چكيده به لاتين
Effective removal of excess sulfate from water is essential to protect the environment and
restore water quality, also the removal of hydrogen sulfide (H2S) released from various
source processes is crucial because this compound can cause corrosion and environmental
damage even at low concentrations levels. The porous materials offer a wide variety of
chemical architectures with tunable pore size and high surface area that are very promising
for the adsorption of H2S and sulfate molecules. In the current study, at first, we synthesized
the T-Type of zeolite nanoparticles via hydrothermal method, and optimize some synthesis
parameters such as crystallization time and temperature aiming to obtain nano-sized
zeolites. The hieratical zeolitic imidazole framework 8 (H/ZIF-8) and bimetallic H/ZIF-8,
H/ZIF-8@La and H/ZIF-8@Cu, were prepared using La(NO₃)₃.6H₂O and Cu(NO3)2·3H2O
as a La and Cu sources, respectively, to substitute 50-50% molar La or Cu with the Zn
source, with a simple and green method using water as a solvent. Process parameters
(temperature and time of crystallization), as well as compositional parameters (amount of
2-Methylimidazole and 2-(methylamino)ethanol), were studied. The Taguchi method was
chosen to optimize the procedure of zeolite LTA and ZIF-8 synthesis. samples were
characterized and confirmed with XRD, EDS, FE-SEM, TGA/DTA, FTIR, N2 isotherms,
and their performance was evaluated for removal of H2S from gases and sulfate uptake
from aqueous media.
Under the experimental conditions explored, the adsorption capacities of adsorbents in
breakthrough (5 ppm) for H2S decreased in the sequence: H/ZIF-8@La >H/ZIF-8
>H/ZIF-8@Cu >Nano Zeolite 4A> Commercial Zeolite which were 90, 74, 56, 25, and
8 mg/g, and breakthrough time: 430 min, 355 min, 270 min, 120 min and 40 min,
obtained respectively.
The optimization of sulfate removal from aqueous media was conducted with uptake onto
H/ZIF-8, H/ZIF-8@La, and H/ZIF-8@Cu. Process optimization concentrated on the effect
of independent parameters using CCD in the RSM package. A significant agreement
between the models and experimental data was verified by analysis of variance (ANOVA).
Compared with prepared H/ZIF-8 samples, the H/ZIF-8@La had a higher adsorption
capacity. The further removal efficiency of H/ZIF-8@La could be attributed to the better
textural properties than that of the H/ZIF-8 and H/ZIF-8@Cu. The potential abilities ofthree samples towards sulfate improved with temperature raising from 298 to 318 K. The
calculated thermodynamic parameters like ∆H, ∆S and ΔG revealed that the ongoing
process was endothermic, feasible, and spontaneous in nature.
