micro- and macro-fouling in marine environments are reviewed.
TL;DR: In this article, a new type of photocatalyst is proposed on the basis of aero-β-Ga2O3, which is a material constructed from a network of interconnected tetrapods with arms in the form of microtubes with nanometric walls.
Abstract: A new type of photocatalyst is proposed on the basis of aero-β-Ga2O3, which is a material constructed from a network of interconnected tetrapods with arms in the form of microtubes with nanometric walls. The aero-Ga2O3 material is obtained by annealing of aero-GaN fabricated by epitaxial growth on ZnO microtetrapods. The hybrid structures composed of aero-Ga2O3 functionalized with Au or Pt nanodots were tested for the photocatalytic degradation of methylene blue dye under UV or visible light illumination. The functionalization of aero-Ga2O3 with noble metals results in the enhancement of the photocatalytic performances of bare material, reaching the performances inherent to ZnO while gaining the advantage of the increased chemical stability. The mechanisms of enhancement of the photocatalytic properties by activating aero-Ga2O3 with noble metals are discussed to elucidate their potential for environmental applications.
TL;DR: In this article, a facile hydrothermal approach was developed to fabricate hollow ZnO microspheres via self-assembled rod-like nanostructures, and morphology-controlled synthesis was conducted by altering the treatment temperature (150, 200 and 250°C).
Abstract: Hollow nanostructures have attracted attention because of their unique physiochemical properties and broad potential applications in electronics, optics and photonics. In this study, a facile hydrothermal approach was developed to fabricate hollow ZnO microspheres via self-assembled rod-like nanostructures. The morphology-controlled synthesis was conducted by altering hydrothermal treatment temperature (150, 200 and 250 °C) in solutions containing zinc acetate dihydrate precursor and glycerol as the stabilizing agent. The morphological observations indicated that hydrothermally grown ZnO architectures could be reasonably adjusted by modulating hydrothermal reaction temperature. Possible growth routes are proposed to elucidate the formation process of ZnO microspheres with the rod-like nanostructures. Morphology-dependent absorbance and emission along with red-shifts with improved crystalline qualities were observed with increasing hydrothermal growth temperature. Kerr-type nonlinear optical characteristics examined using single-beam Z-scan technique in the near infrared spectral range under nanosecond Nd-YVO4 laser pulses showed positive values of nonlinear refraction providing an evidence of self-focusing behaviors at the excitation wavelength of 1064 nm in all the samples studied. The highest Kerr-type nonlinear susceptibility was estimated to be 2.31 × 10–6 esu for hollow ZnO microspheres grown at 250 °C, suggesting synergistic effects of surface morphologies on optical nonlinearities.
TL;DR: In this article, a thin layer of functionalized graphene oxide-based tablets (GO-Tabs) was applied on a polyethylene substrate to extract ritonavir (RTV) in human saliva samples.
Abstract: In this work, graphene oxide-based tablets (GO-Tabs) were prepared by applying a thin layer of functionalized GO on a polyethylene substrate. The GO was functionalized with amine groups (-NH2 ) by poly(ethylene glycol)bis(3-aminopropyl) terminated (GO-NH2 -PEG-NH2 ). The functionalized GO-Tabs were used for the extraction of ritonavir (RTV) in human saliva samples. RTV in plasma and saliva samples was analyzed using LC-MS/MS. Gradient LC system with MS/MS in the positive-ion mode [electrospray ionization (ESI+)] was used. The transitions m/z 721 → 269.0 and m/z 614 → 421 were used for RTV and the internal standard indinavir, respectively. This study determined the human immunodeficiency virus protease inhibitor RTV in human saliva samples using functionalized GO-Tab and LC-MS/MS, and the method was validated. The standard calibration curve for plasma and saliva samples was constructed from 5.0 to 2000 nmol L-1 . The limit of detection was 0.1 nmol L-1 , and the limit of quantification was 5.0 nmol L-1 in both plasma and saliva matrices. The intra- and inter-assay precision values were found to be between 1.5 and 5.8%, and the accuracy values ranged from 88.0 to 108% utilizing saliva and plasma samples. The extraction recovery was more than 80%, and the presented functionalized GO-Tabs could be reused for more than 10 extractions without deterioration in recovery.
TL;DR: In this paper, the anodic current density (J) of aluminum oxide films in 0, 2, 4, 5, 6, 8 and 10% sulfuric acid solutions (H2SO4) was measured by Fabry-Perot interferometry under a potentiostatic condition of 9V with respect to the open circuit potential of the aluminum samples in the H2SO 4 solutions, for 90min.
Abstract: Both Fabry–Perot interferometry and the DC electrochemical method have been simultaneously used for the first time to measure in situ the anodic current density (J) of aluminum oxide films in 0, 2, 4, 5, 6, 8 and 10% sulfuric acid solutions (H2SO4). The calculated values of J by Fabry–Perot interferometry were verified by the DC electrochemical method, i.e., a potentiostat, and the AC electrochemical method, i.e., a potentiostat with an accessory of AC impedance spectroscopy (EIS). The corresponding thickness (d) of the aluminum oxide (Al2O3) film to the anodic current density was determined by Fabry–Perot interferometry under a potentiostatic condition of 9 V with respect to the open circuit potential of the aluminum samples in the H2SO4 solutions, for 90 min. Then, the obtained d of the Al2O3 films by Fabry–Perot interferometry was verified by scanning electron microscopy (SEM) and compared to d values that were obtained by the EIS. The calculated J by Fabry–Perot interferometry was found to be in agreement with those of the DC electrochemical method. In contrast, the calculated J by Fabry–Perot interferometry was found to have a threefold discrepancy with data obtained by the EIS.