Novel composite biopolymers of sodium alginate/natural rubber/coconut waste for adsorption of Pb(II) ions

A novel composite adsorbent in the form of beads for removal of Pb ²⁺ from wastewater was prepared by blending a sodium alginate (NaAlg) solution, natural rubber (NR) latex, and coconut waste (cofiber). After being crosslinked by calcium chloride, the beads were highly stable, flexible, and easily used in the environment. The optimum composition of the beads with an average size of 1.1-1.2 mm was 4% NaAlg:NR latex (60% dry rubber content):cofiber at 50:1:0.72 and a 2%w/w CaCl₂ solution used for cross linking. The physico-chemical properties of the beads were examined by the swelling ratio measurement, ATR-FTIR, and SEM. The effects of the amount of cofiber, NR, and initial Pb²⁺ ions, the pH of the medium, the bead content, and the contact time, on the adsorption of Pb²⁺ were investigated. NR improved the water resistance and, hence, the stability of the beads. The cofiber increased the porosity and contact area and, hence, the efficiency of the composite beads to adsorb the Pb²⁺ up to 99.6%. The prepared beads are promising material to use for the effective and economical removal of Pb²⁺ from water.