Modifi cation of Cellulose Nanocrystals with Fe<sub>2</sub> O<sub>3</sub> for Linear Alkyl-benzene Sulfonate Removal from Laundry Wastewater

This research is significant to investigate the eff ect of synthesis parameters (weight loading ratio CNCs: Fe<sub>2</sub>O<sub>3</sub>, sonication temperature, sonication time) on cellulose nanocrystals (CNCs) modified with iron oxide (Fe<sub>2</sub>O<sub>3</sub>) nanoparticles. The CNCs/Fe<sub>2</sub>O<sub>3</sub> adsorbent was synthesized via the ultrasonic-assisted chemical co-precipitation method. All synthesized samples were analysed using linear alkyl-benzene sulfonate (LAS) removal from laundry wastewater using a batch adsorption study. The CNCs/Fe<sub>2</sub>O<sub>3</sub> adsorbent was characterised using FTIR, TGA, N<sub>2</sub> sorption-desorption, and SEM-EDX analyses to understand its chemical and physical properties. The highest removal of LAS was found at a 1:1.5 ratio of CNCs: Fe<sub>2</sub>O<sub>3</sub>, 80°C of sonication temperature, and 90 min of sonication time, with ±90% removal of LAS. The FTIR analysis revealed several functional groups in the CNCs and CNCs/Fe<sub>2</sub>O<sub>3</sub> adsorbent. The CNCs showed a hydroxyl group and aromatic ring in lignin around the spectrum of 3000 – 3400 cm<sup>-1<sup></sup> and 1640 cm<sup>-1</sup>, respectively. The broad shoulder for the hydroxyl group in the CNCs was reduced to a small peak due to the formation of iron oxide. Thermal analysis from the TGA analysis showed a significant weight loss of around 50 – 200°C due to the destruction of the cellulose structure. As for the N<sub>2</sub> sorption-desorption analysis, the CNCs/Fe<sub>2</sub>O<sub>3</sub> adsorbent exhibits a larger surface area compared to the CNCs, in which the porous structure can be observed in the CNCs/Fe<sub>2</sub>O<sub>3</sub> adsorbent from the SEM morphology. Overall, the addition of Fe<sub>2</sub>O<sub>3</sub> via ultrasound-assisted coprecipitation method contributes to the development of the CNCs structure while changing the properties of the CNCs/Fe<sub>2</sub>O<sub>3</sub> as a potential adsorbent for LAS in the laundry wastewater application, thereby offering a practical solution for wastewater treatment.