Self-enhanced and efficient removal of arsenic from waste acid using magnetite as an in situ iron donator

Removal of arsenic from smelting wastewater using Fe3O4as anin situFe source: the effect of pre-dissolution and the evolution process of scorodite

“…A low pH could accelerate the dissolution of the generated amorphous ferric arsenate and scorodite, 8 while a higher pH was not conducive to dissolving Fe 3 O 4 and releasing Fe for the synthesis of scorodite, which resulted in a high As leaching of the As-bearing precipitates in the TCLP. 39 When the pH was about 2.5, the As removal rate (99.1%) and the toxic leaching of precipitates (0.3 mg L −1 ) can reach a good level. At the same time, the initial pH value has a very important influence on the scorodite synthesis.…”

“…Initial pH is the key factor affecting scorodite synthesis. 39 The effect of Fe 3 O 4 on the synthesis of scorodite in the pH ranges from 2 to 4 was explored. It can be seen from Fig.…”

Production of H2S with a Novel Short-Process for the Removal of Heavy Metals in Acidic Effluents from Smelting Flue-Gas Scrubbing Systems

“…Sulfidation is an efficient method for the removal of HMs from acid-scrubbing effluents. − However, the addition of metal sulfide reagents (Na 2 S, NaHS, or FeS) to the acid effluents would not only introduce unexpected metal cations, but also lower acid recovery efficiency. , Adding gaseous H 2 S as the reagent in the liquid-phase can remove HMs by direct sulfidation process (DSP), which can successfully overcome the above problems. − The concentration of HMs is relatively high (up to 10 000 mg/L) while the emission limit of most HMs in these industries is relatively low (0.5 mg/L). , Increasing the H 2 S concentration can shorten HMs removal time and increase removal efficiency. , However, the transportation and storage of high concentrations of H 2 S (HC-H 2 S) are not allowed in many districts because of its high toxicity once released to the environment . In practical applications, there are some interim HC-H 2 S production processes.…”

“…12−15 The concentration of HMs is relatively high (up to 10 000 mg/L) while the emission limit of most HMs in these industries is relatively low (0.5 mg/ L). 16,17 Increasing the H 2 S concentration can shorten HMs removal time and increase removal efficiency. 18,19 However, the transportation and storage of high concentrations of H 2 S (HC-H 2 S) are not allowed in many districts because of its high toxicity once released to the environment.…”

The effect of precursor speciation on the growth of scorodite in an atmospheric scorodite synthesis

“…Ni, Sn, Pb, Cu and Zn) [2,3]. The occurrence of arsenic release during non-ferrous metal metallurgy poses a huge threat to the environment and human health all around the world [4]. The toxicity of arsenic links to its solubility.…”