Synthesis and characterization of carboxymethyl starch-g-polyacrylic acids and their properties as adsorbents for ammonia and phenol.

Cigarette smoke contains a lot of harmful chemicals which cause different diseases like cancer, heart disease, bronchitis and ulcer etc. Ammonia and phenol are among those chemicals which cause cancer, fibrosis, respiratory disorder and pneumonia. So, to remove ammonia and phenol from cigarette smoke, five different types of carboxymethyl starch-g-polyacrylic acids (CMS-g-PAAs) were synthesized by using different initiators, different mole ratio of acrylic acid to CMS anhydroglucose unit (AGU) and different amount of water. Three types of modified CMSs, CMS-g-PAA1, CMS-g-PAA3 and CMS-g-PAA4 were selected for further characterization and application for ammonia and phenol adsorption. The 1H NMR and FT-IR spectroscopy confirmed the successful grafting of PAA on CMS. Crystallinity of CMS and three modified CMSs was checked by their XRD analysis. The XRD analysis showed that CMS had crystalline nature which was lost after modification. The thermal properties of CMS and the modified samples were checked by TGA and DTG which also gave information about the successful grafting on PAA on CMS. Finally the modified CMSs were further used for the adsorption applications of ammonia and phenol from the gaseous stream. It was found that CMS-g-PAA4 showed the highest adsorption efficiency towards ammonia (0.352 mmol/g) and phenol (0.18 mmol/g).

Advances in chemical modifications of starches and their applications.

Starch is a homopolysaccharide made up of glucose units which are linked together via a glycosidic linkage. This biopolymer is well known for its low cost, biodegradability, renewability and easy availability. In spite of all these beauties, starch has some problems with their solubility in water, retrogradation, loss of viscosity due to rupturing of glucosidic bond when subjected to treatment and absence of some groups of primary importance like different functional groups especially carboxylic group, ester group, ether group and amino group. In order to overcome these shortcomings and enhance its applications, starch must be modified. The modification can be done chemically, physically and enzymatically, but noteworthy one is the chemical modification. In this review article, we focused on the recently used ways of chemical modification such as acid hydrolysis, cross-linking, acetylation/esterification, dual modification, oxidation and grafting of starch, and their properties. This review article highlighted the application of modified starch as an adsorbent for the removal of ammonia, phenol, heavy metals, and dyes.

Synthesis of carboxymethyl starch-g-polyvinylpyrolidones and their properties for the adsorption of Rhodamine 6G and ammonia.

Carboxymethyl starch-g-polyvinylpyrolidones (CMS-g-PVPs) were prepared by grafting of carboxymethyl starch (CMS) with N-vinylpyrolidone (NVP) using different initiators. The grafting percentage of all the modified starches was determined and the modified starch (CMS-g-PVP-5) with maximum grafting percentage was characterized by elemental analysis, 1H NMR and FT-IR spectroscopy. Crystallinity and thermal properties of CMS-g-PVP-5 were analysed by XRD and TGA, respectively. CMS-g-PVP-5 was then utilized for the adsorption of Rhodamine 6G (dye) from water under different pH, temperature, adsorbate doze and adsorbent concentration. This modified starch showed good adsorption ability towards Rhodamine 6G. CMS-g-PVP-5 was also applied for the adsorption of ammonia gas and proved an exciting adsorbent for ammonia.

Synthesis of hydrogel-bearing phenylboronic acid moieties and their applications in glucose sensing and insulin delivery.

In past few years, phenylboronic acids (PBAs) have attracted researcher's attention due to their unique responsiveness towards diol-containing molecules such as glucose. This property allows hydrogel-bearing PBAs potentially to serve as an alternative for glucose-sensing and insulin-delivery systems. This review provides an outlook on the binding mechanism of PBA moieties with diols and the approaches to increase their binding selectivity and response for glucose molecules. The preparation methods and strategies of hydrogel-bearing PBA moieties along with their properties are discussed. In the last section, their applications in glucose-sensing and insulin-regulatory systems are described.