Evaluation of Sugarcane Straw Derived Biochar for the Remediation of Chromium and Nickel Contaminated Soil
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Date
2018-12-06
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Addis Ababa University
Abstract
Soil constitutes a crucial component of rural and urban environments. This fact is making role of
heavy and trace elements in the soil system an issue of global concern. Heavy metals constitute
an ill-defined group of inorganic chemical hazards, whose main source is anthropogenic
activities mainly related to fabrications. This accumulation of heavy metals soils can prove toxic
to the environment. The application of biochar to soil is one way of immobilizing these
contaminants through sorption by exploiting the high surface area of this material among its
other essential properties. This research examined the ability of sugar cane straw, an organic
waste material from sugar farm, derived biochar and ash to remediate soil contaminated with
heavy metals mainly Chromium and Zinc from the effluent of electroplating industry. Biochar
was produced by varying the temperature from 300°C to 500°C and ash at 700°C. The highest
yield (50%) was obtained at the lowest temperature (300°C). The proximate analysis showed ash
content of 42.8%, ultimate analysis with carbon content of 67.18%, the Hydrogen to Carbon ratio
of 0.54 and the results from FTIR analysis disclosed the organic nature of biochar. Methylene
blue absorption indicated its fine surface area and pore structure which increases with severity of
temperature. Biochar was mixed with soil with at a ration varying from 4%w/w to 10%w/w of
soil and the response variables was determined at a time interval of 150 days, 180days and
210days. As for ash (10% w/w), the characterization was performed at incubation time of
210days. The results of pH indicated that biochar (9.24) had a notable liming capacity of acidic
soil (4.8) by increasing it to 6.89 whereas ash increased it to 7.5. The immobilization capacity of
biochar was found to effected mostly by the highest production temperature (500°C) which was
75.5% for Chromium and 80.5% for Nickel. In addition, ash was shown to possess an
outstanding immobilization capacity of 95.5% and 90.5% for Chromium and Nickel respectively.
All in all, The results from these methods showed that biochar produced from this specific
biomass possesses the typical functional groups that enable it to store carbon, the appropriate pH
that could remediate acidic soil, a fine amount of macro and micro nutrients that would aid plant
growth.
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Keywords
Sugarcane Straw, Nickel Contaminated Soil, Chromium, Biochar