Metal-azolate framework-6-derived porous carbon: A remarkable adsorbent to remove carbamazepine from water

Removal of pharmaceuticals from water is crucial for our health and clean environment. In this work, porous carbon, which is suitable for carbamazepine (CBMZ) adsorption, is produced via two-step-pyrolysis of a Zn-based metal-organic framework (MOF), MAF-6(Zn), especially in the presence of KOH activator in various quantities in the second step. After comprehensive characterizations of the derived carbon, adsorption of CBMZ was carried out under wide conditions. One carbon, named MDC-4, prepared from carbonization of MAF-6(Zn)-pyrolyzed product (obtained in the first step), with 4 times the weight of KOH, showed a large adsorption capacity for CBMZ (1295 mg/g). This capacity is higher than that of any reported adsorbent; moreover, this is around 2 times that of the most efficient adsorbent reported so far. MDC-4 was readily recyclable with acetone washing. Based on CBMZ adsorption and surface charge of MDC-4 under wide pH conditions and XPS analysis of MDC-4 (with or without CBMZ adsorption), a plausible adsorption mechanism like π–π and hydrophobic interactions could be suggested. Pyrolyzing Zn-based MOFs like MAF-6(Zn) in the existence of much KOH activator will be effective in preparing an adsorbent like MDC-4 to remove hydrophobic organics with ample π-electrons (like polycyclic aromatic hydrocarbons) from water.