Successive Extraction of As(V), Cu(II), and P(V) Ions from Water Using Surface Modified Ghee Residue Protein

Renewable adsorbents are interesting for water purification owing to easy access and presence of multiple functional groups for extraction of pollutants. The biowaste, ghee residue from the milk industry was washed to remove fat contents, coated with polyethylenimine (PEI) and Fe(III) ions (Prot-PEI-Fe) was synthesized for the successive adsorption of As(V), Cu(II) and P(V) ions from spiked water samples. The pretreated ghee residue was characterized using FTIR, SEM, ζ-potential and elemental analysis. Batch mode experiments and kinetic regression results showed that the adsorption processes of As(V) and P(V) anions were more accurately described by a pseudo-second-order model, whereas the adsorption of Cu(II) ions followed a pseudo-first-order model. The maximum adsorption capacities estimated by Langmuir model for As(V), Cu(II) and P(V) ions were 45.1, 80.7 and 21.7 mg/g, respectively. The successive adsorptions of As(V), Cu(II) and P(V) ions were achieved through electrostatic attraction, which was demonstrated by the changes in ζ-potentials of the adsorbent after each experiment. The dynamic column adsorption behavior of the adsorbent was described by Thomas model. The simulated results showed good agreement between the theoretical values ( q 0 ) generated by using Thomas model and the experimental values ( q exp ). The results presented in this paper could be used for developing new adsorbent from the renewable waste materials for water purification.