Abstract
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 (AsO
) species from aqueous solution. The CNN structures are considered to be a potentially attractive adsorbent for AsO
species due to 1) superior removal and trapping capacity from water samples and 2) selective trapping of AsO
from real water samples that mainly contained chloride and nitrate anions and Fe
, and Mn
, Ca
, and Mg
cations. The structural stability of the hierarchal geodes was evident after 20 cycles without any significant decrease in the recovery efficiency of AsO
species. To achieve low-cost adsorbents and toxic-waste management, this superior CNN AsO
dead-end trapping and recovery system evidently enabled the continuous control of AsO
disposal in water-scarce environments, presents a low-cost and eco-friendly adsorbent for AsO
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.