A critical review of Pongamia pinnata multiple applications: From land remediation and carbon sequestration to socioeconomic benefits.

Pongamia pinnata (L.) Pierre (Pongamia) is a tree native to Southeast Asia. Recently, interest in Pongamia focused on its potential as a biofuel source as its seeds contain around 40% oil. However, Pongamia has multiple applications beyond biofuel production. It is a legume, can form symbiotic associations with mycorrhizal fungi, has been shown to be tolerant to drought, salinity, and heavy metals in soil, and has potential to mitigate climate change. Additionally, Pongamia oil has medicinal properties, can be used as biopesticide, insect repellent, to produce soap, and as a source of edible grade vegetable oil. The seed cake can be used as a source of bioenergy, food and feed protein, and organic fertiliser, and the flowers are a good source of pollen and nectar. Pongamia can also bring socio-economic benefits as its ability to restore degraded and contaminated land provides opportunities for local communities through novel valorisation pathways. These multiple applications have potential to form part of a circular bioeconomy in line with sustainable development goals. Although research on the multiple applications of Pongamia has grown considerably, knowledge gaps remain and these need to be addressed so that the full potential of Pongamia can be achieved. Further understanding of the mechanisms underlying its resilience to abiotic stresses, phytoremediation potential and biotic interactions should be a priority, and co-ordinated breeding efforts will be key. Here, we critically review the available literature on Pongamia and highlight gaps in knowledge in which future research should focus on to ensure that the full potential of this versatile tree can be achieved. We conclude that Pongamia can potentially form part of a circular bioeconomy and that harnessing the multiple applications of Pongamia in a holistic manner, with collaboration among key stakeholders, is crucial for the successful application of its benefits far beyond biofuel production.

Safety and toxicologic evaluation of Edible Pongamia Oil: A novel food ingredient.

Edible Pongamia Oil (EPO) was evaluated in an acute oral toxicity study, GLP 14-Day and 90-Day repeated dose isocaloric dietary toxicity studies in rats, and in vitro Bacterial Reverse Mutation, and in vivo Mammalian Bone Marrow Chromosome Aberration genotoxicity studies for potential use as a food ingredient. In a non-GLP acute study, an LD50 > 5000 mg/kg was determined. Subacute 14-day repeated dose dietary administration of 0, 5, 10 and 15% oil revealed no adverse changes in clinical pathology, liver histology, body weight or weight gain, food consumption or food efficiency. In a 90-day dietary study fed 0, 2.5, 5.0, 7.5 and 10.0%, no mortalities, clinical or ophthalmologic signs, body weight, body weight gain, food consumption, food efficiency or Functional Observational Battery/Motor Activity changes occurred with EPO consumption, nor were there any adverse changes in hematology, clinical chemistry, coagulation, urinalysis, or thyroid hormone values. There were no adverse macroscopic, estrus cycle, histopathologic or spermatogenesis findings, or absolute or relative organ weight changes related to administration of EPO. The No-Adverse-Effect-Level (NOAEL) was 10% in the diet, the highest dose tested, equivalent to 5163 (male) and 6469 (female) mg/kg/day in rats. No mutagenic or clastogenic genotoxic potential was reported.

Therapeutic Potential of Genus Pongamia and Derris: Phytochemical and Bioactivity.

Genus Pongamia and Derris belong to the Leguminosae family and are reported synonymously in literature. Although many compounds have been isolated from different plant parts but seed oil is known to produce non-edible medicinally important furanoflavonoids. The seed oil, commonly known as Karanj oil in Ayurvedic and Siddha traditional systems of medicine, is reported for the treatment of various skin infections and psoriasis. Several phytopharmacological investigations have proved the medicinal potential of furanoflavonoids in the skin and other disorders. Not only furanoflavonoids but several other important phenolic constituents such as chalcones, dibenzoylmethanes, aurones, isoflavones, flavanone dihydroflavonol, flavans, pterocarpans, rotenoids, coumarins, coumestans, stilbenoids and peltygynoids and their glycosides have been reported for different biological activities including antihyperglycemic, anti-inflammatory, anticancer, insecticidal, anti-alzheimer's, gastro protective, antifungal, antibacterial, etc. In the present review, the phytochemistry and pharmacological activities of the genera Pongamia and Derris have been summarized.

