The world needs to increase renewable and alternative fuel sources such as Biomass, Bioethanol, and Biodiesel to compete with fossil fuels. Biodiesel is an important renewable fuel source since it can be used in regular diesel vehicles without requiring engine modifications. Conventional biodiesel production takes around 90 min of reaction time. A longer reaction time is not suitable for commercial production. Furthermore, traditional products such as oil react with biodiesel methoxide to produce a maximum of 90% biodiesel yield. As the catalyst is not involved with the reaction, pure methanol and methoxide (methanol with KOH catalyst) are separately added to the system to enhance the pre-reaction step. By changing the methanol to methoxide ratio, biodiesel is produced, and yield is calculated. The highest yield, which is 95%, is obtained with a 5:15% methanol to methoxide ratio. The total reaction time with the new experimental procedure is only 20 min. That is a significant reduction by saving operating costs such as energy consumption. Produced biodiesel show similar properties to that of standard biodiesel.

The objective of this work was to evaluate the adsorption capacity of alkylated modified porous biochar prepared by esterification and etherification (PSAC-2) for low concentrate volatile organic compounds (VOCs, toluene and ethyl acetate) in high humidity environment by experiments and theoretical calculations. Results showed that PSAC-2 has a large specific surface area and weak surface polarity, at 80% relative humidity, its capacities for toluene and ethyl acetate adsorption could be maintained at 92% and 87% of the initial capacities (169.9 mg/g and 96.77 mg/g). The adsorption behaviors of toluene, ethyl acetate, and water vapor were studied by adsorption isotherms, and isosteric heat was obtained. The desorption activation energy was obtained by temperature programmed desorption experiment. The outcomes manifested that the PSAC-2 can achieve strong adsorption performance for weakly polar molecules. Through density functional theory (DFT) simulations, owing to the interaction of hydrogen bonds, oxygen-containing groups became a significant factor influencing the adsorption of VOCs in humid environments. These results could provide an important reference for VOCs control in a high humidity environment.

This study lays great emphasis on establishing a reliable analytical platform to quantify and specify volatile fatty acids (VFAs) in the aqueous phase by derivatizing VFAs into their corresponding alkyl esters via thermally-induced rapid esterification (only 10 s reaction time). To this end, reaction conditions for the thermally-induced rapid esterification are optimized. A volumetric ratio of 0.5 at 400 °C for VFA/methanol is identified as the optimal reaction conditions to give ∼90% volatile fatty acid methyl ester (VFAME) yield. To maintain a high yield of VFAMEs, this study suggests that dilution of the sample to an optimum concentration (∼500 ppm for each VFA) is required. Derivatization of VFAs into VFAMEs via the thermally-induced rapid esterification is more reliable to quantify and specify VFAs in the aqueous phase than conventional colorimetric method.

Bisphenol S is an endocrine disruptor exhibiting metabolic disturbances, especially following perinatal exposures. To date, no data are available on the obesogen effects of BPS in a mutligenerational issue.We investigated obesogen effects of BPS in a multigenerational study by focusing on body weight, adipose tissue and plasma parameters in male and female mice.Pregnant C57BL6/J mice were exposed to BPS (1.5 μg/kg bw/day ie a human equivalent dose of 0.12 μg/kg bw/day) by drinking water from gestational day 0 to post natal day 21. All offsprings were fed with a high fat diet during 15 weeks. Body weight was monitored weekly and fat mass was measured before euthanasia. At euthanasia, blood glucose, insuline, triglyceride, cholesterol and no esterified fatty acid plasma levels were determined and gene expressions in visceral adipose tissue were assessed. F1 males and females were mated to obtain the F2 generation. Likewise, the F2 mice were cross-bred to obtain F3. The same analyses were performed.In F1 BPS induced an overweight in male mice associated to lipolysis gene expressions upregulation. In F1 females, dyslipidemia was observed. In F2, BPS exposure was associated to an increase in body weight, fat and VAT masses in males and females. Several plasma parameters were increased but with a sex related pattern (blood glucose, triglycerides and cholesterol in males and NEFA in females). We observed a down-regulation in mRNA expression of gene involved in lipogenesis and in lipolysis for females but only in the lipogenesis for males. In F3, a decrease in VAT mass and an upregulation of lipogenesis gene expression occurred only in females.BPS perinatal exposure induced sex-dependent obesogen multigenerational effects, the F2 generation being the most impacted. Transgenerational disturbances persisted only in females.

