# Chemically Modified Soluble Starches as Green Scale Inhibitors in Petroleum Production

## TL;DR

This paper explores modified starches as eco-friendly inhibitors to prevent scale formation in petroleum production.

## Contribution

The study introduces starch maleate as a superior green scale inhibitor with improved performance and a sustainable modification process.

## Key findings

- Starch maleate reduced the minimum inhibitory concentration to 125 mg L–1, outperforming unmodified starch.
- Carboxymethyl starch and starch maleate both distorted calcium carbonate morphology more effectively than unmodified starch.
- The esterification process for starch maleate is solvent-free and simplifies production steps.

## Abstract

The development of
green scale inhibitors is crucial for the petroleum
industry. This work investigates chemically modified starches as green
alternatives for scale control. Soluble starch was modified through
two routes: carboxymethylation with chloroacetic acid and esterification
with maleic anhydride. The modifications were confirmed by infrared
spectroscopy, and degrees of substitution were quantified by titration.
Tube-blocking tests demonstrated that both modified starches markedly
improved calcium carbonate inhibition, reducing the minimum inhibitory
concentration from 500 mg L–1 for unmodified starch
to 150 mg L–1 for carboxymethyl starch and 125 mg
L–1 for starch maleate. The superior performance
of starch maleate can be attributed to its higher degree of substitution
and presumable steric effects. Scanning electron microscopy and X-ray
diffraction analysis revealed that carboxymethyl starch promoted distortion
of both the shape and size of calcium carbonate solids, while starch
maleate more effectively reduced particle size. These morphological
modifications were more pronounced than those induced by unmodified
starch, contributing to the enhanced inhibitory performance. In addition
to superior performance, the maleic anhydride esterification route
offers a simpler and more sustainable modification process, as it
proceeds under solvent-free conditions and eliminates neutralization
and purification steps. Overall, these results demonstrate that chemically
modified starches, particularly starch maleate, are promising candidates
for effective and sustainable scale inhibition in petroleum facilities.