Viscosity prediction of Pongamia pinnata (Karanja) oil by molecular dynamics simulation using GAFF and OPLS force field.

The increasing concern on the harmful effects caused by mineral oil-based lubricants towards the environment has given impetus to the evolution of green-lubricants. Vegetable oils are highly biodegradable, renewable, and possesses good lubricating property. In the present study Pongamia pinnata, non-edible vegetable oil, also known as Karanja Oil (KO) was used as the base oil for a lubricant. The preliminary properties, such as fatty acid profile and viscosity, which has a vital role in governing the performance of lubricants were evaluated experimentally as per international standards. The shear viscosity of KO which constitutes 8 major fatty acids were predicted using non-equilibrium molecular dynamics (NEMD) and periodic perturbation (PP) method using Optimised Potentials for Liquid Simulations (OPLS) and Generalized Amber Force Field (GAFF). The shear viscosities were evaluated at temperatures ranging from 313K to 373 K and pressure P = 0.1 MPa. The experimental and simulation data of KO shear viscosity are in line with each other using OPLS. The kinematic viscosities were calculated using the shear viscosities and densities obtained from simulation. The variation between experimental and simulation data is less while using OPLS, while GAFF force fields resulted in higher deviations.

The Role of Transposable Elements in Pongamia Unigenes and Protein Diversity.

Pongamia pinnata (also called Millettia pinnata), a non-edible oil yielding tree, is well known for its multipurpose benefits and acts as a potential source for medicine and biodiesel preparation. Due to increase in demand for cultivation, understanding of genetic diversity is an important parameter for further breeding and cultivation programme. Transposable elements (TEs) are a major component of plant genome but still, their evolutionary significance in Pongamia remains unexplored. In view to understand the role of TEs in genome diversity, Pongamia unigenes were screened for the presence of TE cassettes. Our analysis showed the presence of all categories of TE cassettes in unigenes with major contribution of long terminal repeat-retrotransposons towards unigene diversity. Interestingly, the insertion of some TEs was also observed in both organellar genomes. The study of insertion of TEs in coding sequence is of great interest as they may be responsible for protein diversity thereby influencing the phenotype. The present investigation confirms the exaptation phenomenon in pyruvate decarboxylase (PDC) gene where the entire exon sequence was derived from Ty3-gypsy like retrotransposon. The study of PDC protein revealed the translation of gypsy element into protein. Furthermore, the phylogenetic study confirmed the diversity in PDC gene due to insertion of the gypsy element, where the PDC genes with and without gypsy insertion were clustered separately.

A non-edible waste as a potential sorptive media for removal of herbicide from the watershed.

A non-edible waste, from biodiesel processing industry is being turned to carbonaceous material (biochar) using slow pyrolysis. The material was found to be amorphous with hydroxyl, methyl, carbonyl and carboxyl functional groups onto the surface. The influencing parameters, namely adsorbate concentration (0.05-5 mg/l), biochar loading (0.02-0.4 g), pH(3-12) and particle sizes (0.03-0.13 mm) were studied to observe the effect on the sorption of simazine using biochar. A multivariate optimization using central composite design in response surface methodology was performed employing desirability function. The optimized biosorption efficiency (B%) and capacity qe was found to be 91.98 % and 0.83 mg/g respectively with the optimized parameters as 3.76 mg/l of adsorbate concentration, 0.12 g of biochar loading, pH of 5.26 and 0.0535 mm of particle size. The simazine adsorption phenomena were found to be multilayer heterogeneous sorption based on Langmuir and Freundlich models. The kinetics investigation shows that chemisorption was involved for the transfer of simazaine to the surface of biochar with three distinct intra particulate diffusional zones. An adsorption process requires activation energy of 11.27 kJ/mol and the negative magnitude of ΔH* indicates the exothermicity involved in the process.

Unravelling the MicroRNA-Mediated Gene Regulation in Developing Pongamia Seeds by High-Throughput Small RNA Profiling.

