Hydroxysodalite zeolite nanoparticles with different crystallite sizes (37.61–64.88 nm) were synthesized using a hydrothermal
method in the absence and presence of low-cost aliphatic organic acids as templates. The templates used were oxalic acid
dihydrate, tartaric acid, citric acid monohydrate, succinic acid, maleic acid, and ethylenediaminetetraacetic acid (EDTA). The
synthesized nanoparticles were characterized using HR-TEM, FE-SEM, FT-IR, and XRD techniques. The hydroxysodalite
zeolite synthesized using ethylenediaminetetraacetic acid (EDTA) has the smallest crystallite size (37.61 nm) whereas the
template free one has the largest crystallite size (64.88 nm). The synthesized nanoparticles could be effectively applied to
purify polluted water from the zinc(II) ions, and the maximum adsorption capacity was 8.53 mg/g. Kinetic study displayed
that the adsorption process of zinc(II) ions obeyed pseudo-second-order, intra-particle diffusion, liquid film diffusion, and
pore diffusion models whereas the rate determining step of the adsorption is only controlled by the pore diffusion model. In
addition, equilibrium study showed that the adsorption process fitted well with the Langmuir isotherm model compared to
the Freundlich isotherm model. Besides, thermodynamic study showed that the adsorption process is exothermic, spontaneous,
and chemisorption. Moreover, desorption and reusability study revealed that there is a slight decrease in both of the
% removal and adsorption capacity of the hydroxysodalite adsorbent with progressing five cycles. Hence, we can infer that
this new hydroxysodalite adsorbent can possibly be utilized repeatedly without sacrificing its adsorption capacity towards
zinc(II) ions.