Among the several chemical elements that may be present in water, potentially toxic elements (PTEs) are a class of compounds with high toxicity and persistence (depending on their concentration), generating several problems, including accumulating these elements in living organisms along the entire food chain. In turn, nanocellulose has unique properties, such as excellent mechanical properties, high stability, and high functionality. Besides, it has a large specific surface area and abundant hydroxyl groups. Despite all its advantages, nanocellulose can be modified to improve its adsorptive performance. In surface modification, functional groups are added to the surface structure of nanocellulose. One of these approaches involves the optimization of nanocellulose for metal removal in an aqueous solution using surface modification with methods such as anionization, cationization, or hydrophobization methods. This work aims to modify the cellulose nanostructures using a chelating agent derived from the diethylenetriaminepentaacetic acid molecule (DTPA) to remove Cr(VI), Cd(II), Zn(II), Mn(II), Ni(II), and Cu(II) from simulated water. The nanocellulose was modified in two different ways: The first was using a chelating agent derived from DTPA at concentrations of 1 and 3% by weight and implemented NaPO?H? (SHP) on the reaction. For surface modification using PS-DTPA (PrimerSurf-DTPA) chelating agent, an alkaline aqueous solution with pH 12 was initially prepared. The solutions were heated to approximately 70 °C and stirred for 24 h. After 24 h, the previously calculated nano cellulose weights were added considering 1% and 3% in solution, considering that nano cellulose and PS-DTPA were reacted in a 1:1 ratio. The samples remained under agitation at approximately 105 °C for 4 h. Besides, in addition to adding the volume of DTPA 40% considering 1% and 3% of the compounds to be dispersed in this solution, sodium hypophosphite (SHP) NaPO?H? was also added in the proportion of 5:1 of DTPA and SHP respectively. The solutions were heated to approximately 70 °C and stirred for 24 h. After 24 h, the 1% and 3% nanocellulose weights were added. The samples remained under agitation and heated at 105 °C for 4 h. The chemical groups present in nanocellulose and modified nanocelluloses were evaluated using Fourier transform infrared spectroscopy (FTIR); the particles' average size and the nanostructures' colloidal stability were evaluated DLS and Zeta potential, respectively; elemental analysis was performed to determine carbon, nitrogen, and hydrogen content before and after surface modification of the NECs using elemental analyzer, and metal ion sorption tests were conducted through a multielement evaluation of Cd(II), Zn(II), Ni(II), Mn(II), Cu(II), and Cr(VI) ions from a 0.3 mMol.L-1 solution, at pH 4.0 and room temperature, under agitation at 135 rpm, for 24 h, whose dosage of nanocellulose and modified nanocelluloses was 1g.L-1. These measurements were performed in ion chromatography. The modified nanocellulose showed distinct groups of the PS-DTPA chelating agent molecules compared to neat nanocellulose, as evidenced by groups C=O stretching vibration and the bending vibration of N-H of PS-DTPA chemical structure. Besides, a decrease in the elemental hydrogen concentration than CNS, and an increase in particle size of the cellulose nanostructure and the surface charges observed by the Zeta potential value, proving the change in surface charges of nanocellulose after modification with PS-DTPA, in 3% concentration by weight. As for the multielement removal of Cr(VI) and divalent metal ions, CNS showed a removal efficiency superior to Cr(VI) ions. However, a decrease in the removal of Cr(VI) was verified for nanostructures modified with PS-DTPA with and without sodium hypophosphite, still showing that the modification with 3% chelating agent was more satisfactory than 1%, having specificities in agreement with the presence of SHP. Without SHP, the modified nanocellulose had more significant removal for Cu(II), and modified in the presence of SHP, more significant removal of Ni(II) was verified. Therefore, an efficient modification was verified, whose modification with PS-DTPA and in the absence of SHP promoted better colloidal stability, particle size, and a tendency to remove all ions, highlighting Cu(II) and Cr(VI), unlike in the presence of SHP, which preferred to remove Ni(II) and Cr(VI), in greater removal efficiency.
Bem-vindo(a) aos Anais do VII NanoMat, evento organizado pela Pós-graduação em Nanociências e Materiais Avançados da Universidade Federal do ABC (UFABC) com o intuito de reunir e debater trabalhos desenvolvidos por alunos e pós-doutorandos em Materiais e áreas afins.
Comissão Organizadora
Pedro Alves da Silva Autreto
Andre Luiz Martins de Freitas
Aryane Tofanello
Comissão Científica
Ferramenta completa de submissão, avaliação e publicação de anais para eventos científicos.
