Colorimetric Hydrogel from Natural Indicators: A Tool for Electrochemistry Education

Abstract

The electrolysis of water is popular both as lab work and as a demonstration. In this activity, the electrolysis of water in the presence of a pH indicator is used to produce text and symbols. This report describes the design of an environmentally friendly setup of a writing board utilizing the electrolysis of water in a hydrogel environment. The activity can be performed by only using chemicals and materials that are easily accessible to everyone, with no special permit needed. The writing board has been developed mainly as an outreach activity for our faculty and has been assessed during visits from upper secondary school students.

CuS‐Carrageenan Composite Grown from the Gel/Liquid Interface

“…Among biopolymers, carrageenans have been extensively investigated due to their unique properties such as high‐water content, softness, flexibility and biocompatibility [13–15] . The presence of many hydroxyl groups and anionic sulfate groups in their structures makes carrageenan a hydrophilic, anionic polyelectrolyte.…”

(Calcium‐Phosphate)/Carrageenan Gardens Grown from the Gel/Liquid Interface

“…In this study, the syntheses and characterizations have been focused on tubes which were grown from the calcium‐ and phosphate‐based hydrogels consisted of 1.5 wt% of carrageenan. As we have shown in our earlier study [6] that it gives an excellent hydrogel with Epsom salt (Mg 2+ ), this was our first choice regarding the amount of carrageenan to begin with. Therefore, the ions of interest (Ca 2+ and PO 4 3− ) have been tested under mentioned condition.…”

“…In our recent work, κ‐carrageenan is complexed with Mg 2+ to form hydrogels which have interesting features to be used as colorimetric and electrolytic materials [6] . Carrageenans are a family of linear sulfated polysaccharides that can be extracted from some species of red algae ( Rhodophyta ).…”

Color 3D printing of pulped yam utilizing a natural pH sensitive pigment

“…In terms of pH, the electrolysis method is an effective technique to adjust the pH of materials containing water [23], [24], [25], [26]. Wu, et al reported that electrolysis can change the pH of a hydrogel resulting in a color reaction of phenolphthalein in the hydrogel [27].…”