Table 1.

Elemental chemical composition for protocatechuic acid and its nanocomposites

Sample	Ca (%w/w)	Na (%w/w)	Mgb (%w/w)	Alb (%w/w)	Xb	Aniona (%w/w)	Mg/Alb	Empirical formulab
PANE	13.37	0.676	19.1	6.1	0.23	24.5	3.3	$[{\text{Mg}}_{0.77}\text{A}{1}_{0.23}{(\text{OH})}_2]{({\text{PA}}^{-})}_{0.177}{({\text{NO}}_3^{-})}_{0.053}\cdot y{\text{H}}_2\text{O}$
PAND	14.98	0.607	17.3	6.7	0.26	27.5	2.9	$[{\text{Mg}}_{0.74}\text{A}{1}_{0.26}{(\text{OH})}_2]{({\text{PA}}^{-})}_{0.209}{({\text{NO}}_3^{-})}_{0.051}\cdot y{\text{H}}_2\text{O}$

Notes:

^aEstimated from CHNS analysis;

^bestimated from inductively coupled plasma analysis.

Abbreviations: C, carbon; N, nitrogen; Mg, magnesium; Al, aluminum; X, aluminum mole fraction; Y, the mole of water molecules; PAND, protocatechuic acid-Mg/Al nanocomposite synthesized by direct method; PANE, protocatechuic acid-Mg/Al nanocomposite synthesized by ion-exchange method; CHNS, carbon, hydrogen, nitrogen, sulphur.