An effective and facile method was developed to remove As(V) and alkali simultaneously from alkaline wastewater based on the repeated in-situ formation of Zn-Al-AsO4 layered double hydroxide (ZnAl-AsO4 LDH). The removal efficiency of As(V) was almost 100% and the pH of the treated alkaline wastewater decreased from 12 to 7.47. Removal of As(V) was not affected by competitive anions such as SO42-, F-, Cl-, and NO3- due to the large binding energy between As(V) and LDH sheets as confirmed by calculations based on the Castep Module of Materials. About 96% of As(V) can be released and concentrated into a small volume of Na2CO3 solution for disposal or recovery. The LDH was then dissolved in HNO3 and the solution can be used to treat wastewater to reform Zn-Al LDH for further removal of arsenate. This process was repeated four times but after the fifth cycle, the removal efficiency went down by the loss of Al3+ to solution but the process can be repeated by replenishing the solution with Al3+. The newly developed process is eminently suited for remediation of arsenate and alkali simultaneously from alkaline wastewater.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials