Cleaner Chemical Engineering最新文献

Biodiesel has proven to be better in terms of emission and engine performance when compared to diesel. The reason for this can be attributed to the fact that they are environmentally friendly and combust well in diesel engines. Implementing the use of Cashew Nut Shell Liquid (CNSL) for biodiesel production on a commercial scale has the potential to be profitable as the feedstock is a waste. The environmental concern associated with improper waste disposal and combustion of fossil fuel for energy production is a huge issue that is ravaging most developing regions of the world. Providing research-based solutions to these problems is expedient and meets major sustainable development goals. The waste-to-fuel technique has proven to be an effective tool that can be harnessed in ending these concerns. Hence, improving the efficiency of wastes used as feedstock to produce clean fuel is pivotal to building a sustainable environment. CNSL is inexpensive and using it as fuel can help mitigate the environmental effects of improper waste disposal in cashew processing factories. CNSL is obtained from cashew nuts through different methods, including mechanical extraction, thermal extraction and solvent extraction. This paper reviews the state of research on the utilization of cashew nut shell liquid biodiesel (CNSLBD) in diesel engines. Further research gaps that need to be addressed for this fuel to be more efficient were also mentioned. This work weighs the potential of this fuel as a good alternative energy source. Performance parameters such as brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC) were considered in this review. This article established that CNSLBD gives a BTE as low as 12.3% and as high as 25.7% depending on the experimental conditions involved. It gives high BSFC and low HC, CO and CO₂ emissions. It produces high NO_X emission, but this can be reduced with techniques like Exhaust Gas Recirculation and blending the fuel with other additives. The main problem with CNSLBD is its high density and viscosity. However, this can be fixed by blending the fuel with another low viscous fuel. The ideal mix ratio for CNSLBD blends is 80% diesel: 20% CNSL. This work also established that the yield of CNSLBD during transesterification can be increased through ultrasonication. Finally, CNSLBD can be said to be a promising alternative fuel that has the potential to benefit both cashew nut companies and the energy industry.

A deeper understanding of the kinetic and thermodynamic parameters of thermal degradation of sugarcane bagasse (SCB) is fundamental to defining appropriate conditions for primary biorefining in the production of renewable fuels. In this work, the kinetics of thermal degradation of high polymers of SCB was investigated through thermogravimetric data. Model-free and model-fitting methods were used to calculate apparent activation energies (E_a) and other related reaction parameters. An essential advance of this work is related to the quantitative interpretation of the degradation process (an endothermic and non-spontaneous process) via a multi-stage model governed by diffusion-controlled reactions and order-based models, which helps explain the differences observed in the mass balance of biorefining processes. Based on derivative thermogravimetric curves, three major peaks were associated with pseudo-components (PSE): PSE 1 (hemicelluloses + extractives and lignin), PSE 2 (cellulose + extractives and lignin), and PSE 3 (lignin + extractives and residual holocellulose). For PSE 1, PSE 2, and PSE 3, respectively, E_a ranges of 124–154, 147–153, and 230–530 kJ⋅mol⁻¹ were obtained using the Kissinger-Akahira-Sunose method, and 120–152, 144–150, and 232–545 kJ⋅mol⁻¹ were obtained using the Flynn-Wall-Ozawa method. These data support the calculation of many critical operating parameters of biorefinery processes, such as the minimum pretreatment temperature. SCB biorefining could lead to a degradation of up to 10, 0.5, and 11% of PSE 1, PSE 2, and PSE 3, respectively, at 473.15 K for 200 min.