Although biochar (BC) has been widely used to adsorb pollutants in environment due to its natural and green characteristics, the structural defects of BC limit the ability to remove various environmental pollutants in aqueous solution. In this study, oxidized biochar (OBC) and sulfhydryl biochar (SBC) derived from pomelo peel (PP) were prepared through an oxidation and esterification reaction. BC and modified BC were used for the removal of methylene blue (MB), Cd²⁺, and phenanthrene (PHE) in aqueous solution. The adsorption behavior and efficiency toward different types of pollutants were studied by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), Raman, X-ray photoelectron spectroscopy (XPS), kinetics, and isotherm model fitting. The results showed that the change of pH had great effect on MB and Cd²⁺ adsorption, but not on PHE. SBC not only possessed the newly formed sp²-hybridized domains with easy access to aromatic pollutants but also had multiple functional groups (-COOH, -OH, -SH, -NH₂) that provided adsorption sites for positively charged pollutants. SBC was more flexible and efficient in purifying pollutants compared to BC and OBC, with the saturated adsorption capacities of MB (209.16 mg/g), Cd²⁺ (786.19 mg/g), and PHE (521.58 mg/g). Moreover, the adsorption kinetic and isotherms fitting showed that the adsorption mechanisms were closely related to the structure of biochar and the properties of pollutants, including π-π interaction, surface charge, electrostatic interaction, surface functional groups, and Van der Waals force. In addition, the analysis of structure-function relationship demonstrated the enhanced hydrophilicity and the easy exposure of the binding sites on OBC and SBC. Hence, it was significantly effective to regulate microstructure and interfacial properties to promote its adsorption behaviors of biochar.

Scale-up and commercialization of biodiesel is often delimited by costly feedstock that adds up to the process costs. These underlying issues demand the exploration of unconventional cheap feed to improve the process economics. Conversion of waste cooking oil (WCO) into biodiesel could reduce the process costs by 60–70%. However, the continuous exposure to heat during frying leads to oxidation as well increase in the free fatty acid (FFA) content which intensifies the time and energy required for transesterification. The present study analyzes the effect of parameters over the conversion of WCO (with 8.17% FFA) into biodiesel via two-step acid-alkali-based microwave-assisted transesterification. Response surface methodology (RSM) was used to optimize the oil:methanol volume ratio, microwave power, and reaction time during the acid-catalyzed esterification to bring down the FFA below 1%. Microwave irradiation of 250 W, with methanol:oil molar ratio of 19.57:1 [oil:methanol volume ratio of 1.31 (expressed as decimal)] and reaction time of 35 s, resulted in 0.082% of FFA. Alkali-catalyzed transesterification with methanol:oil molar ratio of 5:1 with 2% sodium hydroxide at 65 °C thereby produced fatty acid methyl esters (FAMEs) with the volumetric biodiesel yield of 94.6% in 30 min. Physiochemical properties of the transesterified WCO were well comparable with the biodiesel standards. The study highlights the essentiality of multivariate optimization for the esterification process that could aid in understanding the interactive effects of variables over FFA content. Such studies would benefit in scaling up of the transesterification process at industrial level by improving the economics of the overall bioprocess.

The presented study discusses biodiesel synthesis by utilizing two wastes: Mesua ferrea Linn (MFL) seed shells (inert support for developing catalysts) and used cooking oil (feedstock). The MFL shells were used for heterogeneous acid and base catalyst development through carbonization, steam activation and subsequent doping of H₂SO₄ or KOH, which upon instrumental examination showed effective doping of functional groups on the MFL char. The conversion approach uses methanol with sulfonated char (SC) for esterification, while the second stage utilizes 2-propanol for transesterification with KOH-doped char (KC) as a catalyst. Both stages optimize 5 controlling parameters such as mixing intensity, duration of reaction, catalyst load, alcohol concentration and reaction temperature in an L16 Taguchi experimental matrix. Thus, the obtained biodiesel has an ester content of 99.16%, while 97.35% of the free fatty acids (FFA) were converted, resulting in the product showing improved physico-chemical properties as assessed through fuel characterization tests. Reusability tests for the catalysts showed 4 reuses for acid catalyst compared to 9 reuses for base catalyst. Catalyst development costs were only $1.27/kg for activated char, while due to reuse, the prepared catalysts cost only $0.53/kg of biodiesel. Hence, the catalytic process holds great potential for commercialization if scaled up appropriately.

