Environmental assessment of four waste cooking oil valorization pathways

Characterizing three generation biodiesel feedstocks: A statistical approach and empirical modeling of fuel properties

Biodiesel fuels are classified into three generations according to their feedstock origin. Biodiesel cost and fuel properties substantially depend on the feedstock type. In this study, to characterize the biodiesel feedstocks of three generations, some critical fuel properties (kinematic viscosity, density, acid, iodine, calorific, peroxide, and saponification values) and also fatty acid compositions of 25 different biodiesel feedstocks (vegetable oils, waste animal fats, waste cooking oils and algae oil) were determined. After the characterization step, statistical studies (correlation-regression analyses) were performed and empirical formulas were developed to estimate the related fuel properties of biodiesel feedstocks from their fatty acid compositions. The investigated biodiesel feedstocks' fuel properties and fatty acid compositions were generally very different from each other, indicating their heterogeneous nature. Overall correlation coefficients obtained for all feedstocks were quite low. Similarly, the general empirical formulas developed for 25 feedstocks did not give very accurate results (except for the fuel properties of waste animal fats). Therefore, statistical analyses were repeated specifically for vegetable oils and algae oil (9 feedstocks). As a result, higher correlation coefficients were determined. Moreover, the fuel properties were estimated much more precisely with the new empirical formulas. The mean absolute relative error obtained using new models were 0.003% for saponification value, 0.027 % for iodine value, 0.074 % for kinematic viscosity, 0.142 % for peroxide value, 4.393 % for acid value, while density and calorific value were calculated without error. The findings could be useful in further academic investigations and also in biodiesel industry for feedstock characterization and waste management.

Multifunctional 3D-Printable Photocurable Elastomer with Self-Healing Capability Derived from Waste Cooking Oil

This study presents a sustainable approach to transform waste cooking oil (WCO) into a multifunctional 3D-printable photocurable elastomer with integrated self-healing capabilities. A linear monomer, WCO-based methacrylate fatty acid ethyl ester (WMFAEE), was synthesized via a sequential strategy of transesterification, epoxidation, and ring-opening esterification. By copolymerizing WMFAEE with hydroxypropyl acrylate (HPA), a novel photocurable elastomer was developed, which could be amenable to molding using an LCD light-curing 3D printer. The resulting WMFAEE-HPA elastomer exhibits exceptional mechanical flexibility (elongation at break: 645.09%) and autonomous room-temperature self-healing properties, achieving 57.82% recovery of elongation after 24 h at 25 °C. Furthermore, the material demonstrates weldability (19.97% retained elongation after 12 h at 80 °C) and physical reprocessability (7.75% elongation retention after initial reprocessing). Additional functionalities include pressure-sensitive adhesion (interfacial toughness: 70.06 J/m2 on glass), thermally triggered shape memory behavior (fixed at -25 °C with reversible deformation/recovery at ambient conditions), and notable biodegradability (13.25% mass loss after 45-day soil burial). Molecular simulations reveal that the unique structure of the WMFAEE monomer enables a dual mechanism of autonomous self-healing at room temperature without external stimuli: chain diffusion and entanglement-driven gap closure, followed by hydrogen bond-mediated network reorganization. Furthermore, the synergy between monomer chain diffusion/entanglement and dynamic hydrogen bond reorganization allows the WMFAEE-HPA system to achieve a balance of multifunctional integration. Moreover, the integration of these multifunctional attributes highlights the potential of this WCO-derived photocurable elastomer for various possible 3D printing applications, such as flexible electronics, adaptive robotics, environmentally benign adhesives, and so on. It also establishes a paradigm for converting low-cost biowastes into high-performance smart materials through precision molecular engineering.

