Determination of Orthophosphate by Using the Vanadomolybdo Phosphoric Acid Colorimetric Method

DETERMINATION OF ORTHOPHOSPHATE
BY USING THE VANADOMOLYBDO
PHOSPHORIC ACID COLORIMETERIC
METHOD
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ABSTRACT

ORTHOPHOSPHATEBY USING THE VANADOMOLYBDO PHOSPHORIC ACID COLORIMETERIC METHOD
In this experiment, the main purpose was to find out the absorbance versus the
concentration of samples placed in flasks with different concentrations of working
phosphate solution. After introducing the different concentrations of the sample into the
spectrophotometer, the results were recorded and analyzed. The concentration range used
was divided into three categories for three selected wavelengths and a calibration curve
was drawn. The study of spectrophotometry deals with the interaction of light with
matter. Chemical substances can be categorized by the specific emission or absorption of
light. In this experiment, the analytical methods based on the amount of light that is
transmitted or absorbed when it passes through a sample.. Based on this concept, the
phosphorus concentration in a water solution is determined. The developed method helps
to determine the phosphorus content in traces of water with reduced reagent
consumption, low waste production and high sensitivity. (NEVES et al., 2008)
OBJECTIVES
To identify the components and functions of different components of a UV / Vis
spectrophotometer
Preparation of a set of standards for calibration
Measurement of the absorption of solutions at the specified wavelength.
Application of Beer-Lambert Law to find out the concentration of a colored species in
solution.
To draw and make use of calibration curves to determine the concentration of
phosphorus in the analytical solution (Worsfold et al., 2016)
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ORTHOPHOSPHATEBY USING THE VANADOMOLYBDO PHOSPHORIC ACID COLORIMETERIC METHOD
INTRODUCTION
Phosphorus is found in abundance as phosphate in natural water and wastewater. These
phosphorus is classified as, condensed phosphates (pyro-, meta- and other
polyphosphates) and orthophosphates and phosphates in the form of organic
compounds. They are found in many solutions in the dissolved form , in many particles
or detritus or in the aquatic organisms like fish etc.
These phosphates actually is found because they are coming from different sources.
Some water supplies are treated with small amounts of condensed phosphate during the
treatment. Because of these compounds are used in our washing and cleaning processes,
they contribute to the major share of the phosphorus found in water bodies like lakes,
rivers etc. Phosphates, which are used as fertilizers in irrigation lands are swept away by
storm water into surface waters and to a lesser extent with snow. Phosphates found in
organic materials are formed due to biological processes. .Because of that the sewage
water which contain waste of these organic organisms , food residues and from biological
treatment processes in the form of orthophosphates contribute to high phosphorus
percent.
Phosphorus is known to be the major nutrient needed for algae growth in inland
landscapes (Federation 2005). The accelerated eutrophication is one of the major
challenge of the nation's water bodies.. Eutrophication, caused by too many nutrients in
the water, can cause a number of water quality issues, including fish deaths, harmful
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ORTHOPHOSPHATEBY USING THE VANADOMOLYBDO PHOSPHORIC ACID COLORIMETERIC METHOD
odors and odors, clogged piping, and limited recovery. In freshwater, phosphorus is
responsible for accelerated eutrophication. Many algal blooms in rivers and lakes are
attributed to increased phosphorus levels due to human activities. The reason for
phosphorus contamination in water bodies is because of waste water from agriculture,
industry and urban sewage treatment plants. (Adams, 2017)
There is no criteria in place regarding what should be the concentration of phosphorus
compounds in water, Anyway to arrest EPO and eutrophication, there are some
recommendations (Jastrzębska, 2009) followed in some countries listed below :
• The phosphates content should not cross 50 μg / l ( phosphorus) at the entry point of a
lake or reservoir.
• Total phosphorus in small waterways which do not flow into lakes or reservoirs should
not exceed 100 μg / l.
Municipal wastewater treatment plants are required to be established in more areas to
remove phosphorus in their treatment plants .Though biological treatment plants can
remove some quantum of phosphorus ,but phosphorus precipitation in the form of
insoluble metal phosphates is required to be treated in most cases to meet the discharge
requirements. (Grobbelaar, 2013)
The removal of insoluble phosphorus involves two steps: (a) conversion of insoluble
phosphorus to dissolved orthophosphate and (b) to determine quantum of dissolved
orthophosphates using calorimetric method. (Nagarkatti, 1991)
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