Direct Electric Potential Research Articles

Evaluating plant micronutrient retention using an electric potential around the root zone in Rice (Oryza sativa L.)

Deficiency in micronutrients lead to poor health and performance in plants and hidden hunger in many developing countries. This could be inherited by unavailability micronutrients around the root zone especially, in rice, where water logged conditions are maintained. Hence, adding electric potential around the root zone to retain micronutrients would be a beneficial. Therefore, this study was designed to evaluate the effect of direct electric potential (EP) in retaining soil nutrient around the root zone using iron as an index ion. The experimental setup consisted of two concentric iron mesh pots, inner pot connected to the negative end and outer pot connected to the positive end. An electric potential of 5.0 V was supplied with the direct current of 0.1 A for 8 hours per day. Soil was characterized for available iron (Fe) content around three zones at the time of panicle initiation and time of harvest using ICPMS plant growth and performance was measured. At the time of panicle initiation soil-available Fe content was higher around the negative electrode than the positive electrode in plants supplied with EP (WEP).Plant height, above ground biomass, and paddy yield were significantly lower in WEP plants than the contol plants (P<0.05). WEP plants showed a 45% reduction in paddy yield compared to the NEP plants. Results confirms that Fe provided in the presence of an electric potential increases the Fe concentration around the root zone and enhances the Fe absorption. This underpins the use of electric potential to retain micronutrients especially, cations around the root zone ultimately enhancing their availability for plants.

A Multiphysics Model for Evaluating Electrokinetic Remediation of Nuclear Waste-Contaminated Soils

With the widespread use of nuclear power, soil contamination by nuclear waste is causing increasing concerns around the world. Traditional technologies for soil remediation, such as geomelting, have limited uses due to high cost of energy. More sustainable solutions such as electrokinetic remediation using low direct current, within this context, are gaining more popularity for cleaning up contaminated soils. In this paper, a mathematical model was developed to evaluate the technique of electrokinetic remediation as a potential strategy for removing nuclear waste from variably saturated soils. Multiple species-driven mechanisms were coupled in one governing partial differential equation of high nonlinearity, which was then solved using the finite element method (FEM). The binding effect between transporting species and soil matrix was taken into account in the FEM model based on Langmuir adsorption isotherm. The numerical model was validated experimentally and then applied to evaluate the effectiveness and efficiency of electrokinetically removing a typical radioactive species from nuclear waste, uranium dioxide ions (UO22+). According to the predicted results, a soil sample at the dimensions of 10 cm in width and 10 cm in depth can be cleaned 12 h by applying a level of 8-V direct electric potential between two panel electrodes.

Peaty Soil Improvement by Using Cationic Reagent Grout and Electrokintic Method

Peat is known as soft soil with low shear strength and high compressibility. Electrokinetic injection technique is being used by applying a direct electrical potential across the soil specimens to improve physicochemical characteristics of the peat. Such applications cause electrochemical effects on the soil, leading to changes in the soil’s chemical, physical, and mechanical properties. This paper presents the results of the undrained shear strength, pH, water content across the electrokinetic box after injecting the cationic grouts. Four cationic grouts namely; calcium chloride, calcium oxide, Aluminum hydroxide, and sodium silicates were selected as grout. The microstructures of the stabilized peats were investigated by scanning electron microscopy and energy dispersive X-ray spectrometer analysis. The result showed that the cationic stabilizer injected by the electrokinetic technique could significantly increase the peat soil’s shear strength. Furthermore, the result showed that the effect of calcium oxide was the highest on the shear strength of peat due to its physico-chemical properties. The shear strength, pH and moisture content of peats across the electrokinetic box also altered depending on the used electrolytes and time.

