A HOMEMADE SPIN COATER BASED ON ELECTRONIC WASTE: A VERSATILE AND LOW COST ALTERNATIVE. High-precision equipment generally represents a significant portion of a laboratory budget, leading the access by laboratories with limited financial resources difficult. Then, adaptation of materials such as electronic trash may be a key factor to overcome financial obstacles. As the technological advancement brings with it an increase in the disposal of pieces of equipment considered obsolete, these pieces however can still be used in the construction of new equipment. The present work shows the employment of a scrapped computer HD in addition to an Arduino microcontroller and other electronic components to build a low-cost spin coater. The thickness of films obtained in the handmade equipment presented approximately five percent of difference in relation to films obtained in a commercial equipment.

There is a global concern with pollutants and organic contaminants and efficient and inexpensive methods are sought for the treatment of these toxic products. Generally, large volume reactors and the use of expensive equipment are required to monitor a photoreaction. The present work proposes the construction of a colorimetric equipment, which allows the online monitoring of photoreactions, using low-cost materials that allow the analysis from small aliquots. To show the applicability of the system, we studied the reduction reaction of 4-nitrophenol (4NP) with NaBH4. The impedimetric sensor enabled to construct the kinetic curve of the decrease in the chromophore band. It was possible to observe that the 4NP reduction reaction depends on: (i) chromophore concentration; (ii) stability of the reducing agent and; (iii) repulsion between the anions. The system developed here opens doors, as it can be used using a photocatalyst in the form of film, and it has also proved to be an inexpensive alternative for both research and teaching laboratories, as it allows the execution of chemical physics practices such as kinetic monitoring of reactions and mathematical adjustment of the curves.