Vanadium removal from spent sulfuric acid plant catalyst using citric acid and Acidithiobacillus thiooxidans

Bartosz Mikoda,Harry Kucha,Ewa Kmiecik,Anna Potysz

doi:10.1007/s43452-020-00136-9

Abstract

Spent catalysts being considered hazardous wastes exhibit a high metal content in mobile forms. In addition, growing demand for circular economy policy applications requires proper utilization of these wastes. This study aimed at the assessment of vanadium leaching from spent desulfurization catalyst derived from sulfuric acid plant dump located nearby a copper smelter. Chemical and phase composition of the catalyst has been characterized. The extraction has been performed using chemical (0.1-M and 1-M citric acid) and biological (biotic solution with Acidithiobacillus thiooxidans) methods, using different experimental parameters (pulp density, particle size, leaching time) to observe V leaching behavior and kinetics. The results revealed that both citric acid and bacteria carried out the extraction process well. The optimal parameters for acid leaching were < 0.2-mm particle size and 2% pulp density, which allowed to leach out 95% of V from spent catalyst within 48 h. The bacterially mediated extraction resulted in 93% V leached out within 21 days with 2% pulp density. The experiments showed that V present in the catalyst is susceptible to bioleaching and organic acid leaching with the latter being a quicker process.

Highlights

To meet quality and/or environmental standards, sulfur dioxide has to be removed from products or gaseous emissions by a process called oxidative desulfurization [1], most commonly performed using catalysis—a process that relies on alteration of reaction rates using a solid-state catalyst [2]
The X-ray powder diffraction (XRD)-identified phases of spent desulfurization catalyst (SDC) sample studied here are given in Fig. 1a, and the XRD patterns ofleached residues are given in Fig. 1b
Apart from support phase, the vanadium oxide phase (V2O5), and salt phases such as N H4VOF(SO4) · 3 H2O, K2S2O7 and KAl(SO4)2 were determined as crystalline phases in SDC sample

Summary

Introduction

To meet quality and/or environmental standards, sulfur dioxide has to be removed from products or gaseous emissions by a process called oxidative desulfurization [1], most commonly performed using catalysis—a process that relies on alteration of reaction rates using a solid-state catalyst [2]. The catalysts used are mainly highly porous, made of synthetic or natural SiO2 (cristobalite/tridymite), and contain different active substances, mainly metal (e.g., Co, Mo, V) salts or oxides (e.g., potassium pyro-sulfo-vanadates: K2S2O7 · V 2O5) in the pore spaces [3, 4]. Global production of V has been doubled in the last 15 years, reaching

Objectives

Methods

Results

Conclusion