Optimized fabrication of chitosan-hydroxy apatite (HAp/CS) nano hybrid for removal of nitrite from water samples

Chitosan can be used as an adsorbent to remove pollutants due to the presence of amino and hydroxyl groups, which can serve as the active sites, but typically suffers from low specific gravity and sensitivity to pH [1]. In order to improve chitosan’s performance as an adsorbent, crosslinking reagents [2] are widely utilized. In this work. Chitosan/hydroxyapatite (HAp/CS) nanohybrid has been fabricated in an optimized synthesis condition to be employed for the removal of nitrite from water samples. The method was optimized using the design of experiments developing a three-factor, central composite design model. Particle size of the optimum nanohybrid was 17.1 nm. HAp/CS as an adsorbent hybrid was also characterized by X-ray diffraction and Fourier transform infrared spectroscopy to specify its morphology, functionality, and structure. In order to remove nitrite ions by the nanohybrid, cross-linked chitosan-apatite nanohybrid was prepared and the process was monitored by (UV-Vis) spectrophotometry. The UVVis spectrum of cross-linked chitosan-apatite nanohybrid suspension was recorded every 5 min to obtain and evaluate the analyte concentration. These spectra were applied as a data matrix while its rows were the time and its columns were wavelengths, to investigate concentration profile of nitrite. PCA revealed that there is one active component in system. After performing of EFA, decomposition is performed by an initial estimation of one of the concentrations or spectral profiles, utilizing a curve resolution method such as evolving factor analysis (EFA), resulted concentration profile was used as initial estimation. The resolved concentration profile obtained from MCR-ALS It is assumed that there is a bilinear relationship between data. Least squares (LS) calculation is error criteria [3]