Waste cooking oils as a sustainable feedstock for bio-based application: A systematic review

Waste cooking oils (WCOs) are common wastes and promising green, eco-friendly and sustainable feedstocks for bio-based applications. While the primary valorisation strategy revolves around the concept of waste-to energy, new research trends have emerged in the last decade. This systematic review provides a comprehensive analysis of the current state of the art in the conversion of WCOs into bio-based molecules. Based on the PRISMA methodology, 64 papers were selected using different databases and sources, such as: PubMed, ScienceDirect, Scopus and MDPI. The data extraction process focused on studies reporting the biological and chemical conversion of WCOs into value-added bioproducts. Many of the selected publications deal with the development of bioactive molecules, including biosurfactants, with application in pharmaceuticals, food, cosmetics, and bioremediation. Bioconversion processes mainly featured engineered Yarrowia lipolytica and Escherichia coli strains, even if additional microorganisms were also employed. In the same way, different chemical processes have been thoroughly studied. A smaller segment of research is directed to the production of feed supplements and soaps. Regulatory constraints limit further development in feed supplements due to potential contaminants, while soap production needs further stability studies. The present systematic review shows promising outcomes in the valorisation of WCOs through the development of value-added molecules and products. Despite the wide range of applications, these findings identify that the scalability and economic sustainability of the selected processes require further investigation. This study seeks to summarize the current state of the art and identify potential gaps to advance the industrialization of WCOs valorisation.

Energy and environmental analysis of a condensate recovery thermal energy storage for the building cooling system

In the pursuit of sustainability and reduced environmental impact, waste-to-energy conversion methods are gaining importance. This study investigates the untapped potential of air-conditioning (AC) condensate as a source of chilled energy in AC systems of varying cooling capacities expressed in tons of refrigeration (TR) including 10 TR, 25 TR, and 50 TR. Field assessments revealed daily condensate generation of 37-148 L at 15 ± 1 °C, indicating significant cooling potential for energy recovery. Waste coconut oil (WCO) is proposed as a phase change material (PCM) for this purpose, aiming to examine its thermal characteristics and effectiveness for energy storage. Characterization of WCO reveals a latent heat of 101 J/g and a phase transition temperature of 22.1 °C. Thermal degradation occurs between 346 and 462 °C, while stability is maintained below 60 °C. WCO exhibits solid thermal conductivity of 0.181 W/mK at 10 °C and liquid conductivity of 0.175 W/mK at 30 °C, with specific heat capacities of 1.19 J/g K (solid) and 2.43 J/g K (liquid), ensuring efficient heat transfer during phase change. A pilot experiment examines the charging and discharging dynamics of WCO. It achieves complete solidification in 160 min at a freezing temperature of 21.3 °C, with 1.1 °C supercooling. During melting at ambient conditions (32 ± 1 °C), it takes 92 min, with a melting temperature of 21.9 °C. The study extends to evaluate the reduction in environmental impact through life cycle assessment (LCA). The significant impact values such as acidification, eutrophication, ozone depletion, fossil depletion, climate change, and metal depletion are calculated using the ecoinvent database. Overall, our study underscores the promise of WCO-based energy recovery systems in advancing sustainability efforts within the realm of air conditioning.

A 4D-Printable Photocurable Resin Derived from Waste Cooking Oil with Enhanced Tensile Strength

In pursuit of enhancing the mechanical properties, especially the tensile strength, of 4D-printable consumables derived from waste cooking oil (WCO), we initiated the production of acrylate-modified WCO, which encompasses epoxy waste oil methacrylate (EWOMA) and epoxy waste oil acrylate (EWOA). Subsequently, a series of WCO-based 4D-printable photocurable resins were obtained by introducing a suitable diacrylate molecule as the second monomer, coupled with a composite photoinitiator system comprising Irgacure 819 and p-dimethylaminobenzaldehyde (DMAB). These materials were amenable to molding using an LCD light-curing 3D printer. Our findings underscored the pivotal role of triethylene glycol dimethacrylate (TEGDMA) among the array of diacrylate molecules in enhancing the mechanical properties of WCO-based 4D-printable resins. Notably, the 4D-printable material, composed of EWOA and TEGDMA in an equal mass ratio, exhibited nice mechanical strength comparable to that of mainstream petroleum-based 4D-printable materials, boasting a tensile strength of 9.17 MPa and an elongation at break of 15.39%. These figures significantly outperformed the mechanical characteristics of pure EWOA or TEGDMA resins. Furthermore, the EWOA-TEGDMA resin demonstrated impressive thermally induced shape memory performance, enabling deformation and recovery at room temperature and retaining its shape at -60 °C. This resin also demonstrated favorable biodegradability, with an 8.34% weight loss after 45 days of soil degradation. As a result, this 4D-printable photocurable resin derived from WCO holds immense potential for the creation of a wide spectrum of high-performance intelligent devices, brackets, mold, folding structures, and personalized products.

