Developing construction materials from biomass and biowaste as a substitute for conventional cement has been receiving immense global interest in recent times, due to issues like greenhouse gas (GHG) emissions (e.g. CO 2 ), rapid depletion of non-renewable resources, and extensive energy consumption during cement production. Supplementary cementitious materials (SCMs) like fly ash, slag, and natural pozzolans can substitute conventional cement partially and can contribute to reducing GHG emissions and the environmental footprint of cement production. This study aims to prepare bio-based pozzolans from East-Indian lemon grass ( Cymbopogon flexuosus ) and poultry litter and to investigate the mechanical properties of concrete through their utilization as SCMs. The optimization process involves central composite design (CCD)-based response surface methodology (RSM) for modelling and statistical analyses using experimental data from the study. Analysis of variance (ANOVA) revealed the model’s significance, with coefficient of determination ( R 2 ) of 0.9956. The individual and synergistic effects of the considered factors on compressive strength were analysed using three-dimensional response surface plot. Based on RSM analysis, concrete prepared by substituting 17.57% of ordinary Portland cement with SCM (which was cured for 25.82 days with a water–cement ratio of 0.54) yielded the optimum compressive, flexural and split tensile strengths of 33.94 ± 0.12, 8.78 ± 0.02 and 3.06 ± 0.02 N/mm 2 , respectively. Furthermore, the SCM-mixed concrete exhibited enhanced durability properties compared to traditional ones. The findings also demonstrate the robustness of RSM as a significant tool for optimization of concrete performance. Moreover, the characterization results of pyrolytic lemon grass bio-oil (LG-BO) confirm its bioenergy potential, thereby suggesting its diverse utilization in various applications.

The economic viability of algal biodiesel can be improved by enhancing the microalgal lipid accumulation and using agricultural waste as a cheap and sustainable source of catalysts. In the current study, the effect of various nitrogen concentrations on the growth and lipid of Chlorella homosphaera were investigated. Furthermore, two-step catalytic conversion was applied to convert the oil of C. homosphaera with high free fatty acids (FFA) to biodiesel using waste radish leaves as a source of a heterogeneous base catalyst. The result revealed that the maximum lipid productivity of 25.0 mg L−1 day−1 and lipid content of 30.83% were obtained under nitrogen-depleted and limited nitrogen conditions, respectively. The FFA was reduced from 18.79 to 0.76%, and the acid value was decreased from 37.4 to 1.52 mg KOH g−1 using a 15:1 methanol to oil molar ratio (MTOR), 1.5 wt.% H2SO4, at 60 °C for 150 min. Under the optimized conditions, i.e., MTOR of 10:1, 3 wt.% of catalyst ratio for 120 min at 60 °C, the highest oil conversion of 96.61% was obtained. The physicochemical properties of the produced biodiesel were in the range of the standard specification norms for biodiesel. Hence, the proposed two-step catalytic conversion using calcined radish leaves as a heterogeneous catalyst has thus exhibited good potential for biodiesel production using algal oil with high FFA.

This study investigated an integrated approach to the biowaste transformation and valorization of byproducts. Biochar obtained from the banana pseudostem was calcined to synthesize a heterogeneous catalyst and sustainably prepare a highly alkaline solution. The ash was utilized directly as a heterogeneous catalyst in biodiesel production from waste cooking oil. At the same time, an alkaline solution prepared from the ash was used for delignification and recovery of lignin from bamboo leaves by the hydrothermal reaction. Techniques like Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), Brunauer-Emmett-Teller (BET), Transmission electron microscopy (TEM), and Energy dispersive X-ray (EDX) were applied to characterized the catalyst. The alkaline solution was analyzed with Atomic absorption spectroscopy (AAS). The Response surface methodology (RSM) technique was considered for the optimization of different parameters in the transesterification and hydrothermal reaction. Under the optimized condition, waste cooking oil (WCO) to Fatty acid methyl ester (FAME) conversion was 97.56 ± 0.11%, and lignin recovery was 43.20 ± 0.45%. While at the best operating pyrolysis temperature, the liquid fraction yield from the banana pseudostem (500 °C) was 38.10 ± 0.31 wt%. This integrated study approach encourages the inexpensive, sustainable, and environment-friendly pathway for synthesizing catalysts and preparing a highly alkaline solution for the valorization of biowaste into biofuel and biochemicals.

Biodiesel production from cheap and available feedstocks using agriculture waste as catalysts is success strategy towards making biodiesel more commercially competitive. Hence, in the current study, a green heterogeneous catalyst (CSPL) derived from the waste sweet potato leaves was synthesized and employed for biodiesel production using Scenedesmus obliquus oil (OSO) and waste soybean cooking oil (WSCO). The CSPL was characterized by XRD, FTIR, FE-SEM, TEM, BET, EDX, and TGA. The CSPL showed high catalytic activity for converting the OSO and WSCO to biodiesel, attributable to the predominant potassium content in carbonates and oxides form. The maximum OSO and SWCO conversion of 99.50% and 98.0% were obtained using 7 wt% and 5 wt% catalyst loading and 15:1, 9:1 methanol to oil molar ratio for 90 and 120 min at 60 degrees C, respectively. The physicochemical characteristics of the produced biodiesel were in good agreement with the standard specifications norms of the fuel.

