Color and shade parameters of ultramarine zeolitic pigments synthesized from kaolin waste

Abstract

Ultramarine pigments were successful synthesized from zeolite A obtained from kaolin waste. This waste has been used as an excellent source of silicon and aluminum for zeolite synthesis because of its high kaolinite concentrations and low contents of other accessory minerals. The cost is naturally less than the industrialized product. Color additives (Sulfur and Sodium Carbonate) were mixed with different proportions of zeolite A and further calcined for 5 h at 500 °C. They were characterized by XRD and XRF in addition to visual classification by color and shade. These products show colors from blue to green at different shades, both influenced by the amount of additives and cooling rate after calcination. Thus, a different quantity of the same additives in the same zeolitic matrix provides an increase in the color intensity. Cooling rate after calcination induces the color change which is substantially important in the pigments production.

Use of Brazilian Kaolin as a Potential Low-cost Adsorbent for the Removal of Malachite Green from Colored Effluents

“…Kaolin is a clay predominantly composed by kaolinite (Al 2 Si 2 O 5 (OH) 4 ) 25 , which has been widely used in a variety of technological applications [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] . Due to the low-cost and large availability, the use of clays like kaolin becomes the adsorption process an attractive and promising technology.…”

Synthesis of Ultramarine from Reservoir Silts

“…An aliquot of sodium carbonate (reagent grade, Fisher Scientific, Leicestershire, UK) solution of assigned concentrations was slowly added to the powder and was hand-kneaded to balls and then dried in air. It was reported [29,30] that in the reaction, sulfur and sodium carbonate are reacted as: 3Na 2 CO 3 + 1.25S 8 ↔ 2Na 2 S 4 + Na 2 S 2 O 3 + 3CO 2 (1)…”

“…Besides kaolin, other aluminosilicate sources, including pure chemicals, natural or synthetic minerals and wastes have been used. Chemicals, such as sodium silicate and tetramethylammonium hydroxide [22]; silicon tetrachloride and aluminum chloride [8]; silica, diatomaceous earth and sodium aluminate [23]; natural or synthetic minerals, like zeolite A, X, Y [24][25][26], cancrinite [27], hydroxycancrinite [28]; wastes, such as fly ash [20] and kaolin mine tailings [29], were reported to be technologically feasible. In a previous study, the reservoir silts were first treated hydrothermally to transform them to hydroxycancrinite [28]; then the hydroxycancrinite was transformed to ultramarine blue via a solid-state reaction process.…”

Encapsulation of red sulfur chromophores in a zeolitic imidazolate framework (ZIF-8) via solvent assisted linker exchange

“…Moreover the coloration and properties of the product can be varied by varying the zeolite synthesis conditions [8]. During the preparation of zeolitic ultramarine pigments, the zeolite is heated to temperatures varying from 500 to 800 C with sodium carbonate and sulfur [12,13]. The zeolite structure types most appropriate for ultramarine preparation so far include LTA, FAU and SOD [2,8,10].…”

“…Among the sulfur species present in ultramarines, the radicals S 3 À and S 2 À are most common which correspond to blue and yellow colors respectively [4,12,15] Depending on the proportion of each radical, a green color can also be formed [12,13,16,17]. A red shade seen in some ultramarines is due to the presence of the neutral S 4 molecule [6,16,18].…”