Use of electrochemical techniques to characterize methamidophos and humic acid specifically adsorbed onto Pt and PtO films

Abstract

Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed to study methamidophos (MAP) and humic acid (HM) specifically adsorbed onto Pt and PtO films in pH-7.0 universal buffer. The approach was found to be sufficiently selective for use in studies involving adsorption of species in environmental systems (e.g., soil minerals), typically evaluated by batch experiments and high performance liquid chromatography (HPLC) or gas chromatography (GC). The proposed method allowed quantification of active hydrogen adsorption sites blocked by HM, both when this compound is adsorbed alone or co-adsorbed with MAP. At higher amounts of MAP in the adsorption solution, the compound was co-adsorbed more effectively than HM (kept at constant concentration). In the case of sequential specific adsorption, the first compound adsorbed typically predominates over the second. EIS was more effective for determining the number of blocked active sites on Pt than CV, which was superior for PtO films.

Electrocoagulation and ultrasonic removal of humic acid from wastewater

“…Observation showed that HA removal at alkaline condition is not noticeable, however, at neutral and acidic pH, the HA removal was obvious. These findings were confirmed by other researchers . Considering the HA precipitation in acidic solution (pH <2) , the range 3–8 for pH was selected for the experiments.…”

“…They explained that small electrode interval, high current density, and lower pH value leads to higher removal rate of HA. Adsorption of HA on Pt and PtO films at neutral pH was investigated with the cyclic voltammetry (CV) and electrochemical impedance spectroscopy by Silva et al . Alsheyab and Muñoz used H 2 O 2 /O 3 , O 3 /UV and H 2 O 2 /O 3 /UV methods with 0.04 H 2 O 2 /O 3 at 20 min to remove synthetic humic solution; where 78% and 50% of TOC and COD, respectively, were removed and the best result was achieved with H 2 O 2 /O 3 .…”

“…They explained that small electrode interval, high current density, and lower pH value leads to higher removal rate of HA. Adsorption of HA on Pt and PtO films at neutral pH was investigated with the cyclic voltammetry (CV) and electrochemical impedance spectroscopy by Silva et al [30]. Alsheyab [31].…”

Tunable Adsorption and Film Formation of Mussel Adhesive Protein by Potential Control

“…Moreover, the width of the double-layer-charging zone is larger in the Mef p-1 solution, indicating that the adsorbed protein is subjected to an electrochemical oxidation/reduction in this region. 42 Pt oxidation and reduction processes occur in region III. The oxidation of Pt in acidic solutions involves the following two steps: the discharge of H 2 O, forming chemisorbed oxygen (eq 3), and interfacial place exchange, forming a quasi-3D lattice comprising Pt 2+ and O 2− (eq 4).…”

“…Despite the existence of an electrostatic repulsion between the sample and Mefp-1 molecules, the difference in curves a and b (Figure ) suggests the presence of the protein on the Pt surface. Moreover, the width of the double-layer-charging zone is larger in the Mefp-1 solution, indicating that the adsorbed protein is subjected to an electrochemical oxidation/reduction in this region …”