***Optimization of an electrochemical direct air capture process with decreased CO2 desorption pressure and addition of background electrolyte***
Authors: Qingdian Shu a,b, Ching Shing Sin a,b, Michele Tedesco a, Hubertus V. M. Hamelers a,b, and Philipp Kuntke a,b.
a Wetsus, European Centre of Excellence for Sustainable Water Technology, The Netherlands
b Environmental Technology, Wageningen University, The Netherlands

Corresponding author: Philipp Kuntke and Qingdian Shu 

Contact imformation: 

philipp.kuntke@wur.nl 
Environmental Technology, Wageningen University & Research, 
Bornse Weilanden 9, 6708 WG Wageningen;  
P.O. Box 17, 6700 AA Wageningen, The Netherlands

qingdian.shu@wetsus.nl
Wetsus, European Centre of Excellence for Sustainable Water Technology,
Oostergoweg 9, 8911MA Leeuwarden; 
P.O. Box 1113, 8900 CC Leeuwarden, The Netherlands

***General Introduction***

This dataset contains data collected during experiments on optimization of an electrochemical direct air capture process with decreased CO2 desorption pressure and addition of background electrolyte. It is being made public both to act as supplementary data for publication and in order for other researchers to use this data in their own work.
This work was performed at Wetsus, European Centre of Excellence for Sustainable Water Technology, between September 2021 and March 2022. 
File: Decreased CO2 desorption pressure experiment condition 1.csv - includes the data recorded every second by the Iviumstat and mass flow meter in the experiment under Condition 1. The CO2 desorption pressure was set at 0.9 bar initially, then decreased to 0.7 Bar at 10:24:00, and decreased to 0.5 bar at 14:55:00, and decreased to 0.3 bar at 16:10:00. The recorded variables were: Date_(D-M-Y), Time_(h:m:s), Current_(mA), Voltage_(V), Gas production_%.
File: Decreased CO2 desorption pressure experiment condition 2.csv - includes the data recorded every second by the Iviumstat and mass flow meter in the experiment under Condition 2. The CO2 desorption pressure was set at 0.9 bar initially, then decreased to 0.7 Bar at 11:36:00, and decreased to 0.5 bar at 13:19:00, and decreased to 0.3 bar at 14:55:00. The recorded variables were: Date_(D-M-Y), Time_(h:m:s), Current_(mA), Voltage_(V), Gas production_%.
File: Decreased CO2 desorption pressure experiment condition 3.csv - includes the data recorded every second by the Iviumstat and mass flow meter in the experiment under Condition 3. The CO2 desorption pressure was set at 0.9 bar initially, then decreased to 0.7 Bar at 16:15:00 on 15.12.2021, and decreased to 0.5 bar at 17:02:00 on 15.12.2021, and decreased to 0.3 bar at 09:41:00 on 14.12.2021. The recorded variables were: Date_(D-M-Y), Time_(h:m:s), Current_(mA), Voltage_(V), Gas production_%.
File: 1M K+ no buffer Load ratio 0.7.csv - includes the data recorded by the Iviumstat, mass flow meter, pH probe, conductivity probes, and reference electrodes in the experiment with 1M K+ and no buffer at load ration of 0.7. The recorded variables were: Date_(D-M-Y), Time, Current_(A), Voltage_(V), Gas production_%, pH_acidifying_solution, Conductivity_acidifying_solution_(µS/cm), Conductivity_catholyte_(µS/cm), Anode_potential_(V), Cathode_potential_(V).
File: 1M K+ no buffer Load ratio 0.8.csv - includes the data recorded by the Iviumstat, mass flow meter, pH probe, conductivity probes, and reference electrodes in the experiment with 1M K+ and no buffer at load ration of 0.8. The recorded variables were: Date_(D-M-Y), Time, Current_(mA), Voltage_(V), Gas production_%, pH_acidifying_solution, Conductivity_acidifying_solution_(µS/cm), Conductivity_catholyte_(µS/cm), Anode_potential_(V), Cathode_potential_(V).
File: 1M K+ no buffer Load ratio 0.9.csv - includes the data recorded by the Iviumstat, mass flow meter, pH probe, conductivity probes, and reference electrodes in the experiment with 1M K+ and no buffer at load ration of 0.9. The recorded variables were: Date_(D-M-Y), Time, Current_(mA), Voltage_(V), Gas production_%, pH_acidifying_solution, Conductivity_acidifying_solution_(µS/cm), Conductivity_catholyte_(µS/cm), Anode_potential_(V), Cathode_potential_(V).
File: 1M K+ no buffer Load ratio 1.0.csv - includes the data recorded by the Iviumstat, mass flow meter, pH probe, conductivity probes, and reference electrodes in the experiment with 1M K+ and no buffer at load ration of 1.0. The recorded variables were: Date_(D-M-Y), Time, Current_(mA), Voltage_(V), Gas production_%, pH_acidifying_solution, Conductivity_acidifying_solution_(µS/cm), Conductivity_catholyte_(µS/cm), Anode_potential_(V), Cathode_potential_(V).