A novel bio-based polymeric adsorbent was fabricated and used for the removal of methylene blue (MB) from aqueous solutions. The method includes the synthesis of polymeric adsorbent from biocompatible chemicals such as poly(vinyl alcohol) (PVA) and 3,4,5-trihydroxybenzoic acid (gallic acid, GA) by using acid catalyzed esterification reaction. The obtained PVA/GA adsorbent was successfully characterized by the spectral, morphological, and thermal investigations using FTIR, SEM, DSC, and TGA. In the batch experiments, the adsorption performances of PVA/GA for MB were systematically investigated at various dye concentration, pH, contact time, and temperature conditions. The adsorption capacity of the PVA/GA reached a maximum value of 633.3 mg g⁻¹ at 25 °C. Possible reasons for high adsorption capacity of PVA/GA may be that the porosity and functional groups of PVA and GA afford sufficient active spots to advance the affinity of MB to the surface of adsorbent. The reusability efficiency of the adsorbent maintained above 96% after four adsorption–desorption cycles. In the data of adsorption process, it was most consistent with the Langmuir isotherm and pseudo-second-order kinetic models. Furthermore, it was confirmed that the adsorption is spontaneous and favorable from the thermodynamic point of view. The results demonstrated that the low-cost PVA/GA adsorbent system is simple to prepare and operate and exhibits promising properties as a reusable adsorbent for removal of hazardous dyes from aqueous solutions.

Biosorbents are the natural origin adsorbents, which popularity in environmental engineering is steadily increasing due to their low price, ease of acquisition, and lack of the toxic properties. Presented research aimed to analyze the possibility of chemical modification of the straw, which is a characteristic waste in the Polish agriculture, to improve its biosorption properties with respect to removal of selected metals from aquatic solutions. Biosorbents used during the tests was a barley straw that was shredded to a size in the range of 0.2–1.0 mm. The biosorption process was performed for aqueous solutions of zinc at a pH 5. Two different modifications of straw were analyzed: esterification with methanol and modification using the citric acid at elevated temperature. The results, obtained during the research, show a clear improvement in sorption capacity of the straw modified by the citric acid. In the case of straw modified with methanol, it has been shown that the effectiveness of zinc biosorption process was even a twice lower with respect to the unmodified straw. Moreover, it was concluded that the removal of analyzed metals was based mainly on the ion-exchange adsorption mechanism by releasing a calcium and magnesium ions from the straw surface to the solution. Graphical Abstract ᅟ

The present work encompasses the production of biodiesel from an inexpensive waste, viz., used rice bran oil (URBO) through concurrent esterification and transesterification reactions employing the prepared waste duck bone (WDB)-derived natural hydroxyapatite (NAHAp) supported vanadium impregnated solid catalyst (VNAHAp). The optimal VNAHAp catalyst possessed 92.23 m²/g surface area which was much superior to 61.46 m²/g of the V-catalyst (VCHAp) prepared using commercially available hydroxyapatite (CHAp). The optimal (Box–Behnken design) concurrent trans/esterification reaction conditions for biodiesel (FAME) production from URBO and methanol were 5 wt.% catalyst concentration, 8:1 methanol/URBO mole ratio, and 35 wt% NH₄VO₃ loaded VNAHAp (35VNAHAp) catalyst that resulted in 99.05% FAME yield deploying a low-energy infrared radiator assisted batch reactor (LIRABR) which ensured significantly high FAME yield at milder temperature (60°C) and in shorter reaction time (30 min) compared to a conventionally heated batch reactor. The product biodiesel and its blend with commercial diesel conformed to ASTM D7467-10 specifications. The life cycle assessment (LCA) of the entire process advocated superior sustainability of the biodiesel production using 35VNAHAp catalyst in the LIRABR compared to their conventional counterparts. Valorization of two potential wastes, viz., URBO and WDB, under milder process conditions involving LIRABR and 35VNAHAp resulted in lower environmental impacts, thus rendering a sustainable biodiesel production process towards a greener earth.