Arsenic removal from groundwater by a newly developed adsorbent

Area of Science:

• Environmental Science
• Water Treatment Technologies
• Materials Science

Background:

• Arsenic contamination in groundwater poses significant health risks.
• Conventional adsorbents for arsenic removal have limitations in capacity and efficiency.
• Developing novel adsorbents is crucial for effective arsenic remediation.

Purpose of the Study:

• To evaluate a novel adsorbent, initially developed for phosphate removal, for its efficacy in arsenic remediation from groundwater.
• To investigate the adsorption characteristics, including isotherm, pH dependence, and kinetics, of the novel adsorbent for arsenic.
• To assess the performance of the granular adsorbent in a continuous flow system using actual groundwater.

Main Methods:

• Batch adsorption experiments were conducted to determine adsorption isotherms, pH dependence, and adsorption rates.
• Laboratory-scale continuous flow experiments utilized granular adsorbent (1.8 mm diameter) with arsenic-spiked groundwater (50 mg As m⁻³).
• Adsorbent performance was evaluated based on arsenic adsorption capacity and bed volumes treated until breakthrough.

Main Results:

• The novel adsorbent demonstrated a high arsenic adsorption capacity of 10 g As kg⁻¹ at pH 7.0 and an equilibrium concentration of 10 mg As m⁻³.
• Adsorption capacity was comparable to, but only 5% higher than, conventional activated alumina.
• The adsorbent achieved twice the bed volumes treated until breakthrough compared to conventional materials.
• A self-pH decrease function, attributed to Al(III) aquoion dissociation and proton release, was observed, enhancing apparent adsorption capacity.

Conclusions:

• The novel adsorbent shows promise for arsenic removal from groundwater, particularly due to its enhanced performance in continuous systems.
• The self-pH decrease mechanism is a key factor contributing to the adsorbent's improved efficiency.
• Further research into optimizing this adsorbent could lead to more effective and economical arsenic water treatment solutions.