Phyto-adsorption integration for removal of ferric ion from acid mine drainage: an experimental and molecular modelling approach

A significant environmental issue associated with mining and sulphide minerals is acid mine drainage (AMD). Soil, groundwater, and surface water are all negatively impacted by AMD's high acidity and harmful metal concentration. Oxidation of sulphide and indirect oxidation of ferric ion led to creation of AMD. The water quality is bad with pH level is acidic and not suitable for recreation. The quality of water needs to be restored by removal of ferric ion and suitable treatment methods need to be developed. Hence, for this study, Tasik Puteri is selected as a research base. Among the objectives to be achieved was to characterise water quality of Tasik Puteri based on heavy metals analysis using Inductively Coupled Plasma - Optical Emission Spectrometry (ICP-OES) and pH before ferric ion removal. Next, to prepare and characterise CAMC using Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetry Analysis (TGA) as an adsorbent in phyto-adsorption integration. Then, the effectiveness of phyto-adsorption integration for the removal of ferric ion experimentally based on pH and ferric ion content in water, plant and sand before and after treatment. The interaction of ferric ion and CAMC through molecular modelling by BIOVIA Material Studios were also being analysed in this study. A novelty approach is done through an integrated phyto-adsorption for the removal of ferric ion from acid mine drainage. The advantages of integrated phytoremediation and adsorption using modified cellulose are cost effective and environmental friendly. The study was initiated with an analysis of Tasik Puteri water followed by CAMC synthesis and characterisation. Next, pilot plant study of integrated phyto-adsorption was conducted along with an investigation of the molecular interaction of CAMC and ferric ion. The study confirmed that the water is higher of iron content of 1.652 ± 0.159 ppm to 2.213 ± 0.052 ppm. The results is higher than permissible limit by Interim National Water Quality Standards for Malaysia (INWQS) with pH value around 3-4 and fall under Class V that is suitable for irrigation confirmed the occurrence of AMD. Synthesis and characterisation of CAMC as a new potential adsorbent for ferric ion showed that the carbonyl group is successfully embedded in CAMC through FTIR and TGA. Finally, phyto-adsorption integration successfully reduce the ferric ion in water by 98.71% simultaneously increase pH in water by 83.33% and decrease of Fe in sand by 17%. Other than that, based on radial distribution function (RDF) analysis in molecular modelling, it can be concluded that ferric ion were adsorbed on CAMC solvent molecules surface via the formation of Fe-O2 bond, Coulomb interaction as well as Van der Waals forces. In conclusion, phyto-adsorption integration successfully remove ferric ion and proved by molecular modelling. Furthermore, phyto-adsorption integration can also be a model for an industrial field that relates to iron.