Pongamia (Millettia pinnata syn. Pongamia pinnata) is a multipurpose biofuel tree which can withstand a variety of abiotic stresses. Commercial applications of Pongamia trees may substantially benefit from improvements in their oil-seed productivity, which is governed by complex regulatory mechanisms underlying seed development. MicroRNAs (miRNAs) are important molecular regulators of plant development, while relatively little is known about their roles in seed development, especially for woody plants. In this study, we identified 236 conserved miRNAs within 49 families and 143 novel miRNAs via deep sequencing of Pongamia seeds sampled at three developmental phases. For these miRNAs, 1327 target genes were computationally predicted. Furthermore, 115 differentially expressed miRNAs (DEmiRs) between successive developmental phases were sorted out. The DEmiR-targeted genes were preferentially enriched in the functional categories associated with DNA damage repair and photosynthesis. The combined analyses of expression profiles for DEmiRs and functional annotations for their target genes revealed the involvements of both conserved and novel miRNA-target modules in Pongamia seed development. Quantitative Real-Time PCR validated the expression changes of 15 DEmiRs as well as the opposite expression changes of six targets. These results provide valuable miRNA candidates for further functional characterization and breeding practice in Pongamia and other oilseed plants.

Biochemical and toxicological investigation of karanjin, a bio-pesticide isolated from Pongamia seed oil.

Karanjin, a furanoflavonol from Pongamia pinnata L is used in agricultural practices for its pesticidal, insecticidal and acaricidal activities. It is commercially available as a bio-pesticide targeting a wide variety of pests. The present study was intended to evaluate the biochemical interactions of karanjin with bovine serum albumin (BSA) and study its toxicological effects on mammalian and bacterial cell lines. Karanjin bound to BSA at a single site with a dissociation constant of 19.7 µM. Evaluation of BSA-karanjin interactions at three different temperatures indicated the involvement of static mode of quenching. Binding experiments in the presence of warfarin and computational docking analysis indicated that karanjin bound closer to the warfarin binding site located in the Subdomain IIA of BSA. Using Förster resonance energy transfer analysis the distance between TRP 213 of BSA and karanjin was found to be 20 Å. Collective results from synchronous fluorescence spectra analysis, differential scanning calorimetry, and circular dichroism analysis indicated that binding of karanjin induced conformational changes in the secondary structure of BSA. Karanjin exhibited low toxicity against human cervical cancer cells and normal mouse fibroblast L929 cells and modestly inhibited the growth of B. subtilis and E. coli cells. The data presented in this study provides insights for understanding the binding interactions of karanjin with BSA and its possible toxicological effects on mammalian cell lines and bacteria.

Thermo-kinetics and product analysis of the catalytic pyrolysis of Pongamia residual cake.

Catalytic fast pyrolysis of Pongamia residual cake (PRC) and the kinetics of this were evaluated using thermogravimetry and pyrolysis-gas chromatography/mass spectrometry analyses. The influence of the heating rate on the devolatilization process was studied to obtain corresponding kinetic information. Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) model-free isoconversion methods were used to predict the kinetic parameters. The major thermal degradation of PRC occurred around 150-550 °C with an activation energy of 97.2-394.3 kJ/mol or 114.5-412.2 kJ/mol as determined by the KAS and FWO methods, respectively. Micro-scale pyrolysis trials were performed to determine the effects of the PRC particle size, reaction temperature and PRC: catalyst weight ratio on the pyrolytic product distribution and upgraded pyrolytic vapor properties for the 5 wt% Ni impregnated on activated carbon (AC), aluminium(III) oxide (Al2O3), kaolin and zeolite NaA supports. The results indicated that using a 1:5 PRC: Ni/AC catalyst weight ratio with medium-sized PRC particles (125-425 µm) was the most effective condition for the conversion of oxygenated (O)-compounds to hydrocarbons (HCs) through decarbonylation, decarboxylation and dehydration reactions, giving the highest decrease (99%) in O-compounds. Increased HC yields, to more than 58%, were also obtained with this catalyst. Similarly, using the other synthesized Ni catalysts resulted in a reduction in the O-compounds and production of favorable HC species, albeit to a lesser extent. Therefore, the catalytic pyrolysis process of this residue, especially with a Ni/AC catalyst, has the potential to be a viable option for producing upgraded pyrolysis oil, which may be applied as a quality alternative biofuel.