Direct electrodeposition of a biocomposite consisting of reduced graphene oxide, chitosan and glucose oxidase on a glassy carbon electrode for direct sensing of glucose

We have electrodeposited a composite film consisting of graphene oxide, chitosan and glucose oxidase directly on a glassy carbon electrode (GCE) through electrochemical reduction of a solution of the 3 components under controlled direct electrical potential. The procedure takes only several minutes, and the thickness of the resulting film is uniform and controllable. The GOx has uncompromised bioactivity and exhibits reversible 2-proton and 2-electron transfer in presence of glucose. It therefore can be used amperometric sensing of glucose. The biosensor has a fast response (<3 s), a detection limit of 0.4 μM (which is 50-fold lower compared to the biosensor prepared by drop-casting solutions of the same materials onto an GCE), and a linear response in the 0.4 μM to 2 mM concentration range (which again is much better than that of the biosensor prepared by the drop-casting method). Other features include high reproducibility, long-time storage stability, and satisfactory selectivity. We presume that the direct single-step electrodeposition of this nanocomposite offers a promising approach towards novel types of highly sensitive and stable electrochemical biosensors.

Electrokinetic iron pan generation in unconsolidated sediments: implications for contaminated land remediation and soil engineering

Electrokinetic remediation is an emerging technology that has generated considerable interest as a technique for the in situ remediation of clay-rich soils and sediments. Despite promising experimental results, however, at present there is no standardised universal electrokinetic soil/sediment remediation approach. Many of the current technologies are technically complex and energy intensive, and geared towards the removal of 90% or more of specific contaminants, under very specific field or laboratory-based conditions. However, in the real environment a low-tech, low-energy contaminant reduction/containment technique may be more appropriate and realistic. Such a technique, FIRS (Ferric Iron Remediation and Stabilisation), is discussed here. The FIRS technique involves the application of a low magnitude (typically less than 0.2 V/cm) direct electric potential between two or more sacrificial, Fe-rich, electrodes emplaced in, or either side of, a contaminated soil or sediment. The electric potential is used to generate a strong pH (and E h) gradient within the soil column (pH 2–13), and force the precipitation of an Fe-rich barrier or “pan” in the soil between the electrodes. Geochemical and geotechnical data for FIRS-treated sediments from the Ravenglass estuary, Cumbria, UK indicate that the technique can significantly reduce contaminant concentration in treated soil, by remobilisation of contaminants and concentration on, or around, the Fe-rich barrier. Arsenic, in particular, seems highly amenable to the FIRS treatment, due to its solubility under the high pH conditions generated near to the cathode, and its marked geochemical affinity with the freshly precipitated Fe oxides and oxyhydroxides in the Fe barrier. Geotechnical tests indicate that the Fe barrier produced by the technique is practically impervious (permeability = 10 −9 m/s or less), and has moderate mechanical strength (UCS ∼11 N/mm 2). Notably, a large increase in shear strength in the treated soil near to the anode electrode (due to Fe cementation and/or dewatering) is also observed, without significant loss of porosity. The data indicate that the FIRS technique shows considerable promise as an in situ method for contaminated land remediation and soil water containment, and for improving the mechanical properties of soils (contaminated or otherwise) for civil engineering purposes.

Effect of electroosmosis on relative permeabilities of sandstones

Dynamic displacement experiments were performed to investigate the effect of electroosmosis on relative permeability. Berea sandstone cores, Arabian light crude oil and a 20 g/l NaCl aqueous solution were used. Direct electrical potential gradients of up to 3 V/cm were applied across the core with the cathode placed at the injection end. The application of the electrical potential gradient increased the oil relative permeability and decreased the water relative permeability. The changes in relative permeabilities increased with increasing the applied electrical potential gradient. The breakthrough water saturation at the outlet end generally shifted towards successively higher values with increasing electrical potential gradients, and the two-phase flow period increased resulting in higher breakthrough and ultimate recoveries.

Investigation of waterflooding under the effect of electrical potential gradient

An experimental study has been conducted to investigate the effect of electrical potential gradient on oil recovery, water, production and water-oil ratio during water flooding. The experiments were performed using a linear model packed with 30 40 mesh sand. Oil of 28.7° API gravity and water having 30,000 ppm NaCl were used in the experiments. Direct electrical potential gradients ranging from 0.5 to 7.5 V/cm were examined. The potential gradient was applied across the oil-water bearing formation such that the injection end was the cathode and the production end was the anode. It was found that the application of the direct electrical potential gradient results in increasing the oil recovery and reducing water production and water-oil ratio ( WOR). Further, these effects were directly proportional to the increase in the applied electrical potential difference, and were only appreciable after water breakthrough.