Preparation, characterization, and performance of 4A zeolite based on opal waste rock for removal of ammonium ion

Abstract

In this study, 4A zeolite was prepared from opal waste rock by hydrothermal method and applied in ammonium ion adsorption. To optimize synthesis conditions, the effect of crystallization time (1-8 h), crystallization temperature (65-115 C), Na 2 O/SiO 2 (0.6-2.0), H 2 O/Na 2 O (20-70), and SiO 2 /Al 2 O 3 (1.0-3.5) was investigated. X-ray diffraction, scanning electron microscope imaging, cation exchange capacity, static water adsorption, Fourier transform infrared spectroscopy, and N 2 adsorption-desorption isotherm were used for assessing properties of 4A zeolite. Adsorption experiments were performed by 1.0 g l À1 4A zeolite with NH 4 þ solution (5-300 mg l À1) for 4 h at room temperature. The experiment results revealed with a crystallization time of 3 h, a crystallization temperature of 85 C, Na 2 O/SiO 2 ¼1.0, H 2 O/Na 2 O ¼ 40, and SiO 2 /Al 2 O 3 ¼2.0, the 4A zeolite synthesized had excellent performance with cation exchange capacity of 2.93 mmol (g dry zeolite) À1 and static water adsorption of 22.3%. The adsorption process was described by Freundlich model (R 2 >0.99) and the maximum adsorption capacity could reach to 53.11 mg g À1. The experimental results provided a novel approach for the utilization of opal waste rock, which is produced during the mining of opal-rich palygorskite, and for the synthesis of 4A zeolite and the removal of ammonium ion.

Nitrogen fixation with renewable electricity: Plasma catalysis as an alternative for small-scale ammonia synthesis?

“…The XRD spectra of zeolite 4A is shown in Figure 65. The results are in line with previously reported data [368,369] .…”

Fundamentals, antibacterial, and photocatalysis properties of Ag@Se@PVDF nanocomposite membrane synthesized via laser ablation technique

“…The band that band at 1374 cm -1 was related to CH 2 wagging mode-related PVDF chain [43]. A broad band at 3402 cm -1 was assigned to O-H vibrations of the absorbed water [44]. FTIR spectrum of PVDF scattered by different ratios of (Ag@Se) nanocomposites shows decreasing in the intensity bands that related to PVDF by increasing the ratios of (Ag@Se) at about 1219 cm -1 , 1374 cm -1 , and 1733 cm -1 .…”

Removal of Ammonium from Aqueous Solutions Using Zeolite Synthesized from Electrolytic Manganese Residue

“…As seen in Figure 7, there is a reduction on ammonium adsorption to some extent in the presence of competitive cations in each case. Because K + , Ca 2+ , Na + , and Mg 2+ ions present in the solution can compete with the ammonium for the available ion-exchange sites on the EMRZ, resulting in a decrease in the uptake amount of ammonium onto EMRZ [36][37][38], with increasing the concentrations of Mg 2+ , Ca 2+ , K + , and Na + from 0 mg/L to 250 mg/L, the uptake amount of ammonium onto EMRZ decreased from 16.62 to 12.98, 11.25, 9.06, and 8.52 mg/g, respectively. At the identical concentration level of competitive cations, the reduction follows the sequence of Na + >K + >Ca 2+ >Mg 2+ , indicating the competitive degree of cations in the process of adsorbing ammonium followed the same sequence of Na + >K + >Ca 2+ >Mg 2+ .…”