Facile and eco‐friendly fabrication of hierarchical superhydrophobic coating from eggshell biowaste

Abstract

This study reports a facile and sustainable approach to fabricate superhydrophobic coating from eggshell biowaste. The coating was prepared by ball milling chicken eggshells, composed of hydrophilic calcium carbonate (CaCO3), to microsized particles followed by surface hydrophobilizing with stearic acid (C17H35COOH) to form low surface energy nanosized calcium stearate ((C17H35COO)2Ca) through the esterification of hydroxyl groups (‐OH) absorbed on a surface of CaCO3 with carboxyl groups (–COOH) of stearic acid. Then, a layer of modified eggshell particles dispersed in polystyrene (PS) binder was dip‐coated on a substrate. A coated surface with water contact angles of 151° ± 1° on glass and 153° ± 1° on cotton fabric substrates was achieved when a 4:1 weight ratio of the modified eggshell:PS was used. The uniform distribution of the modified eggshell particles throughout the coating led to a surface with high degree of hierarchical micro‐nanoscale roughness which resulted in superhydrophobicity. The superhydrophobic eggshell coating showed good environmental stability, self‐cleaning, and oil/water separation properties. These results suggest that eggshell biowaste can be utilized for superhydrophobic applications.

State-of-the-Art of Eggshell Waste in Materials Science: Recent Advances in Catalysis, Pharmaceutical Applications, and Mechanochemistry

“…The works on bioceramics preparation and the preparation of nano-eggshell dominate. Nevertheless, some new application spheres have emerged, e.g., biogas production (Sari et al, 2020 ), filtration (Seeharaj et al, 2019 ), dentistry (Onwubu et al, 2019a , b ), and electrochemistry (Cherdchom et al, 2019 ; Senthil et al, 2019 ; Karuppiah et al, 2020 ). A reference to the study using ball milling of eggshell for the application in catalysis (Mosaddegh and Hassankhani, 2014 ) has been already mentioned earlier.…”

“…The hydrophobic eggshell waste was prepared by mechanical activation and subsequent modification with stearic acid mixed with polymer binder in Seeharaj et al ( 2019 ). The obtained material was then dip-coated on glass and cotton fabric.…”

“… A photograph of the experimental setup for diesel/water separation test (water was dyed blue with methylene blue for better contrast) (Seeharaj et al, 2019 ) copyright 2019. The American Ceramic Society.…”

“…Some studies emphasize the positive effect of lycopene on ESM guidance channels in sciatic nerve regeneration in rats, with ESM acting as a nerve guidance channel (NGC). Ideally, NGC FIGURE 8 | A photograph of the experimental setup for diesel/water separation test (water was dyed blue with methylene blue for better contrast) (Seeharaj et al, 2019) copyright 2019. The American Ceramic Society.…”

Surface modification of ceramic coating for enhanced hydrophobicity and wear properties

“…Seeharaj et al studied the contact angle of superhydrophobic eggshell coatings in aqueous solutions with different pH values and also found that the contact angle has a greater effect under alkaline conditions. 26 This is because the long hydrophobic chain (−CF 3 , −CF 2 , and C-C (H)) on the coating is connected to the coating material through the ester bond (COO-R), 13,26 and the ester bond is easily hydrolyzed under alkaline conditions (OH-). The more hydrophobic long-chain molecules are lost, and the hydrophobicity will also decrease.…”