The proton binding properties of biosorbents

Abstract

A broad variety of materials of biological origin have been successfully used in 27 recent decades for the removal of pollutants from solution. These biosorbents 28 present a range of natural polymers that play a key role on their adsorption capacity. It is therefore critical to understand the physicochemical properties of the chemical groups that form these polymers. The acid-base properties of 31 biomass are affected by pH, ionic strength and medium composition. 32Nevertheless, these crucial parameters are not always considered during 33 biosorption studies. 34According to bibliography, less than 3% of biosorption papers include studies 35 on proton binding. Moreover, in 60% of these papers there is key 36 experimental information missing such as the calibration of the electrodes 37 employed in potentiometric titrations. We consider therefore that there is an 38 important need for reviewing the role of proton binding on biosorption studies. 39This paper outlines the major advances on proton binding data interpretation 40 and modelling on biosorbents. In addition, we propose some experimental 41 considerations that cover all issues raised in this paper concerning the acid-42 base properties of biosorbents. 43

Acid-base properties of dissolved organic matter extracted from the marine environment

“…Potentiometric titrations using glass/selective electrodes are routinely applied for the physicochemical analysis of e.g. biomass (Lodeiro et al, 2019) and fulvic and humic substances of terrestrial or freshwater origin (David et al, 2010;Koopal et al, 2005). In coastal waters like the Baltic Sea, a significant part of the DOM pool is of terrestrial origin and supplied by rivers (Deutsch et al, 2012;Hoikkala et al, 2015;Seidel et al, 2017), although overall a very small fraction of terrestrial DOM (b0.03%) is exported to the ocean (Cai et al, 1998;Carlson and Hansell, 2015;Dittmar and Stubbins, 2014).…”

Proton Binding Characteristics of Dissolved Organic Matter Extracted from the North Atlantic

“…The total amount of proton binding groups in the North Atlantic SPE–DOM ( Q maxH,tot ) was not significantly different between the surface (112.7 ± 5.8 mmol·mol C –1 ) and deep (117.3 ± 5.6 mmol·mol C –1 ) samples. The total proton binding represents a maximum of binding sites for chemical species that can compete with protons for the DOM binding sites, with a predominantly covalent behavior, 40 e.g., most trace metals in seawater. On average, 11.4 ± 0.6% of the C atoms in our extracted North Atlantic DOM therefore have a functional group with a binding site for ionic species.…”

Integrated valorization of Sargassum muticum in biorefineries

“…In particular, the mechanism of ion exchange exerts a fundamental control, at least for the retention of specific metals. In this context, the elevated proton binding capacity of Sargassum muticum (2.40-2.61 mol/kg of alga) anticipates success of micro-macronutrient amendments using this alga or its residues [69]. For example, S. muticum collected from the same geographical area as the specimens used for the present study showed adsorption capacities ranging between 1.12-1.42 mmol metal/g seaweed [23].…”