abstract
Water pollution by toxic metals, especially by lead ions, is a serious environmental concern due to these metals' persistence, bioaccumulation, and toxicity. Aiming to reduce metal concentrations to non-toxic levels, this study analyzed the removal of lead from water through adsorption with bio-adsorbents. The adsorbent potential of the following four lignocellulosic byproducts were tested: walnut and chestnut shells, pine wood, and burnt pine wood. Removal rates of 97-99% were achieved at optimized conditions, i.e., at a pH of approximately 7, adsorbent dose of 4 g L-1, and 12 h of reaction. The BET specific surface area was between 1.74 and 4.85 m2 g-1. The pore size of the wood bio-adsorbent was 26.54 nm, and those of the remaining materials were between 5.40 and 7.33 nm. With R2 = 0.998-1.000, the kinetics fit the pseudo-second-order model better, suggesting that chemisorption is the dominant mechanism. Both Langmuir and Freundlich isothermal models fit the data well, with R2 = 0.946-0.999. It can be concluded that all the bio-adsorbents tested have the potential to efficiently remove lead ions from water.
keywords
AQUEOUS-SOLUTION; ACTIVATED CARBON; COMPETITIVE ADSORPTION; PB(II) IONS; METAL-IONS; BIOSORPTION; CU(II); PB2+; EQUILIBRIUM; KINETICS
subject category
Chemistry; Materials Science; Metallurgy & Metallurgical Engineering; Physics
authors
Macena, M; Pereira, H; Grosche, L; Esteves, B; Santos-Vieira, I; Cruz-Lopes, L
our authors
Isabel Cristina Maia da Silva Santos Vieira
Junior Researcheracknowledgements
This research was funded by national funds through the FCT-Foundation for Science and Technology, I.P., by a doctoral scholarship with the reference number 2023.03677.BDANA; by the CERNAS-IPV Research Centre under the project UIDB/00681, DOI 10.54499/UIDP/00681/2020; and by the Forest Research Centre (CEF), within the scope of the projects UIDB/00239/2020, DOI 10.54499/UIDB/00239/2020, and LA/P/0092/2020 of the Associate Laboratory TERRA, DOI 10.54499/LA/P/0092/2020.