Synthesis and application of novel sodium carboxy methyl cellulose-g-poly acrylic acid carbon dots hydrogel nanocomposite (NaCMC-g-PAAc/ CDs) for adsorptive removal of malachite green dye
Hayder Jihad Majeed, Thulfiqar Jasim Idrees, Makarim A. Mahdi, May Jaleel Abed, Maryam Batool, Seyede Raheleh Yousefi, Anusha Thumma, Layth S. Jasim
Abstract
This study aimed on synthesizing novel sodium carboxy methyl cellulose-g-poly acrylic acid carbon dots hydrogel nanocomposite (NaCMC-g-PAAc/ CDs) to remove malachite green (MG) dye from aqueous media. The characterisation of functionalities, morphology, particle size and crystallography of NaCMC-g-PAAc/ CDs nanocomposite both before and after adsorption. The results of the characterization analysis revealed the presence of numerous ionic functionalities such as carboxyl, amino and hydroxyl groups in nanocomposite. The morphological study revealed the presence of porosity, heterogenous and amorphous nature of adsorbent favoring the adsorption of MG. Furthermore, elemental analysis also confirmed the presence of carbon and oxygen as main elemental composition of nanocomposite. The temperature of 30 °C and the nanocomposite (having pH PZC of 3) dose of 0.06 g at pH 10 results in achieving 96.92 % of MG dye removal. The experimental data fits closely with pseudo-second and Freundlich models. The enhanced MG dye adsorption by NaCMC-g-PAAc/ CDs was attributed to different mechanisms such as electrostatic or H-bonding as well as pi-pi interactions. Thermodynamically, the studied process was spontaneous and is of endothermic kind. Overall, the study reveals adsorptive property of novel NaCMC-g-PAAc/ CDs nanocomposite as a promising adsorbent for MG dye adsorption from water. • First report on the synthesis and characterization of the novel carbon dots (CDs) cross-linked hydrogel nanocomposite. • The maximum adsorption capacity of 3.26 mg/g was achieved for MG dye removal at pH 10 within 120 min. • Optimized conditions include 0.75g hydrogel using CDs dose of 0.008g with 0.06g of nanocomposite for 700 mg/L of dye at 30 °C. • Electrostatic, π-π interactions and the H-bonding are the main adsorption forces for MG dye removal.