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Arsenic (As) is among the most dangerous metalloids and is harmful to human wellbeing. In this laboratory study, Al(III)-modified kapok fibres (Al-Kapok) were used to remove As(V) from water. The sorbent was characterised using Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDX). Batch experiments were performed to observe the performance of Al-Kapok in the removal of As(V) and to examine the effects of pH, temperature, adsorbent dose, and coexisting ions on the adsorption process. The surface of the sorbent changed after aluminium modification, and the results of the batch experiments showed that the adsorption of As(V) occurred mainly via endothermic-spontaneous chemisorption at the solution and solid interface of Al-Kapok. The As(V) removal efficiency was approximately 76%–84%, and it was slightly affected at pH levels below 8.0. Further study showed that the maximum adsorption capacity of Al-Kapok for As(V) was 118 μg/g at 30 °C and pH 6, and notable adverse effects were caused by the presence of SO 4 2 − and PO 4 3 − . It was also found that the boundary layer and film diffusion contributed more to As(V) adsorption. After five adsorption/desorption cycles, regeneration recovered approximately 92% of the adsorption capacity of Al-Kapok used. Overall, Al-Kapok appears to be a suitable adsorbent material for the purification of As-contaminated water. [Display omitted] • The adsorption of As(V) on the Al-Kapok is slightly affected by pH at pHs below 8.0 • As(V) adsorption is mainly a chemical process and inhibited by multi-valent anions. • Boundary layer and film diffusion shows more contribution to the adsorption of As(V). • 92% of the Al-Kapok's adsorption capacity could be recovered through regeneration. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe-Kapok has been made by easy hydrothermal method. • Fe-Kapok showed Fe positive impact for As (V) removal. • High and fast As (V) adsorption. • Fe-Kapok could be regenerated and reused several times. Arsenic (As) is one of the most toxic metals for human health. In the present work, kapok fibers were modified using iron Fe(III) to enhance As(V) adsorption and then characterized using Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy (EDS). The impacts of pH, dose of adsorbent, contact time, initial concentration, temperature, and coexisting ions on the adsorption of As(V) onto Fe-modified kapok fiber (Fe-kapok) surfaces were investigated. The results showed that the adsorption process fit more to the Langmuir isotherm equation and pseudo second kinetic equation, thus demonstrating that the adsorption was an endothermic, spontaneous, monolayer chemisorption process with some disorder at the solid/solution interface. The adsorption process was controlled by the film diffusion step, and the maximum adsorption capacity of Fe-kapok was calculated to be approximately 367 µg/g. Further study showed that after 8 adsorption/desorption cycles with 1 regeneration cycle, Fe-kapok was still able to remove 45% of the arsenic (100 µg/L) present in the water. A notable negative impact on the removal of As(V) from water was linked to the concentrations of SO 4 2- and PO 4 3- in the water. [ABSTRACT FROM AUTHOR]

More than 170 million individuals have been influenced by arsenic (As) because of the ingestion of As-polluted groundwater. The presence of As in water bodies, particularly groundwater, has been found to become a widespread issue in the past few decades. Because arsenic causes extreme wellbeing impacts, even at a low concentration in drinking water, the innovations of As removal from contaminated water are of significant importance. Traditional strategies, for example, reverse osmosis, ion exchange, and electro-dialysis are generally utilized for the remediation of As-polluted water; however, the high cost and/or sludge production restricts their application in less-developed areas. The utilization of adsorbents acquired from natural materials has been explored as an alternative for the costly techniques for As removal. This paper aims to review the past and current developments in using naturals adsorbents or modified natural materials for arsenic removal and show the different parameters, which may influence the As removal effectiveness of the natural adsorbent, such as contact time, adsorbent dosage, flow rate, pH, reusability, temperature, and influence of others ions. [ABSTRACT FROM AUTHOR]