Doped-polyaniline based sorbents for the simultaneous removal of heavy metals and dyes from water: Unravelling the role of synthesis method and doping agent

Recently, the engineering of alternative adsorbents with better functional and sorbing ability towards the purification of wastewaters has received much attention from the scientific community. Currently polymers, in particular, are regarded as attractive soft materials in the field of environmental remediation due to their several unique properties. In this regard, the synthesis method is key point to fabricate polymer-based adsorbent with targeted characteristics. In the present work, four polyaniline (PANIs) samples were synthesized by two alternative chemical approaches, a traditional one and an eco-friendly one, and two different dopants were used, HCl and H2SO4, respectively. All PANIs were characterized for their thermal, optical, morphological, and structural properties and their capability to remove simultaneously dyes and heavy metals from water have been investigated. It was deduced that the sorption ability is dependent on the as-synthesized PANI using different procedures and dopants. All the PANIs from traditional method showed high levels of pollutants removal (from 89 to 97%). Even though the materials obtained from the green way are overall less active, H2SO4-doped corresponding polymer showed high sorption capability (75–97%). Finally, the most performing PANIs were selected for recycling tests exhibiting high sorption efficiency retention up to four runs without any regeneration treatment. Most important, the cycling tests were stopped well before the sample sorption limit could be reached.