File: 1M K+ no buffer Load ratio 1.1.csv - includes the data recorded by the Iviumstat, mass flow meter, pH probe, conductivity probes, and reference electrodes in the experiment with 1M K+ and no buffer at load ration of 1.1. The recorded variables were: Date_(D-M-Y), Time, Current_(mA), Voltage_(V), Gas production_%, pH_acidifying_solution, Conductivity_acidifying_solution_(µS/cm), Conductivity_catholyte_(µS/cm), Anode_potential_(V), Cathode_potential_(V).
File: 1M K+ 0.1M buffer Load ratio 0.7.csv - includes the data recorded by the Iviumstat, mass flow meter, pH probe, conductivity probes, and reference electrodes in the experiment with 1M K+ and no buffer at load ration of 0.7. The recorded variables were: Date_(D-M-Y), Time, Current_(A), Voltage_(V), Gas production_%, pH_acidifying_solution, Conductivity_acidifying_solution_(µS/cm), Conductivity_catholyte_(µS/cm), Anode_potential_(V), Cathode_potential_(V).
File: 1M K+ 0.1M buffer Load ratio 0.8.csv - includes the data recorded by the Iviumstat, mass flow meter, pH probe, conductivity probes, and reference electrodes in the experiment with 1M K+ and no buffer at load ration of 0.8. The recorded variables were: Date_(D-M-Y), Time, Current_(A), Voltage_(V), Gas production_%, pH_acidifying_solution, Conductivity_acidifying_solution_(µS/cm), Conductivity_catholyte_(µS/cm), Anode_potential_(V), Cathode_potential_(V).
File: 1M K+ 0.1M buffer Load ratio 0.9.csv - includes the data recorded by the Iviumstat, mass flow meter, pH probe, conductivity probes, and reference electrodes in the experiment with 1M K+ and no buffer at load ration of 0.9. The recorded variables were: Date_(D-M-Y), Time, Current_(mA), Voltage_(V), Gas production_%, pH_acidifying_solution, Conductivity_acidifying_solution_(µS/cm), Conductivity_catholyte_(µS/cm), Anode_potential_(V), Cathode_potential_(V).
File: 1M K+ 0.1M buffer Load ratio 1.0.csv - includes the data recorded by the Iviumstat, mass flow meter, pH probe, conductivity probes, and reference electrodes in the experiment with 1M K+ and no buffer at load ration of 1.0. The recorded variables were: Date_(D-M-Y), Time, Current_(A), Voltage_(V), Gas production_%, pH_acidifying_solution, Conductivity_acidifying_solution_(µS/cm), Conductivity_catholyte_(µS/cm), Anode_potential_(V), Cathode_potential_(V).
File: 1M K+ 0.1M buffer Load ratio 1.1.csv - includes the data recorded by the Iviumstat, mass flow meter, pH probe, conductivity probes, and reference electrodes in the experiment with 1M K+ and no buffer at load ration of 1.1. The recorded variables were: Date_(D-M-Y), Time, Current_(mA), Voltage_(V), Gas production_%, pH_acidifying_solution, Conductivity_acidifying_solution_(µS/cm), Conductivity_catholyte_(µS/cm), Anode_potential_(V), Cathode_potential_(V).
File: 1M K+ 0.2M buffer Load ratio 0.7.csv - includes the data recorded by the Iviumstat, mass flow meter, pH probe, conductivity probes, and reference electrodes in the experiment with 1M K+ and no buffer at load ration of 0.7. The recorded variables were: Date_(D-M-Y), Time, Current_(A), Voltage_(V), Gas production_%, pH_acidifying_solution, Conductivity_acidifying_solution_(µS/cm), Conductivity_catholyte_(µS/cm), Anode_potential_(V), Cathode_potential_(V).
File: 1M K+ 0.2M buffer Load ratio 0.8.csv - includes the data recorded by the Iviumstat, mass flow meter, pH probe, conductivity probes, and reference electrodes in the experiment with 1M K+ and no buffer at load ration of 0.8. The recorded variables were: Date_(D-M-Y), Time, Current_(mA), Voltage_(V), Gas production_%, pH_acidifying_solution, Conductivity_acidifying_solution_(µS/cm), Conductivity_catholyte_(µS/cm), Anode_potential_(V), Cathode_potential_(V).
File: 1M K+ 0.2M buffer Load ratio 0.9.csv - includes the data recorded by the Iviumstat, mass flow meter, pH probe, conductivity probes, and reference electrodes in the experiment with 1M K+ and no buffer at load ration of 0.9. The recorded variables were: Date_(D-M-Y), Time, Current_(mA), Voltage_(V), Gas production_%, pH_acidifying_solution, Conductivity_acidifying_solution_(µS/cm), Conductivity_catholyte_(µS/cm), Anode_potential_(V), Cathode_potential_(V).
File: 1M K+ 0.2M buffer Load ratio 1.0.csv - includes the data recorded by the Iviumstat, mass flow meter, pH probe, conductivity probes, and reference electrodes in the experiment with 1M K+ and no buffer at load ration of 1.0. The recorded variables were: Date_(D-M-Y), Time, Current_(mA), Voltage_(V), Gas production_%, pH_acidifying_solution, Conductivity_acidifying_solution_(µS/cm), Conductivity_catholyte_(µS/cm), Anode_potential_(V), Cathode_potential_(V).
