Modelling and optimization of nonylphenol biosorption by novel low-cost magnetic Chlorella vulgaris

Abstract

Discharging untreated wastewater causes environmental pollution. This research examined the efficiency of removal and the adsorption process of Emerging Contaminant nonylphenol (NP) using magnetic Chlorella vulgaris (M-Chlorella vulgaris). The characterization of M-Chlorella vulgaris involved XRD, FESEM, EDS-Mapping, BET, FTIR, and VSM analyses. The impact of four different parameters—pH, M-Chlorella vulgaris dose, initial concentration of NP, and contact time on the biosorption process was investigated. To model and optimize the study while minimizing costs and the number of experiments, Response Surface Methodology (RSM) with Central Composite Design (CCD) was employed. According to the findings, the quadratic model with adjusted R² = 0.96 was the best fitted among the other models. With pH = 3.5, dosage = 2.5 g/l, NP concentration = 4 mg/l, and reaction time = 70 min, which are the optimal parameters, the maximum removal effectiveness was about 91%. The Langmuir model (R² = 0.998) and pseudo-second-order model (R² = 0.997) exhibited the best fits for the adsorption isotherm and kinetic studies, respectively. The characteristics of M-Chlorella vulgaris were determined to facilitate a spontaneous nature, and thermodynamic experiments indicated that the process of adsorption of nonylphenol is exothermic. The inexpensiveness and availability of adsorbent, suitable efficiency in the biosorption of pollutant and magnetic collection of pollutant from the aquatic environment can be mentioned as the advantages of this process.