Experiment
1
Title
Analysis of dye using UV-Vis spectrophotometer
Introduction
Synthetic dyestuffs used extensively in textile, printing industries and their effluent being
discharged into surface water resource thus led to aquatic ecosystem pollutants. Dye wastewater
needs to be treated due to the high chemical and biological oxygen demands, suspended solids
and also the colour itself which easily being recognized by the human eye. Adsorption processes
are being widely used by various researchers for the removal of dye due to its simplicity,
inexpensiveness and efficiency.
Chemicals/
Materials
 1000 mg/L of malachite green
 Unknown concentration of malachite green solution
Apparatus
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Procedure
Volumetric flask (100 mL, 10 mL)
Pipette (1mL, 10mL)
Droppers
UV-Vis spectrophotometer
Quartz cuvettes (UV transparent)
Soft tissue (cuvettes wiping)
Beaker (100 mL)
1. Prepare 100 mg/L of malachite green solution from stock solution however
further dilution need to be conducted in order to have a 10, 8, 6, 4 and 2 mg/L
of malachite green for the calibration curve purposes.
2. Record the initial spectra of unknown malachite green using UV-Vis
spectrophotometer (618 nm).
3. Determine the concentration of the unknown sample using calibration curve
recorded in step 1.
Result
Concentration of
malachite green
Colour of
malachite green
solution
Absorbance value
2 mg/L
4 mg/L
6 mg/L
8 mg/L
10 mg/L
Unknown
concentration
Question
1. Draw the calibration curve for the malachite green standard solution.
2. Define ʎmax
3. What is the ʎmax for malachite green solution?
4. What is the concentration of unknown concentration?
Reference
1. Liu, Shihao & Wang, Shi & Lei, Chunsheng & Li, Ruyi & Feng, Siyang & Jin,
Qiyu. (2022). Study of the efficiency of g-C3N4-loaded P25 for photocatalytic
degradation of malachite green in aqueous and Pickering emulsion systems.
Journal of Materials Science: Materials in Electronics. 33. 10.1007/s10854022-07767-z.