Synthesis of Zeolitic Material from Paper Sludge Ash Using Diatomite

Abstract

Paper sludge ash (PSA) was partially converted into zeolites by reaction with 3 M NaOH solution at 90°C for 24 h. The PSA had a low abundance of Si and significant Ca content, due to the presence of calcite that was used as paper filler. Diatomite, which contains amorphous silica and dissolves easily in alkali solution, was mixed with the ash, and then added to the NaOH solution to increase its Si content during alkali reaction and thus synthesize zeolites with high cation exchange capacity (CEC). The original ash without addition of diatomite yielded hydroxysodalite with CEC ca. 0.5 mmol/g. Addition of diatomite to the ash yielded zeolite-P with a higher CEC (ca. 1 mmol/g). The observed concentrations of Si and Al in the solution during the reaction explain the crystallization of these two phases. The reaction products were tested for their adsorption capacity for nutrients from liquid fertilizer, such as K + , NH 4 + and PO 4 3¹ . The product with zeolite-P exhibits high ability to adsorb these nutrients from liquid fertilizer, which is desirable for application in soil improvement.

Preparation of Zeolitic Material with the Ability to Simultaneous Remove NH4+ and PO43^|^minus; from Paper Sludge using Calcination and Alkali Treatment

“…The condition to prepare a novel adsorbent with the ability to simultaneously remove NH 4 + and PO 4 3-from PS set in reference to my previous studies [9][10][11][12][13][14][15][16][17][18][19][20][21] various temperatures from 200 to 1000 °C for 6 h at a heating rate of 10 °C/min in an electric furnace under an air atmosphere. It was then cooled to room temperature to obtain the calcined PS samples.…”

“…Some products from the ash indicate simultaneous removal ability of NH 4 + and PO 4 3-, due to the zeolitic phases and amorphous calcium aluminosilicate hydrate (CASH) phases synthesized by alkali treatment, respectively [13][14][15][16][17] . The product can be used for water purification such as farm wastewater, (xxx) agricultural wastewater and domestic sewage, which contains high nutrients such as NH 4 + and PO 4 3-, and it can then be reused as a derived material for planting or agricultural soil 18,19) , because it is normally extremely low in potentially toxic components among industrial wastes [20][21][22] .…”