Transforming lignin into porous graphene via direct laser writing for solid-state supercapacitors

Cost-effective valorization of lignin into carbon-based electrode materials remains a challenge. Here we reported a facile and ultrafast laser writing technique to convert lignin into porous graphene as active electrode material for solid-state supercapacitors (SCs). During laser writing, alkaline lignin experienced graphitization. By controlling laser parameters such as power the porous structure and graphitization degree can be well modulated. Graphene obtained at 80% of laser power setting (LIG-80) had higher graphene quality and more porous structure than that obtained at the lower power levels (i.e., 50%, 70%). TEM images revealed that LIG-80 had few-layer graphene structure with fringe-like patterns. LIG-80 proved to be an active electrode material for SCs with a specific capacitance as high as 25.44 mF cm⁻² in a H₂SO₄/PVA gel electrolyte, which is comparable or even superior to SCs based on pristine LIG obtained from other carbon precursors. Taken together, our proposed technical route for lignin-based LIG and subsequent application in SCs would not only open a new avenue to lignin valorization, but also produce porous graphene from a renewable carbon precursor for energy storage applications.

Direct laser writing transforms alkaline lignin into porous graphene for solid-state supercapacitors with high electrochemical performance.     

Simulation of Depth of Wear of Eco-Friendly Concrete Using Machine Learning Based Computational Approaches

To avoid time-consuming, costly, and laborious experimental tests that require skilled personnel, an effort has been made to formulate the depth of wear of fly-ash concrete using a comparative study of machine learning techniques, namely random forest regression (RFR) and gene expression programming (GEP). A widespread database comprising 216 experimental records was constructed from available research. The database includes depth of wear as a response parameter and nine different explanatory variables, i.e., cement content, fly ash, water content, fine and coarse aggregate, plasticizer, air-entraining agent, age of concrete, and time of testing. The performance of the models was judged via statistical metrics. The GEP model gives better performance with R² and ρ equals 0.9667 and 0.0501 respectively and meet with the external validation criterion suggested in the previous literature. The k-fold cross-validation also verifies the accurateness of the model by evaluating R², RSE, MAE, and RMSE. The sensitivity analysis of GEP equation indicated that the time of testing is the influential parameter. The results of this research can help the designers, practitioners, and researchers to quickly estimate the depth of wear of fly-ash concrete thus shortening its ecological susceptibilities that push to sustainable and faster construction from the viewpoint of environmentally friendly waste management.     

Mechanical Property Improvement in Dissimilar Friction Stir Welded Al5083/Al6061 Joints: Effects of Post-Weld Heat Treatment and Abnormal Grain Growth

The 5083 and 6061(T6) aluminum (Al) alloys are widely used in transportation industries and the development of structural designs because of their high toughness and high corrosion resistance. Friction stir welding (FSW) was performed to produce the dissimilar welded joint of Al5083-Al 6061(T6) under different welding parameters. However, softening behavior occurred in the friction stir welded (FSWed) samples because of grain coarsening or the dissolution of precipitation-hardening phases in the welding zone. Consequently, this research intended to investigate the effect of the post-weld heat treatment (PWHT) method on the mechanical property improvement of the dissimilar FSWed Al5083-Al6061(T6) and governing abnormal grain growth (AGG) through different welding parameters. The results showed PWHT enhanced the mechanical properties of dissimilar joints of Al5083-Al6061(T6). AGG was obtained in the microstructure of PWHTed joints, but appropriate PWHT could recover the dissolved precipitation-hardening particle in the heat-affected zone of the as-welded joint. Further, the tensile strength of the dissimilar joint increased from 181 MPa in the as-welded joint to 270 MPa in the PWHTed joint, showing 93% welding efficacy.     

