Geopolymers and Alkali-Activated Materials for Wastewater Treatment Applications and Valorization of Industrial Side Streams

Abstract

The EU has the ambitious goal to transition from linear to circular economy. In circular economy, the old saying of “one’s waste is the other’s treasure” is being implemented. In this chapter, valorisation of industrial side streams, traditionally branded as waste, is discussed with respect to their applications as raw materials for new adsorptive products – geopolymers (GP) and alkali-activated materials (AAM) – as adsorbents in wastewater treatment. The chemical nature and structure of materials generally have great influence on GP/AAM adsorption capability. The approaches used for the raw materials preparation (chemical or physical) prior geopolymerization to increase the adsorption capacity of the final products will be discussed. Adsorption properties and performance of GPs/AAMs towards various contaminants are described, and the latest research on testing those materials as water remediation are reviewed. Special attention is paid to regeneration of exhausted materials and available resource recovery options that the regeneration approach opens. New forms of geopolymer adsorbent such as foams or core-shell structures are described and in the last part of the chapter, a short economic evaluation of resource recovery models is provided.

Supported Geopolymer Adsorbents for Nutrient Removal from Urban Run-off Waters: Pilot Case Study

“…Light expanded clay aggregate (LECA) was chosen as a substrate material enabling to bring lightweight and floating properties to new composites, while inorganic polymers (geopolymers, GPs) served as functional responsive materials. In order to find cost-effective solution for non-point source pollution, various industrial by-products were used as precursors for manufacturing of adsorption layers on the adsorbents [9]. Despite the fact that LECA have been investigated previously as adsorptive material for nutrient removal [10], the efficiency and adsorption capacity of the raw material were low.…”

Adsorption-Desorption of Critical Metals from Simulated Acid Mine Drainage by Metakaolin Geopolymer

“…Geopolymers have great potential for several applications within the framework of circular economy [1]. Thus, geopolymers or alkaline activated materials have recently found attention as adsorbents in the treatment of waste water, containing cationic contaminants [2] [3]. Because geopolymers can be produced cheaply from a wide variety of industrial side streams, their selectivity can be tailored to the metal of concern.…”