Synthesis and characterization of zeolite 4A from soft kaolin

Abstract

A B S T R AC TThe synthesis of zeolite 4A from soft kaolin has been studied. Kaolin was converted to metakaolin by fi ring at 550 °C for 2 h, which was then added to NaOH solutions of appropriate concentration. The optimum molar ratios for the main constituents in the starting gel were SiO 2 /Al 2 O 3 = 1.7, Na 2 O/SiO 2 = 2.8 and H 2 O/Na 2 O = 61.7. The gels were vigorously stirred at 70 °C for 2 h and aged under the room temperature for 24 h, then stirred again with intermediate speed at 90 °C. After 4 h, the product was centrifugated and washed till pH 10∼11. Examination with XRD, IR and SEM proved that the product was zeolite 4A.

Green and low-cost synthesis of zeolites from kaolin: a promising technology or a delusion?

“…Impurities are quartz, mica, illite, anatase, rutile, pyrite, siderite, feldspar, smectite, muscovite, gibbsite, iron oxides, hydroxides, etc. 84,118 The presence of impurities in the raw material contaminates the product, but their influence on the crystallisation process is ambiguous. 42,119 In addition, soluble impurities after hydrothermal synthesis may remain in the mother liquor.…”

Utilization of Bengkalis Beach Sand Silica as Raw Material in the Synthesis of Zeolite 4A

“…As a porous material, zeolite 4A has various uses, including water purification and toxic heavy metals removal (Rahman et al, 2018;Wu et al, 2018;Al-Jubouri et al, 2019), adsorbent (Wang et al, 2019) , catalysts, ion exchange membranes, and molecular sieve (Ginting et al, 2019) . The source of silica in the synthesis of zeolite 4A can come from kaolin (Du and Yang, 2010;Li et al, 2010;Omisanya et al, 2012;H Kareem et al, 2014;Golbad et al, 2017;Garcia Mendoza, 2017;Du and Yang, 2010;Rahman et al, 2018;Mgbemere et al, 2019;Wang et al, 2019;Dahani et al, 2020;Sowunmi et al, 2022) sugar cane bagasse, rice husks, coal bottom ash (CBA), coal fly ash (CFA), natural zeolite (Ginting et al, 2019) , basalt rock (Hwang et al, 2018) , opal waste rock (Wu et al, 2018) , bauxite (Rahman et al, 2021) , from chemicals (Menad et al, 2016;Paprica et al, 2022) and waste sludge from water treatment plants (Wongwichien et al, 2014) . In this research, the silica extracted from BBS was used as raw material for making zeolite 4A.…”