Development of cellulose as substrates for adsorbents and sensors

Abstract

This thesis deals with two parts of development of novel sensors based on cellulose substrate platform. The first part is the development of fluorescence sensors and adsorbents for metal ions using bacterial cellulose as the platform. The second part is the development of colorimetric sensors for smartphone detection of oil marker using filter paper as the platform.

In the first part, bacterial cellulose (BC) has several advantageous properties over plant cellulose such as high purity, high surface area, high porosity, and high water-holding capacity due to its three-dimensional network of nanofibrils structure, that make BC appealing for applications related to surface capacity. In this work, BC is utilized as a substrate for immobilization of a 2-chloro-N-(quinolin-8-yl)acetamide (QA) via a nucleophilic substitution reaction using K2CO3 as a base. The QA modified BC film exhibit green fluorescence turn-on emission upon addition of Zn2+. The metal ion adsorption study by the ICP-OES analysis showed the adsorption capacity of 38.2 and 56.8 mg/g for Zn2+and Cd2+, respectively. The functionalized BC sheet is thus potentially useful for detection of Zn2+ and retrieving or removal of Zn2+ and Cd2+ from aqueous solution.

In the second part, a convenient method for sensitive detection of gasoline marker using a smartphone camera and image processing application are developed. Phenolphthalein (PhP) is used as a colorless dye marker in commercial gasoline. The color was developed by the interaction of PhP with NaOH on filter paper strips and evaluated based on the CMYK color system by ImageJ program. The counter-flowing technique, in which a gasoline sample and NaOH solution are allowed to travel on a filter paper strip from the opposite end, give the naked eye detection concentration of PhP as low as 1 ppm with the LOD of 0.31 ppm using a smartphone camera. The high sensitivity is attributed to the preconcentration derived from accumulation of PhP at the immiscible liquid interface. The counter-flowing method can thus be a new facile analytical technique for enhancing chemical detection sensitivity.