Valorization of carnauba straw and cashew leaf as bioadsorbents to remove copper (II) ions from aqueous solution

• Published in: Environmental technology & innovation 2021-08, Vol.23, p.101706, Article 101706
• Main Authors: Pereira, Jéssyca E.S., Ferreira, Ruan L.S., Nascimento, Paula F.P., Silva, Alfredo J.F., Padilha, Carlos E.A., Barros Neto, Eduardo L.
• Format: Article
• Language: English
• Subjects: Biomass; Biosorption; Heavy metals; Solid waste
• ISSN: 2352-1864; 2352-1864
• DOI: 10.1016/j.eti.2021.101706

This work proposes the use of cashew leaf (CL) and carnauba straw (CS) powders as natural bioadsorbents to remove cooper (II) ions from aqueous solution. The bioadsorbents were evaluated from physical nitrogen adsorption (BET), thermogravimetry (TGA), scanning electron microscopy (SEM), infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The parameters studied were: pH effects, bioadsorbent dose and particle size. The adsorption experiments for both powders showed a low equilibrium time of about 120 min. The adsorption kinetics followed for both bioadsorbents the pseudo-second order model. The experimental CS data were best adjusted by the Langmuir monolayer model while the CL data were adjusted for the Freundlich model. For the same experimental conditions, the maximum adsorption capacity of copper (II) was 9.51 mg/g and 1.73 mg/g for CS and CL powders, respectively. Therefore, the results described in this study value the use of native plant residues to remove copper (II) ions in order to provide a more suitable destination. •The use of plant waste as adsorbents has been investigated.•Both biosorbents presented functional groups that favor the adsorption process.•Kinetic equilibrium was achieved after 120 s of reaction.•Carnauba straw powder was more efficient in removing copper (II) ions.