Industrial wastewater discharge into aquatic environments poses a significant threat to both human health and aquatic life. Among the available water treatments, adsorption is a particularly efficient approach for removing pollutants. In this context, chemically-modified Tunisian smectite clay (named 1CEC and 2CEC) was used as an adsorbent material for removing proteins from poultry slaughterhouse wastewater. The structural modification of smectite clay, detected using X-ray diffraction, Fourier-transform infrared spectroscopy and scanning electron microscopy, confirmed the intercalation of the surfactant used (CTAB) into smectite layers. According to X-ray results, the basal spacing (d 001 ) of the newly produced composite material (2CEC) was determined to be 13.63Å. The appearance of N-H stretching vibrations near to 3000 cm −1 along with the C-H stretching bands from CH 2 groups, in the modified samples provides clear evidence of CTAB interaction. Batch adsorption experiments were carried out as a function of sorbent dose, initial protein concentration, pH solution and contact time. Turbidity and chemical oxygen demand (COD) were also assessed. The results revealed that modified clay 2CEC showed the best adsorption capacity of protein (3251±104 mg/g), with optimum conditions achieved with sorbent dose of 10 mg, a contact time of 4 h, pH = 9 and an initial protein concentration of 10 mg/l. However, raw and 1CEC-modifed smectite showed adsorption capacities of 2746±103 mg/g and 1578±100 mg/g, respectively. Turbidity measurements showed a value of 8.175 NTU for 2CEC, compared to 53 NTU for 1CEC and 57 NTU for raw smectite. The adsorption isotherm analysis revealed that the equilibrium data were best described by the Freundlich model (R 2 = 0.99) for all samples, suggesting a multi-layer protein sorption onto smectite. The pseudo-second order (R 2 = 0.99) fitted well the three used clays, suggesting a chemisorption process. Interestingly, while they remain prone to water sorption and associated to a swelling behavior, the studied modified smectite clay could be an effective and environmentally adsorbent for proteins’ removal from poultry wastewater. This study opens the perspectives for exploring other types of modifications to further enhance the performance of clay as a natural adsorbent for wastewater treatment.
Sayah et al. (Sun,) studied this question.