Stainless steel mesh coated with defect engineered ZIF-67 toward pH-switchable wettability and efficient organic liquids separation

Abstract

In this work, stainless steel mesh coated with stearic acid and tetradecanedioic acid modulated ZIF-67 (SA+TDA/mZIF-67@SSM) was prepared via facile electrodeposition. The composite modulators supply defect engineering on the MOFs, endowing the as-prepared meshes with pH-switchable wettability. The ratio of modulators significantly affected the crystal morphology and wetting property of SA+TDA/mZIF-67@SSM, resulting from the competitive coordination between the modulation and crystal growth process. The SA+TDA/mZIF-67@SSM exhibited highly hydrophobic, while it became amphiphilic after soaked in alkaline solution because some exposed carboxylic acid groups on the mesh were deprotonated. The SA+TDA/mZIF-67@SSM achieved efficient and adjustable organic liquids separation, with the separation efficiency both up to 98% before and after the wettability transition. In addition, the SA+TDA/mZIF-67@SSM could realize the separation of oil/water/oil mixtures, with the separation efficiency larger than 98%. This work introduces a new technique of modulated MOFs coated mesh with pH-responsivity for separating organic liquids based on defect engineering.