Abstract:
Acid mine drainage is an environmental problem associated with mining operations
and activities. Its treatment is essential to achieving environmental sustainability. In this study,
a polyethersulphone (PES) membrane infused with chitosan is proposed as a point-of-use material for
treating acid mine drainage (AMD). The composite material explored the synergetic effect between
chitosan and polymer, particularly considering the effect of the degree of deacetylation (DD) of
chitosan on the performance of membrane. Chitosan was produced from chitin under various
synthesis process conditions and infused within polyethersulphone membrane. The results obtained
show that chitosan with the highest degree of deacetylation was achieved with a temperature of 100 ◦C
and NaOH concentration of 40 wt%. Increasing the temperature above 100 ◦C started degrading
already formed or exposed amine groups, thus, reducing the DD of the chitosan sample. The contact
angle and porosity analysis indicated that the hydrophilic nature of the membrane was enhanced with
increasing DD of the chitosan. The performance of the membranes was conducted on a Dead-end
filtration cell using synthetic acid mine drainage. The results showed that the flux and rejection of the
membrane was enhanced with increasing degree of deacetylation. PES 5 and PES 1 were blended
with chitosan having the highest (95.97%) and lowest (33.93%) degree of deacetylation, respectively.
PES 5 reported pure water flux of 123 L/m2
·h and PES 1 was recorded as 104 L/m2
·h. Similarly, the
rejection of the membrane was improved with increasing chitosan’s degree of deacetylation. PES
5 had higher rejection and PES 1 had the least rejection. Maximum rejection for the contaminants
was determined as 98.05, 97.39, 96.25, 95.24 and 80.34% for Mn2+, Fe2+, Mg2+ and Ca2+ and SO4
2−,
respectively. The results obtained show that chitosan’s degree of deacetylation has a positive effect on
the performance of polyethersulphone membrane during the treatment of acid mine drainage.
