Mussel-inspired polydopamine decorated pomelo peel as a durable biosorbent for adsorption of cationic dyes

In this work, an eco-firendly biosorbent was simply fabricated via self-polymerization of polydopamine on the porous pomelo peel. The composition and morphology of the obtained polydopamine modified pomelo peel (PP-PDA) were confirmed by Fourier transform infrared, emission scanning electron microscopy and Brunauer−Emmett−Teller surface area measurements, respectively. Next, the adsorption capacity of the PP-PDA towards various anionic and cationic dyes was investigated. Interestingly, the PP-PDA exhibited high adsorption capacity towards cationic dyes with the maximum adsorption capacities of 434.78 mg/g for methylene blue, 208.33 mg/g for neutral red and 143.88 mg/g for malachite green, respectively. Due to this adsorption feature, the PP-PDA can achieve selective adsorption of cationic dyes from mixtures. Meanwhile, the adsorption kinetics and adsorption isotherms of the PP-PDA towards cationic dyes obeyed pseudo-second-order kinetic and Langmuir isotherm model, respectively. Additionally, the results presented that the adsorption capacity of the PP-PDA increased with the increment of pH value of the aqueous solution, however, its adsorption capacity decreased with increasing of the salt concentration. Most importantly, the fabricated PP-PDA could be easily regenerated, its adsorption capacity could be maintained well even after twenty cycles. Therefore, the as-prepared PP-PDA can be employed as a promising biosorbent for dye-contaminated wastewater of treatment.