Hairy chitin nanocrystals: Sustainable adsorbents for efficient removal of organic dyes

Chitin nanocrystals (ChNCs) are typically produced using a combination of strong acid hydrolysis and mechanical treatments. In this study, a mild, energy-efficient, and environmentally friendly method was developed to prepare a novel form of chitin nanocrystals called hairy chitin nanocrystals (HChNCs) without the need of any mechanical treatments. The HChNCs were made by sequential oxidations on partially deacetylated chitin, resulting in a unique morphology with chitin molecular chains protruding from central chitin nanorods. These HChNCs have a high content of carboxyl groups, reaching up to 2.72 mmol/g, which enhances their ability to adsorb methylene blue (MB) effectively. Within just 1 min, the HChNCs can adsorb as much as 909.11 ± 17.44 mg/g of MB, a significantly higher capacity compared to other chitin-derived materials. Additionally, the HChNCs showed remarkable synergistic removal efficiency for both MB and methyl orange (MO) in a mixed dye system, making them a promising sustainable option for treating wastewater from industrial printing and dyeing processes.