[A-GE29] Energy-Environment-Water Nexus and Sustainable Development

[AGE29-P02] Evaluation of Adsorption performance of laterite soil for removal of arsenic from contaminated water bodies.

*Nayaka Bandaralage Indraji Madhushan Nayaka Bandara¹, Ryutaro Yanagisawa¹, Akihiro Matsuno¹, Nakamura Kengo¹, Ken Kawamoto¹ (1.Saitama University, Japan)

Keywords:Arsenic, Water treatment, Laterite soil, Calcination process

Extensive research has meticulously documented arsenic's toxicity, categorizing it into acute and chronic forms. Arsenic is unequivocally classified as one of the most hazardous chemicals globally due to its widespread prevalence, heightened toxicity, and carcinogenic nature. Keen awareness and continued exploration are vital to mitigate its profound health implications and safeguard public well-being. This study investigates the efficacy of raw laterite (RL) (obtained from Thach That district, Hanoi, Vietnam) and calcined laterite (CL) soil, subjected to a calcination temperature of 550-degree Celsius for 1 hour (Muffle Furnace -FO300), in treating arsenic-contaminated water through the adsorption process. In the assessment of arsenic removal affinity of the adsorption material, a comprehensive testing procedure is initiated to inspect material properties, evaluate the effectiveness of the calcination process, and analyze the adsorption mechanism. At the beginning, four columns were tested to investigate the performance improvement of laterite soil due to the calcination process. In CL soil, adsorption breakthrough occurred in 470 min of operation while RL soil was only 240 min. Therefore, better treatment of arsenic was achieved with calcined laterite soil in a continuous column adsorption system confirming the effectiveness of the calcination process. Even though the surface area was not increased due to the calcination process, decomposition of organic matter and removal of volatile substances may be the reason for the increment of breakthrough time (surface area of RL and CL are 61.0 m²/g and 60.2 m²/g, respectively). Moreover, the height of the adsorption column significantly impacts the process performance with an indication of a reduction of breakthrough time from 470 min to 230 min when decreasing the column height from 20 cm to 10 cm. Furthermore, particle size made a comparatively high impact on the adsorption performance of calcined laterite soil in such a way that, when decreasing the particle size from the range of 0.6 mm to 2.0 mm to the range of 0.25 mm to 0.6 mm, breakthrough time was increased from 230 min to 330 min in 10 cm high column pack. This is mainly attributed to the surface area; when decreasing the particle size, the effective surface area within the column pack increased. The result was validated in the scanning electron microscopy (SEM) analysis indicating the improvement of roughness and pores structure of the material. In conclusion, calcined laterite soil demonstrates higher effectiveness over raw laterite soil in adsorbing arsenic in fixed bed column adsorption systems.