Abdulaziz A. Alhamid, Ahmad S. Alamoudi, Wafaa M. Morsy, Mahmoud M. Selim, Sherif A. El-Safty, Izumi Ichinose, Naeem Akhtar, Satoshi Kawada, Mohamed A. Shenashen, Hitoshi Yamaguchi, Naoki Ohashi
Because of the devastating impact of arsenic on terrestrial and aquatic organisms, the recovery, removal, disposal, and management of arsenic-contaminated water is a considerable challenge and has become an urgent necessity in the field of water treatment. This study reports the controlled fabrication of a low-cost adsorbent based on microscopic C-,N-doped NiO hollow spheres with geode shells composed of poly-CN nanospherical nodules (100 nm) that were intrinsically stacked and wrapped around the hollow spheres to form a shell with a thickness of 500–700 nm. This C-,N-doped NiO hollow-sphere adsorbent (termed CNN) with multiple diffusion routes through open pores and caves with connected open macro/meso windows over the entire surface and well-dispersed hollow-sphere particles that create vesicle traps for the capture, extraction, and separation of arsenate (AsO43−) species from aqueous solution. The CNN structures are considered to be a potentially attractive adsorbent for AsO43− species due to 1) superior removal and trapping capacity from water samples and 2) selective trapping of AsO43− from real water samples that mainly contained chloride and nitrate anions and Fe2+, and Mn2+, Ca2+, and Mg2+ cations. The structural stability of the hierarchal geodes was evident after 20 cycles without any significant decrease in the recovery efficiency of AsO43− species. To achieve low-cost adsorbents and toxic-waste management, this superior CNN AsO43− dead-end trapping and recovery system evidently enabled the continuous control of AsO43− disposal in water-scarce environments, presents a low-cost and eco-friendly adsorbent for AsO43− species, and selectively produced water-free arsenate species. These CNN geode traps show potential as excellent adsorbent candidates in environment remediation tools and human healthcare.
Open wide: Hollow-sphere geodes with multiple vast-mouth caves and controllable entrance sizes, based on C-,N-doped NiO (CNN), were effectively used for the capture, extraction, and separation of arsenate (AsO43−) species from water (see figure). The CNN structures showed selective superior removal and trapping capacity from real samples, and have the potential to be excellent adsorbent candidates for environment remediation tools and human healthcare.
