Capparis spinosa L waste activated carbon as an efficient adsorbent for crystal violet toxic dye removal: Modeling, optimization by experimental design, and ecological analysis

Abstract

Textile dyes are dramatic sources of pollution and non-aesthetic disturbance of aquatic life and therefore represent a potential risk of bioaccumulation that can affect living species. It is imperative to reduce or eliminate these dyes from liquid effluents with innovative biomaterials and methods. Therefore, this research aims to highlight the performance of Capparis spinosa L waste-activated carbon (CSLW-AC) adsorbent to remove crystal violet (CV) from an aqueous solution. The mechanism of CV adsorption on CSLW-AC was evaluated based on the coupling of experimental data and different characterization techniques. The efficiency of the CSLW-AC material reflected by the equilibrium adsorption capacity of CV could reach more than 195.671 mg·g –1 when 0.5 g·L –1 of CSLW-AC (Particle size ≤250 μm) is introduced into the CV of initial concentration of 100 mg·L –1 at pH 6 and temperature 65 °C and in the presence of potassium ions after 60 min of contact time according to the one parameter at a time studies. The adsorption behavior of CV on CSLW-AC was found to be consistent with the pseudo-second-order kinetic model and Frumkin's linear isothermal model. The thermodynamic aspects indicate that the process is physical, spontaneous, and endothermic. The optimization of the process by the Box Behnken design of experiments resulted in an adsorption capacity approaching 183.544 mg·g –1 ([CV] = 100 mg·L –1 and [CSLW-AC] = 0.5 g·L –1 at 35 min). The results of the Lactuca sativa seeds germination in treated CV (70%), adsorbent solvent and thermal regeneration (more than 5 cycles), and process cost analysis (1.0484 USD·L –1 ) tests are encouraging and promising for future exploitations of the CSLW-AC material in different industrial fields.