Optimization of desorption parameters using response surface methodology for enhanced recovery of arsenic from spent reclaimable activated carbon: Eco-friendly and sorbent sustainability approach.

Desorption and adsorbent regeneration are imperative factors that are required to be taken into account when designing the adsorption system. From the environmental, economic, and practical points of view, regeneration is necessary for evaluating the efficiency and sustainability of synthesized adsorbents. However, no study has investigated the optimization of arsenic species desorption from spent adsorbents and their regeneration ability for reuse as well as safe disposal. This study aims to investigate the desorption ability of arsenic ions adsorbed on hybrid granular activated carbon and the optimization of the independent factors influencing the efficient recovery of arsenic species from the spent activated carbon using central composite design of the response surface methodology. The activated carbon before the sorption process and after the adsorption-desorption of arsenic ions have been characterized using SEM-EDX, FTIR, and TEM. The study found that all the investigated independent desorption variables greatly influence the retrievability of arsenic ions from the spent activated carbon. Using the desirability function for the optimization of the independent factors as a function of desorption efficiency, the optimum experimental conditions were solution pH of 2.00, eluent concentration of 0.10 M, and temperature of 26.63 ℃, which gave maximum arsenic ions recovery efficiency of 91 %. The validation of the quadratic model using laboratory confirmatory experiments gave an optimum arsenic ions desorption efficiency of 97 %. Therefore, the study reveals that the application of the central composite design of the response surface methodology led to the development of an accurate and valid quadratic model, which was utilized in the enhanced optimization of arsenic ions recovery from the spent reclaimable activated carbon. More so, the desorption isotherm and kinetic data of arsenic were well correlated with the Langmuir and the pseudo-second-order models, while the thermodynamics studies indicated that arsenic ions desorption process was feasible, endothermic, and spontaneous.

Investigation of bio-based rigid polyurethane foams synthesized with lignin and castor oil.

In this study, polyurethane (PU) foams were manufactured using kraft lignin and castor oil as bio-based polyols by replacing 5-20 wt% and 10-100 wt% of conventional polyol, respectively. To investigate the effects of unmodified bio-based polyols on PU foam production, reactivity and morphology within PU composites was analyzed as well as mechanical and thermal properties of the resulting foams. Bio-based PU foam production was carried out after characterizing the reagents used in the foaming process (including hydroxyl group content, molecular weight distribution, and viscosity). To compare the resulting bio-based PU foams, control foam were produced without any bio-based polyol under the same experimental conditions. For lignin-incorporated PU foams, two types, LPU and lpu, were manufactured with index ratio of 1.01 and 1.3, respectively. The compressive strength of LPU foams increased with lignin content from 5 wt% (LPU5: 147 kPa) to 20 wt% (LPU20: 207 kPa), although it remained lower than that of the control foam (PU0: 326 kPa). Similarly, the compressive strength of lpu foams was lower than that of the control foam (pu0: 441 kPa), with values of 164 kPa (lpu5), 163 kPa (lpu10), 167 kPa (lpu15), and 147 kPa (lpu20). At 10 wt% lignin content, both foams (LPU10 and lpu10) exhibited the smallest and most homogenous pore sizes and structures. For castor oil-incorporated PU foams with an index of 1.01, denoted as CPU, increasing castor oil content resulted in larger cell sizes and void fractions, transitioning to an open-cell structure and decreasing the compressive strength of the foams from 284 kPa (CPU10) to 23 kPa (CPU100). Fourier transform infrared (FT-IR) results indicated the formation of characteristic urethane linkages in PU foams and confirmed that bio-based polyols were less reactive with isocyanate compared to traditional polyol. Thermogravimetric analysis (TGA) showed that incorporating lignin and castor oil affected the thermal decomposition behavior. The thermal stability of lignin-incorporated PU foams improved as the lignin content increased with char yields increasing from 11.5 wt% (LPU5) to 15.8 wt% (LPU20) and from 12.4 wt% (lpu5) to 17.5 wt% (lpu20). Conversely, the addition of castor oil resulted in decreased thermal stability, with char yields decreasing from 10.6 wt% (CPU10) to 4.2 wt% (CPU100). This research provides a comprehensive understanding of PU foams incorporating unmodified biomass-derived polyols (lignin and castor oil), suggesting their potential for value-added utilization as bio-based products.

