Resource utilization of organic spent adsorbent to prepare three-dimensional sulfate-functionalized layered double oxide for superior removal of azo dye

Developing superior, rapid, cost-effective adsorbents derived from organic spent adsorbent is an economically sustainable way for purifying azo dye wastewater. Herein, we report a precursor-calcination strategy the recycle of to high value-added three-dimensional sulfate-functionalized MgAl-layered double oxide (3S-LDO). Thanks unique property sulfate group and LDO, 3S-LDO exhibited superior (4340.71 mg/g) ultrafast (<1 h) adsorption toward methyl orange (MO, as representative dye). A thermodynamic study revealed that reaction process was spontaneous exothermic. FT-IR, XPS, XRD results confirmed played vital role in MO removal wherein S=O bond (with electrophilic character) SO42- interacted with N=N rich electron) through electron donor-acceptor mechanism. And “memory effect” surface complexation further strengthened adsorption. More importantly, could work efficiently wide pH range even presence competitive anions (e.g., Cl-, NO3-, CO32-). Multiple cyclic runs selective tests demonstrated excellent reusability explicit selectivity 3S-LDO. This not only provides prospective waste rapid wastewater but also achieves utilization waste.