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.

In-situ study of electrochemical migration of tin in the presence of bromide ion

The miniaturization of electronic devices and the consequent decrease in the distance between conductive lines have increased the risk of short circuit failure due to electrochemical migration (ECM). The presence of ionic contaminants affects the ECM process. This work systematically investigates the ECM of tin (Sn) in the presence of bromide ions (Br−) in the range of 10−6 M to 1.0 M. Water drop test (WDT) was conducted in the two-probe semiconductor characterization system under an optical microscope as an in-situ observation. Polarization test was carried out to study the correlation between the corrosion properties of Sn and its ECM behaviour. The products of ECM were characterized by scanning electron microscope coupled with an energy dispersive X-rays spectrometer (SEM/EDX) and X-ray photoelectron spectrometer (XPS). The results confirm that the rate of anodic dissolution of Sn monotonously increases with the Br− concentration. However, the probability of ECM failure follows a normal distribution initially, but later increases with the Br− concentration. The main products of the ECM reactions are identified as Sn dendrites and tin hydroxide precipitates. The mechanisms of the ECM process of Sn in the presence of Br− are also suggested.

Sustainability in ElectroKinetic Remediation Processes: A Critical Analysis

In recent years, the development of suitable technologies for the remediation of environmental contaminations has attracted considerable attention. Among these, electrochemical approaches have gained prominence thanks to the many possible applications and their proven effectiveness. This is particularly evident in the case of inorganic/ionic contaminants, which are not subject to natural attenuation (biological degradation) and are difficult to treat adequately with conventional methods. The purpose of this contribution is to present a critical overview of electrokinetic remediation with particular attention on the sustainability of the various applications. The basis of technology will be briefly mentioned, together with the phenomena that occur in the soil and how that will allow its effectiveness. The main critical issues related to this approach will then be presented, highlighting the problems in terms of sustainability, and discussing some possible solutions to reduce the environmental impact and increase the cost-effectiveness and sustainability of this promising technology.

In-Situ Study of Electrochemical Migration of Tin in The Presence of Bromide Ion

The miniaturization of electronic devices and the consequent decrease in the distance between conductive lines have increased the risk of short circuit failure due to electrochemical migration (ECM). The presence of ionic contaminants in the devices can accelerate the ECM process. This work systematically investigates the ECM of tin (Sn) in the presence of bromide ions (Br−) in the range of 10-6 M to 1.0 M. Water drop test (WDT) was conducted in the two-probe semiconductor characterization system under an optical microscope for in-situ observations. Anodic polarization test (APT) was carried out to study the correlation between corrosion properties of Sn and its ECM behaviour. The products of ECM were characterized by scanning electron microscope coupled with an energy dispersive X-rays spectrometer (SEM/ EDX) and X-ray photoelectron spectrometer (XPS). The results confirm that the rate of anodic dissolution of Sn monotonously increases with Br− concentration. However, the probability of ECM failure follows a normal distribution initially, but later increases with the Br− concentration. The main products of the ECM reactions are identified as Sn dendrites and tin hydroxide precipitates. The mechanism of the ECM process of Sn in the presence of Br− is also suggested.

Architecting highly hydratable polymer networks to tune the water state for solar water purification

Water purification by solar distillation is a promising technology to produce fresh water. However, solar vapor generation, is energy intensive, leading to a low water yield under natural sunlight. Therefore, developing new materials that can reduce the energy requirement of water vaporization and speed up solar water purification is highly desirable. Here, we introduce a highly hydratable light-absorbing hydrogel (h-LAH) consisting of polyvinyl alcohol and chitosan as the hydratable skeleton and polypyrrole as the light absorber, which can use less energy (<50% of bulk water) for water evaporation. We demonstrate that enhancing the hydrability of the h-LAH could change the water state and partially activate the water, hence facilitating water evaporation. The h-LAH raises the solar vapor generation to a record rate of ~3.6 kg m−2 hour−1 under 1 sun. The h-LAH-based solar still also exhibits long-term durability and antifouling functionality toward complex ionic contaminants.

Lithosphere Protection with Hardening Phosphate-Containing Soil-Cement Technology

This research is relevant in the light of a need to protect lithosphere from pollution. A solution to this problem can be the exercise of a geoecoprotective function by using building and construction technologies. Phosphate-containing bonding agents usually have low solubility in water. They are made of aluminosilicates that occur in common clay. These minerals react with phosphoric acid to release phosphates and silica gel with absorption properties. The purpose of this research is to make fake rocks from phosphate clay material, intended for building and construction purposes, and to investigate their longevity. The material used was treated to neutralize and detoxify the mobile ionic contaminants and heavy metal compounds, as well as petroleum pollutants, so that at the end we could get construction material like fake rocks or improved aggregates that would be good for the environment. These cement systems are called the geoecoprotective systems. The leading methods that were applied were thermodynamic and experimental studies of service and geoecoprotective properties of phosphate-containing cement systems, more specifically fake landscape rocks. Selected studies lasted for more than 10 years, and were carried out in accordance with the guidelines, adopted in the Russian Federation. This research shows that phosphate-containing cement systems made from contaminated clay/sandy artificial soils have long-lasting properties like strength, frost resistance, water resistance and contaminant binding. From this perspective, they are good for building and construction. For example, they can be used to improve the contaminated soil on road construction sites by detoxifying it until water-resistant products, and to make long-lasting water-resistant solutions from local raw materials that would be good for waste storage.