Simplified Low-Cost LED Nephelometer and Turbidity Experiments for Practical Teaching

Abstract

This work describes the design and testing of a low-cost light-emitting diode (LED)-based nephelometer for turbidity analysis. It also describes the use of this nephelometer for context-based learning (CBL) experiments designed for teaching laboratories. The LED nephelometer is simple, low-cost, and robust, providing similar results as a commercial device. Data collection and analysis is quick and intuitive, allowing time and opportunity for discussion about the analytical process and the chemistry involved. The experiments described here are based on real-world applications to emphasize the usefulness of chemical analysis and quantification of turbidity in everyday life.

A new Desmodesmus sp. from the Tibetan Yamdrok Lake

“…According to the above values, fit the absorbance algae concentration curve and establish the linear regression equation. The same was done for algal turbidity and the concentration curve [23,24].…”

Taking School Instrumentation One Step Forward: A Do-It-Yourself Type Spectrophotometer and a Jupyter Notebook That Enable Real Time Spectroscopy during School Lessons

“…The introduction of spectroscopy in schools worldwide faces a significant challenge: the commercially available analytical instruments are relatively expensive. Moreover, even when available, their educational impact is up to a point questionable, since there is always the problem of students viewing them as black boxes. − In order to diminish instrument cost and properly discuss instrumentation in the classroom, the construction of several do-it-yourself (DIY)-type devices has been reported in the past decade, e.g., spectrophotometers, ,− single wavelength spectrophotometers, − fluorometers, ,,,,,,− atomic emission spectrophotometers, polarimeters, nephelometers, and Raman spectrometers, , many of which contain “smart” phones as optical detectors. − Despite the fact that most of them are well built, their main drawback, when the discussion comes to full wavelength scanning, is that they require time-consuming postprocessing of the acquired spectral images, e.g., with ImageJ, Spectral Workbench, or other relative software.…”

Waste Iron Oxidation Reaction-Assisted Electrochemical Flocculation for Rhodamine B Extraction from Wastewater: A Hands-On Experiment for Undergraduates

“…Achieving global carbon neutrality can be effectively accomplished through the implementation of pollution reduction and carbon emission reduction strategies. − Wastewater from various industries poses a significant threat to the environment, ecology, and human living. − The detection and purification of water quality are particularly important . Generally, the nephelometer, colorimeter, and turbidity are used for water quality detection. − Traditional techniques of removing pollutants from wastewater via chemical oxidation can be energy-intensive and emit carbon, nitrogen, and sulfur species, making it urgent to find alternative methods that do not produce secondary pollution. − Flocculation is a highly effective technique for extracting dye molecules and heavy ions from wastewater through static adsorption, without oxidizing the pollutants into gaseous species. , Recent studies have explored the use of biocoagulants extracted from Moringa oleifera seeds for coagulation-flocculation processes to treat paint wastewater, achieving a significant reduction in turbidity with a yield of 99.9% under optimized conditions . Electrochemical flocculation, with its excellent adsorption capacity, has also been found to apply to water purification and can be integrated with other chemical processes to achieve greater value .…”