key: cord-1005143-0a43h6xd authors: Orjuela, Alvaro; Clark, James title: Green Chemicals from Used Cooking Oils: Trends, Challenges and Opportunities date: 2020-06-07 journal: Curr Opin Green Sustain Chem DOI: 10.1016/j.cogsc.2020.100369 sha: 4548549e5ca9fed572913435f9a11b458a029e5c doc_id: 1005143 cord_uid: 0a43h6xd Food waste reduction is fundamental for sustainable development and pursuing this goal, recycling and the valorization of used cooking oil (UCO) can play a major contribution. Although it has been traditionally used for biofuels production, the oleochemical potential of UCOs is vast. UCOs can be used as feedstock for a large variety of value added green chemicals including plasticizers, binders, epoxides, surfactants, lubricants, polymers, biomaterials, and different building blocks. Thus, UCOs transformation into functional chemicals can bring long-term stability to the supply chain, avoiding the current dependence on commodity products. In this regard, this work describes some of the potential benefits of using UCOs as feedstock in oleochemical biorefineries. Also, some of the most recent investigations on the valorization of UCOs other than biofuel are presented. Finally, major challenges and future directions are discussed. Reduction of food loss and waste is paramount to fulfil the UN's Sustainable Development Goals, and 27 crucial to curtail their associated economic, social and environmental life cycle impacts. Current 28 estimations indicate that average per capita food waste generation in Europe ranges between 173 -290 29 kg/person· yr [1] . Equally alarming numbers (in kg/person·yr) are observed in Australia (361), USA (278), 30 Canada (123), India (51), China (44), and other countries [2] . Reported data also reveals that nearly 60% 31 of food waste is generated as consumption and post-consumption residues (e.g. bones, cooking oils, peels, 32 leftovers, etc.), and a large fraction is unavoidable or inedible [1] . In order to mitigate the impacts, 33 The main raw materials of the oleochemical industry are vegetable oils and animal fats, with the former 68 having a 99.9% share in volume, and the remaining small fraction corresponding to butter, fish oils, and 69 fats from animal rendering [16] . Figure 1 presents the historical production of vegetable oils and the 70 corresponding distribution regarding final use. As observed, 68% of current world production is used for 71 food applications (i.e. cooking oils, food ingredients), and 23% in biofuels, mainly biodiesel 72 (~1.1kg Oil /1kg Biodiesel ). The remaining fraction (~9%) is destined for feed and other oleochemical uses 73 including drop-in applications (e.g. additive for polymers, resins, asphalt, lubricants, greases, drying oils, 74 rubber products, etc.) and as feedstock for different chemical derivatives. Taking into account the 75 estimated global UCO generation (41 Mt, [9] ), this amount can replace the virgin vegetable oil currently 76 required as feedstock for the oleochemical industry, a part of which is used as a biodiesel feedstock. The valorization of UCOs via transformation into suitable oleochemical products have captured the 143 attention from academic and industrial researchers during the last two decades. Figure 3 presents the 144 evolution of the scientific production (i.e. papers and patents) dealing with the exploitation of UCOs. 145 While the studies on biodiesel are still predominant, there is an increasing trend to explore novel 146 applications, mainly focused on value-added products. In addition to the availability of financial 147 resources, most research have been conducted in countries where UCOs mismanagement can be a major 148 problem, either because of their large population (e.g. China, India), or for the large per capita generation 149 Year Papers Papers -Non Biodiesel Patents processes [32, 33] . While this is not intended to be a comprehensive review of the available literature, 174 Table 1 presents a summary of the most recent attempts for UCOs harnessing, including the production of 175 plasticizers, binders, epoxides, surfactants, lubricants, polymers, biomaterials, building blocks etc. [74] Valeric acid Anaerobic fermentation with open microbiome. High valerate extraction rates with medium and maximum values of 12.9 and 30.0 g COD /m3 day, were obtained with low ethanol addition (15% of the glycerol-COD) [75] 1,3 Propanediol 1,3-PDO production with a mixed culture, A maximum productivity of 7.49 g/Ld [76] Lipids Lipid production via fermentation with Trichosporon oleaginosus. The highest lipid yield 0.19 g/g glycerol