Combustion, performance, and emissions of a compression ignition engine using Pongamia biodiesel and bioethanol.

Concerns over the depletion of conventional fuels have increased interest in new renewable energy sources like alcohol- and vegetable-based oils. Major drawbacks of using esters of vegetable oils, known as biodiesel, include reduced engine performance and increased emissions of oxides of nitrogen. In the present study, the effects of ethanol on biodiesel and mineral diesel blends in a diesel engine are experimentally investigated. The ethanol is produced from cashew apple juice by fermentation. Experiments are conducted using B20 Pongamia biodiesel with ethanol in proportions of 5, 7.5, and 10% by volume at varying load conditions. The results indicate that a B20 biodiesel blend with 7.5% ethanol yields a higher brake thermal efficiency and lower brake-specific energy consumption than pure B20 (20% biodiesel + 80% diesel), as well as significantly reduced emissions such as oxides of nitrogen, carbon monoxide, hydrocarbons, and smoke.

Biosorptive removal of Zn(II) ions by Pongamia oil cake (Pongamia pinnata) in batch and fixed-bed column studies using response surface methodology and artificial neural network.

Design of experiment and artificial neural networks (ANN) have been effectively employed to predict the rate of uptake of Zn(II) ions onto defatted pongamia oil cake. Four independent variables such as, pH (2.0-7.0), initial concentration of Zn(II) ions (50-500 mg/L), temperature (30ºC-50 °C), and dosage of biosorbent (1.0-5.0 g/L) were used for the batch mode while the three independent variables viz. flowrate, initial concentration of Zn(II) ions and bed height were employed for the continuous mode. Second-order polynomial equations were then derived to predict the Zn(II) ion uptake rate. The optimum conditions for batch studies was found to be pH: 4.45, metal ion concentration: 462.48 mg/L, dosage: 2.88 g/L, temperature: 303 K and on the other hand the column studies flow rate: 5.59 mL/min, metal ion concentration: 499.3 mg/L and bed height: 14.82 cm. Under these optimal condition, the adsorption capacity was 80.66 mg/g and 66.29 mg/g for batch and column studies, respectively. The same data was fed to train a feed-forward multilayered perceptron, using MATLAB to develop the ANN based model. The predictive capabilities of the two methodologies were compared, by means of the absolute average deviation (AAD) (4.57%), model predictive error (MPE) (4.15%), root mean square error (RMSE) (3.19), standard error of prediction (SEP) (4.23) and correlation coefficient (R) (0.99) for ANN and for RSM AAD (16.27%), MPE (21,25%), RMSE (13.15%), SEP and R (0.96) by validation data. The findings suggested that compared to the prediction ability of RSM model, the properly trained ANN model has better prediction ability. In batch studies, equilibrium data was used to determine the isotherm constants and first and second order rate constants. In column, bed depth service time (BDST) and Thomas model was used to fit the obtained column data.

Functional characterization of Helicoverpa armigera trehalase and investigation of physiological effects caused due to its inhibition by Validamycin A formulation.

Trehalase catalyzes hydrolysis of trehalose and plays a crucial role in insect metabolism. In the present study, phylogenetic analysis and multiple sequence alignment suggested that H. armigera trehalase-1 (HaTre-1) is closely related to other soluble trehalases with conserved signature features and functional sites. We have expressed and purified recombinant HaTre-1 having Vmax ~0.16mM/min and KM ~1.34mM. Inhibition kinetics and Microscale thermophoresis illustrated competitive inhibition of HaTre-1 by Validamycin A having Ki ~3nM and KD ~542nM, respectively. Docking studies of HaTre-1 with Validamycin A indicated that it binds at the active site with multiple hydrogen bonds. Ingestion of Validamycin A resulted in impediment of H. armigera growth and developmental defects. Treated larvae showed concentration dependent decrease in fecundity. It also led to total inhibition of ex-vivo trehalase activity and down-regulation of gene expression of HaTre-1. Relatively high insect mortality was observed on tomato plants sprayed with combination of Validamycin A with Azadirachta indica (neem) and Pongamia pinnata (karanj) oil as compared to the individual treatments. This report has re-emphasized trehalase inhibition as a potential insecticidal strategy and also recommends Validamycin A as a prospective value-added ingredient to commercial bio-pesticide formulations.

