Manufacturing biodegradable lignocellulosic films with tunable properties from spent coffee grounds: A sustainable alternative to plastics

Manufacturing biodegradable lignocellulosic films from spent coffee grounds (SCG) as an alternative to commercial plastics is a viable solution to address plastic pollution. Here, the biodegradable lignocellulosic films from SCG were fabricated via a sequential alkaline treatment and ionic liquid-based dissolution process. The alkaline treatment process could swell the cell wall of SCG, change its carbohydrates and lignin contents, and enhance its solubility in ionic liquids. The prepared SCG films with different lignin contents exhibited outstanding UV blocking capability (42.07–99.99 % for UVB and 20.96–99.99 % for UVA) and light scattering properties, good surface hydrophobicity (water contact angle = 63.2°–88.7°), enhanced water vapor barrier property (2.28–6.79 × 10−12 g/m·s·Pa), and good thermal stability. Moreover, the SCG films exhibit excellent mechanical strength (50.10–81.56 MPa, tensile strength) and biodegradability (fully degraded within 30 days when buried in soil) compared to commercial plastic. The SCG films represent a promising alternative that can replace non-biodegradable plastics. [Display omitted] •SCG films are fabricated through alkali pretreatment followed by an ionic liquid dissolution-regeneration process.•SCG films exhibit excellent mechanical strength, UV blocking and thermal stability.•The properties of SCG films could be tailored by adjusting the lignin content.•The biodegradable SCG films offer a promising potential alternative to plastic.