The development of biopolymeric drug carriers is gaining interest due to their biocompatibility. Porous particles are the preferred drug-loading choice due to the high surface area. Lipids and collagen are widely explored biopolymers for various tissue engineering applications as drug carriers. In the present study, an attempt has been made to develop porous particles using collagen and lipid through a freeze-drying technique with cyclohexane and t-butyl alcohol as solvents. Porous particle formation has been confirmed using a Scanning Electron Microscope (SEM) in three different solvent ratios of cyclohexane and t-butyl alcohol viz., 1:2, 2:1, 1:1 respectively. The particle size of the lipid-collagen particles prepared from different solvent ratios was found to be 1032nm, 1612 nm, and 589 nm respectively. The mean pore diameter of prepared particles in the 1:2 and 2:1 solvent mixture was found to be 3.64 and 3.97 nm respectively. Similarly, the lipid -collagen interaction has been ascertained through Transmission Electron Micreoscope (TEM) image. The influence of lipid on collagen has been studied using a fibrillogenesis assay and found that a higher incubation period influences the self-assembling process of the collagen. However, it aids in particle formation. Furthermore, a model drug curcumin has been loaded in the prepared particles and assessed for loading efficiency and release. The drug release studies confirms that a sustained drug release pattern acts as a prominent drug carrier for therapeutic applications prepared through the simple freeze-drying technique.

In this work, carbon-sulphur co-doped ZrO₂ nanocomposites were synthesised using the aqueous leaves extract of Plumeria acuminate, zirconia salt precursor, polyvinylpyrrolidone and sodium hydrosulphide. The structural, elemental and morphological properties of the synthesized nanomaterials were examined by different analytical techniques UV-visible spectrophotometer, HRSEM-EDS, HRTEM-SAED, XRD and BET. HRSEM analysis of C-S-ZrO₂ revealed the presence of spherical and irregular hexagonal shapes. The XRD pattern demonstrated formation of crystalline tetragonal and a mixture of tetragonal and orthorhombic phases for ZrO₂ and C-S-ZrO₂ composite with an average size of 20.03 nm and 12.40 nm respectively. The band gap values of 5.2 eV and 3.4 eV were obtained for ZrO₂ and C-S-ZrO₂ respectively. The adsorptive and photocatalytic properties of ZrO₂ based nanomaterials for the removal of azo dye in local dyeing wastewater were investigated. The electrochemical activities of the nanomaterials were assessed using cyclic voltammetry, while Agar well diffusion, DPPH and ABTS methods were followed for the determination of antibacterial and antioxidant activities of ZrO₂ and C-S-ZrO₂. The maximum COD, BOD, TOC, SO₄^2-, CO₃^2, Cl⁻ and NO₃⁻removal efficiencies of 77.3%, 87.6%, 97.7% 63.9%, 84.4%, 70.3% and 83.3 % at 120 min were obtained using C-S-ZrO₂ composite due to its higher surface area (80.165 m²/g) and lower band gap (3.4 eV) compared with ZrO₂ (10.682 m²/g). Carbon-sulphur co-doped ZrO₂ composite exhibited moderate antioxidant activity and increased peak current than other ZrO₂ based nanomaterials due to its highest surface area than ZrO₂ alone. The order of antibacterial activity of the nanomaterials against the Salmonella typhi, Pseudomonas aeruginosa, Escherichia coli is ZrO₂-C-S (15.40±1.11 mm, 25.10±1.80 mm, 20.03±2.50 mm) > C-ZrO₂ (9.45±2.65 mm, 11.18±0.33 mm, 15.45±3.25 mm) > S-ZrO₂ (7.52±1.55 mm, 12.45±0.11 mm, nil) >ZrO₂ (6.33±0.90 mm, 4.25±0.52 mm, nil). The experimental data best described by pseudo-first-order, followed by parabolic-diffusion and modified Freundlich models. The results showed that the synthesized C-S-ZrO₂ nanocomposite is highly efficient with excellent regenerative potential even after five cycles.