Adsorption and desorption processes of toxic heavy metals, regeneration and reusability of spent adsorbents: Economic and environmental sustainability approach.

A growing number of variables, including rising population, water scarcity, growth in the economy, and the existence of harmful heavy metals in the water supply, are contributing to the increased demand for wastewater treatment on a global scale. One of the innovative water treatment technologies is the adsorptive removal of heavy metals through the application of natural and engineered adsorbents. However, adsorption currently has setbacks that prevent its wider application for heavy metals sequestration from aquatic environments using various adsorbents, including difficulty in selecting suitable desorption eluent to recover adsorbed heavy metals and regeneration techniques to recycle the spent adsorbents for further use and safe disposal. Therefore, the recovery of adsorbed heavy metal ions and the ability to reuse the spent adsorbents is one of the economic and environmental sustainability approaches. This study presents a state-of-the-art critical review of different desorption agents that could be used to retrieve heavy metals and regenerate the spent adsorbents for further adsorption-desorption processes. Additionally, an attempt was made to discuss and summarize some of the independent factors influencing heavy metals desorption, recovery, and adsorbent regeneration. Furthermore, isotherm and kinetic modeling have been summarized to provide insights into the adsorption-desorption mechanisms of heavy metals. Finally, the review provided future perspectives to provide room for researchers and industry players who are interested in heavy metals desorption, recovery, and spent adsorbents recycling to reduce the high cost of adsorbents reproduction, minimize secondary waste generation, and thereby provide substantial economic and environmental benefits.

Bioactive and Hemocompatible PLA/Lignin Bio-Composites: Assessment of In Vitro Antioxidant Activity for Biomedical Applications.

In this study, acetylated soda lignin (ASL) and non-acetylated soda lignin (SL) were extruded with PLA in different concentrations to fabricate antioxidant polylactic acid (PLA)/lignin composites for potential biomedical applications. After lignin acetylation, good compatibility was observed between PLA and lignin in scanning electron microscopy images. All the PLA/ASL composites displayed higher mechanical properties than PLA/SL composites. PLA/ASL5 displayed the highest mechanical characteristics with elongation at break of 10% and tensile strength of 57 MPa, while PLA/SL15 and PLA/SL20 demonstrated superior UV-blocking potential with UV transmittance less than 10%. Addition of ASL in PLA lead to an increase in the hydrophobic character, with all the PLA/ASL displaying a higher water contact angle. The antioxidant test using 2,2-diphenyl-1-picrylhydrazyl assay showed that PLA/SL composites rendered superior radical scavenging activity (RSA), with PLA/SL20 composites displaying an RSA of 80%. Furthermore, in vitro antioxidant activity and cytocompatibility were analyzed using human colon cancer cells (HCT-15) and gastric epithelial cells (NCC-24). In vitro antioxidant activity, evaluated by H2O2 exposure was confirmed by a live/dead assay. PLA/SL composites protected both types of cells from oxidative stress. In addition, all PLA/SL and PLA/ASL composites promoted cell proliferation compared to PLA. PLA/SL5 and PLA/SL10 displayed the highest cell proliferation of all composites. Lastly, all PLA/SL and PLA/ASL composites had a hemoglobin release less than 2%. The antioxidant properties, cytocompatibility, and hemocompatibility of lignin/PLA demonstrated in our study indicate that these lignin/PLA composites possess the desirable attributes for potential biomedical applications.

Catalytic conversion of waste corrugated cardboard into lactic acid using lanthanide triflates.

