Sustainable Chemistry for Climate Action最新文献

A practical technique for removing fluoride from aqueous solutions by adsorption was created using the natural adsorbent known as Terminalia Chebula with a primary emphasis on adsorption isotherms and kinetic studies. The experimental results showed the best conditions for removing fluorine ions as follows: the dosage of the natural adsorbent: 50 mg/L, contact reaction time: 40 min, shaking speed = 120 rpm, temperature = 32 °C. The amount of removal of fluorine ions was found to be >98 % fluoride within a shorter time and reached adsorption equilibrium within 40 min with a maximum defluoridation capacity of 20.92 mg/g. At lower solution pH (3 to 5), there is higher fluoride adsorption on the adsorbent surface and as the pH becomes alkaline (pH > 7) the adsorption capacity decreased. The two co-ions namely NO₃⁻ and Cl⁻ removed the fluoride 79 % whereas, the phosphate ions did not have any marked effect on the defluoridation. The pseudo-second-order kinetic order such Langmuir, Empirical Freundlich, Temkin and Dubinin–Radushkevich isotherms can well predict the adsorption equilibrium rate to be at 0.044 mg/L with contact time (t) of 30 min. In addition to that the adsorption is characterized by SEM, X-ray diffraction and FTIR techniques. This study has ultimately found that the Terminalia Chebula is a workable, natural material for fluoride elimination.

In recent years, waste-to-energy systems are receiving more attention due to their dual benefit of reduction of pollution caused by waste materials and reducing the overconsumption of fossil fuels. Since plastic waste is readily available and has a high heating value, it is a viable source of energy.; plastic garbage makes an excellent source of energy. Today, a feedstock made up of several types of plastic is used to quickly pyrolyze and produce plastic pyrolysis oil (PPO) or waste plastic oil (WPO). The oil could be utilized in internal combustion engines to produce heat and power. In the current work, waste polythene covers were transformed into value added products by utilizing fly ash catalyst and oil obtained is examined for suitability to run in the diesel engine. In the primary phase simulation study is performed on a four-stroke single cylinder DI Compression ignition engine using Diesel-RK engine simulator, results indicated that, waste plastic oil was found to emit higher oxides of nitrogen compared to diesel therefore in the secondary phase the same engine simulated by implementing exhaust gas recirculation at 3.5 %,7 %,10.5 % and 14 % rates. In the end engine parameters get optimized using 3D parametric optimization technique.

Simulation Results indicate that, performance parameters such as brake power, brake thermal efficiency and brake specific fuel consumption were found to be decreased slightly under EGR conditions. Furthermore, combustion parameters such as cylinder peak pressure and peak temperature decrease up on implementing the exhaust gas recirculation, similarly the emission characteristics such as CO₂, PM and smoke found to be increase with increase in EGR ratio while oxides of nitrogen emissions significantly decreased under EGR conditions. In order to reduce the emissions further, a 3D parametric optimization technique was adopted and optimal results obtained when engine runs at compression ratio of 16.5, injection timing of 19.38 and EGR percentage of 4.8 %.

Global climate change may have a significant effect on several environmental components in many different nations worldwide. Variations in the pattern of precipitation have an immediate impact on the management of water resources. To improve water resource management techniques, it is critical to investigate differences in the temporal and geographical rainfall patterns. The current study looks at rainfall patterns in the Kuzhithuraiyar sub-basin of the Kodayar basin, Kanyakumari District. Utilizing the mean monthly data from four distinct rain gauge locations, we have comprehensively compiled and analysed rainfall statistics over an extensive timespan of 30 years (1991–2020). For precision in temporal categorization, this data was meticulously divided into four seasonal classifications: pre-monsoon, post-monsoon, southwest monsoon (SW), and northeast monsoon (NE). Using ArcGIS 10.8, the rainfall pattern was analysed, and spatial distribution maps for the four seasons listed above were created using the inverse distance weighting (IDW) approach. The region receives an average of 1456.78 mm of precipitation each year, with the post-monsoon, pre-monsoon, SW monsoon, and NE monsoon providing 32.87 mm, 335.28 mm, 538.67 mm, and 549.97 mm, respectively. The results reveal that the model correlates mean rainfall and rainfall variability over areas of Tamil Nadu's Kuzhithuraiyar sub-basin with some accuracy in terms of the number of rainfall extremes and their spatial distribution maps.

