Arsenate removal by layered double hydroxides embedded into spherical polymer beads: Batch and column studies

Area of Science:

• Environmental Science
• Materials Science
• Water Treatment

Background:

• Arsenate contamination in water poses significant health risks.
• Effective and sustainable adsorbents are needed for arsenate removal.
• Layered double hydroxides (LDHs) show potential for heavy metal adsorption.

Purpose of the Study:

• To investigate the performance of poly(LDHs) beads for arsenate removal.
• To evaluate the adsorption kinetics, isotherms, and reusability of the poly(LDHs) beads.
• To assess the impact of solution parameters and co-existing anions on arsenate adsorption.

Main Methods:

• Preparation of poly(LDHs) beads by immobilizing LDHs in alginate/PVA-glutaraldehyde matrix.
• Batch adsorption experiments varying contact time, pH, initial concentration, and co-existing anions.
• Adsorption data analyzed using pseudo-second-order kinetics and Langmuir isotherm models.
• Fixed-bed column study using real arsenic-containing water.

Main Results:

• Poly(LDHs) beads removed 79.1-91.2% of arsenate from synthetic solutions.
• Adsorption followed pseudo-second-order kinetics and Langmuir isotherm models.
• Adsorption capacity ranged from 1.64 to 1.73 mg As g(-1) at pH 8.
• Adsorbent performance decreased by 5-6% after 5 cycles; phosphates significantly inhibited removal.
• Column study showed a breakthrough time of 7-10 h, with >82% arsenic removal under optimized conditions.

Conclusions:

• Poly(LDHs) beads are effective and reusable adsorbents for arsenate removal.
• The material demonstrates good performance in both batch and column studies.
• Poly(LDHs) beads offer a promising, cost-effective solution for water treatment.
• Further research for field-scale application and pilot plant design is warranted.