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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]

[Display omitted] • The COF-Tr-BA was prepared for selective adsorption and Li-S battery. • COF-Tr-BA shows excellent selectivity for genistein isomer by chemical interaction. • The introduction of boric acid group helps to improve electrochemical performance. Functional triazine-based covalent organic frameworks (COFs) with boric acid units, COF-Tr-BA, are designed and synthesized via cycloaddition of imine-linked COFs, COF-Tr, with (4-ethynylphenyl) boronic acid. Owing to the chemical interaction between boric acid units and adjacent dihydroxyl groups, COF-Tr-BA is used as the adsorbent for the selective adsorption of genistein isomer 4′6,7-trihydroxyisoflavone, showing an excellent selectivity and great adsorption performance with 5.4 times adsorption capacity (67.5 mg g−1) as high as 4′5,7-trihydroxyisoflavone (12.5 mg g−1). Meanwhile, COF-Tr-BA as the sulfur host for lithium-sulfur (Li-S) battery also exhibits a better electrochemical property, giving an initial discharge capacity up to 1349 mA h g−1 and a substantial capacity of 627 mA h g−1 after 200 cycles at 0.5C. It is attributed to the sulfiphilic interaction between the introduced boric acid groups and polysulfides (PSs), as well as the lithiophilic interaction between N atoms from quinoline and triazine moieties on the backbone of COF-Tr-BA and lithium ions (Li+), thus alleviating the dissolution and reducing the shuttle effect of LiPSs. The boric acid functionalized material COF-Tr-BA with the dual-function for selective adsorption and Li-S battery proposed here lays a significant foundation for multifunctional COFs as a versatile platform in practical application. [ABSTRACT FROM AUTHOR]