This work presents an infectious medical waste-to-energy (IMWtE) thermal and environmental analysis using combined heat and power (CHP) technology. Steam sterilization can be operated with an infectious medical waste (IMW) of 375 kg/h⋅unit, a maximum per day of 12,000 kg/day for double sterilization units, and a running time of 16 h/day. The CHP system uses a dried IMW of 797 kg/h, generating a power output of 128.98 kW_e, providing a drying heat of 382.91 kW, and achieving an overall system efficiency of 8.45 %. Results are obtained for a life cycle assessment (LCA) of the IMWtE by CHP system technology. The endpoint effectiveness comprises considerations of human health: 2.83E+01 DALY, ecosystem quality is represented value of: 9.32E+00 Species⋅y, and natural resource value of: 1.08E+06 USD, all of these are fundamentally linked to the utilization of steel, copper, paint, and gypsum. The LCA impacts are primarily due to the operation phase (93 %), with the smaller contribution of the decommissioning phase (4 %), and the construction phase (3 %), respectively.

The disposal of Waste Foundry Sand (WFS) poses a significant challenge for the foundry industry today, primarily due to its composition of metal oxides (Al₂O₃, Fe₂O₃, MgO, CaO, and Na₂O) and sand. These metal oxides, categorized as loosely and strongly bound clays, are considered impurities in core production. This study proposes a chemical reclamation technique for WFS using fresh acid solutions or acidic industrial effluent. Experiments were conducted to remove the loosely and strongly bound clays from the WFS, optimizing parameters such as acid concentration, sand to acid loading, temperature, stirring speed, and reaction time to achieve optimal performance. The quality of the reclaimed sand was evaluated using various foundry standard tests, including determination of clay contents, compressive strength, Grain Fineness Number (GFN), Loss on Ignition (LOI), Acid Demand Value (ADV), and scanning electron microscopy. The reclaimed sand exhibited a loosely bound clay content of 1.5 %, oolitic content of 5.5 %, a grain fineness number of 55, a loss on ignition of 1.92 %, and an acid demand value of 1.5 ml/100 g of sand. Field trials demonstrated that the reclaimed sand can be effectively used for core production at an economical rate.

The present research article demonstrates the dispersion of manganese dioxide (MnO₂) nanoparticles in polythiophene (PTh) to enhance the optical and gas sensing properties of PTh/MnO₂ nanocomposites. The structural aspects of the as-synthesized nanocomposites were demonstrated by the techniques such as X-ray diffraction (XRD), Fourier transmission infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FE-SEM). Furthermore, the optical characterization of the resulting composite was investigated using UV–Vis spectroscopy. UV–Vis analyses of obtained nanocomposite revealed a forbidden band of ∼ 3.7 eV. The prepared nanocomposites were exposed to CO₂ gas to investigate the composites suitability for gas sensing application, which prove to be promising materials. The prominent exploit of the present work is that 0.8 Wt. % MnO₂ loaded PTh composite material exhibits significant sensing response at low operating temperature including good stability and fast response and recovery time. The core objective of this work is the discussion of the enhancement in stability, response and recovery time as a consequence of the interaction between the CO₂ gas and the as-synthesized nanocomposites.

