Buffer solution

About: Buffer solution is a research topic. Over the lifetime, 6948 publications have been published within this topic receiving 112440 citations. The topic is also known as: pH buffer & buffer.

V2O5/WO3 Mixed Oxide Films as pH-EGFET Sensor: Sequential Re-Usage and Fabrication Volume Analysis

Abstract: A vanadium and tungsten mixed oxide was deposited onto glassy carbon substrates and used as pH sensor in extended gate field effect transistor (EGFET) devices. WO3 at a molar ratio of about 5% was mixed with V2O5 by means of the sol-gel method. The main focus of this investigation was to determine the operation conditions for the best response of the device and to propose the mechanism involved in the sensor response. The use of either original or reused films were employed and the importance of the total volume of the starting solution was also examined. The time response of the V2O5/WO3-pH-EGFET sensor is due to a deprotonation mechanism of vanadium and tungsten oxide, similarly to a discharging capacitor. The loss of protons by the oxide film depends on the time it remains immersed in the buffer solution and this process is accelerated upon raising the pH value. The increase of the films fabrication volume reduces the importance of the changes of the surface charges compared to the charges of the bulk, leading to less sensitive and less stable sensor response. Therefore, the smaller the amount of material used, the better the sensing properties of the device.

Vaterite Synthesis via Gas–Liquid Route under Controlled pH Conditions

Abstract: The purpose of this work was to obtain precipitated calcium carbonate (PCC) particles in polymorphic form of vaterite via gas–liquid route in controlled pH conditions. The effect of CO2 concentration (12.5–100%), feed gas (CO2–air) flow rate, pH, and conductivity of solution upon the PCC particles properties was studied. On the basis of the experimental data, the main factors leading to vaterite formation as major product were established. It was found that the buffer solution has a decisive role in determining polymorphic phase of PCC while CO2 concentration and feed gas flow rate have no significant influence. It was demonstrated that spherical vaterite particles of high purity can be produced under controlled reaction conditions. Also, some considerations on the mechanism of carbonation process were formulated.