Surface Recognition Directed Selective Removal of Dyes from Aqueous Solution on Hydrophilic Functionalized Petroleum Coke Sorbents. A Supramolecular Perspective

Novel controlled hydrophilic nonporous carbon-based sorbents from petroleum coke were obtained by using a hydrothermal oxidation treatment of shot coke with different H2O2 concentrations. The ability of resulting carbon materials for the selective adsorption of cationic dyes from aqueous solution directed by surface recognition is highlighted for the first time. This approach provides an eco-friendly, low-cost alternative for the preparation of sorbents with unprecedented properties to achieve remarkable selective adsorption independent of the presence of intrinsic porosity. A further advantage of these sorbents is their efficient regeneration capability and reusability without appreciable changes in their adsorption capacity. Results reveal that the dye adsorption capacity is significantly enhanced on multivalent hydrophilic surfaces in comparison to the pristine surface. In addition, a deep insight is offered into the explanation of selective adsorption processes on hydrophilic coke in the function of surface recognition processes based on cooperative multivalent supramolecular interactions such as classical synthons: pyridine-carboxylic acid, O-H center dot center dot center dot N, cation-pi, pi-pi, and electrostatic interactions. Likewise, this adsorption capacity is highly dependent on the fine-tuning of donor/acceptor binding sites between adsorbate and sorbent. A further type of important supramolecular interaction was observed on the adsorption of dyes onto the hydrophobic coke-raw surface, which is controlled mainly by cation-pi and pi-pi interactions.