A highly active zinc glutarate-double metal cyanide (DMC) composite catalyst (ZnGA/Zn-CrDMC) was designed for the carbon dioxide (CO₂) and propylene oxide (PO) copolymerization reaction. The composite catalyst was synthesized in a rheological phase reaction and characterized using Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM). The synthesized composite catalysed the solvent free reactions of PO and CO₂ to afford biodegradable polypropylene carbonate (PPC) copolymer. ¹H NMR,¹³C NMR, FT-IR and ESI-TOF mass spectrometry measurements were employed to confirm the characteristics of the PPC produced. Under optimal reaction conditions (50 bar CO₂, 70 °C, 24 h), the ZnGA-Zn₃[Cr(CN)₆]₂ composite displayed higher catalytic activities in the copolymerization reactions than the individual catalysts. The ZnGA:Zn₃[Cr(CN)₆]₂ ratio of 15:1 gave PPC yield of 47.9 g polymer/g cat compared to ZnGA that produced 42.6 g polymer/ g cat in 24 h. In addition, the PPC produced from the composite catalyst displayed higher carbonate linkage content (Fc = 85.4 %) compared to the value of Fc = 33.9 %. obtained using the Zn₃[Cr(CN)₆]₂ catalyst. Similaly, the composite catalsyt produced PPC with molecular weight of 4200 g/mol and narrow polydispersity index of 2.2. The resultant PPC copolymer displayed good thermal stability, exhibiting a high degradation temperatures (TGA_-10%) of 229 °C and complete decomposition at 350 °C.

Chemical composition of aerosols is of great concern in the Arctic because of its great influence on climate. In this communication, we report the physico-chemical properties of size-separated aerosol data archived at Gruvebadet lab in Ny-Ålesund (78.55°S, 11.55°E) as a part of the Indian Arctic Mission over the station "Himadri" in 2010. The results reveal that the mass-size distribution (MSD) of aerosol composition exhibits tri-modal distribution with coarse-mode (62%), fine-mode (32%) and weak nucleation-mode (6%) indicating dominance of natural sources over the study region. MSD of chemical components showed a significant contribution to coarse-mode particles for Ca²⁺, Mg²⁺, Na⁺ and Cl⁻; fine-mode particles for SO₄²⁻, NO₃⁻, NH₄⁺ and K⁺. The marine sources contributed maximum for SO₄²⁻ (89%) and Mg²⁺ (44%) in the coarse fraction, and in the fine fraction, 31% to SO₄²⁻ and 86% to Mg²⁺. Non-marine sources were major contributors (80 to 95%) in both mode fractions for Ca²⁺and K⁺. The estimated aerosol radiative forcing in the atmosphere of ∼3.21 W/m² could be attributed to the loading of black carbon aerosols (62%) over the site. The backward trajectories show air masses from Canada and Greenland travelling from 6000 m elevation, bringing the pollutants to Ny-Ålesund and lower altitudes; the oceanic region within Arctic circle contributes more.

The CO₂ and N₂ adsorption on small-pore zeolite |Na_12-xK_x|-A was hypothesized to be affected by the ion exchange sequence used for the zeolite preparation. Zeolites were prepared by ion exchange of a commercially available zeolite |Na₁₂|-A (4A) and a zeolite |K₁₂|-A (3A) composition prepared from zeolite 4A. The CO₂ and N₂ adsorption properties were studied experimentally, and the binary CO₂-over-N₂ selectivity was estimated from single-component adsorption data using the apparent Henry's law coefficients. It was observed that the level of CO₂ adsorption was reduced by increasing the K content for both series of zeolite NaKA. Zeolite |Na_12-xK_x|-A-from-4A had the highest CO₂ adsorption capacity (at 1 atm and 273 K) for a given K content. At low K content, zeolite |Na_12-xK_x|-A-from-3A had the highest CO₂-over-N₂ selectivity. At an intermediate K content, the zeolites prepared from 4A had the highest selectivity. These differences show that non-equilibrium processes during the ion exchange are important for the CO₂ and N₂ adsorption properties of the derived zeolites. As of now, we refrain from speculating whether they relate to the detailed positioning of K⁺ and Na⁺ cations in the local structure of the zeolite or to mass-transport-related concentration gradients of the cations in the structure. Irrespectively, it was observed that the ion-exchange sequence affects the CO₂ and N₂ adsorption properties of the zeolites, which could be of general importance when it comes to the tuning of the properties of cation-rich zeolites.