ELECTRONIC SUPPORTING INFORMATION Role of Life Cycle Externalities in the Valuation of Protic Ionic Liquids – A Case Study in Biomass Pretreatment Solvents

Husain Baaqel, Ismael Diaz, Vı́ctor Tulus, Benôıt Chachuat∗1,2, Gonzalo Guillén-Gosálbez†4, and Jason P. Hallett Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom Centre for Process Systems Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom Departamento Ingeniera Qúımica y del Medio Ambiente, Escuela Técnica Superior de Ingenieros Industriales, Madrid, Spain Institute for Chemical and Bioengineering, Swiss Federal Institute of Technology, Vladimir-Prelog-Weg 1, Zurich 8093, Switzerland Departament d’Enginyeria Qumica, Universitat Rovira i Virgili, Tarragona, Spain

∆H L is the lattice energy calculated from Equation S2 below 6 .
The parameters n m and n x depend on the nature of the cation and anion, respectively. They are equal to 3 for monoatomic ions, 5 for linear polyatomic ions, and 6 for non-linear polyatomic ions. p and q are the oxidation states of the cation and anion, respectively. The potential energy U pot is calculated from Equation S3 below.
The parameters ρ m and M m denote the density and the molecular weight of the IL, respectively. The coefficients γ and δ depend on the stoichiometry of the IL.

S2
Here, C e is the cost of purchased equipment e on a U.S. Gulf Coast basis as of January 2006, and F e is the corresponding equipment installation factor. Due to unavailability of current equipment data, their costs are calculated as: where a and b are cost constants, n is equipment type exponent and S is a size parameter. Finally, because of inflation, capital costs need to be escalated to reflect up-to-date costs. This is usually done using cost indices: In this work, the Chemical Engineering Plant Cost Index (CEPCI) for 2006 and 2019 are used. CEPCI is one of the most commonly-used published composite indices and was developed based on 4 main components: process equipment, construction labor, buildings and supervision and engineering.

Appendix C. Environmental assessment
This appendix details the proxy data, processes and flows used in the inventory phase of LCA as well as the midpoint results from the characterization phase. For both human health and ecosystem quality expressed in biophysical units, monetization factors using the values in Table S18 were applied. Overall, the monetization proceeds as follows: where MF i denotes the monetization factor for endpoint impact i, and EP i the corresponding damage. Next, a currency exchange factor and inflation factor are applied to express a monetary value in USD 2019 . For resource availability already expressed in monetary value, only an inflation factor is used for the conversion into USD 2019 . Uncertainty in LCA data is quantified using the Pedigree matrix approach 11 , where a score U D,i between 1 and 5 is assigned to the data based on five criteria: reliability, completeness, temporal, geographical and technological differences. All of these scores are combined with a basic uncertainty factor U D,b to determine the standard deviation σ k of a log-normal distribution for each mass and energy flow k: 90% by mass of carbon in waste stream is assumed to be completely burned in waste treatment to produce CO 2 as per the following complete combustion equation: The chemical oxygen demand (COD) or total oxygen consumed is assumed to be equivalent to the amount of oxygen needed to react with the amount of carbon remaining in the waste stream after treatment which is assumed to be 10% of total carbon BOD For worst case scenario, the biological oxygen demand (BOD) which is the oxygen consumed due to biological aerobic digestion by organisms is assumed to be equivalent to the amount of COD TOC The total organic carbon (TOC) which is the total amount of carbon is assumed to be equivalent to 10% of the total carbon in the waste stream which is the amount of carbon remaining after treatment DOC For waste case scenario, dissolved organic carbon (DOC) is assumed to be equivalent to TOC

Appendix D. Additional results
This appendix presents the direct cost and environmental impacts of the solvents using biomass loading as the functional unit. The data used to convert functional unit from kg of solvent to kg of biomass are reported in Table S19.  Figure S1: Direct costs of solvents per kg of treated biomass Figure S2: Endpoint environmental impacts of solvents per kg of treated biomass S17