Evaluating the Performance of Aluminum Sacrificial Anodes with Different Concentration of Gallium in Artificial Sea Water

In this manuscript, the influence of gallium content additions of Al-Zn-In-Mg alloy was investigated through electrochemical techniques and microstructure observation in 3.5 wt% NaCl solution. The results indicated that Al-Zn-In-Mg-0.03Ga alloy has the best discharge performance among all alloys. We propose that this is due to the fact that gallium addition to the Al-4Zn-In-Mg alloy improves the discharge activity of the alloy as well as elevating its anodic efficiency. In particular, the effect of gallium addition to improve discharge activity tends to be a parabolic curve, in which there is an increase when the gallium is first added that rises to the maximum anode current efficiency of about 98.25% whenever gallium content is 0.03 wt%.

Sulfate (SO4 2−) removal by electrocoagulation process under combined electrical connection of electrodes

Inorganic compounds in water can have detrimental effects on human health and the environment due to the high toxicity level of these ionic contaminants. This study assessed the efficiency of electrocoagulation process for removing sulfate (SO4 2−). The technology of electrocoagulation depends mainly on electrical applied that produce coagulant species in a certain position via electro-dissolution of sacrificial anodes which are often made of iron or aluminum. EC process illustrated great potential as a vital method in eliminating numerous types of contaminants including inorganic contaminants at a lesser cost, and ecologically friendly technique. In the present study, aluminum materials were utilized in both cathode and anode electrodes. Water samples were obtained from Sawa Lake, Al-Muthanna Province located in Iraq. Electrocoagulation formations with static electrodes were used under mutual electrical connection. The effects of the different variables such as pH, current density, inter electrode distance, reaction time and stirring speed were scrutinized to obtain a higher removal of SO4 2−. Preliminary outcomes exhibited the following optimal and functional conditions; pH = 8, current density = 0.8A, reaction time (RT) = 80 min, IED = 1 cm, temperature = 27 °C and agitation speed = 500 rpm. The maximum removal efficiency of SO4 2− is 88 %. The present statistical rates proved the effectiveness of EC method in terms of removing salts from lake water.

The Effect of Increasing the Amount of Indium Alloying Material on the Efficiency of Sacrificial Aluminium Anodes

Al-Zn-In alloys having 4.2% zinc content and various indium content in the range of 0.02–0.2% were tested with respect to the most important electrochemical properties of sacrificial anodes in a cathodic protection, i.e., the current capacity and potential of the operating anode. The distribution of In and Zn in the tested alloys was mapped by means of the EDX technique, which demonstrated that these elements dissolve well in the alloy matrix and are evenly distributed within it. The current capacity of such alloys was determined by means of the method of determining the mass loss during the dissolution by a current of known charge. The results obtained demonstrate that the current capacity of Al-Zn-In alloy decreases with the increase in the In content, which results in an increased consumption of anode material and shorter lifetime of anodes. With 0.02% In content, the capacity amounted to approx. 2500 Ah/kg, whereas the alloy with 0.2% In had as much as 30% lower capacity amounting to approx. 1750 Ah/kg. Microscopic examination for the morphology and surface profile of the samples after their exposure demonstrated that a higher indium content in the alloy results in a more uneven general corrosion pattern during the dissolution of such alloy, and the cavities (pits) appearing on the alloy surface are larger and deeper. As the indium content is increased from 0.02% to 0.05%, the Al-Zn-In alloy potential decreases by about 50 mV to −1100 mV vs. Ag/AgCl electrode, which is advantageous in terms of using this alloy as a sacrificial anode. When the indium content is further increased from 0.05% to 0.2%, the potential of the alloy is no longer changed to a more negative one. The results obtained from all these tests demonstrate that alloys containing up to 0.05% of In additive are practically applicable for cathodic protection.