Electrochemical determination of trace As(III) via stable rGO wrapped ammoniojarosite hydrothermally recovered from a processed liquor

Abstract

The current research elucidates a simple, cost effective and highly selective platform for electrochemical detection of trace As(III) by a stable rGO wrapped ammoniojarosite. The ammoniojarosite has been recovered via pH-dependent urea-based hydrothermal pathway from a surfactant mediated acidic leach liquor of polymetallic nodules. The obtained products in the order of increasing urea concentration are ammoniojarosite (AmJ), pyrite and hematite, where the highest purity with lowest urea concentration and excellent electrochemical selectivity was showcased by AmJ. All the obtained precipitates have been characterized by SEM, EDS, XRD, RAMAN, XPS and HRTEM techniques and investigated for their electrochemical sensing application towards the presence of As (III). Since AmJ exhibited remarkable detection results and selectivity, we have synthesized a rGO@AmJ composite to amplify the detection further. As(III) was detected using cyclic voltammetry(CV), square wave anodic stripping voltammetry (SWASV) and amperometry (i-t) technique. The lower detection limit for rGO@AmJ was 0.0365 & mu;M with ultra-high sensitivity of 114.14 & mu;A & mu;M-1cm-2 and correlation coefficient R2 = 0.971.