Journal
ENVIRONMENTAL SCIENCE & TECHNOLOGY
Volume -, Issue -, Pages -Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.est.2c00828
Keywords
humic substances; proton titration curves; potentiometry; soft particle electrostatics; nanoparticles
Categories
Funding
- ANR [ANR-18-CE01-0008]
- Agence Nationale de la Recherche (ANR) [ANR-18-CE01-0008] Funding Source: Agence Nationale de la Recherche (ANR)
Ask authors/readers for more resources
Potentiometric acid-base titration curves of humic (nano) particles are influenced by the electrostatics and chemical charges of the particles. This study presents a method for accurately analyzing the titration curves using proton affinity spectra, allowing for a better understanding of the reactivity of the particles towards metals.
Potentiometric acid-base titration curves collected on humic (nano) particles as a function of pH and salt concentration reflect the electrostatics of the particles and the amount of chemical charges (Q) they carry. In turn, the interpretation of titration data helps quantify their reactivity toward metals provided that both intrinsic chemical and nonspecific electrostatic contributions to proton binding are correctly unraveled. Establishing a titration curve requires several steps, i.e., blank subtraction, relative curve positioning with respect to the electrolyte concentration, and absolute curve positioning achieved by the estimation of particle charge Q(0) at low pH. Failure to properly establish each step may lead to the misevaluation of nanoparticle charging behavior. Here, we report (i) a simple procedure to measure and position titration curves for humic substances (HS) versus salt concentration and (ii) an original approach for absolute curve positioning upon the exploitation of proton affinity spectra. The latter do not depend on Q(0) and they thus constrain the titration data analysis using the soft Poisson-Boltzmann-based titration (SPBT) formalism for nanoparticles in the thick electric double-layer regime. We illustrate the benefits of our approach by analyzing titration measurements for a large range of humic nanoparticles and by comparing the outcome with results from the literature.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available