Obtaining and Microstructural Study of a Multifunctional Highly Phosphorylated Starch

Abstract

We phosphorylated the starch by a method that we used for kraft fibres. Energy dispersive x‐ray (EDX) analysis shows that this product contains 20% phosphorus and 9% nitrogen. The corresponding degrees of substitution, on the anhydroglucose repeating unit (AGU), by phosphorus‐containing (DSP) and nitrogen‐containing (DSN) groups are 2.32 and 1.38 respectively. The various conventional microstructural characterization techniques (13C and 31P NMR, ATR‐FTIR), indicate the existence of several functional groups simply linked or acting as bridges between the chains. The insolubility of the product confirms the existence of bridging and cross‐linking of the phosphorylated product. The degree of charge (4446 mmol/kg), determined by potentiometry, is lower than that calculated theoretically (6617 mmol/kg). This is due to a transformation of the phosphate groups (‐O‐PO3H2) into (‐O‐PO3H‐) forming inter‐chain bridges. Water retention is lower than for linear polar polymers (acrylamides). It is due to cross‐linking that prevents chain expansion. The viscosimetric increment varies very little with concentration, indicating that we are dealing with particles made up of highly cross‐linked polysaccharide chains, whose hydrodynamic volume expansion is strongly restricted. The thermogravimetric study, mass loss as a function of temperature, generates levoglucosan as the majority product. It indicates the persistence of AGU despite modification reactions. All the results point to a highly charged, insoluble and cross‐linked product, making microstructural studies extremely difficult. However, by pooling all the data, we were able to propose an approximate structure. Application tests as a fertilizer, adsorbent, flame retardant, water retainer and gelling agent were conclusive.This article is protected by copyright. All rights reserved

Phosphorylating Tannin in Urea System: A Simple Approach for Enhanced Methylene Blue Removal from Aqueous Media

“…Notably, the peak at 3400 cm –1 decreased for the PT, indicating a reduction in the availability of O–H groups. ,− The band around 1000 cm –1 corresponds to the P–O–P stretching groups, while the P–O–C aliphatic bond, P–OH and PO stretching modes are associated with peaks at around 834, 900–940, and 1230 cm –1 , respectively . Given the distinctive features of the functionalization process and the presence of these adsorption bands, there is a clear indication that the phosphorylation of tannin took place, resulting in the insertion of the phosphate-containing groups into the tannin structure. , …”