Removal of hexavalent chromium from wastewater by PVA-Ag2Se-chitosan nanocomposites

• Synthesis of Ag 2 Se–PVA capped nanoparticles through sol-gel method • TEM images shows the improved shape and sizes of the particles when the stabilizer was used • Optimum pH of 3 was recovered for all adsorbents. • Absorption of the chromium ions was achieved through amino functional groups (-NH 2 ) and the hydroxyl functional groups (–OH) active sites. • Highest percentage removal of above 87 % of Cr(VI) ions was achieved when PVA-Ag 2 Se-chitosan nanocomposites was used as an adsorbent. Silver selenide nanoparticles capped with polyvinyl alcohol were synthesized and incorporated with chitosan to form PVA-Ag 2 Se-Chitosan nanocomposites. The polymer nanocomposites were utilized to remove Cr(VI) ions from wastewater through adsorption process. Ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction, Fourier transforms infrared (FTIR), transmittance electron microscopy (TEM), scanning electron microscope (SEM), and Brunauer–Emmett–Teller (BET) were used to characterize the nanoparticles and the nanocomposites. TEM images of PVA-Ag 2 Se showed nicely packed spherical particles as the stabilizer was used with the average particle of 3.65±1.36 nm. BET surface area and the average pore size of PVA-Ag 2 Se-Chitosan nanocomposite are 3.28 (m 2 /g) and 10.73 nm, respectively. Adsorption of chromium (VI) onto chitosan and PVA-Ag 2 Se-Chitosan nanocomposite was investigated using atomic adsorption spectroscopy (AAs). The parameters such as contact time, pH and initial metal concentration were investigated during this process. The results showed that PVA-Ag 2 Se-Chitosan nanocomposite is a promising candidate as a new generation adsorbent as it displayed high percentage removal of Cr(VI) ions than pure chitosan. The crucial parameters of Langmuir and Freundlich adsorption isotherms were successively applied to analyze the adsorption mechanism. The adsorption of hexavalent chromium is better described by the Langmuir model (R 2 = 0.9683) than by the Freundlich model (R 2 = 0.8782).