Preparation and use of a Grafted Silica with Imidazole Groups for Cadmium Sorption and Subsequent Voltammetric Detection of Ascorbic Acid

Abstract

Inorganic-organic hybrid materials, such as silica gel functionalized with an organic group, offer many applications in several areas of interest. The adsorptive properties provided by these materials due to the presence of active donor atoms such as O, N and S of grafted organic groups, suggests their application in metal ions adsorption as well as in the preparation of electrochemical sensors for substances of interest. In this work a hybrid material formed by interaction of a 3-chloropropyl silica gel modified with imidazole was characterized by techniques such as infrared spectroscopy, 29 Si and 13 C nuclear magnetic resonance and analysis of surface area and porosity. Adsorption studies were carried out for cadmium (II) in different media, and the quantity of adsorbed metal increased according the following order of solvents: water < ethanol 42% < ethanol 99%. After cadmium ions adsorption, the material was reacted with potassium hexacyanoferrate forming the material CdHSGI that was incorporated into a graphite paste electrode. Electrochemical studies were conducted with cyclic voltammetry. The cyclic voltammogram showed one redox couple with average potential E θ = 0.25 V (vs Ag/AgCl, NaNO 3 1.0 mol L −1 ; v = 20 mVs −1), attributed to the Fe 2+ (CN) 6 / Fe 3+ (CN) 6 process. The modified electrode allowed the electrocatalytic ascorbic acid determination. Through voltammograms it was possible to observe a linear range from 1.0 × 10 −4 mol L −1 to 9.0 × 10 −4 mol L −1 (R = 0.996) for the ascorbic acid determination with a Devaney Ribeiro do Carmo

Preliminary Evaluation of the Silica and Others Chemical Constituents of the Lyophilized Tea of Equisetum Arvense and Application of Its Biomass Wastes for Copper Adsorption

“…The adsorption is one of natural processes that results in immobilization and accumulation of a metallic ion, contained in a certain liquid, which fixes on a static solid surface the adsorbent (Datta et al, 2013). The adsorption process can be used to reduce the concentration of pollutant species when they are at levels above that are allowed to humans (Da Silveira et al, 2018).…”

“…The complete adsorption process can be described quantitatively by adsorption isotherms, which in constant temperature provides data related to adsorbed amount (Nf) and solute concentration (C) after the equilibrium be established (Da Silveira et al, 2018).…”