Preparation of activated charcoal adsorbent from pitombeira seeds (Talisia esculenta) and its application for Ca2+ ions removal

Water quality that the population has access to can undergo a series of changes, contaminations and interferences. Poor water quality may be related to several contamination sources and can pose a health risk for the ecosystem and for people. The calcium ion is a determinant of water hardness, and its excess in the human body can result in a series of complications and diseases such as renal and bladder lithiasis. The seeds of the pitombeira (Talisia esculenta) were used to produce phosphoric acid activated carbon (PAC). Adsorption studies were conducted by batch technique, and isothermal and kinetic models were systematically used to evaluate the potential of PAC to remove Ca2+ ions from aqueous media. The adsorbent was characterized using BET surface area (141.6 m2/g), SEM, pHPZC (2.75), Boehm titration, and by content analysis of the moisture and ashes. The time required for the system to equilibrate was only 5 min. According to the kinetics study, the data were best fitted by the pseudo-second-order model, while the equilibrium sorption data fitted well with the Freundlich model, with a maximum adsorption capacity of 19.05 mg/g, with 90% of Ca2+ ions removal. Therefore, due to its efficiency and low cost, PAC could be employed as an alternative adsorbent for Ca2+ removal.