Abstract
The stability of graphene oxide (GO) in water is extremely relevant because of its application as an adsorbent material, as well as for its fate and behavior in the environment. Zeta potential was used to study the effect of secondary salts (carbonate, sulfate, and phosphate), temperature (20 to 60 °C), and pH (5 to 9) on the stability of six different GOs produced from natural, synthetic, and amorphous graphite—with and without the use of attrition milling. Generally, GOs produced with attrition-milled graphites had lower ζ-potentials than their unmilled counterparts because of their smaller particle sizes and higher concentration of oxygen-containing functional groups. It was observed that GO produced from graphite and synthetic graphite had ζ-potential values lower than −30 mV, even at 30 °C. However, it was observed that all the GOs studied were unstable in the presence of carbonate and sulfate salts at concentrations between 170 and 1695 mg L−1, as they reached a ζ-potential of −4.1 mV. Density-functional theory electronic structure calculations suggested that the instability of GO in the presence of carbonate and sulfate was caused by the abstraction of a proton resulting in interaction energies Eint of 28.3 and 168.9 kJ mol−1, respectively. Our results suggest that temperatures above 30 °C, as well as carbonate and sulfate salts at concentrations relevant to arid and semi-arid regions, could promote the formation of agglomerates of GO, thus limiting its use and mobility in water.
Original language | English |
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Pages (from-to) | 2435-2443 |
Number of pages | 9 |
Journal | Nanoscale Advances |
Volume | 4 |
Issue number | 11 |
DOIs | |
State | Published - Apr 22 2022 |
Funding
This work was supported by a grant from the Secretar\u00EDa de Energ\u00EDa and Consejo Nacional de Ciencia y Tecnolog\u00EDa (SENER-CONACYT) as part of the Mexican Centre for Innovation in Ocean Energy (CEMIE-Oc\u00E9ano, project number 249795). The authors would like to acknowledge CONACYT for the PhD scholarship awarded to S. Mancillas-Salas and A.C. Reynosa-Mart\u00EDnez. JBF thanks DGTIC\u2014UNAM for granting access to their supercomputer known as \u2018Miztli\u2019 and to Ms. Citlalit Mart\u00EDnez-Soto for keeping local computing facilities running.
Funders | Funder number |
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Consejo Nacional de Humanidades, Ciencias y Tecnologías | |
Secretaría de Energía | |
Mexican Centre for Innovation in Ocean Energy | |
Centro Mexicano de Innovación en Energía Océano | 249795 |
Centro Mexicano de Innovación en Energía Océano |