Vol.:(0123456789) International Journal of Precision Engineering and Manufacturing-Green Technology (2022) 9:941–953 https://doi.org/10.1007/s40684-021-00360-5 1 3 REGULAR PAPER Inkjet Printing and In‑Situ Crystallization of Biopigments for Eco‑Friendly and Energy‑Efcient Fabric Coloration Yujuan He 1  · Yu Cao 1  · Hyun‑jun Hwang 2  · Sarath M. Vega Gutierrez 3  · Shujie Li 1  · Hsiou‑Lien Chen 4  · Seri C. Robinson 3  · Chih‑hung Chang 1  · Rajiv Malhotra 2 Received: 5 August 2020 / Revised: 17 April 2021 / Accepted: 26 April 2021 / Published online: 1 June 2021 © Korean Society for Precision Engineering 2021 Abstract Current methods of fabric dyeing have a signifcant negative efect on the environment via toxic efuent emissions, high water usage, and high energy consumption. We demonstrate, for the frst time, low-energy inkjet printing of an ecofriendly and biodegradable pigment derived from widely available spalting fungi with synthesis by-products that are fully biodegradable. Vivid and stable coloration is achieved on polyester and cotton using benign acetone-based and ethanol-based biopigment inks, with no liquid efuent or runof, and without any synthetic dyes or mordants. We investigate the infuence of fabric type, solvent type, and the number of printing passes on the color type, intensity, and uniformity, pigment crystallization, and environmental stability. Greater spatial defnition of the printed pigment in inkjet printing efects greater crystallization and more vivid and uniform coloration as compared to drop-casting, the primary method used till date to color fabrics with such fungal biopigments. pH-driven interactions between the fabric, solvent, and biopigment cause solvent-driven changes in color type (from bluish to reddish) and fabric-governed changes in color intensity. The impact of our fndings on minimizing the environmental impact of fabric dyeing is discussed. Keywords Inkjet printing · Fabric · Biopigment · Energy efciency · Crystallization 1 Introduction Dyeing and printing of fabrics are signifcant contributors to environmental pollution. Discharged wastewater from con- ventional dyeing processes like pad-dyeing or rotary screen printing contains thousands of toxic chemicals [1–3]. This toxic water has poor biodegradability [4, 5], which causes harmful diseases in humans and wildlife [5, 6] and increases the cost of wastewater treatment [7–12]. A secondary, but essential impact, is via the sheer volume of water used in conventional dyeing and printing. For example, it has been estimated that a single mill can use nearly 200 tons of fresh water per ton of fabric, of which 85% is used in the dyeing process [5, 13]. This impact extends beyond consumer fab- rics, e.g. it is estimated that the water consumption of the fashion dyeing industry will reach nearly 120 billion cubic meters of water by 2030. Textile dyeing is estimated cause about 20% of global industrial water pollution [14], waste about 6 trillion liters of water per year as untreatable efu- ent [15], and use nearly 390 Billion KWh of thermal energy annually [5]. Thus, there is signifcant interest in eliminating or minimizing the water and toxic chemicals used in fabric dyeing. In particular, supercritical CO 2 dyeing and inkjet printing are of immediate interest due to the availability of scalable equipment [16]. Supercritical CO 2 or sCO 2 dyeing uses carbon dioxide gas as the carrier to deposit dyes onto the fabrics under high pressure (≈ 100 s of bars) and temperature (typically > 100 ℃) over a period of an hour or more [2, 17, 18]. This process Online ISSN 2198-0810 Print ISSN 2288-6206 * Chih-hung Chang chih-hung.chang@oregonstate.edu * Rajiv Malhotra rajiv.malhotra@rutgers.edu 1 School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR 97331, USA 2 Department of Mechanical and Aerospace Engineering, Rutgers University, 98 Brett Road, Piscataway, NJ 08854, USA 3 Department of Wood Science and Engineering, Oregon State University, Corvallis, OR 97331, USA 4 College of Business, Oregon State University, Corvallis, OR 97331, USA