Selective Phosphorus Removal from Wastewater Using Graphene Aerogel Loaded with Ferrocene-Polyaniline: Synergetic Adsorption and Electrochemically Mediated Oxidation

Abstract

Selective removal and recovery of phosphorus from wastewater is a huge challenge for water purification. In particular, phosphite is an often-neglected contaminant that is more soluble and resistant to biotransformation than phosphate. Herein, we develop an electrochemical system for phosphorus removal using nitrogen-doped graphene aerogel loaded with ferrocene-polyaniline (Fc-PANI@NGA) electrodes. The results demonstrate that this electrochemical system can selectively adsorb phosphate and phosphite in comparison to other anions and promote the oxidation of phosphite to phosphate. The high affinity of Fc-PANI@NGA to both phosphate and phosphite due to the faradic reactions and specific hydrogen-bonding interactions ensures high selectivity of P over Cl − , SO 4 2− , and NO 3 − . The redox reversibility of Fc to Fc + due to its interaction with O 2 /H 2 O 2 led to the formation of • O 2 − and • OH, which are predominantly responsible for the oxidation of phosphite to phosphate. This system enables the phosphate and phosphite adsorption capacities of 29 mg PO 4 3− g −1 and 24 mg HPO 3 2− g −1 , respectively, and high phosphite conversion efficiency (99.3% at a cell voltage of ±1.6 V), exhibiting high selection efficiency and stable regeneration performance. Density functional theory calculation verifies the selective adsorption mechanism of phosphate and adsorption/oxidation of phosphite on the Fc-PANI@NGA electrode.

Ferrocene Bis(Sulfonate) Salt as Redoxmer for Fast and Steady Redox Flow Desalination

“…Recently, there has been significant interest in ferrocene-based redox flow cell viable energy storage solution [18,19]. While initial investigations have explored th of ferrocene materials in deionization [20][21][22][23], the predominant focus has been on ca tive deionization (CDI), which is constrained by its charge and discharge opera modes [24]. The potential of ferrocene materials in RFD, which is characterized by co uous operation and has theoretically unlimited capacity, remains largely unexplored tably, anionic and cationic ferrocenes have emerged as promising candidates, due to high water solubility and reversible redox activity [19], making them ideal materia RFD applications.…”