Chemistry of zeolites and zeolite based composite membranes as a cutting-edge candidate for removal of organic dyes & heavy metal ions: Progress and future directions

Abstract

The quality of water has become a serious concern due to excessive industrial effluent production and poor wastewater treatment. Membrane technology has received immense attention due to its mild operating conditions, and highly efficient process. Polymer-based membranes are generally applied in various separation operations for their highly reproducible fabrication and low-cost approaches. Fouling aspects and the trade-off between selectivity and permeability are the main disadvantages of polymeric membranes. In this regard, zeolites are an attractive and promising candidate with 3D crystalline microporous systems, large and medium-pore molecular sieves, low-cost, and due to their distinct framework, are considered potential ceramic membranes for water treatment. Incorporating inorganic zeolite particles into the polymer matrix improves permeability while maintaining selectivity, and promotes mechanical strength in challenging environments and fouling conditions. Zeolite-based composite membranes can remove heavy metals and dye effluents from the aqueous medium thanks to their high adsorption capability and well-defined pore size. In this review, we focused on the significance of membranes in water treatment, structural/chemical features of zeolite-based membranes, and their design. The various strategies involved in integrating zeolites to obtain composite based membranes, an overview of toxicity issues of dyes, and heavy metals followed by an exploration of zeolite based composite membranes for the treatment of various dyes and heavy metal pollutants. Also, we tried to provide a cost analysis of zeolite-based membranes followed by commercial and industrial outlooks. Lastly, conclusion and future perspectives are drawn for the zeolite-based composite membranes.