Preparation of superhydrophobic ZIF67/cellulose-based adsorbent and highly efficient treatment of emulsified oily wastewater

Cellulose-ZIF67 adsorption of emulsified oily wastewater was systematically studied. • Excellent environmental tolerance under high salinity and pH 6-10 range. • Synergistic electrostatic adsorption and hydrophobic interactions for emulsified oil removal. • Real textile oil fume wastewater achieved 68.77% oil and 92.42% turbidity removal. • Real marine diesel wastewater achieved 80.60% oil and 80.57% turbidity removal. Emulsified oily wastewater has emerged as a major challenge in the field of water treatment due to the difficulty of oil-water separation and its severe impact on environmental ecosystems. Cellulose offers excellent modifiability and biodegradability, while metal-organic frameworks have demonstrated unique advantages in oil-water separation owing to their high specific surface area and tunable pore structures. In this study, a hydrophobic cellulose-based MOF adsorbent was successfully fabricated by in situ growth of ZIF67 on cellulose via diazonium chemistry, followed by depositing of hydrophobic monomers. The results showed that at dosages of 60   mg/L and 40   mg/L, the oil removal efficiencies for emulsified oily wastewater at concentrations of 300   mg/L and 150   mg/L reached 93.88% and 93.55%, respectively, while the turbidity removal efficiencies both exceeded 99.6%. The adsorbent maintained satisfactory oil removal performance under high-salinity conditions and over a pH range of 6-10. The adsorption process conformed to the Sips isotherm model and pseudo-second-order kinetics, and was characterized as spontaneous, endothermic, and entropy-driven. The interaction mechanism between the adsorbent and oil was primarily attributed to the synergistic effect of hydrophobic interactions and electrostatic attraction. The adsorbent demonstrated significant removal of esters, ethers, and siloxanes from real textile oil fume purification wastewater, as well as alkanes and cycloalkanes from marine diesel wastewater. This work systematically investigated the adsorption performance of the as-prepared adsorbent toward surfactant-stabilized emulsified oily wastewater. Its practical applicability was preliminarily evaluated using two real oily wastewaters with different compositional characteristics.