Adsorption of Methylene blue and Rhodamine B by using biochar derived from Pongamia glabra seed cover.

Biochar obtained through the pyrolysis of Pongamia glabra seed cover (PGSC) at 550 °C with a heating rate of 40 °C/min was characterized and its ability to adsorb the dyes Methylene blue (MB) and Rhodamine B (RB) from aqueous solutions was investigated. The effect of pH, temperature and initial concentration of the dyes on adsorption behavior were investigated. The equilibrium sorption data were analyzed by using Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich (D-R) isotherms. Equilibrium data were well fitted for D-R isotherm in case of MB and Langmuir isotherm in case of RB dyes. The kinetics of dye adsorption on PGSC biochar was well described by applying pseudo-second-order rate equations. The surface of adsorbent before and after the removal of dyes was characterized by using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) analysis. The study suggested that PGSC biochar could be used as a highly efficient adsorbent for the removal of synthetic dyes.

Viscous Flow Behaviour of Karanja Oil Based Bio-lubricant Base Oil.

Karanja oil (KO) is widely used for synthesis of bio-fuel karanja oil methyl ester (KOME) due to its competitive price, good energy values and environmentally friendly combustion properties. Bio-lubricant is another value added product that can be synthesized from KO via chemical modification. In this work karanja oil trimethylolpropane ester (KOTMPE) bio-lubricant was synthesized and evaluated for its viscous flow behaviour. A comparison of viscous flow behaviours of natural KO and synthesized bio-fuel KOME and bio-lubricant KOTMPE was also made. The aim of this comparison was to validate the superiority of KOTMPE bio-lubricant over its precursors KO and KOME in terms of stable viscous flow at high temperature and high shear rate conditions usually encountered in engine operations and industrial processes. The free fatty acid (FFA) content of KO was 5.76%. KOME was synthesized from KO in a two-step, acid catalyzed esterification followed by base catalyzed transesterification, process at 65°C for 5 hours with oil-methanol ratio 1:6, catalysts H2SO4 and KOH (1 and 1.25% w/w KO, respectively). In the final step, KOTMPE was prepared from KOME via transesterification with trimethylolpropane (TMP) at 150°C for 3 hours with KOME-TMP ratio 4:1 and H2SO4 (2% w/w KOME) as catalyst. The viscosity versus temperature studies were made at 0-80°C temperatures in shear rate ranges of 10-1000 s-1 using a Discovery Hybrid Rheometer, model HR-3 (TA instruments, USA). The study found that viscosities of all three samples decreased with increase in temperature, though KOTMPE was able to maintain a good enough viscosity at elevated temperatures due to chemical modifications in its molecular structure. The viscosity index (VI) value for KOTMPE was 206.72. The study confirmed that the synthesized bio-lubricant KOTMPE can be used at high temperatures as a good lubricant, though some additives may be required to improve properties other than viscosity.

Effect of lower and higher alcohol fuel synergies in biofuel blends and exhaust treatment system on emissions from CI engine.

