Various carbon-based MgAl2O4 adsorbents and their removal efficiency of CR dye and antibiotics in aqueous media: High selective adsorption capacity, performance prediction and mechanism insight

Various carbon-based MgAl2O4 (MAO) adsorbents were synthesized by a simple ultrasound irradiation technology with the activated carbon (AC), carbon quantum dots (CQDs), C3N4 (CN) and graphene oxide (GO) as carbon sources. The optimum synthesis conditions for the carbon-based MAO adsorbents were determined by the study of the addition of different types of carbon and different mass ratios of mVarious carbon: mMAO = 2.5%, 5.0%, 7.5% and 10%. The carbon-based MAO adsorbents were used for the adsorption of Congo red (CR) dye, tetracycline hydrochloride (TCH), oxytetracycline hydrochloride (OCH), ciprofloxacin (CIP), naproxen sodium (NPS) and tetrabromobisphenol A (TBBPA) and the seven factors affecting the adsorption behavior were discussed, including the type of carbon, AC content, initial dye concentration (CCR), adsorbent dosage (Ccarbon-based MAO adsorbents), adsorption time (At), pH value and reaction temperature (T). The corresponding adsorption isotherm models such as Langmuir, Tempkin, Koble-Corrigan, Toth and Freundlich models and thermodynamics of carbon-based MAO adsorbents for the adsorption of CR dye were also studied. When pH = 7.8, CCR = 200 mg/ L, At = 90 min, T = 287 K and CAC 5.0 wt%-MAO = 1 g/L, the removal rate of CR dye reaches 89.7%. The back propagation (BP) neural network model was used to predict the adsorption percentage of carbon-based MAO adsorbents, which was consistent with the experimental results. The high adsorption capacity of AC 5.0 wt %-MAO adsorbents for the adsorption of CR dye can be assigned to the synergistic effects of electrostatic interaction, intermolecular force, n-t interaction and hydrogen bonding, while for the adsorption of TCH, OCH and CIP can be ascribed to the electrostatic interaction. This study demonstrated a huge potential of carbon-based MAO adsorbents as an eco-friendly adsorbent for the adsorption of dyes and drugs.