Functionalised amino acids for improving direct air capture (DAC) capacity of conventional paints: a preliminary study

Negative carbon emission pathways are deemed necessary to meet the net-zero goals by year 2050 and limit the atmospheric temperature increase to 1.5oC, as detailed in the Paris Agreement. One interesting pathway is to use decorative materials like varnishes, coatings, and paints to passively capture carbon dioxide directly from air. For example, UK households consume 350+ million litres of paint each year. If these paints are modified by addition of specially functionalised biochemical materials, they can passively capture 10,000 – 14000 tons of carbon dioxide per year directly from air and perhaps, store it for long timescales.
This study investigates the direct air carbon capture performance of commercial paint products mixed with functionalised amino acid (FAA) liquid. In the first stage of this study, the FAA liquid was prepared using L-lysine, an alkaline amino acid. In the second stage, the prepared FAA liquid was added to different commercial paint samples in proportions of 1vol% and 10vol% of the total paint volume. The treated paints were coated on an impervious plastic surface and left exposed to air at room conditions (20oC±1oC, 1018hPa±30hPa, 560 ppm CO2 ±20ppm CO2). Microsamples of treated paint samples were then taken at intervals of 0, 4, 8, and 12 days, and tested for total carbon dioxide content by barium chloride wet analysis. All paint samples mixed with FAA liquid showed higher carbon dioxide content (1.15 – 5.08wt% CO2) compared to the control samples (0.47 – 2.99wt% CO2) for different paint type and exposure time. With addition of 1vol% of FAA liquid, the direct air carbon dioxide capture capacity of treated paints increased at an average of 98.5%, while the paint samples mixed with 10vol% of FAA liquid showed an average increase of 111.7% in capacity for direct carbon dioxide capture from air.
Hence, this study proves the hypothesis that paints treated with specially prepared FAA liquid can be used to capture carbon dioxide directly from air when applied to a surface. However, further research is required to make them fully carbon negative that includes studying the effect of FAA liquid(s) on paints’ application properties, their ability to hold carbon dioxide for long timescales, a detailed lifecycle carbon footprint analysis, and achieving comparative costing to other commercial paint products.