File: 1M K+ 0.2M buffer Load ratio 1.1.csv - includes the data recorded by the Iviumstat, mass flow meter, pH probe, conductivity probes, and reference electrodes in the experiment with 1M K+ and no buffer at load ration of 1.1. The recorded variables were: Date_(D-M-Y), Time, Current_(A), Voltage_(V), Gas production_%, pH_acidifying_solution, Conductivity_acidifying_solution_(µS/cm), Conductivity_catholyte_(µS/cm), Anode_potential_(V), Cathode_potential_(V).
File: Fixed total carbon feeding rate with 0.1M buffer.csv - includes the data recorded by the Iviumstat, mass flow meter, pH probe, conductivity probes, and reference electrodes in the experiment with fixed carbon feeding rate and 0.1M buffer addition. The recorded variables were: Date_(D-M-Y), Time, Current_(mA), Voltage_(V), Gas production_%, pH_acidifying_solution, Conductivity_acidifying_solution_(µS/cm), Conductivity_catholyte_(µS/cm), Anode_potential_(V), Cathode_potential_(V).
File: Fixed total carbon feeding rate with 0.2M buffer.csv - includes the data recorded by the Iviumstat, mass flow meter, pH probe, conductivity probes, and reference electrodes in the experiment with fixed carbon feeding rate and 0.2M buffer addition. The recorded variables were: Date_(D-M-Y), Time, Current_(A), Voltage_(V), Gas production_%, pH_acidifying_solution, Conductivity_acidifying_solution_(µS/cm), Conductivity_catholyte_(µS/cm), Anode_potential_(V), Cathode_potential_(V).
File: 1M K+ 0.1M sulphate Load ratio 0.7.csv - includes the data recorded by the Iviumstat, mass flow meter, pH probe, conductivity probes, and reference electrodes in the experiment with 1M K+ and no buffer at load ration of 0.7. The recorded variables were: Date_(D-M-Y), Time, Current_(A), Voltage_(V), Gas production_%, pH_acidifying_solution, Conductivity_acidifying_solution_(µS/cm), Conductivity_catholyte_(µS/cm), Anode_potential_(V), Cathode_potential_(V).
File: 1M K+ 0.1M sulphate Load ratio 0.8.csv - includes the data recorded by the Iviumstat, mass flow meter, pH probe, conductivity probes, and reference electrodes in the experiment with 1M K+ and no buffer at load ration of 0.8. The recorded variables were: Date_(D-M-Y), Time, Current_(A), Voltage_(V), Gas production_%, pH_acidifying_solution, Conductivity_acidifying_solution_(µS/cm), Conductivity_catholyte_(µS/cm), Anode_potential_(V), Cathode_potential_(V).
File: 1M K+ 0.1M sulphate Load ratio 0.9.csv - includes the data recorded by the Iviumstat, mass flow meter, pH probe, conductivity probes, and reference electrodes in the experiment with 1M K+ and no buffer at load ration of 0.9. The recorded variables were: Date_(D-M-Y), Time, Current_(A), Voltage_(V), Gas production_%, pH_acidifying_solution, Conductivity_acidifying_solution_(µS/cm), Conductivity_catholyte_(µS/cm), Anode_potential_(V), Cathode_potential_(V).
File: 1M K+ 0.1M sulphate Load ratio 1.0.csv - includes the data recorded by the Iviumstat, mass flow meter, pH probe, conductivity probes, and reference electrodes in the experiment with 1M K+ and no buffer at load ration of 1.0. The recorded variables were: Date_(D-M-Y), Time, Current_(A), Voltage_(V), Gas production_%, pH_acidifying_solution, Conductivity_acidifying_solution_(µS/cm), Conductivity_catholyte_(µS/cm), Anode_potential_(V), Cathode_potential_(V).
File: 1M K+ 0.1M sulphate Load ratio 1.1.csv - includes the data recorded by the Iviumstat, mass flow meter, pH probe, conductivity probes, and reference electrodes in the experiment with 1M K+ and no buffer at load ration of 1.1. The recorded variables were: Date_(D-M-Y), Time, Current_(A), Voltage_(V), Gas production_%, pH_acidifying_solution, Conductivity_acidifying_solution_(µS/cm), Conductivity_catholyte_(µS/cm), Anode_potential_(V), Cathode_potential_(V).

All calculations are included in the manuscript. DOI: to be added
Data specific information: 
Current_(A)/Current_(mA): current applied on the electrochemical cell.
Voltage_(V): measured cell voltage. 
Gas production_%: the ratio of the gas production rate to the full capacity of the mass flow meter (50 mln/min).
pH_acidifying_solution: pH of the acidifying solution. 
Conductivity_acidifying_solution_(µS/cm): conductivity of the acidifying solution. 
Conductivity_catholyte_(µS/cm): conductivity of the catholyte. 
Anode_potential_(V): potential difference between anode and acidifying compartment. 
Cathode_potential_(V): potential difference between catholyte and cathode. 
