Multifunctional biocomposites based on cross-linked Shrimp waste-derived chitosan modified Zn2+@Calcium apatite for the removal of methyl orange and antibacterial activity

Abstract

In this work, the cross-linked chitosan composite modified with zinc-doped hydroxyapatite was synthesized and grown in its polymer matrix. The final composite material was tested for the removal of methylene orange coloring pollutants and antimicrobial activity. The obtained materials' physicochemical properties were characterized by techniques such as ASAP BET, SEM-EDX, XRD, FTIR, XPS, pH drift measurements, and thermal analysis. The test results show that the synthesized material is characterized by good structural textural properties and high resistance to high temperatures. Several parameters affecting the adsorption process were studied in this work, such as the mass, time, pH, and the effect of initial concentration. The adsorption kinetics and equilibrium results were well described with the pseudo-second order model and the Langmuir isotherm model, respectively. The maximum adsorption capacity of Zn2+@Hap@Cs for MO was 453.15 mg/g at 60 °C. The adsorption mechanism of OM on Zn2+@Hap@Cs can be attributed to several types of interactions (e.g., electrostatic attractions, hydrogen bonds). Finally, antimicrobial activity was carried out on Gram-positive and Gram-negative bacteria, showing better antibacterial activity. Additionally, DFT calculations and NCI analyses were carried out to better understand the adsorption mechanism of MO dye onto the prepared biocomposite.