A review on non-edible oil as a potential feedstock for biodiesel: physicochemical properties and production technologies

There is increasing concern regarding alleviating world energy demand by determining an alternative to petroleum-derived fuels due to the rapid depletion of fossil fuels, rapid population growth, and urbanization. Biodiesel can be utilized as an alternative fuel to petroleum-derived diesel for the combustion engine. At present, edible crops are the primary source of biodiesel production. However, the excessive utilization of these edible crops for large-scale biodiesel production might cause food supply depletion and economic imbalance. Moreover, the utilization of edible oil as a biodiesel feedstock increases biodiesel production costs due to the high price of edible oils. A possible solution to overcome the existing limitations of biodiesel production is to utilize non-edible crops oil as a feedstock. The present study was conducted to determine the possibility and challenges of utilizing non-edible oil as a potential feedstock for biodiesel production. Several aspects related to non-edible oil as a biodiesel feedstock such as overview of biodiesel feedstocks, non-edible oil resources, non-edible oil extraction technology, its physicochemical and fatty acid properties, biodiesel production technologies, advantages and limitation of using non-edible oil as a feedstock for biodiesel production have been reviewed in various recent publications. The finding of the present study reveals that there is a huge opportunity to utilize non-edible oil as a feedstock for biodiesel production.

There is increasing concern regarding alleviating world energy demand by determining an alternative to petroleum-derived fuels due to the rapid depletion of fossil fuels, rapid population growth, and urbanization.     

Removal of toluene as a toxic VOC from methane gas using a non-thermal plasma dielectric barrier discharge reactor

Methane is the main component of biogas, which could be used as a renewable energy source for electricity, source of heat, and biofuel production after upgrading from biogas. It also contains toxic compounds which cause environmental and human health problems. Therefore, in this work, the removal of a toxic compound (toluene) from methane gas was studied using a dielectric barrier discharge (DBD) reactor. It was observed that the removal of the toxic compound could be achieved from methane carrier gas using a dielectric barrier discharge reactor, and it depends on plasma input power. The maximum removal of the toxic compound was 85.9% at 40 W and 2.86 s. The major gaseous products were H₂ and lower hydrocarbons (LHC) and the yield of these products also increases with input power. In the current study, the yield of gaseous products depends on the decomposition of toxic compounds and methane, because the decomposition of methane also produces H₂ and lower hydrocarbons. The percentage yield of H₂ increases from 0.43–4.74%. Similarly, the yield of LHC increases from 0.56–7.54% under the same reaction conditions. Hence, input power promoted the decomposition of the toxic compound and enhanced the yield of gaseous products.

The removal of toluene as a toxic volatile organic compound from methane gas, which is the major component of biogas, is carried out using a non-thermal plasma dielectric barrier discharge reactor.     

Chitosan hydrogel for topical delivery of ebastine loaded solid lipid nanoparticles for alleviation of allergic contact dermatitis

Ebastine, is an antihistamine drug that exerts its effect upon oral administration in humans for the treatment of allergic contact dermatitis (ACD), it also has some systemic side effects like gastric distress, headache, drowsiness, and epistaxis. Moreover, topical corticosteroids are used for treatment of ACD, which causes the human skin to lose its thickness and elasticity. Hence, ebastine-loaded solid lipid nanoparticles (E-SLNs) were prepared and their topical efficacy against allergic contact dermatitis was determined. Compritol 888 ATO and tween 80 were used to prepare E-SLNs by cold dilution of the hot micro-emulsion. E-SLNs were optimized statistically by employing a central composite design using Design-Expert® version 11.0. Optimized E-SLNs showed spherical surface morphology, zeta potential of −15.6 ± 2.4 mV, PDI of 0.256 ± 0.03, and particle sizes of 155.2 ± 1.5 nm and th eentrapment efficiency of ebastine was more than 78%. Nanoparticles were characterized using FT-IR, XRD, and TEM. An E-SLNs loaded hydrogel was prepared using chitosan as a gelling agent and glutaraldehyde as a crosslinker. In vitro drug release studies performed for 24 hours on the E-SLNs dispersion and E-SLNs loaded hydrogel showed a sustained release of maximum 82.9% and 73.7% respectively. In vivo studies were conducted on BALB/c mice to evaluate the topical efficacy of the E-SLNs loaded hydrogel for allergic contact dermatitis. ACD was induced on the ear using picryl chloride solution. After induction, ears were treated daily with the E-SLNs loaded hydrogel for 15 days. Swelling behavior, mast cell count, and histopathological studies of the ear confirmed that the hydrogel alleviated the symptoms of allergic contact dermatitis.

Ebastine exerts its effect upon oral administration in humans for the treatment of allergic contact dermatitis (ACD), but it has some systemic side effects. Hence, ebastine-SLNs loaded hydrogel was prepared to increase topical efficacy of ebastine.