Surface Properties of Graffiti Coatings on Sensitive Surfaces Concerning Their Removal with Formulations Based on the Amino-Acid-Type Surfactants

Abstract

Water-in-oil (w/o) nanoemulsions stabilized with amino acid surfactants (AAS) are one example of nanotechnology detergents of the “brush on, wipe off”-type for removing graffiti coatings from different sensitive surfaces. The high-pressure homogenization (HPH) process was used to obtain the nanostructured fluids (NSFs), including the non-toxic and eco-friendly components such as AAS, esterified vegetable oils, and ethyl lactate. The most effective NSF detergent was determined by response surface methodology (RSM) optimization. Afterwards, several surface properties, i.e., topography, wettability, surface free energy, and the work of water adhesion to surfaces before and after their coverage with the black graffiti paint, as well as after the removal of the paint layers by the eco-remover, were determined. It was found that the removal of graffiti with the use of the NSF detergent is more dependent on the energetic properties and microporous structure of the paint coatings than on the properties of the substrates on which the layers were deposited. The use of NSFs and knowledge of the surface properties could enable the development of versatile detergents that would remove unwanted contamination from various surfaces easily and in a controlled way.

Benefits of using nonionic saccharide surfactant‐based detergents for nanostructured fluids as stubborn graffiti paint remover

“…Other advantages of HPH comprise the unnecessity of organic solvents usage and the small particles production of a low polydispersity index (Estanqueiro et al, 2015;Severino et al, 2012). Therefore, in accordance with our previous work (Bartman et al, 2023a(Bartman et al, , 2023b, a two-stage homogenization process was used to generate w/o nanoemulsion particles with a size between 200 and 500 nm: first, mechanical homogenization under normal pressure was used, resulting in emulsion particles that are not thermokinetically stable, and then high-pressure homogenization (HPH) was used to obtain a very high thermokinetic stability of the nanoemulsion with specific particle sizes. In the first stage, 12 sets of emulsions were prepared in 250 cm 3 (see Table S1) at a temperature of 25 C using a rotor-stator stirrer (IKA Works GmbH & Co. KG, Staufen, Germany) equipped with a four-blade propeller.…”

“…Through the response surface exploration, the randomized nonlinear D-optimal model in the coordinate exchange mode was studied using the Design Expert program (ver. 13.0.12.0, State-Ease USA; Bartman et al, 2023aBartman et al, , 2023b. The (3-4) 3 fractional factorial D-optimal design (as indicated in ESI Table S2) was used to determine the optimum range for the process variables.…”

“…In addition, the removal of stubborn graffiti coatings can be a difficult process due to a number of factors, such as the substrates (chemical composition, texture, porosity, hardness, etc. ), the aging process of the paint (and the substrate), and the amount of time that has passed between applications and removals (Bartman et al, 2023a(Bartman et al, , 2023bWilhelm et al, 2021).…”

“…Nanostructured fluids (NSFs), such as water-in-oil nanoemulsions (NEs), are among the most effective nanodetergents for removing graffiti coatings, especially when using the "brush-on, wipe-off" approach (Bartman et al, 2023a(Bartman et al, , 2023bMaravelaki, 2022). These cutting-edge formulations outperform the conventional organic solvent-based preparations when it comes to eradicating the stubborn graffiti coatings, especially on the delicate surfaces that cannot withstand mechanical cleaning and become destroyed (Bechikh et al, 2020;Sanmartín et al, 2014).…”

“…The purpose of the study was to develop new environmentally friendly professional products for removing graffiti coatings by utilizing nanodetergents of the "brush-on, wipe-off" range. High-pressure homogenization (HPH) was used to produce water-in-oil nanoemulsions (Bartman et al, 2023a(Bartman et al, , 2023b) that included nontoxic and ecofriendly components such as esterified vegetable oils, alkyl polyglucosides (APG), and biosolvents such as D-limonene (LIM) and 3-methoxy-3methyl-1-butanol (MMB). In order to determine the most efficient cleansers, an optimization method known as the design of experiments (DoE) was utilized.…”