The green synthesis of nanoparticles (NPs) is the safest, ecofriendly, cost-effective, and non-hazardous approach of nanotechnology. In the current study, we described the green synthesis of silver nanoparticles (AgNPs) using Cuphea carthagenensis aqueous leaf extract as a reducing, capping, and stabilizing agent. The study aims at the synthesis, characterization, optimization, and determination of the antibacterial activity of Cc-AgNPs against clinically important human pathogens. Coating of cotton fabrics with Cc-AgNPs and their efficacy against skin infection causing organisms was also evaluated. Furthermore, antioxidant activity, growth assay and time kill assay of Cc-AgNPs were also performed in the study. The biosynthesized Cc-AgNPs were characterized by UV-visible spectrometry, energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). The spectroscopic and microscopic analysis demonstrated biosynthesis of face-centered cubic (fcc) crystalline spherical Cc-AgNPs with an average particle size of 10.65 +/- 0.1 nm. Optimized peak synthesis of Cc-AgNPs was reported at pH7, 55 degrees C, 4 mM silver nitrate, and 5:45 (plant extract: silver nitrate). Cc-AgNPs exhibited potent antioxidant effect and antibacterial activity against both Gram-positive and Gram-negative bacteria. The lowest MIC (15 mu g/ml) and MBC (25 mu g/ml) values were reported against S. typhimurium. The Cc-AgNPs coated fabrics demonstrated potent antibacterial activity against tested strains. This application could be helpful in wound healing management. Furthermore, the hemolytic analysis demonstrated that Cc-AgNPs exhibit non-toxic nature against Red Blood Cells (RBCs) at the tested concentrations. In conclusion, the investigation demonstrated a fast, stable, and eco- friendly approach to the biosynthesis of Cc-AgNPs along with their antibacterial and antioxidant properties.

In this study, a novel heterogeneous catalyst from the unexploited radish leaves (Raphanus sativus L.) was synthesized and employed for biodiesel production using waste soybean cooking oil (SWCO) and Scenedesmus obliquus oil (OSO). The synthesized catalyst (CLP) was characterized by FTIR, BET, XRD, TGA, SEM, TEM, EDX, BET, and XPS. Moreover, the Hammett indicator test and CO2-TPD were used to assess the derived catalyst's basicity. The results reported the presence of Ca, S, Si, Cl, Al, P, Mg, Mn, Na, and a high percentage of potassium (57.30 wt%) in the form of carbonates and oxides. The maximum SWCO and OSO conversion of 98.0% and 91.32% were obtained using 6 wt% and 5 wt% catalyst loading and 12:1, 16:1 methanol to oil molar ratio for 150 and 90 min at 60 degrees C, respectively. The CLP exhibits excellent recyclability, achieving 90.57% oil conversion after four successive cycles. The fuel properties of the produced biodiesel were compatible with international standards. The synthesized catalyst is highly efficient, cheap, renewable, green, and can help reduce biodiesel production costs. Thus, the CLP catalyst might be a promising candidate for large-scale biodiesel production with a competitive price. (c) 2022 Elsevier Ltd. All rights reserved.

The sustainable processing approach has been followed to transform the potato peel as the potential source for bio-oil and green heterogeneous catalysts. The byproduct (biochar) obtained from the thermochemical conversion was reused as a green, renewable and sustainable source for heterogeneous catalysts. The alkali and alkaline-rich biochar was recovered and transformed into bio-based mixed metal oxide and carbonates through calcination. The catalyst was characterized with the Energy Dispersive X-Ray Analysis, Fourier Transform Infrared, Brunauer-Emmett-Teller, X-Ray Diffraction, Field Emission Scanning Electron Microscope, and Transmission Electron Microscopy. The best operating temperature for pyrolysis was found to be 500 degrees C, which produced the highest bio-oil (23.60%) and relatively high bio-char (29.50%). The synthesized catalyst showed high catalytic activity due to high potassium content (36.54%) in oxide and carbonate form. The maximum oil conversion (97.50%) was obtained using the optimized parameters: temperature 60 degrees C; 9:1 methanol to oil ratio; time 2 h, and catalyst loading 3 wt%. The integrated catalyst synthesizing method helped to valorize the food waste to high value-added products like biochar and bio-oil, which have the property of fuel and platform chemicals. Moreover, as the catalyst is derived from biomass, it is more environmentally benign, sustainable, and recyclable.

