Effectiveness of Sequential Pre-treatment and Application of High-porosity Hybrid Fly Ash Geopolymer/alginate Adsorbent for the Treatment of Batik Wastewater

In this work, hybrid fly ash geopolymer / alginate spheres (GSA) were produced and used as an effective and economical adsorbent in a treatment of batik wastewater. A preparation of GSA adsorbent involved a facile method where the fly ash (FA) based geopolymer was entrapped into sodium alginate (SA) followed by cross-linking of Ca2+ and SA. In additional to that, natural egg white was utilized as a foaming agent. Characterization of the GSA adsorbent strongly confirmed the formation of hybrid spheres that composed of geopolymer and alginate with extremely porous microstructure with porosity of 87.64. Surface area, average pore diameter and pore volume was 12.874 m2 g-1, 3.3110 nm and 0.1684 cm3 g-1, respectively. Prior to the adsorption process, the batik wastewater was pre-treated using high concentration acid hydrofluoric (HF) and magnesium oxide (MgO). The optimum acidification pre-treatment at pH=3 removed ~ 93 of chemical oxygen demand (COD). In the subsequent stage, the highest percentage of COD removal was ~27 by utilizing 1500 mg L-1 of MgO powder. In the final stage, different dosages of GSA adsorbent was used in order to treat the remaining COD and resulted in as maximum as ~67 of the COD removal. According to the finding, the sequential pre-treatment and application of high-porosity hybrid GSA adsorbent offered a great potential to be implemented as an economical and effective batik wastewater treatment. © 2021, Islamic Azad University. All rights reserved.