was obtained at 50 g/L purified glycerol in which the biomass concentration and lipid content were 10.75 g/L and 47% w/w, respectively. [77] Citric acid, Succinic acid A Suitable Substrate for the Growth of Candida zeylanoides Yeast Strain ATCC 20367. Biosynthesis of organic acids (e.g., citric 0.66 g/L; and succinic, 0.6 g/L) was significantly lower compared to pure glycerol and glucose used as main carbon sources. [78] 178 As observed, UCOs can be used as raw material for a large variety of green chemicals. In addition to the 182 technical limitations observed in some of the processes, there are a number of issues that need to be 183 overcome in order to enable industrial implementation. As in any other biorefinery, the supply chain plays 184 a major role in the sustainability of the proposed production schemes. In this case, a major fraction of the 185 generated UCOs comes from the Household segment, for which very low recovery efficiencies are typical 186 (< 6%, [11]). Hence, it is necessary to deploy effective policies and regulated practices to enhance UCOs 187 recycling and collection rates, under multi-stakeholders considerations (i.e. authorities, generators, 188 collecting companies, biorefineries). This also indicates that there is need to optimize the collection 189 schemes to ensure that the consumed resources (e.g. energy, financial) do not surpass those from the 190 obtained UCOs, mainly when the biorefineries operate as centralized facilities far from the source. For 191 instance, one study has shown that from a life cycle perspective, biodiesel from European rapeseed UCOs 192 is less sustainable than petroleum diesel and even less than biodiesel from Indonesian's palm oil UCOs 193 Table 198 1 there were reports of impurities in the raw material affecting the catalytic and biologically conversion 199 steps, the drop-in uses, and even the thermochemical transformations. Also, unpleasant sensory properties 200 (e.g. color, appearance, odour) are of major concern. Therefore, suitable upgrading processes must be 201 implemented to enable the efficient transformation of UCOs to the desired biobased chemicals without 202 compromising the economic feasibility [81] . Also, resilient and intensified technologies must be 203 developed to enable the use of other types of waste lipids (e.g. trap grease, rancid oils, food/solid waste 204 lipids, etc.). In any case, even after pretreatment and upgrading, the presence of trace impurities also 205 might prevent that some of the derivatives could be used in sensitive applications (e.g. personal care 206 products, cosmetics, food or pharmaceuticals) where the market is more attractive. Alternatively, they 207 could be directed to other markets such as construction materials, asphalt, rubbers, lubricants, surfactants, 208 fuels, etc. Value-added processing of crude glycerol into chemicals and 396 polymers A Review Value-added processing of crude glycerol into chemicals and polymers via biological or 399 chemical conversion, including UCOs-based glycerol Chemical and biological 402 conversion of crude glycerol derived from waste cooking oil to biodiesel A study of crude glycerol composition and bio-valorization as carbon source for lipids production Structural modification of 408 waste cooking oil methyl esters as cleaner plasticizer to substitute toxic dioctyl phthalate Sustainable synthesis of epoxidized 412 waste cooking oil and its application as a plasticizer for polyvinyl chloride films An efficient bio-based 416 plasticizer for poly (vinyl chloride) from waste cooking oil and citric acid: Synthesis and evaluation in 417 PVC films Investigation of 420 epoxidation of used cooking oils with homogeneous and heterogeneous catalysts A strategy for nonmigrating plasticized PVC 424 modified with mannich base of waste cooking oil methyl ester Coupling effects of wasted cooking oil and antioxidant on aging of 428 asphalt binders Crack resistance of waste cooking oil modified 431 cement stabilized macadam Development of a novel binder rejuvenator composed by waste 434 cooking oil and crumb tire rubber Research on the pyrolysis process of crumb tire rubber in waste cooking oil 441 Performance of Waste Cooking Oil on Aged Asphalt Mixture Investigation of carbonyl of asphalt binders containing 445 antiaging agents and waste cooking oil using FTIR spectroscopy This work try to elucidate the physicochemical action of UCOs in asphalt binders Voids Characteristic of Hot Mix Asphalt Containing Waste Cooking Oil 452 Evaluation of Waste Cooking Oil as 455 Sustainable Binder for Building Blocks