Simultaneous removal of lead and cadmium ions from simulant and industrial waste water: using Calophyllum Inophyllum plant materials as sorbents

Simple effective sorbents derived from stem powders of Calophyllum inophyllum (CISP) and its active carbon (CISAC) are investigated to remove simultaneously lead and cadmium ions from wastewater with respect to various extraction conditions. Sorbents are characterized by conventional and surface morphological techniques. Maximum removal of Lead and Cadmium with CISP are: 85.8 and 82.8%; with CISAC are: 95.0 and 92.0%, respectively. The optimum conditions of extraction are: pH: 6.5, 7.0; dosage: 2.25, 2.0 g/L; agitation time: 75, 120 min for CISP and for CISAC respectively. The sorption capacities for Pb2+ and Cd2+, respectively are: 14.9 and 17.0 mg/g with CISP; 16.2, 18.5 mg/g with CISAC. The sorption nature is analyzed thermodynamically and by adopting kinetic and isothermal models. High ΔH values of: 32.789& 45.869 kJ/mole for Pb2+ &Cd2+ for sorption on CISP; 26.682 and 33.15 kJ/mole for Pb2+ and Cd2+ for sorption on CISAC, indicate a sort of ‘complex formation and/or ion-exchange’ mechanism between the metal ions and functional groups of sorbents. Positive ΔS and negative ΔG values show disorder in the vicinity of solid–liquid interface and spontaneity of sorption process, respectively. Spent bio-adsorbents can be regenerated-cum-reused. The real effluent samples from industries are successfully treated with these simple bio-sorbents developed.Novelty statement The merit of this investigation is that simple and effective bio-sorbents based on Calophyllum inophyllum plant materials with high sorption capacities, are developed for the simultaneous removal of the toxic Pb2+ and Cd2+ at neutral or nearly neutral pHs. These sorbents are successful in water remediation of Pb2+ and Cd2+ ions from real effluents from industries. These findings have great significance as the identified bio-sorbents are simple, effective and renewable in extracting highly toxic lead and cadmium ions from the effluents from industries or polluted water.