Synthesize and applications of green custard apples leaves biosorbents for adsorptions of sulphates and fluorides from water

Industrial and domestic waste water release sulphur and fluoride metals into the water, thereby polluting the environment and affecting the humans and animals health. There are various techniques are available for eliminating sulphates and fluorides found in the water. Among these techniques, biosorption is a simple, cost-effective and environmentally friendly approach for removing the sulphates and fluorides from water. Biosorption is a physiochemical process that physically produces in specific biomass, enabling it to passively concentrate and bind sulphates and fluorides to its cellular structure. The custard apple leaf biosorbents are among the most effective biosorbents for the removal of fluorides and sulphates from water. In the experimental work observed that the using of 5.6 g dosage of custard apple leaf biosorbents, successfully removed the sulphates and fluorides from water and a stable condition was reached. The optimal sorption of sulphur and fluoride over custard apple leaves biosorbents was achieved at a basic pH of 4–8, a concentration of 4.3 g, contact time of 60 min, temperature of 25°C, and an agitation speed of 100 rpm. The particles present in custard apple leaves biosorbents have a size of 3.26 µm and crystallite size 3.02 nm. The surface area, pore volume and pore size of 43.68 m²/g, 0.428 cm³/g, and 38.64 Å respectively. The adsorption of sulphates and fluorides on regenerated custard apple leaves biosorbents remained consistent for up to three cycles, but then decreased by 82.36 % in the fourth cycle. The regeneration of custard apple leaf biosorbents was also calibrated, and it was observed that the custard apple leaves do not exhibit any high concentrations of changes in their performances, even after being reused for the removals of sulphates and fluorides from water. The adsorption rate move to equilibrium was due to the accessibility of lower amount of existing opening sites on the custard apple leaves biosorbents surface and also due to the binding forces between the custard apple leaves biosorbents and fluorides and sulphates molecules in the aqueous solution.