The efficient strategy for waste conversion and resource recovery is of great interest in the sustainable bioeconomy context. This work reports on the catalytic upcycling of waste corrugated cardboard (WCC) into lactic acid using lanthanide triflates catalysts. WCC, a primary contributor to municipal solid wastes, has been viewed as a feedstock for producing a wide range of renewable products. Hydrothermal conversion of WCC was carried out in the presence of several lanthanide triflates. The reaction with erbium(III) triflate (Er(OTf)3) and ytterbium(III) triflate (Yb(OTf)3) resulted in high lactic acid yields, 65.5 and 64.3 mol%, respectively. In addition, various monomeric phenols were readily obtained as a co-product stream, opening up opportunities in waste management and resource recovery. Finally, technoeconomic analysis was conducted based on the experimental results, which suggests a significant economic benefit of chemocatalytic upcycling of WCC into lactic acid.

A study on activation mechanism in perspective of lignin structures and applicability of lignin-derived activated carbons for pollutant absorbent and supercapacitor electrode.

In this study activated carbons were produced from the biorefinery waste lignin (Asian lignin (AL) USA & Inbicon lignin (IL) Denmark) to evaluate their potential in waste water treatment and as energy storage devices. These products were studied for their surface characteristics as a function of reaction temperature, time, and catalyst loading accordingly. Under the conditions with a temperature lower than 750 °C and within a reaction time of 1 h, the catalytic reaction of alkali-carbon bonding occurred from the external surface, and a turbostratic disorder structure with a large aromatic ring system was formed. More severe reaction conditions accelerated the volatile release of de-alkylated aromatics such as benzene and naphthalene, along with structure and surface collapse. The maximum BET surface area of 2782 m2/g was obtained at 750 °C, 2 h and catalyst ratio of 4. Lignin-derived activated carbon was more efficient for the removal of organic pollutants (<50% adsorption capacity) rather than heavy metals (adsorption capacity >90%) due to interaction of π-π bonding. Furthermore, the activated carbon has a potential to be used as a supercapacitor electrode with high specific capacitance (214.0 F/g AL lignin) and an excellent cyclic stability (95% of their initial capacity). The results of this study demonstrate that lignin is an attractive precursor to produce activated carbons with diverse applications both as biosorbent and as a carbon electrode material even so with acceptable performance.

Transcriptional activation of rice CINNAMOYL-CoA REDUCTASE 10 by OsNAC5, contributes to drought tolerance by modulating lignin accumulation in roots.

Drought is a common abiotic stress for terrestrial plants and often affects crop development and yield. Recent studies have suggested that lignin plays a crucial role in plant drought tolerance; however, the underlying molecular mechanisms are still largely unknown. Here, we report that the rice (Oryza sativa) gene CINNAMOYL-CoA REDUCTASE 10 (OsCCR10) is directly activated by the OsNAC5 transcription factor, which mediates drought tolerance through regulating lignin accumulation. CCR is the first committed enzyme in the monolignol synthesis pathway, and the expression of 26 CCR genes was observed to be induced in rice roots under drought. Subcellular localisation assays revealed that OsCCR10 is a catalytically active enzyme that is localised in the cytoplasm. The OsCCR10 transcript levels were found to increase in response to abiotic stresses, such as drought, high salinity, and abscisic acid (ABA), and transcripts were detected in roots at all developmental stages. In vitro enzyme activity and in vivo lignin composition assay suggested that OsCCR10 is involved in H- and G-lignin biosynthesis. Transgenic rice plants overexpressing OsCCR10 showed improved drought tolerance at the vegetative stages of growth, as well as higher photosynthetic efficiency, lower water loss rates, and higher lignin content in roots compared to non-transgenic (NT) controls. In contrast, CRISPR/Cas9-mediated OsCCR10 knock-out mutants exhibited reduced lignin accumulation in roots and less drought tolerance. Notably, transgenic rice plants with root-preferential overexpression of OsCCR10 exhibited higher grain yield than NT controls plants under field drought conditions, indicating that lignin biosynthesis mediated by OsCCR10 contributes to drought tolerance.

Evaluation of pyrochar and hydrochar derived activated carbons for biosorbent and supercapacitor materials.