Millet chaff constitutes one of the most abundant agro-residues in the sub-Saharan Africa and its utilisation as a feedstock in developing sustainable bioenergy solutions is very sketchy. This study presents the first comprehensive physicochemical and combustion characteristics of millet chaff via thermogravimetric analysis and process simulation using Aspen Plus. The millet chaff sample was collected and assessed as received for proximate and ultimate analyses. The results showed the biomass has 71.25 wt%, 15.35 wt%, 13.40 wt% and 13.15 MJ/kg for volatile matter, fixed-carbon, ash content and higher heating value respectively. The material consists of low nitrogen and sulphur content with potassium, aluminium, magnesium, calcium, iron and sodium as the inorganic components. Kinetic study using distributed activation energy model (DAEM) revealed an average frequency factor and activation energy of 1.41 × 10¹⁸(s⁻¹) and 149.39 kJ/mol. Ignition and burnout temperature in the range of 232-244°C and 430-489°C were recorded. The average combustion thermodynamic parameters; ΔH, ΔG and ΔS were found to be 144.75 kJ/mol, 167.12 kJ/mol and -40.08 J/mol. The combustion process analysis coupled with steam turbine cycle via process simulation revealed an excellent combustion efficiency at air-fuel ratio of 5.14. (stoichiometric air). The power generation and electric efficiency of 0.7kWh/kg and 21.07% respectively were recorded at 24% excess air with minimal environmental impacts. This suggests that millet chaff is a good biomass feedstock suitable for clean bioenergy production.

The present study develops an effective and sustainable catalytic system using mesoporous (KIT-6 and NbKIT-6) and microporous catalysts (ZIF-8) for the conversion of newspaper waste to value-added products such as TRS (Total reducing sugars) and 5-HMF (5-Hydroxymethyl furfural). The bio-based products were produced using green and biodegradable solvent Choline chloride in presence of sustainable catalysts under mild operating conditions at 1 atm pressure. The study demonstrated the potential of monophasic (Choline chloride and Catalyst) and biphasic (Choline chloride, Catalyst and Extracting solvent) system and revealed their comparative insights. It was observed that both the systems were highly effective but the purity and stability of products were higher in the biphasic system compared to the monophasic system. The synthesised catalysts possess high surface area 588.528, 534.414 and 351.85 m²/g with pore volume 0.7587, 0.3574 and 0.2362 cc/g for KIT-6, NbKIT-6 and ZIF respectively. The selected extracting solvents were found to be promising and the maximum 5-HMF yield was found to be 62.12%, 73.45% and 79.66% in DMSO medium using KIT-6 (160 °C, 135 min), NbKIT-6 (140 °C, 90 min) and ZIF-8 (140 °C, 105 min) catalysts respectively. Also, all the catalysts are reusable for up to five runs with minimal loss in catalyst activity. The proposed catalytic system will help to resolve the challenges associated with biorefineries in terms of product separation and recyclability of catalysts.

The strategy for synthesis of anthraquinone based dyes from anacardic acid were developed. Five anthraquinone derivative dyes (1-hydroxyanthraquinone, 7-bromo-1-hydroxyanthraquinone, 1,7-hydroxyanthrquinone, 1-aminoanthraquinone and indanthrone) were synthesised from anacardic acid isolated from Cashew Nut Shells Liquid (CNSL). The novelty of the strategy is that the dyes have been synthesised from commercially inexpensive and renewable starting materials. The synthesised dyes were characterised by spectroscopic techniques such as FT-IR, NMR, HRMS and UV-Vis spectroscopy. The two synthesised anthraquinone dyes (1-hydroxyanthraquinone and 7-bromo-1-hydroxyanthraquinone) were tested on 100% polyester fabric while the synthesised indanthrone dye was tested on 100% cotton fabric. Reflectance spectrophotometer analysis of the dyed fabrics indicated good colour strength and wash fastness properties. This demonstrates that CNSL is a potential precursor in the synthesis of anthraquinone dyes.

