Papers by Keyword: Electrokinetic

Abstract: Nearshore’s facilities are often require frequent and regular maintenance dredging in maintaining appropriate water depths and enlarging the access channel and turning basin. A large amount of sediment was spawned from the dredging work. The dredged marine sediments (DMS) are not apt to be used in construction activities because of its poor geophysical properties. The purpose of this research is to study the improvement in moisture content and strength of DMS by using electrokinetic (EK) method. DMS are classified as a high plasticity silt (MH) with 240.74 % of its natural water content. Stainless steel plate was invoked as the electrode, while distilled water (DW), citric acid (CA) and calcium chloride (CaCl₂) were applied as the stabilizing agents. The aforementioned stabilizers are electrically injected into the DMS which causing flow of the solutions through the pores in DMS under 50 V/m of applied direct current (DC). The results of treated DMS are presented in moisture content, undrained shear strength and SEM-EDX analysis. The EK treated DMS shows it increases in strength in the dry zone area after the 14 days treatment. The dry zone area was created near the anode and wet zone was made near the cathode. The application of calcium ions in the treatment had increased the strength and alters the pattern of the soil fabric. Largely, EK has significantly improved the quality of DMS even though the strength increase observed was not homogeneous throughout the specimen.

Abstract: Among the available methods of disposing sludge from water treatment is to dispose them in landfills or to deposit them at a certain location to form lagoons. Once fully deposited, the landfills or lagoons can be converted into a recreational area or even housing area depending upon the final strength of the sludge. An attempt to look into the possibility to stabilize and strengthen sludge from underground water source using electroosmotic method was carried out in a laboratory environment. Several samples of sludge containing predominantly ferrous oxide were placed in specially fabricated electro-osmotic cells. Direct current was then applied through the samples via copper electrodes at the two ends of the samples. All the samples were subjected to seven days of treatment with variation in the surcharge/load imposed and voltage applied on the samples. Results from the tests demonstrated positive effects on the treated sludge samples. There were significant increase in the shear strength and reduction of moisture content which could be an early indication that sludge which predominantly contains ferric oxide could be strengthen by means of electroosmotic stabilization.

Abstract: An analytical solution for pressure-driven electrokinetic flows in a narrow capillary is presented based on the Poisson–Boltzmann equation for electrical double layer and the Navier–Stokes equations for incompressible viscous fluid. The analytical solutions indicate that pressure-driven flow of an electrolyte solution in microchannel with charged solid wall induces a streaming potential, which is proportional to the flowrate and induces an electroviscous effect on flow. A device for measuring the electrokinetic flow rate and streaming potential is proposed.

Abstract: The natural and electrokinetic enhanced migration method was studied by the experiments in groundwater contaminated by heavy metal Pb in this work. The experimental results showed that the variation rule of Pb reflected that its migration was weak and the removal efficiency was only 9.30% near the anode in the natural seepage condition, but under the enhanced migration and remediation function, the pollutants could be enriched and removed faster, thus the removal efficiency of Pb was 46.72% near the anode at the end of experiment when the experimental voltage gradient was 0.28V/cm, which made known that this electrokinetic enhanced migration of Pb in contaminated groundwater was more effective method than that of natural seepage migration and enhanced the removal of contaminant in aquifer.

Abstract: Recently, material removal utilising electrokinetic phenomenon was proposed as an alternative to create material removal at the nanometric level [1]. The concept of the introduced material removal process is to impinge particles contained in the slurry, under the influence of hydrodynamic and electrokinetic effects, onto the workpiece with a predetermined velocity to create material removal on the surface. The material removal process proved to be feasible where the material removal rate was reported to be in the range of a few hundred nm/hr with a surface roughness of a few nm (RMS). This paper aims to look into the effect of the electrochemical dissolution on the material removal process since high voltages are involved during the material removal process. During the experimental study, electrochemical dissolution was observed and it contributed a certain proportion of the material removal process. However, the main material removal mechanism still relies on the mechanical action of the abrasive particles on the surface of the workpiece to create material removal during the process.

Abstract: With the demand for precise nanometric material removal with minimal defects, several non-contact ultraprecision machining techniques were developed over recent decades. The electrokinetic material removal technique [1] is one such method that allows material to be removed without any physical contact between the tool and the workpiece. In this work, the influence of the slurry mixture on the material removal rate for the electrokinetic material removal process is studied. During the process, it was observed experimentally that the mixture of the slurry affected the material removal rate. The parameters varied in the slurry mixture experiments were the size and concentration of the particles. Explanations for the behaviour of the material removal rate were also suggested during the study to further understand the electrokinetic material removal technique.