This study investigated effects of different thermal processes on characteristics of activated carbon to produce efficient biosorbents or supercapacitors using biomass resources. Pyrolysis char and hydrochar obtained from woody biomass were used as precursors for activated carbon under different atmospheric conditions (N2 and air). In order to provide functional groups on the carbon surface, activated carbon under N2 condition was subsequently acidified by HNO3 and the other was simultaneously acidified under air condition. Additionally, potential for application as Pb2+ adsorbent and supercapacitor was evaluated. Thermochemical behaviors such as bonding cleavage and dehydration during activation processes were observed by TG and Py-GCMS analysis. Elemental analysis, FT-IR, Raman spectroscopy, and XPS analysis were carried out to confirm changes in structures of each carbon products. New plausible reaction mechanism for this observation was suggested with respect to the formation of a key intermediate in the presence of excess air. As for performance in applications, air activated carbon using hydrochar exhibited high versatility to function as both Pb2+ adsorbent (~41.1 mg/g) and energy storage material (~185.9 F/g) with high specific surface area, mesopore ratio, surface functional groups.

Phenolic Hydroxyl Groups in the Lignin Polymer Affect the Formation of Lignin Nanoparticles.

Alkaline soda lignin (AL) was sequentially fractionated into six fractions of different molecular size by means of solvent extraction and their phenolic hydroxyl groups were chemoselectively methylated to determine their effect on nanoparticle formation of lignin polymers. The effect of the lignin structure on the physical properties of nanoparticles was also clarified in this study. Nanoparticles were obtained from neat alkaline soda lignin (ALNP), solvent-extracted fractions (FALNPs, i.d. 414-1214 nm), and methylated lignins (MALNPs, i.d. 516-721 nm) via the nanoprecipitation method. Specifically, the size properties of MALNPs showed a high negative correlation (R2 = 0.95) with the phenolic hydroxyl group amount. This indicates that the phenolic hydroxyl groups in lignin could be influenced on the nucleation or condensation during the nanoprecipitation process. Lignin nanoparticles exhibited high colloidal stability, and most of them also showed good in vitro cell viability. This study presents a possible way to control nanoparticle size by blocking specific functional groups and decreasing the interaction between hydroxyl groups of lignin.

Formation of pure nanoparticles with solvent-fractionated lignin polymers and evaluation of their biocompatibility.

This study aimed to determine the effects of lignin characteristics (mainly molecular weight, functional groups, and internal linkages) on nanoparticle formation. First, five different lignin fractions (Mw 1460-12,900) were obtained from commercial kraft lignin (KL) by sequential solvent extraction. Functional groups and internal linkages were determined in lignin fractions, each fraction consisting of different levels and ratios. Second, spherical lignin nanoparticles (i.d. 193-1039 nm) were synthesized by nanoprecipitation at different pre-dialysis concentrations (1, 2, 4, and 6 mg mL-1 THF) with the different fractions (F1, F2, F3, F4, and F5). The study revealed that larger particles consisted of lignin fractions of lower molecular weight and higher phenolic group content (KL-F1 and F2), while smaller but non-uniform particles were produced from fractions of higher molecular weight and lower phenolic group content (KLF4 and F5). Every zeta potential value of the particle exceeded -35 mV. The nanoparticles from raw kraft lignin exhibited no significant cytotoxicity, hemotoxicity, and hypersensitivity. This study revealed that molecular weight and hydroxyl group content in the lignin highly correlated with nanoparticle properties. The present kraft lignin nanoparticles have potential for use in various polymer-based nanotechnology.

Pretreatment of bio-oil with ion exchange resin to improve fuel quality and reduce char during hydrodeoxygenation upgrading with Pt/C.

