Low carbonate contaminative and ultra-small NiAl LDH prepared by acid salt treatment with high adsorption capacity of methyl orange

Layered double hydroxides (LDHs) are attracting intense research interests as methyl orange (MO) adsorbent due to the unique anionic exchange ability. Herein, ultra-small NiAl LDHs with Cl- intercalation were prepared by a facile method combining hydrothermal method with acid salt treatment. As a result, the as-prepared NiAl LDHs displayed favorable removal performance toward MO from aqueous solution due to the negligible carbonate contamination and ultra-small nanosheets (about 50 nm). The maximum experimental and theoretical adsorption capacities of 853.19 and 900.14 mg g-1 at pH=7 and T=298 K for MO were achieved for Ni4Al1-Cl LDH. The adsorption mechanism is dominated by chemisorption and the adsorption process is spontaneous and endothermic. Possible “Intercalation-split mechanism” for MO on NiAl-Cl LDH is proposed to explain the split of (003) plane. The improvement of adsorption capacity indicates that the acid salt treatment is an effective strategy to construct the rapid and high-effective anioni...