The present study deals with performance, emission and combustion studies in a single cylinder CI engine with lower and higher alcohol fuel synergies with biofuel blends and exhaust treatment system. Karanja oil methyl ester (KOME), widely available biofuel in India, and orange oil (ORG), a low carbon biofuel, were taken for this study, and equal volume blend was prepared for testing. Methanol (M) and n-pentanol (P) was taken as lower and higher alcohol and blended 20% by volume with KOME-ORG blend. Activated carbon-based exhaust treatment indigenous system was designed and tested with KOME-ORG + M20 and KOME-ORG + P20 blend. The tests were carried out at various load conditions at a constant speed of 1500 rpm. The study revealed that considering performance, emission and combustion studies, KOME-ORG + M20 + activated carbon are found optimum in reducing NO, smoke and CO2 emission. Compared to KOME, for KOME-ORG + M20 + activated carbon, NO emission is reduced from 10.25 to 7.85 g/kWh, the smoke emission is reduced from 49.4 to 28.9%, and CO2 emission is reduced from 1098.84 to 580.68 g/kWh. However, with exhaust treatment system, an increase in HC and CO emissions and reduced thermal efficiency is observed due to backpressure effects.

Detailed characterization of bio-oil from pyrolysis of non-edible seed-cakes by Fourier Transform Infrared Spectroscopy (FTIR) and gas chromatography mass spectrometry (GC-MS) techniques.

Bio-oil obtained from pyrolysis is highly complicated mixture with valued chemicals. In order to reduce the complexity for unambiguous characterization of components present in bio-oil, solvent extractions using different solvents with increasing polarity have been adopted. The fractions have been analyzed by Fourier transform infrared (FTIR) spectroscopy for identifying the functional groups and Gas chromatography-mass spectrometry (GC-MS), for detailed characterization of components present in various fractions, thereby providing in-depth information at molecular level of various components in bio-oil. This paper reveals the potential of the analytical techniques in identification and brings out the similarities as well as differences in the components present in the bio-oil obtained from two non-edible oil seed-cakes, viz., Jatropha and Karanjia.

Natural Predominance of Abscisic Acid in Pongammia pinnata ("Karanj") Honey Contributed to its Strong Antimutagenicity.

Various samples of raw (unprocessed) floral honey collected from different geographical locations of India were assayed for its antimutagenicity against ethyl methanesulfonate in E. coli MG1655 cells through rifampicin resistance assay. A monofloral honey ("Pongammia pinnata", local name "Karanj") displayed maximum antimutagenicity (78.0 ± 1.7; P ≤ 0.05). Solid phase extraction (using Amberlite XAD-2 resin) followed by HPLC resulted into different peaks displaying varying antimutagenicity. Peak at retention time (Rt) 27.9 min (henceforth called P28) displayed maximum antimutagenicity and was further characterized to be abscisic acid (ABA) using ESI-MS and NMR. Its antimutagenicity was reconfirmed through human lymphoblast cell line (TK6) mutation assay using thymidine kinase (tk+/-) cell line. Although ABA from this honey displayed strong antimutagenicity, it lacked any in vitro antioxidant capacity indicating noninvolvement of any radical scavenging in the observed antimutagenicity.

Salt management strategy defines the stem and leaf hydraulic characteristics of six mangrove tree species.

Mangroves in hypersaline coastal habitats are under constant high xylem tension and face great risk of hydraulic dysfunction. To investigate the relationships between functional traits and salt management, we measured 20 hydraulic and photosynthetic traits in four salt-adapted (SA) and two non-SA (NSA) mangrove tree species in south China. The SA species included two salt secretors (SSs), Avicennia marina (Forsskål) Vierhapper and Aegiceras corniculatum (L.) Blanco and two salt excluders (SEs), Bruguiera gymnorrhiza (L.) Savigny and Kandelia obovata (L.) Sheue et al. The two NSA species were Hibiscus tiliaceus (L.) and Pongamia pinnata (L.) Merr. Extremely high xylem cavitation resistance, indicated by water potential at 50% loss of xylem conductivity (Ψ50; -7.85 MPa), was found in SEs. Lower cavitation resistance was observed in SSs, and may result from incomplete salt removal that reduces the magnitude of xylem tension required to maintain water uptake from the soil. Surprisingly, the NSA species, P. pinnata, had very low Ψ50 (-5.44 MPa). Compared with NSAs, SAs had lower photosynthesis, vessel density, hydraulic conductivity and vessel diameter, but higher sapwood density. Eight traits were strongly associated with species' salt management strategies, with predawn water potential (ΨPD) and mean vessel diameter accounting for 95% flow (D95) having the most significant association; D95 separated SAs from NSAs and SEs had the lowest ΨPD. There was significant coupling between hydraulic traits and carbon assimilation traits. Instead of hydraulic safety being compromised by xylem efficiency, mangrove species with higher safety had higher efficiency and greater sapwood density (ρSapwood), but there was no relationship between ρSapwood and efficiency. Principal component analysis differentiated the species of the three salt management strategies by loading D, D95 and vessel density on the first axis and loading ΨPD, Ψ50 and water potential at 12% loss of xylem conductivity (Ψ12), ρSapwood and quantum yield on the second axis. Our results provide the first comparative characterization of hydraulic and photosynthetic traits among mangroves with different salt management strategies.