Air quality at two traffic junctions representing GLA indicating pollution at highway and Iradatnagar indicating rural pollution was evaluated in Uttar Pradesh, India. The present study aimed to determine the concentration of size-segregated PM with the characterization of metals at different traffic junctions i.e. (Agra and Mathura). In the study, PM_2.5–1.0 and PM_1.0–0.5 were measured with the help of Cascade Sioutas Impactor during the study period December to January 2018. The size fraction of PM_2.5–1.0 was found to be higher at GLA (350.92 µg/m³) followed by Iradatnagar (329.12 µg/m³), whereas the average value of size fraction of PM_1.0–0.5 was found higher at Iradatnagar (341.01 µg/m³) in comparison with GLA (313.47 µg/m³) respectively. The average PM_2.5 concentration in all the sampling sites was found to be 7–8 times higher when compared with the National Ambient Air Quality Standards (60 µg/m³) (NAAQS, India). Twelve metals viz. (Al, Ba, Ca, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb, and Zn) were subsequently determined by ICP-OES. Al, Ba, Ca, and Mg, were found in higher concentrations in comparison with other metals. Source apportionment of metals was done by PCA (Principal Component Analysis) which shows that metal loading of Al, Ca, Cr, Cu, Fe, and Ni was influenced by vehicular emission with 33.6% constitutes of the total variance. Higher bioavaiablity was observed for PM_2.5–1.0 (5.12–6.46%) and least was found for PM_1.0–0.5 (4.56–7.055%). For health risk estimation, the average value of HQs was found higher for PM_1.0–0.5 size fraction. HQ values were recorded higher for GLA (7.95) for PM_2.5–1.0 and (9.50) for PM_1.0–0.5 fraction. Overall, the observed HQs values far exceeded the acceptable level. Average value (1 × 10^–6) of carcinogenic risk factor was found higher for an adult and child respectively.

In this work, a novel metal-organic framework ZIF-8 is fabricated with poly-o-anisidine/zinc oxide (POA/ZnO) to obtain poly-o-anisidine/zinc-oxide nanohybrid material (PAZ@ZIF-8) via in-situ approach at room temperature. The characteristics of as-prepared nanocomposites were investigated by employing sophisticated techniques such as SEM, TEM, FTIR, XRD, and SEM-EDAX. The PAZ@ZIF-8 nanohybrid material exhibits a significant rational function for the adsorption of highly toxic organic pollutants. The as-synthesized nanohybrid materials are employed to remove Malachite Green (MG) dye from aqueous solutions. PAZ@ZIF-8 has displayed excellent removal efficiency towards the removal of MG dye, and almost 96% of the dye is removed within a very short period as compared to ZIF-8 (34%) and POA/ZnO (61%), respectively. The experiments were carried out at different pH values (3 - 9) and adsorbent amounts (1 - 1.5 mg/g). The Langmuir sorption model is a better fit for the removal of MG dye on PAZ@ZIF-8, and the maximum adsorption capacity of 613 mg/g is observed. The sorption kinetics of MG dye on PAZ@ZIF-8 is well followed by the pseudo-second-order model. PAZ@ZIF-8 has shown excellent recyclability for three consecutive cycles, and almost 90% of the dye is removed in the third cycle. This research will overlay the road to developing innovative nanohybrid 3D-MOF adsorbent systems for detoxification and wastewater treatment.

Polyamide 6 (PA6, polycaprolactam, Nylon 6) is a thermoplastic polymer widely used in construction, automotive, packaging, etc. It is a semi-crystalline polymer known for its good mechanical properties, and chemical, and thermal stability, with a low price, compared to the other polyamides. PA6 can be synthesized by anionic polymerization of ε-caprolactam, initiated by sodium hydride, and activated by N-acetylcaprolactam. This poorly biodegradable material has quickly proven to be a source of considerable pollution both visually and in terms of ecosystem preservation, particularly due to its increasing annual global production. This issue raises the need to develop environmentally friendly protocols for the degradation of this waste. One of the methods that can prove to be effective is the degradation by microorganisms. The objective of our research is to study the degradation of PA6 by the bacteria Lysinibacillus sp. (LB), Alcaligene faecalis (AF), and Enterococcus faecalis (EF) isolated from the landfill. The three bacteria, isolated and previously identified, were able to show proliferation in minimal media using PA6 as the sole source of carbon and nitrogen. The weight loss of the PA6 pellets was evaluated at 21% for L. bacillus, 27% for A. faecalis, and 13% for E. faecalis after 48 days of incubation. The biodegradation of PA6 was also confirmed by FTIR and SEM coupled to the elemental detector scanning EDS, which revealed the structural, morphological, and elemental changes that PA6 underwent.