Determining Dye Solution Decoloration using a Low Cost Light-Dependent Resistor

Research on water treatment and purification is crucial for protecting the environment and safeguarding human health. Various efforts have been made to develop the most effective and efficient wastewater treatment techniques. One type of wastewater that has garnered significant attention is dye wastewater from the textile industry1-3. To evaluate the effectiveness of a treatment method or process, several tests and measurements must be performed. A key measurement in dye wastewater treatment is the assessment of the solution's decoloration after treatment. Typically, this is done using a UV-Vis spectrometer4-7, though other measurement methods have also been reported8,9. Assembling a low-cost ($20 - $30) light-dependent resistor (LDR) and measuring the color degradation of a solution provides students and opportunity to learn about light trasnmitance and contect for how spectroscopy is applied in real life.This study aims to demonstrate how Lambert-Beer's law can be used in an affordable and practical task to determine the percent color degradation of a solution, providing students with a hands-on project as an alternative to using a commercial colorimeter. Through this project, students can apply fundamental physics principles to build simple measuring devices. Students will not only take measurements and record their findings but also gain experience in assembling measurement instrument components, measuring samples, processing data, obtaining measurement results, and comparing those results with standard tools. Therefore, this work can be used as an implementable student laboratory activity.