Preparation of Epoxidized Fatty Acid Methyl Ester with in situ Auto-459 Catalyzed Generation of Performic Acid and the Influence of Impurities on Epoxidation. Waste Biomass 460 Valor Effect of 463 homogeneous catalysts on ring opening reactions of epoxidized cooking oils Open-cell 467 rigid polyurethane bio-foams based on modified used cooking oil Open cell 471 polyurethane foams based on modified used cooking oil Hydroxylation and hexanoylation of epoxidized waste cooking oil 475 and epoxidized waste cooking oil methyl esters: Process optimization and physico-chemical 476 characterization In situ epoxidation of waste soybean 479 cooking oil for synthesis of biolubricant basestock: A process parameter optimization and comparison 480 with RSM, ANN, and GA Optimized procedure for the preparation of an enzymatic 483 nanocatalyst to produce a bio-lubricant from waste cooking oil One-step nanohybrid synthesis in waste cooking oil, for direct 487 lower environmental impact and stable lubricant formulation Utilization of waste cooking oil as raw material for 491 synthesis of Methyl Ester Sulfonates (MES) surfactant Cationic gemini-surfactants 495 based on waste cooking oil as new 'green' inhibitors for N80-steel corrosion in sulphuric acid: A 496 combined empirical and theoretical approaches Synthesis of eco-friendly liquid detergent from waste 500 cooking oil and ZnO nanoparticles Solvent-free rapid ethenolysis of fatty esters from spent hen 503 and other lipidic feedstock with high turnover numbers Synthesis of waste cooking oil-based polyurethane 507 for solid polymer electrolyte Linking Food Industry to "Green Plastics" -Polyhydroxyalkanoate (PHA) Biopolyesters 510 from Agro-industrial By-Products for Securing Food Safety The Use of Palm Oil-Based Waste Cooking 514 Oil to Enhance the Production of Polyhydroxybutyrate Conversion of waste cooking oil into 518 medium chain polyhydroxyalkanoates in a high cell density fermentation A cost efficient way to obtain lipid accumulation in the 522 oleaginous yeast Rhodotorula glutinis using supplemental waste cooking oils (WCO) Waste Cooking Oils as Feedstock 526 for Lipase and Lipid-Rich Biomass Production Engineering the 530 oleaginous yeast Yarrowia lipolytica to produce limonene from waste cooking oil Influence of volume variety of waste cooking palm oil as carbon 535 source on graphene growth through double thermal chemical vapor deposition Direct Conversion of McDonald's Waste Cooking Oil into a Biodegradable High-540 Resolution 3D-Printing Resin Water decolorization using waste cooking oil: An optimized 544 green emulsion liquid membrane by RSM Application of gaseous 548 pyrolysis products of the waste cooking oil as coal flotation collector Ordered micro-mesoporous carbon from palm oil cooking waste via nanocasting in 553 HZSM-5/SBA-15 composite: Preparation and adsorption studies Maintinguer 557 S. I. Bioconversion of crude glycerol from waste cooking oils into hydrogen by sub-tropical mixed and 558 pure cultures Bioconversion of waste cooking oil glycerol from 561 cabbage extract to lactic acid by Rhizopus microsporus The effect of crude glycerol impurities on 1,3-propanediol 565 biosynthesis by Klebsiella pneumoniae DSMZ 2026 Bioconversion of Raw Glycerol From Waste 569 Cooking-Oil-Based Biodiesel Production to 1,3-Propanediol and Lactate by a Microbial Consortium Anaerobic production of valeric acid from 574 crude glycerol via chain elongation Production of 1,3-propanediol from 578 pure and crude glycerol using a UASB reactor with attached biomass in silicone support Chemical and biological 582 conversion of crude glycerol derived from waste cooking oil to biodiesel Glycerol Obtained from Renewable Biomass-A Suitable Substrate for the Growth of Candida 587 zeylanoides Yeast Strain ATCC 20367. Microorganisms Stochastic modeling of the transient regime of an electronic nose for waste cooking oil 592 classification 595 Improving the recycling technology of waste cooking oils: Chemical fingerprint as tool for non-biodiesel 596 application. Waste Manage The production of biodiesel from waste frying oils: A comparison of different 599 purification steps Industry source: one third of used cooking oil in Europe is fraudulent. 602 EURACTIV Implications of Imported Used Cooking Oil (UCO) as a Biodiesel Feedstock. NNFCC, 606 2019 Netherlands mulls end to used cooking oil double-counting COVID-19: A hard blow for UCO • World production of used cooking oils (UCOs) and current market data ☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.☐The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: