# Optimization of Chitosan Synthesis Process Parameters to Enhance PES/Chitosan Membrane Performance for the Treatment of Acid Mine Drainage (AMD)

## TL;DR

This study optimizes chitosan synthesis to improve PES membrane performance for treating toxic mine drainage water.

## Contribution

The study identifies optimal deacetylation conditions to maximize chitosan's degree of deacetylation for membrane applications.

## Key findings

- The highest chitosan degree of deacetylation (87.11%) was achieved at 80°C, 40 wt.% NaOH, and 4 hours.
- The PES/0.75 chitosan membrane showed improved hydrophilicity with a 63.62° contact angle compared to 72.83° for the pristine PES membrane.
- Improved hydrophilicity suggests better contaminant rejection and permeate flux for AMD treatment.

## Abstract

Acid mine drainage (AMD) is an environmental issue linked with mining activities, causing the release of toxic water from mining areas. Polyethersulphone (PES) membranes are explored for AMD treatment, but their limited hydrophilicity hinders their performance. Chitosan enhances hydrophilicity, addressing this issue. However, the effectiveness depends on chitosan’s degree of deacetylation (DD), determined during the deacetylation process for chitosan production. This study optimized the chitin deacetylation temperature, alkaline (NaOH) concentration, and reaction time, yielding the highest chitosan degree of deacetylation (DD) for PES/chitosan membrane applications. Prior research has shown that high DD chitosan enhances membrane antifouling and hydrophilicity, increasing contaminant rejection and permeate flux. Evaluation of the best deacetylation conditions in terms of temperature (80, 100, 120 °C), NaOH concentration (20, 40, 60 wt.%), and time (2, 4, 6 h) was performed. The highest chitosan DD obtained was 87.11% at 80 °C, 40 wt. %NaOH at 4 h of chitin deacetylation. The PES/0.75 chitosan membrane (87.11%DD) showed an increase in surface hydrophilicity (63.62° contact angle) as compared to the pristine PES membrane (72.83° contact angle). This was an indicated improvement in membrane performance. Thus, presumably leading to high contaminant rejection and permeate flux in the AMD treatment context, postulate to literature.