Application of Box–Behnken Design for the Optimization of Crystal Violet Removal from Aqueous Solutions Using Acorn Waste from Quercus ilex

Abstract

This study explores the optimization of Crystal Violet (CV) dye removal from aqueous solutions using Quercus ilex acorn waste (AW), a natural and low-cost adsorbent. The Box–Behnken Design (BBD), a response surface methodology (RSM) approach, was employed to assess the effects of three primary operational variables: adsorbent mass, initial CV concentration, and temperature. The main objective was to maximize removal efficiency while minimizing operational costs. Seventeen experiments were conducted, and the results were modeled using a second-order polynomial equation. Analysis of variance (ANOVA) confirmed the statistical significance of the model ( p < 0.0001), with a high coefficient of determination ( R 2 = 0.99), demonstrating strong predictive capability. Adsorbent mass and initial dye concentration positively influenced removal efficiency, whereas temperature had a negative influence. The optimal conditions for maximum removal were an initial CV concentration of 100 mg/L, an adsorbent dosage of 0.5 g/L, and a pH of 10. This study highlights the potential of AW as an effective and sustainable adsorbent for textile dye remediation and demonstrates the value of BBD in optimizing adsorption processes for environmental applications.