To obtain high-quality biofuel, bio-oil obtained from fast pyrolysis of woody biomass was pretreated with ion exchange resin (amberlyst 36) at 50°C, 100°C, and 150°C, and then the recovered liquid product was upgraded using hydrodeoxygenation (HDO) with Pt/C at 300°C. After the two-stage upgrading, 4 types of products (gas, light oil, heavy oil, and char) were obtained. Two-immiscible liquid products were consisted of organic heavy oil, derived from bio-oil, and aqueous light oil, based on the ethanol. The mass balances of the HDO products were influenced by the pretreatment temperature. Ion exchange pretreatment of bio-oil was effective in reducing the char formation during the hydrodeoxygenation (HDO) process. The pretreatment also improved the following heavy oil properties: the water content, heating value, viscosity, acidity, and oxygen level. As a parameter used to indicate the biofuel acidity, the total acid number (TAN) value, was clearly reduced from 114.5 (bio-oil) to 34.1-78.2 (heavy oils). Furthermore, the water and oxygen contents of bio-oil (21.1 and 52.6 wt%, respectively) declined after the pretreatment followed by HDO (ranged 5.1-6.9 and 19.0-25.5 wt%, respectively), thereby improving its higher heating value (HHV) from 17.2 MJ/kg (bio-oil) to 26.2-28.1 MJ/kg (heavy oils). The degree of deoxygenation (DOD) increased as the pretreatment temperature decreased, and the highest energy efficiency (79.8%) was observed after pretreatment at 100°C. In terms of catalyst deactivation during the reaction, both carbon deposition and surface cracking intensified with increasing pretreatment temperatures.

Applicability of lignin polymers for automobile brake pads as binder and filler materials and their performance characteristics.

We present environmentally friendly brake pads produced with three different types of lignin, soda lignin (SL), sulphuric acid lignin (SAL) and heat-treated SAL (HL), as frictional materials to replace phenol formaldehyde resin (PFR, binder) and cashew nut shell liquid (CNSL, filler) in commercial automobile brake pad. Then the performance characteristics of the lignin-added brake pads were tested and compared using several fundamental tests. The results showed that lignin-added brake pads adhered to the SAE standard (0.25) for friction coefficient, which is the primary contributor to the performance of a braking system. In particular, the replacement of PFR with SL demonstrated a better friction coefficient than did replacement with SAL or HL, reaching up to 0.6. On the other hand, when lignin was substituted for CNSL as filler, HL-added brake pads showed a significant improvement in wear resistance of 0.12 g (dust generation) compared to SL and SAL, which had a resistance of approximately 0.25 g.

Utilization of lignin fractions in UV resistant lignin-PLA biocomposites via lignin-lactide grafting.

Lignin was fractionated with several organic solvents and fractions were utilized for UV resistant lignin-PLA composites. First, soda lignin (SL) was sequentially fractionated into six fractions: ethyl acetate (F1), 2-butanone (F2), methanol (F3), acetone (F4), dioxane/water (F5), and an insoluble fraction (INS). Molecular weight of the fractions increased from F1 to F5 and phenolic hydroxyl contents decreased with increasing molecular weight of fractions. Five lignin fractions (SL, F1, F3, F5, and INS) were grafted with l-lactide to produce lignin-grafted poly-l-lactide (PLLA) copolymers. Conversion ratio of l-lactide to PLLA chains increased from 88.3% for F5-PLLA copolymer to 91.2% for F1-PLLA copolymer as the content of hydroxyl groups in the fraction increased, while the molecular weight of the copolymers showed the reverse tendency. Each copolymer was mixed with PLA 2002D, and mechanical and optical properties of the composites were investigated. Composites of F1, F3, and F5 showed a tensile strength around 65 MPa, which is similar to that of neat PLA. The elastic modulus increased from 2197.7 for F1 to 2503.4 MPa for F5. According to the investigation of UV-VIS transmittance of the composite films, composites of F3 and F5 showed better UV blocking ability than the other composites, and this UV blocking ability increased with increasing concentration of lignin copolymer.

Comprehensive characterization of hydrothermal liquefaction products obtained from woody biomass under various alkali catalyst concentrations.

