Conversion of superhydrophilicity to superhydrophobicity by changing the microstructure of carbon-high fly ash

Carbon-high fly ash (CFA) is a reused solid waste. We herein report a simple method to fabricate superhydrophobic CFA. Superhydrophobicity was achieved by decorating ZnO nanoplates and grafting stearic acid (SA). SEM results showed that the micro–nano was established, wherein ZnO nanoplates grew successfully with ∼10 nm thickness on the CFA surface forming a honeycomb structure. FT-IR results showed that the carboxylic acid of SA reacted with surface hydroxyl of ZnO and CFA by esterification. After modification by SA in the best conditions, the water contact angle of CFA-ZnO-SA reached to 156.2° with the petal effect. The material could be an excellent candidate for hydrophobic application.