This study emphasizes the vision of a green, renewable and sustainable integrated route for the catalyst synthesis process and to transform fruit and kitchen wastes into fuel. The alkali and alkaline earth metal rich biochar, a by-product obtained from banana peel thermochemical conversion (pyrolysis), was calcined and utilized as a catalyst for converting soybean waste cooking oil (SWCO) to biodiesel. The catalyst was characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FESEM), Brunauer-Emmett-Teller (BET), Fourier Transform Infrared Spectroscopy (FTIR), Energy-dispersive X-ray spectroscopy (EDX), and Thermogravimetric analysis (TGA). The synthesized catalyst showed a high catalytic activity due to the abundance of potassium in oxide and carbonate form. Under the optimized condition: Catalyst loading of 1.5 wt%, time of 2 h, the temperature of 60 ?, and at 9:1 methanol to oil ratio, the conversion of SWCO to biodiesel was 98.0% with BPBC (Banana peel pyrolyzed calcined biochar catalyst). The integrated catalyst synthesizing method helped to transform the fruit waste to biochar and bio-oil, which have the property of fuel and platform chemicals. Additionally, as the catalyst was synthesized from biomass, it is more eco-friendly, recyclable, and sustainable.(C) 2022 Elsevier Ltd. All rights reserved.

Open-field burning of rice straw contributes significantly to deterioration of air quality. Similarly, defatted algal residue is a surplus by-product of the algal biofuel industry. This study emphasizes on the two-step conversion of agro-industrial residues (rice straw and Scenedesmus obliquus deoiled biomass) into biodiesel and carotenoids using oleaginous red yeast Rhodotorula mucilaginosa R2. The effect of biological pretreatment on degradation of lignocellulosic substrates followed by catalytic saccharification was evaluated using suitable analytical techniques. Mixed biomass favoured the growth and secretion of extracellular cellulose degrading enzymes by Penicillium citrinum PKB20 resulting in the highest specific activity of endoglucanase (83.02 IU/mg), xylanase (103 IU/mg) and β-glucosidase (13.8 IU/mg) under solid-state fermentation. The hydrolysis of pre-treated substrate was achieved with a saccharification yield of 41.41 %. Batch fermentation of detoxified hydrolysate amended with synthetic yeast propagation or lipid production media (YEPD or C/N 75) resulted in maximum lipid content and lipid yield of 30.43 % and 1.19 g/L respectively. GC analysis revealed that oleic acid (29.4-50.39 %) was the predominant fatty acid. The crude carotenoid extract was composed of torularhodin, torulene and β-carotene and exhibited strong antioxidant activity.

Microbial lipids derived from oleaginous fungi are considered as an alternative feedstock for biodiesel production. We attempt to isolate a cellulolytic oleaginous fungi as a potential feedstock for biodiesel production. The fungus was identified by 5.8 S-ITS rRNA gene sequencing. The extracellular enzyme activities were recorded after every 24 h for 7 days. Nile red staining and fluorescence microscopy was used to visualise the lipid bodies within the fungal hyphae. A renewable heterogeneous base catalyst derived from Musa balbisiana cola peels was used for the transesterification of Penicillium citrinum PKB20 derived oil into biodiesel. GC-MS analysis was used to analyse the fatty acid methyl esters (FAME) profile of the transesterified lipids. Penicillium citrinum PKB20 was isolated from detritus rich soil of Assam, India. The endoglucanase, xylanase and β-glucosidase enzyme activities were found to be 292.83 ± 0.29, 111.72 ± 0.45 and 6.54 ± 0.13 U/mg respectively. The specific enzyme activity for extracellular lipase was found to be 3.12 ± 0.16 U/mg. It could accumulate up to 60.61% of lipids in nitrogen-limited medium (7.34 ± 0.45 g/L biomass production). The extracted lipids were converted to biodiesel with 89.3% conversion efficiency. The predominant fatty acids were oleic acid (30.09%), palmitic acid (20.25%) and linoleic acid (33.14%) suggesting a balance between oxidative stability and cold flow properties for suitable biodiesel quality. Penicillium citrinum PKB20 was found to be a potential feedstock for biodiesel production with desirable fuel properties. The cellulolytic nature could be utilised for simultaneous lipid production directly on cellulosic substrates.

Development of solid mixed oxide catalyst from waste biomass is a scarcely studied area. Thus, present protocol aims to prepare an environmentally friendly, efficient, renewable and recyclable heterogeneous base catalyst from Carica papaya stem. The chemical and structural properties of the catalyst were examined by Fourier-transform infrared spectroscopy (FTIR), X-ray diffractograms (XRD), Scanning electron microscopy (SEM), Energy Dispersive X-ray spectrometry (EDX), Transmission Electron Microscopy (TEM) and Brunauer-Emmett-Teller (BET) analysis. The CO2-TPD and Hammett indicator test was conducted to determine the basicity of the prepared catalyst. The study revealed the presence of alkali and alkaline earth metals that provide the basic sites to facilitate transesterification reaction for biodiesel production and formation of benzylidenemalononitrile (BMN). The conversion of the waste cooking oil (WO) and Scenedesmus obliquus (SO) lipid to biodiesel was confirmed by the NMR and Gas chromatography Mass Spectroscopy (GC-MS) technique. Biodiesel conversions of 95.23% and 93.33% were achieved using 2 wt % catalyst loading under optimized reaction conditions for WO and SO respectively. Reusing the catalyst showed a slight drop in activity after 6 repeated uses. The reported catalyst has shown its potential as an alternative and cheaper green solid catalyst for biodiesel production and Knoevenagel reaction. (C) 2019 Elsevier Ltd. All rights reserved.