Preparation of imprinted phenol gel with ultra-high adsorption capacity based on porous biochar: 5-stage tandem column, response surface method, and mechanism analysis

Wastewater from industries like petroleum refining and pharmaceuticals contains high levels of phenolic compounds. Discharging this untreated wastewater can severely pollute water bodies. To address this issue, a biochar-based composite imprinting phenol gel(MgNBC@MIP) was designed to effectively remove phenolic compounds and control phenol levels in water environments. The adjustment of the aromatic structure and pore architecture of the biochar effectively enhanced its affinity for phenolic compounds. Subsequently, the individual effects of factors such as pH, salt, and humic acid on adsorption were explored. Optimization of the adsorption process was carried out using a four-factor, three-level response surface method, yielding a theoretical formula for the adsorption amount, with a maximum adsorption capacity of 308.311 mg/g. Moreover, the adsorption of phenol and its derivatives by MgNBC@MIP followed the Langmuir isothermal model and the PSO kinetic model. A comprehensive mechanism analysis elaborated in detail on the diffusion and adsorption process of phenol from the aqueous phase to the adsorption site. Correlation FTIR and XPS analysis confirmed that π-π electron donor–acceptor interactions, hydrogen bonding, pore filling, and metal complexation were the primary driving forces for phenol adsorption. Significantly, MgNBC@MIP exhibited good reusability in the adsorption–desorption cycle. The design of a five-stage tandem column adsorption experiment opens up avenues for the industrial application of MgNBC@MIP.