Waste Cooking Oil as Eco-Friendly Rejuvenator for Reclaimed Asphalt Pavement

Over 50 MioT of Waste Cooking Oil (WCO) was collected worldwide in 2020 from domestic and industrial activities, constituting a potential hazard for both water and land environments, and requiring appropriate disposal management strategies. In line with the principles of circular economy and eco-design, in this paper an innovative methodology for the valorisation of WCO as a rejuvenating agent for bitumen 50/70 coming from Reclaimed Asphalt Pavement (RAP) is reported. In particular, WCO or hydrolysed WCO (HWCO) was modified by transesterification or amidation reactions to achieve various WCO esters and amides. All samples were characterised by nuclear magnetic resonance, melting, and boiling point. Since rejuvenating agents for RAP Cold Mix Asphalt require a melting point ≤0 °C, only WCO esters could further be tested. Efficiency of WCO esters was assessed by means of the Asphaltenes Dispersant Test and the Heithaus Parameter. In particular, bitumen blends containing 25 wt% of WCO modified with 2-phenylethyl alcohol, showed high dispersing capacity in n-heptane even after a week, compared to bitumen alone (1 h). Additionally, the Heithaus Parameter of this bitumen blend was almost three times higher than bitumen alone, further demonstrating beneficial effects deriving from the use of WCO esters as rejuvenating agents.

Analyzing the performance of synthesized nano-catalysts for transesterification of waste cooking oil as environment friendly drilling fluid

Ester-based drilling fluids (EBDF) are preferred over oil-based drilling fluids (OBDF) and water-based drilling fluids (WBDF) because of their great biodegradability, low toxicity, and improved performance. In this work, waste cooking oil methyl ester (WCOME) was used to prepare an environmentally friendly EBDF. Through a transesterification process utilizing a modified calcium oxide based heterogenous catalyst, the waste cooking oil is transformed into waste cooking oil methyl ester. Response surface approach was used to strengthen the transesterification. The optimize conditions for CaO/Al2O3 resulted in the highest yield of 96.56% at a molar ratio of 11.9:1, 3.19 wt % of CaO/Al2O3, 53.79 °C, and 76.86 min. In contrast, CaO/TiO2 yielded 98.15% at a molar ratio of 11.99:1, with a CaO/TiO2 of 2.53 wt % at 59.79 in 68.14 min. Additionally, two separate densities of 9 ppg and 12 ppg EBDF are formulated with two distinct oil-to-water ratios (70:30 and 80:20) using synthesized WCOME. To assess the effectiveness of formulated EBDF thorough rheological investigation is conducted at 150°. Additionally, the filtration loss at HPHT conditions, emulsion stability, and Barite sag analysis of the drilling fluid are all analyzed at before ageing and after dynamic ageing. With better rheological features, less fluid loss, good emulsion stability, and minimal barite sagging, the designed EBDF performs efficiently. The drilling fluid met the API requirement and demonstrated stability even after ageing at 250 °F for 72 h, suggesting that it may be used for extended periods of time in drilling.

Critical review on waste cooking oil rejuvenation in asphalt mixture with high recycled asphalt

Waste cooking oil (WCO) as a rejuvenator is gaining attention in the pavement industry to incorporate higher reclaimed asphalt (RA) in asphalt mixture. This review article provides a comprehensive review on the current state and the feasibility of turning WCO and RA into cleaner and sustainable asphalt pavement material. Considering the advancements in research related to the utilization of WCO in RA mixture, it was necessary to critically review the past and recent studies to provide a methodological scope for future research. The review discusses a plethora of characteristics focusing on chemical, rheological, simulation, environmental, and economical findings related to the utilization of WCO in RA mixtures. Based on the review, WCO can be adjudged as a potential material to rejuvenate asphalt mixtures with higher recycled asphalt content. Furthermore, although WCO enhances low-to-intermediate temperature performance, studies indicated that moisture damage and higher temperature properties are compromised. Future research scope exists in understanding the rejuvenation capabilities of different WCOs and blends of different types of WCO, optimizing the transesterification process of WCO to improve its quality, molecular dynamic simulations focusing on transesterified WCO, quantification of environmental and economic benefits of recycled asphalt mixtures with WCO, and field performance studies.

