The potential of melt-mixed polypropylene–zeolite blends in the removal of heavy metals from aqueous media

The continued deterioration of the water quality in natural water sources such as rivers and lakes has led to tensions amongst relevant stakeholders to such an extent that cooperative water resource management is being regarded as an ideal solution to culminate conflicts and maximise the benefits. The desire to develop technologies that combine the three most important aspects of integrated water resource management (namely social, economic and environmental) has been encouraged by relevant authorities. This paper therefore reports the application of clinoptilolite–polypropylene (CLI–PP) blends/composites for the removal of lead from aqueous media. Just like many other heavy metals, lead poses a threat to water and soil quality as well as to plant and animal health. The findings on the adsorption behaviour of clinoptilolite–polypropylene composites with respect to Pb2+ are also reported here, with the aim of extending its application to wastewater and environmental water purification. The batch equilibrium adsorption method was employed and the influence of contact time, pH, initial metal-ion concentration, temperature and pretreatment was determined. The optimum pH was found to be between pH 6 and pH 8 while the maximum sorption of lead at optimal pH was 95%. No big difference was observed between the adsorption behaviour of composites functionalised with 20% and 30% clinoptilolite, respectively. The pretreatment with HCl and NaCl made a slight difference to the adsorption capacity of composites.

► A blend of zeolite/clinoptilolite and polypropylene for heavy metals adsorption was prepared, characterize and applied.
► The blend adsorbed heavy metals including Pb, Co, Cu, Fe and Zn from aquatic media simultaneously (>90% efficiency).
► The activation of zeolite-clinoptilolite before mixing with polypropylene was found to be essential.