A Study on the Utilization of Non-Conventional Cements for Immobilization of Some Heavy Metals

Abstract

This study aims to solve the problem of some solid wastes as well as the heavy metals pollution. Solid wastes used in this study were slag and fly ash (FA) . Alkali activation of these solid wastes by using NaOH or NaOH/Na2SiO3 produces what is called geopolymer cement (GP) or alkali activated cement. Such geopolymer cements were used to immobilize lead from lead-bearing sludge and heavy metal sludge produced from electroplating technique. The addition of lead acetate (LA) has resulted in a negative impact on the performance of Gp. Meanwhile, the inclusion of lead-bearing sludge (LBS) in alkali activated system causes a remarkable enhancement in the physical and mechanical properties of the prepared cement. NaOH/Na2SiO3-activated geopolymer mixture possesses higher efficiency on Pb2+ immobilization compared to NaOH–activated geopolymer one. Also this work study the effect of addition of heavy metals rich sludge: HMRS (0 – 10% by weight slag and mixture of slag/Fly ash,60/40 ), and alkali activator type (NaOH or mixture of NaOH/Na2SiO3) on the performance of the prepared cement . The addition of HMRS has resulted in a negative impact on the performance of the prepared cement. The physical and mechanical properties are compared with those of ordinary Portland cement OPC. All the hardened alkali activated slag or slag/fly ash activated by NaOH or mixture of NaOH/Na2SiO3 show high degree of immobilization of lead or other heavy metals in the HMRS.