Optimization of Bauhinia parviflora biodiesel production for higher yield and its compatibility assessment with water and Di-tert-butyl peroxide emulsion

The current study aims to attain a higher yield of biodiesel from Bauhinia tree seed wastes through process optimization using response surface methodology (RSM) and assess its compatibility in the diesel engine blended with water and Di-tert-butyl peroxide (DTBP). The Bauhinia parviflora biodiesel (BPB) transesterification originated using a fixed quantity of catalyst, and the transesterification process parameters such as oil-molar ratio (OMR), process temperature (PT), and reaction time (RT) were optimized. Fourier transform infrared spectroscopy (FTIR) and Gas chromatography-mass spectrometry (GC-MS)analysis were applied to characterize and quantify the BPB, and ASTM standards were followed to measure the properties. The prepared BPB (30%) was blended with 10% water and 2% BTBP to enhance the performance and emission characteristics of the BPB in the diesel engine. The optimization result implies that the higher yield of BPB (91.4%) was attained for OMR of 9.2:1, PT of 76 °C, and RT of 67 min. The FTIR report indicates that the carbon-based components are pretty good in the prepared BPB. The GC-MS report indicates that the fatty acids are converted into corresponding methyl esters, and the measured fuel properties are within the prescribed limits. The diesel engine's performance is effectively improved for the BPB blended with water and DTBP. The proposed fuel's overall improvement in hydrocarbon, carbon monoxide, smoke, and oxides of nitrogen emissions is 27.2%, 34.9%, 16.7%, and 11.2%, respectively.

The Synergistic Effect of Polyphosphates Acid and Different Compounds of Waste Cooking Oil on Conventional and Rheological Properties of Modified Bitumen

In order to conserve non-renewable natural resources, waste cooking oil (WCO) in bitumen can help lower CO₂ emissions and advance the environmental economy. In this study, three different components of WCO were isolated and then, together with polyphosphoric acid (PPA), used separately as bitumen modifiers to determine the suitability of various substances in WCO with PPA. Conventional tests, including penetration, softening point temperature, and ductility, and the dynamic shear rheology (DSR) test, including temperature sweep and frequency sweep, were used to evaluate the influence of WCO/PPA on the traditional performance and rheological properties at high and low temperatures. The results indicate that WCO reduced the ductility and penetration value, when the use of PPA increased the softening point temperature and high-temperature performance. Compared to reference bitumen, the rutting factor and viscous activation energy (Ea) of bitumen modified with 4% WCO and 2% PPA has the most significant increase by 18.6% and 31.5, respectively. All components of WCO have a significant impact on improving the low-temperature performance of PPA-modified bitumen. The performance of the composite-modified bitumen at low temperatures is negatively affected by some waxy compounds in WCO, such as methyl palmitate, which tends to undergo a solid-liquid phase change as the temperature decreases. In conclusion, the inclusion of WCO/PPA in bitumen offers a fresh approach to developing sustainable pavement materials.

The Feasibility of Producing Particleboards with Waste Wood from Civil Construction and Epoxidized Waste Cooking Oils

The feasibility of using epoxidized waste cooking oils as a partial replacement for synthetic resins in the manufacture of lignocellulosic composites where the reinforcement is comprised of mechanically ground wood from civil construction waste wood (CCWW) was investigated. For this study, the wood-epoxy composite was prepared using the thermo-curing technique, and wood particle contents of 20 and 30% (m/m) were studied with a matrix comprised of 50% epoxidized vegetable oil and 50% petroleum-based epoxy resin. The specific mass of the composites was in the range of 1130 to 1380 kg/m3, with the lowest value for the highest content of wood particles. Fourier transform infrared spectroscopy was successfully used to monitor the epoxidation of the vegetable oils and the subsequent curing of the epoxy resins and particleboards. Thermal stability of the composite was dictated by its lignocellulosic content, and significant mass losses occurred at temperatures higher than 300 °C, regardless of the wood particles content. The introduction of CCWW particles into the polymeric matrices did not promote the desired effect of improving the mechanical properties in regard to those of the cured blend of epoxy resins. However, the produced particleboards still met the standards of the American National Standards for general purpose boards in regard to their physical and mechanical properties (e.g., density, tensile strength). Hence, the use of wood waste and waste cooking oil to produce particleboards was deemed justified within the framework of a cascading lifecycle-extended service for both wastes.