Relationship of Chromium (Cr) mobility in soil and pH value using Electrochemical Method
Siti Khadijah C.O. 1, Sabariah A.2, 3Zuliziana S., Jestin Jelani4, Nordila A.5
1,3,4,5 Lecturer, Civil Engineering Department, Faculty of Engineering, Universiti Pertahanan Nasional Malaysia 2 Lecturer, Faculty of Civil Engineering Universiti Teknologi Mara, Selangor, Malaysia Email : firstname.lastname@example.org
Abstract: Heavy metal contamination may provide a better indication of the potential risk to the human life and soil environment. This paper investigates the relationship of chromium (Cr) mobility in soil with respect to pH performance using an electrochemical method. Experiments were conducted on kaolin, which prepared as a fully saturated soil sample spiked with chromium (Cr) in 1000ppm concentration. A total of four different tests was conducted, and each of the tests is divided equally into two sample preparation. A DC power supply is used to achieve electric field strength of 5 V/cm and 10V/cm. The total duration of tests is six hours and the result was taken and recorded at every one hour. The pH value of the soil significantly affects the mobility of heavy metal ions. The mobility of chromium (III) in the soil using the electrochemical method was achieved by considering changes of pH values during experimental works. The pH values are slightly increased at the initial experiment, but then started to decrease after four hours for sample preparation 1 and after three hours for sample preparation 2. The results showed that the increased experimental time induced a higher mobility of chromium in soil due to the changes in pH value.
Key Words: chromium (Cr), electrochemical method, electrolysis process, mobility, pH value
Heavy metals, particularly chromium, lead, nickel, cadmium, mercury, arsenic, and zinc, is a major public health concern at many contaminated sites (U.S. EPA 1995). Heavy metal contamination of soils stills an unsolved problem, although metals are associated with human life and have been widely used for thousands of years. Soil can be contaminated with heavy metals deriving from various sources, including waste from abandoned mines, improper treatment of industrial wastes, incomplete collection of used batteries, leakage of landfill leachate, accidental spills, and military activities (Kim et al., 2005). When introduced into soils, heavy metal compounds are hazardous pollutants because they are not biodegradable, toxic at the relatively low concentrations, and they may be mobilized under changing physicochemical conditions like, redox potential or pH (Stegmann et al., 2001).
Lately, there is growing concern worldwide surrounding issues of soil contamination from a large range of pollutants. The accumulation of heavy metal in soil is of interest because of the adverse effect heavy metals may pose to food quality, soil health and the environment. Experimentally, heavy metals become toxic when they are not metabolized by the body and accumulate in the soft tissues. For instance, it’s may enter the human body through food, water, air, or absorption through the skin when they come in contact with humans. With increasing of heavy metal contamination in the soil environment due to various human and natural activities, further contaminants will be affecting the ecosystems. Chromium is one type of heavy metals that usually contribute to the contaminated soil besides others such as lead, iron, zinc, copper, nickel, cadmium, arsenic, and uranium. There are elements, which can be harmful to people, animals and plants. Moreover, the effects of this contamination are often poorly understood because lack of knowledge about these hazards among people. This phenomenon may lead an increase of various problems to the unhealthy ecosystem. Therefore, there is a need to gain better understanding the behaviour of chromium as well as the other heavy metals which may be risk...
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