Hydrothermal liquefaction (HTL) of lignocellulosic biomass has been widely investigated for the production of renewable and alternative bio-crude oil. In this study, catalytic hydrothermal processing of two biomasses (larch and Mongolian oak) was performed using different K2CO3 concentrations (0, 0.1, 0.5, 1.0 wt% of solvent) to improve fuel yield and properties. HTL oil, hydrochar, water-soluble fraction (WSF) and gas were characterized, and carbon balance was investigated. As a result, the maximum yield of HTL oil, 27.7 wt% (Mongolian oak) and 25.7 wt% (larch), and the highest carbon conversion ratio was obtained with 0.5 wt% of catalyst. The high catalyst concentration also resulted in an increase in higher heating values up to 31.9 MJ/kg. In addition, the amount of organic compounds in HTL oil also increased, specifically for lignin-derived compounds including catechol and hydroquinone which can be derived from secondary hydrolysis of lignin. On the other hand, formation of hydrochar was suppressed with the addition of alkali catalyst and the yield dramatically decreased from 30.7-40.8 wt.% to 20.0-21.8 wt.%. Furthermore, it was revealed that WSF had low organic carbon content less than 3.4% and high potassium content mostly derived from alkali catalyst, indicating that it may be reusable with simple purification. This work suggests that the addition of the proper amount of alkali catalyst can improve the production efficiency and quality of bio-crude oil, and another potential of WSF to be recyclable in further work.

Lignin for white natural sunscreens.

Long-time exposure to the sun's ultraviolet (UV) radiation is harmful and causes various skin problems. Natural sun blockers have been drawing considerable attention recently. Even though lignin, an abundant aromatic polymer from plants, is a natural UV screening agent, its unfavorable dark color hinders its high value-added applications in sunscreens and cosmetics. In this study, we separate lignin under mild conditions (at room temperature with neutral solvents) in order to prevent darkening occurring during delignification and apply the resultant lignin as a natural sunscreen ingredient for the first time. Lignins isolated from Miscanthus sacchariflorus (MWL-M) and from Pinus densiflora (MWL-P) are compared with organosolv lignin (OL), which showed the best sunscreen performance, in color and UV protection. MWLs separated under mild conditions were light in color unlike conventional lignins extracted under harsh conditions. UV absorption of light-colored MWL-M was revealed to be as high as dark-colored OL. MWLs also showed synergistic effects with a commercial sunscreen; exposure of the MWL-added sunscreen to UVA radiation greatly enhanced the sun protection factor (SPF) value of the sunscreen.

Fractionation of lignin macromolecules by sequential organic solvents systems and their characterization for further valuable applications.

Lignin solvent fractionation is one of the promising methods for homogenizing and utilizing lignin commercially. In this work, fractionation characteristics of two lignin fractions were compared to investigate the potential of utilization of fractionated lignin. Two lignins [milled wood lignin(MWL) and organosolv lignin(OL) from yellow poplar] were sequentially fractionated with ethyl acetate(F1), 2-butanone(F2), methanol(F3), acetone(F4), and dioxane/water(F5). Yields of five MWL fractions F1 to F5 were 11.7%, 11.7%, 15.3%, 11.8%, and 49.6%, respectively, and yields of OL fractions were 26.2%, 26.1%, 18.7%, 3.7% and 25.4%. Average molecular weight of F1 (lowest molecular weight fraction) ranged from 1000 to 2400Da, whereas that of F5 (highest molecular weight fraction) was above 10000Da. According to functional group analysis, contents of phenolic hydroxyl groups and methoxyl groups decreased gradually with increasing molecular weight. DFRC analysis was performed to investigate the frequency of ß-O-4 linkages and it revealed that the higher molecular weight fractions yielded larger amounts of DFRC monomers, indicating that those fractions more frequently contain aryl ether linkages. TG/DTG showed that the low molecular weight fractions generally have lower initial thermal stability. Tg of the fractions ranged from 126°C to 156°C, increasing as the molecular weight of the lignin fraction increased.

Protein adsorption of dialdehyde cellulose-crosslinked chitosan with high amino group contents.

Crosslinked chitosan was prepared by Schiff base formation between the aldehyde groups of dialdehyde cellulose (DAC) and the amino groups of chitosan and a subsequent reduction. DAC was obtained through periodate oxidation of cellulose and solubilization in hot water at 100°C for 1h. Three grades of DAC-crosslinked chitosan were prepared by adding various amounts DAC. The degrees of crosslinking as determined by amino group content were 3.8, 8.3, and 12.1%, respectively. DAC-crosslinked chitosan showed higher stability in the pH 2-9 range and no cytotoxicity was identified over the course of a 21-day long-term stability test. Also, DAC-crosslinked chitosan showed remarkably high bovine serum albumin (BSA) adsorption capacity at pH 5.5 as a result of the increased amino group content, due to the reaction between DAC and chitosan molecular chains occurring at multiple points even though DAC-crosslinked chitosan showed a lower degree of crosslinking.

