Characterization of halloysite (North East Rif, Morocco): evaluation of its suitability for the ceramics industry

Abstract

A halloysite clay from Nador (NE Morocco) was studied to evaluate its suitability in the ceramics industry. A cross-section involving all the Messinian facies was performed in the Melilla Neogene basin, at the foot of the Gourougou volcano, to establish the origin of the halloysite and estimate its reserves. White layers of halloysite and red clays rich in smectite occurring in contact with basal-reef limestone were characterized by mineralogical (XRD, IR), textural (SEM) and physico-chemical analyses (grain-size, Atterberg limits, DTA/TG, XRF and specific surface area). Ceramic properties were evaluated for halloysite fired from 500 to 1100°C to evaluate technical processing for ceramic production.The halloysite clay consists of fine particles with a high plasticity and a large specific surface area. The XRD investigation revealed the presence of 7 Å non-hydrated halloysite along with gibbsite, alunite, K-feldspar and traces of smectite and illite.The presence of halloysite was confirmed from the characteristic IR bands at 3695 and 3618 cm−1and the predominance of tubular crystals observed in the SEM. The chemical analysis revealed high contents linked to the presence of Al-rich phases (gibbsite and alunite). DTA/TG and XRD results of fired clay samples proved the dehydroxylation of halloysite and a rearrangement of metakaolinite to form mullite and spinel at 975°C.The Moroccan halloysite might be suitable for refractory ceramic applications. However, addition of quartz sand might be necessary to avoid crack development during firing and to reduce the plasticity of raw halloysite and minimize shrinkage during sintering.

Thermodynamics and kinetics of the removal of methylene blue from aqueous solution by raw kaolin

“…2). In addition, a loss on mass of 2.8% occurs at about 100 °C, which is attributed to the loss of the surface adsorbed water [25]. These results indicated that halloysite adsorbs water molecules both on surface and lumen space of the nanotubes.…”

“…Halloysite is mainly derived from long-term weathering of amorphous silicate, which remained in small amount as relicts associated with raw halloysite [24,25]. Similar to the carbon nanotube, halloysite is of particular importance due to its tubular morphology of 500-1000 nm in length and 10-100 nm in inner diameter [26].…”

Intercalation experiments for morphological alteration of kaolinite present in iron ore tailings

“…In order to understand the rolling mechanism of the 1:1 layer of tetrahedral and octahedral sheets, several models have been proposed [6]. Increasing demand for HNT is observed, although it is not as common as kaolinite [7][8][9]. In recent years, several studies have broadened the field of application of HNT to highly technological applications such as catalytic supports and other functional materials due to their particular morphology and specific properties [8,10].…”

“…Increasing demand for HNT is observed, although it is not as common as kaolinite [7][8][9]. In recent years, several studies have broadened the field of application of HNT to highly technological applications such as catalytic supports and other functional materials due to their particular morphology and specific properties [8,10]. In addition, the nanoparticles are also capable of adsorbing and storing a large number of hydrogen molecules [11] and drugs for controlled release [12][13][14], forming antibacterial biological membranes [15] and polymer-based composites [16][17][18], among other technological uses.…”

Chemical reactions affecting halloysite dispersion in epoxy nanocomposites

“…The HNTs are a kind of aluminosilicate clay [Al 2 Si 2 O 5 (OH) 4 .H 2 O with 1:1 layer] with hollow micro and nanotubular structure. Many researchers have worked on halloysite clay characterization . HNTs contain two types of hydroxyl groups, inner and outer hydroxyl groups, which are situated between layers and on the surface of the nanotubes, respectively.…”