Integrated Chitosan-based coagulation and microbubble pre-treatment for improved microplastic fibre removal from...

Area of Science:

• Environmental Science
• Water Treatment
• Polymer Chemistry

Background:

• Microplastic fibres (MPFs) are prevalent in wastewater influents and challenging to remove using conventional methods.
• Existing pre-treatment methods like coagulation-flocculation are limited by coagulant dosage, pH sensitivity, and environmental concerns.
• Chitosan, a biodegradable polymer, offers a green alternative but faces limitations in solubility and pH sensitivity.

Purpose of the Study:

• To develop and evaluate amphoteric chitosan derivatives for improved microplastic fibre removal.
• To investigate the efficacy of these derivatives in combination with microbubble introduction.
• To assess performance across different water matrices, including those with surfactants and humic acid.

Main Methods:

• Synthesis of two amphoteric chitosan derivatives: CMC-CTA and CMC-g-PDMC.
• Evaluation of MPF removal efficiency using a tailored turbidity measurement approach.
• Analysis of water matrices including deionised water with SDBS surfactant, humic acid (HA) alone, and HA with MPF.
• Zeta potential measurements to understand the coagulation mechanism.

Main Results:

• Optimal MPF removal was achieved with 1 mg/L CMC-CTA at pH 7 in a DI water + SDBS matrix.
• Charge patching and microbubble attachment were identified as key mechanisms in MPF floc removal.
• The hybrid system reduced turbidity by over 50% in both HA-only and HA + MPF matrices.

Conclusions:

• Amphoteric chitosan derivatives show significant promise for enhanced microplastic fibre removal.
• The integration of coagulation-flocculation with microbubble introduction offers a sustainable and effective pre-treatment strategy.
• This research provides valuable insights for developing advanced water treatment processes targeting microplastic pollution.