Sustainable remediation of cationic dyes using Pistacia vera testa-derived nanoparticles: experimental validation and...

This study presents a sustainable, low-cost solid-state synthesis of Pistacia vera-derived nanoparticles (PVNPs) from agro-waste (Pistacia vera testa). The PVNPs were extensively characterized and utilized for the adsorption of crystal violet (CV), methylene blue (MB), and malachite green (MG) dyes. PVNPs exhibited over 95% removal of MB dye and over 85% removal of CV and MG dyes within 10 min under optimized conditions. Key operational parameters (pH, contact time, initial dye concentration, and adsorbent dosage) were optimized using response surface methodology (RSM), revealing significant individual and interactive effects. The adsorption kinetics of the studied dyes were further evaluated using the Elovich model to gain insight into the surface heterogeneity and adsorption mechanism. Pseudo-second-order kinetics and Langmuir isotherm were best-fit, indicating that adsorption of cationic dyes occurred through monolayer chemisorption, with maximum adsorption capacities (Q_max) of 7.83, 17.11, and 7.24 mg·g⁻¹ for CV, MB, and MG, respectively. To enhance reusability and ease of NP recovery, while minimizing leaching, PVNPs were encapsulated in sodium alginate (SA) beads, which exhibited good adsorption efficiency for CV, MB, and MG, respectively. This work exemplifies a waste-to-resource approach, converting agricultural waste into efficient adsorbents for dye remediation, thereby aligning with the principles of green chemistry and the circular economy.