Polydopamine decorated carbon dots nanocomposite as an effective adsorbent for phenolic compounds

Carbon dots (CDs) with an average diameter of 2.3 ± 0.5 nm were prepared from red cabbage by a facile one-step hydrothermal process. The CDs and polydopamine (PDA) were then subjected to ultrasonication to form a polymer composite namely, PDA-doped CDs (PDA@CDs). The PDA@CDs with an average size of 5 μm was proven as effective adsorbents for p-chlorophenol (p-CP) and p-cyanophenol (p-CNP) as two probing models. The adsorption capacity of PDA@CDs was estimated to be 153 mg/g for p-CP and 178 mg/g for p-CNP, compared favorably with those of various adsorbents used in the literature, only 24–123 mg/g. The PDA@CDs significantly improved the adsorption rate of the two phenols at neutral pH and room temperature. The adsorption kinetics was governed by the pseudo second-order and intraparticle diffusion models. The PDA@CDs were reused as an active adsorbent material for the adsorption of phenolic compounds with high adsorption capacities in wastewater.