Levulinic acid production by two-step acid-catalyzed treatment of Quercus mongolica using dilute sulfuric acid.

The objectives of this research were to produce a levulinic acid by two-step acid-catalyzed treatment of Quercus mongolica and to investigate the effect of treatment parameter (reaction temperature range: 100-230°C; sulfuric acid (SA) concentration range: 0-2%) on the levulinic acid yield. After 1st step acid-catalyzed treatment, most of the hemicellulosic C5 sugars (15.6gg/100gbiomass) were released into the liquid hydrolysate at the reaction temperature of 150°C in 1% SA; the solid fraction, which contained 53.5% of the C6 sugars, was resistant to further loss of C6 sugars. Subsequently, 2nd step acid-catalyzed treatment of the solid fractions was performed under more severe conditions. Finally, 16.5g/100g biomass of levulinic acid was produced at the reaction temperature of 200°C in 2% SA, corresponding to a higher conversion rate than during single-step treatment.

Antibacterial Effects of Pyrolysis Oil Against Salmonella Typhimurium and Escherichia coli.

Many issues have been found to be related to food preservation and food contamination caused by various pathogenic bacteria in recent years. Many antibacterial agents act efficiently against Gram-positive foodborne bacteria; however, they are less effective against Gram-negative foodborne bacteria. In the present study, an attempt has been made to evaluate the antibacterial activity of pyrolysis oil manufactured from Pinus densiflora (PLO) against two Gram-negative foodborne pathogenic bacteria, Salmonella Typhimurium and Escherichia coli O157:H7. PLO possessed potent antibacterial activity against both foodborne pathogenic bacteria, as indicated by inhibition zones of 10.33-12.33 mm and minimum inhibitory concentration and minimum bactericidal concentration values of 250-500 µg/mL and 500-1000 µg/mL, respectively. PLO at the minimum inhibitory concentration exhibited an inhibitory effect on the viability of the bacterial pathogens with leakage of 260 nm absorbing materials, an increase in the relative electrical conductivity, and loss of salt tolerance capacity. PLO exhibited promising antibacterial activity against both of the Gram-negative foodborne pathogenic bacteria and thus it can be utilized in the food sector and pharmaceutical industries for the development of antibiotics and preservatives.

Bactericidal Mechanism of Bio-oil Obtained from Fast Pyrolysis of Pinus densiflora Against Two Foodborne Pathogens, Bacillus cereus and Listeria monocytogenes.

Foodborne bacteria are the leading cause of food spoilage and other related diseases. In the present study, the antibacterial activity of bio-oil (BO) manufactured by fast pyrolysis of pinewood sawdust (Pinus densiflora Siebold and Zucc.) against two disease-causing foodborne pathogens (Bacillus cereus and Listeria monocytogenes) was evaluated. BO at a concentration of 1000 µg/disc was highly active against both B. cereus (10.0-10.6 mm-inhibition zone) and L. monocytogenes (10.6-12.0-mm inhibition zone). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration values of BO were 500 and 1000 µg/mL, respectively, for both pathogens. At the MIC concentration, BO exhibited an inhibitory effect on the viability of the bacterial pathogens. The mechanism of action of BO revealed its strong impairing effect on the membrane integrity of bacterial cells, which was confirmed by a marked release of 260-nm absorbing material, leakage of electrolytes and K(+) ions, and reduced capacity for osmoregulation under high salt concentration. Scanning electron microscopy clearly showed morphological alteration of the cell membrane due to the effect of BO. Overall, the results of this study suggest that BO exerts effective antibacterial potential against foodborne pathogens and can therefore potentially be used in food processing and preservation.