Intensification of esterification of non edible oil as sustainable feedstock using cavitational reactors.

Using sustainable feed stock such as non-edible oil for the biodiesel production can be one of the cost effective approaches considering the ever growing interest towards renewable energy and problems in existing approaches for production. However, due to the high free fatty acid content, non-edible oils require considerable preprocessing before the actual transesterification reaction for biodiesel production. The present work focuses on intensification of the esterification reaction used as preprocessing step based on acoustic and hydrodynamic cavitation also presenting the comparison with the conventional approach. Karanja oil with initial acid value as 14.15mg of KOH/g of oil has been used as a sustainable feedstock. Effect of operating parameters such as molar ratio, catalyst loading, temperature and type of catalyst (sulfuric acid and Amberlyst-15) on the acid value reduction has been investigated. The maximum reduction in the acid value (final acid value as 2.7mg of KOH/g of oil) was obtained using acoustic cavitation at optimum molar ratio of oil to methanol as 1:5 and 2% sulfuric acid loading at ambient temperature. In the case of hydrodynamic cavitation, acid value reduced upto 4.2mg of KOH under optimized conditions of first stage processing. In the second stage esterification using hydrodynamic cavitation and conventional approach, the final acid value was 3.6 and 3.8mg of KOH/g of oil respectively. Energy requirement analysis for ultrasound and conventional approaches clearly established the superiority of the ultrasound based approach. The present study clearly demonstrated that significant intensification benefits can be obtained in terms of the reduction in the molar ratio and operating temperature for the case of acoustic cavitation as compared to the conventional approach with somewhat lower effects for the hydrodynamic cavitation.

Green synthesis of silver nanoparticles using Pongamia pinnata seed: Characterization, antibacterial property, and spectroscopic investigation of interaction with human serum albumin.

In recent years, green synthesized nanoparticles from plant extract have drawn a great interest due to their prospective nanomedicinal application. This study investigates a proficient, safer, and sustainable way for the preparation of AgNPs using medicinal plant Pongamia pinnata (family: Leguminoseae, species: Pinnata) seeds extract without using any external reducing and stabilizing agent. Both ultraviolet-visible spectrum at λmax  = 439 nm and energy dispersive X-ray spectra proof the formation of AgNPs. An average diameter of the AgNPs was 16.4 nm as revealed from transmission electron microscope. Hydrodynamic size (d = ~19.6 nm) was determined by dynamic light scattering (DLS). Zeta potential of AgNPs was found to be -23.7 mV, which supports its dispersion and stability. Fourier transform infrared study revealed that the O â”€ H, C â• O, and C-O-C groups were responsible for the formation of AgNPs. The antibacterial activity of the synthesized AgNPs was checked against Escherichia coli ATCC 25922. AgNPs at its LD50 dose exhibited synergistic effect with ampicillin. Because protein-AgNPs association greatly affects its adsorption, distribution, and functionality and can also influence the functions of biomolecules. So in order to understand the adsorption and bioavailability, we investigated by fluorescence, ultraviolet-visible, and circular dichroism spectroscopic methods the interaction of synthesized AgNPs toward human serum albumin. The binding affinity and binding sites of human serum albumin toward AgNPs were measured by using the fluorescence quenching data. The circular dichroism spectroscopic results revealed that there was a negligible change of α-helical content in their native structure. Overall, these AgNPs show versatile biological activities and may be applied in the field of nanomedicine.