Treatment of strongly acidic wastewater with high arsenic concentrations by ferrous sulfide (FeS): Inhibitive effects of S(0)-enriched surfaces

Abstract

h i g h l i g h t sFeS shows higher removal efficiency towards As(III) than As(V). In acidic solution FeS dissolve to S(-II) for As(V) reduction and As 2 S 3 formation. S(-II) react with As(V) to form S(0)-rich surface on FeS and inhibit As removal. S(II)-rich surface inhibit FeS dissolution and arsenic removal. As(V) reduction to As(III) by dosing Na 2 S prior to FeS improve As(V) removal. The utilization of arsenopyrite (FeAsS), the As ore mineral, produces strongly acidic wastewater with extremely high arsenic (As) concentrations. This study investigates the feasibility of using ferrous sulfide (FeS) as a sulfide [S(-II)] source to treat strongly acidic wastewater with high concentrations of arsenite [As(III)] and arsenate [As(V)]. The removal of As(III) by FeS was nearly 30% higher than that of As(V), and higher acidity and elevated FeS doses benefited their removal. At extremely high acidity of above 7 mol/L as H 2 SO 4 , the consumption of S(-II) by H 2 SO 4 inhibited As removal. At lower acidity of below 2 mol/L as H 2 SO 4 , elevated FeS doses up to 4 times the theoretical dose could achieve good As removal. SEM/EDS and XPS analysis indicated the formation of As 2 S 3 precipitates, and sulfur [S(0)] also formed in the As(V)-removing system. The tiny and negatively-charged S(0) particles tend to coat the FeS surface. The S(0)-enriched surface acts as a barrier to inhibit S(-II) detachment and As(V) penetration and inhibits As(V) removal thereafter. The reduction of As(V) to As(III) by Na 2 S, prior to dosing with FeS, is preferred to achieve rapid and favorable As(V) removal. The low-cost FeS provides available Fe(II) and S(-II) for As removal, and is practically valuable to treat acidic high-As wastewater.

Visible-light photocatalysis accelerates As(III) release and oxidation from arsenic-containing sludge

“…During metal smelting, mineral processing, and sulfuric acid production from pyrite ores, a large amount of arsenic-containing acid wastewater and tailings are produced [3]. For example, the arsenic concentration in the wastewater from a sulfuric acid plant can range from several to tens of thousands mg/L [4]. One of the most popular techniques for treatment of the arsenic wastewater in industry is sulfide precipitation, where sulfide is employed to transform arsenic ions into arsenic sulfide precipitate [5].…”

Arsenic accumulation and volatilization in a 260-day cultured upflow anaerobic sludge blanket (UASB) reactor

“…As shown in Fig. 2 [23] and sulfur ions [24,25]. In addition, the retention time of wastewater in the inner was longer than that at the bottom because of the shape of the reactor, which resulted in more reaction time for arsenic with other ions in the inner part of the reactor.…”

“…by Fe-sulfide [25,29]. Arsenic volatilization occurred in the UASB reactor treating wastewater contaminated with roxarsone, emphasizing the importance to protect human and animal from the volatilized arsenic, also indicating that organoarsenic-contaminated poultry litter and pig manure should be well managed because of the potential arsenic volatilization under anaerobic conditions [30].…”

Selective Separation of Arsenic from Lead Smelter Flue Dust by Alkaline Pressure Oxidative Leaching

“…The high content of arsenic not only effectively reduces the economic value of lead smelter flue dust due to requirements for further operations of hazardous emissions, but also creates great risks to the environment and the human body [4,5]. Arsenic has been classified as a Group 1 human carcinogen by the international agency for research on cancer, and arsenic exposure is associated with an increased incidence of human malignancies in skin, lungs, bladder, and liver [6][7][8].…”