An environmental green approach for the effective removal of malachite green from estuarine waters using Pistacia vera L. shell-based active carbon

The study aims in developing strategies for containing dye pollution in water resources, which is a global threat in the current industrial era. The development of ecofriendly and cost-effective materials in dye removal processes are not yet fully explored. Thus, the present work describes the green approach in developing and applying activated carbon prepared from pistachio shell (PisAC) for the removal of malachite green (MG), a cationic dye, from wastewaters. The surface characteristics and properties of the adsorbent were studied using Fourier-transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, elemental analysis, and nitrogen adsorption-desorption. The effects of influential experimental parameters, such as pH, initial dye concentration, temperature and ionic strength, were carried out in batch mode for investigating the conditions apt for maximum removal of cationic dye pollutant. The optimum solution pH for the dye removal was found to be at 7.0. The adsorption process reached equilibrium in 30 min with a maximum removal of 96.7% of MG from aqueous solution for an initial concentration of 75 mg/L. Pseudo-second-order kinetics was found to be the best-fitted model to explain the kinetics of the adsorption. The maximum adsorption capacity obtained from Langmuir isotherm model was 76.92 mg/g. Thermodynamic studies revealed the adsorption of MG onto PisAC was spontaneous and endothermic. The reusability studies of spent adsorbent were also performed. The application of the adsorbent was carried out successfully in removing MG from estuarine water samples and found that 4.0 g/L of PisAC was sufficient for almost 99.9% removal of MG.

Automated summary

This study aims to develop strategies for mitigating dye pollution in water resources by utilizing activated carbon prepared from pistachio shell (PisAC) for removing cationic dyes from wastewater. Experimental results demonstrate that PisAC exhibits high efficiency in removing dye pollutants under appropriate conditions.