Superhydrophobic and corrosion resistant properties of electrodeposited Ni-TiO2/TMPSi nanocomposite coating

Evaluation of zinc adsorption through batch and continuous scale applying Bayesian technique for estimate parameters and select model

This work aims to study the efficiency of zinc adsorption onto granular-activated carbon, predicting the mathematical models that best describe the adsorption behavior in a fixed bed column. First, batch scale experiments were performed to evaluate the influence of pH (3 to 6), contact time (5 to 60 min), and absorbent concentration (5 to 25 g L^-1) using synthetic effluent. Fixed bed column experiments were performed by varying the adsorbent concentration (10, 13, 20, and 40 g L^-1) and the effluent flow rate (15 and 20 mL min^-1). Markov Chain Monte Carlo and Bayesian criteria information were applied to describe the phenomena using Langmuir, Freundlich, Temkin, Redlich-Peterson, Sips, Toth, Khan, Radke-Prausnitz, for isotherm models, and Thomas; Yoon-Nelson; Yan; Clark models for breakthrough curve. Adsorption operating best conditions were pH 5, 20 g L^-1 of solid, and 50 min of contact time. These parameters allowed 80% of Zn removal, being better described by the Tempki model. In tests on a pilot plant, the Yan model was able to predict the second-order kinetic model, with an increase in the effluent flow and a 50% increase in the bed saturation time with a greater amount of adsorbent solid.

Influence of Silica Particle Size on the Corrosion Behavior of Electroplated Silica-Ni Hybrid Layer

Silica-Ni hybrid layers were electroplated on a Q235 steel plate in a Watt nickel plating solution with varying sizes of silica, and a pure nickel layer was prepared as a blank sample. The surface morphology, composition, and crystal structure of the electroplated layers were examined using a field emission scanning electron microscope (FESEM), an energy-dispersive spectrometer (EDS), and a X-ray diffractor (XRD). The corrosion resistance of the samples was evaluated by the experiments of potentiodynamic polarization, electrochemical impedance spectroscopy, and salt spray test in NaCl solutions. The results showed that the smaller the particle size of silicon, the higher the content of silicon in the layer was, and the better the corrosion resistance of the layer was. However, when the particle size is 10 nm, agglomeration would happen, which leads to a decrease in the corrosion resistance performance, 50 nm silica-Ni hybrid layer showed the optimal corrosion resistance with the highest silica content.

Effect of Substrate Grain Size on Structural and Corrosion Properties of Electrodeposited Nickel Layer Protected with Self-Assembled Film of Stearic Acid

In the present study, the impact of copper substrate grain size on the structure of the succeeding electrodeposited nickel film and its consequent corrosion resistance in 3.5% NaCl medium were evaluated before and after functionalization with stearic acid. Nickel layers were electrodeposited on two different copper sheets with average grain size of 12 and 25 µm, followed by deposition of stearic acid film through self-assembly. X-ray diffraction analysis of the electrodeposited nickel films revealed that the deposition of nickel film on the Cu substrate with small (12 µm) and large (25 µm) grains is predominantly governed by growth in the (220) and (111) planes, respectively. Both electrodeposited films initially exhibited a hydrophilic nature, with water-contact angles of 56° and <10°, respectively. After functionalization with stearic acid, superhydrophobic films with contact angles of ~150° were obtained on both samples. In a 3.5% NaCl medium, the corrosion resistance of the nickel layer electrodeposited on the copper substrate with 25 µm grains was three times greater than that deposited on the copper substrate with 12 µm grains. After functionalization, the corrosion resistance of both films was greatly improved in both short and long immersion times in 3.5% NaCl medium.