Box–Behnken optimization and linear–nonlinear regression analysis of cadmium removal from textile wastewater using hydroxyapatite nanorods
Nanotechnology for Environmental Engineering, cilt.11, sa.3, 2026 (Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 11 Sayı: 3
- Basım Tarihi: 2026
- Doi Numarası: 10.1007/s41204-026-00596-z
- Dergi Adı: Nanotechnology for Environmental Engineering
- Derginin Tarandığı İndeksler: Scopus
- Anahtar Kelimeler: Adsorption, Cadmium removal, Hydroxyapatite, Isotherms, Textile wastewater
- Yıldız Teknik Üniversitesi Adresli: Evet
Özet
This study investigates the applicability of synthesized hydroxyapatite nanorods as an adsorbent material for the removal of cadmium ions from textile wastewater. Hydroxyapatite nanorods were synthesized using a conventional chemical method and characterized using X-Ray Diffraction, Fourier Transform-Infrared and Scanning Electron Microscope analysis. Process optimization was performed using a Box–Behnken experimental design, and model significance was evaluated through analysis of variance. The optimum process conditions were determined to be 30 mg of adsorbent, pH 9.0 and a contact time of 20 min. Under the optimized conditions, the removal efficiency (%RE) was calculated as %91.9 ± 0.4 for 96 mg/L cadmium in textile wastewater. Various adsorption isotherm models such as Langmuir, Freundlich, Redlich-Peterson and SIPS were tested using linear and non-linear regression approaches and it was found that the adsorption process best fits the Redlich-Peterson model. The model fit as the determination coefficient was evaluated to be 0.966. Redlich-Peterson exponent (g) was obtained as 0.72, indicating adsorption on a heterogeneous surface with intermediate behavior between Freundlich and Langmuir models. The maximum adsorption capacity was estimated as 123.5 mg/g from the non-linear Langmuir model. The batch adsorption system was further evaluated for its environmental impact using Eco-Scale criteria and classified as a green analytical approach with a green score of 62. These results demonstrate that the hydroxyapatite nanorods are highly effective for cadmium removal over a wide range of cadmium concentrations and represent a promising approach for industrial wastewater treatment.