Adsorption of cationic dyes and antibiotics from aqueous solution by dopamine-modified peanut husk

Dopamine modified peanut husks (PH/DA), a novel adsorbent, were investigated to enhance the adsorption capacity of dyes (neutral red, NR and crystal violet, CV) and fluoroquinolone antibiotics (ofloxacin, OFLX and enoxacin, ENO). Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), thermo-gravimetric analysis and differential scanning calorimetry (TG-DSC) and Brunauer-Emmett-Teller (BET) method were used to characterize PH and PH/DA. The findings demonstrated that the physical and chemical properties of the peanut husks were changed after dopamine-modification. As for adsorption kinetics, NR adsorption properties were satisfactorily explained by the Elovich model, whereas CV adsorption processes suited to the pseudo-second order model. Both OFLX and ENO followed the pseudo-first order model. Isotherm data showed that CV and ENO conform to the Temkin model while NR and OFLX fitted better to the Langmuir model. The <i>q</i>_max of NR, CV, OFLX and ENO by PH/DA were 52.37, 45.92, 46.57 and 58.40 mg/g at 290 K, respectively, according to Langmuir model. The adsorbent maintained an adsorption efficiency of above 70% even after three adsorption-desorption cycles. These findings proved that PH/DA’s successful development offers important insights into the production of sorbents for water treatment based on biomass. The adsorption of dyes and antibiotics on dopamine-modified peanut husk was investigated.The adsorbent was characterized by SEM, FTIR, XRD, XPS, BET and TG-DSC.Adsorption isotherm and kinetics models were fitted with the experimental data.Mechanism for the adsorption of dyes and antibiotics were elucidated. The adsorption of dyes and antibiotics on dopamine-modified peanut husk was investigated. The adsorbent was characterized by SEM, FTIR, XRD, XPS, BET and TG-DSC. Adsorption isotherm and kinetics models were fitted with the experimental data. Mechanism for the adsorption of dyes and antibiotics were elucidated.