kaolinite and feldspar

Heterogeneous reaction of NO

Topics: Aerosols; Arizona; Bentonite; Clay; Dust; Kaolin; Minerals; Nitrogen Dioxide

Despite the massive accumulation of nanoplastics (NPs) in the freshwater system, research so far has highly focused on the marine environment. NPs interaction with mineral surfaces can influence their fate in freshwater, which will further impact their bioavailability and transport to the oceans. Current work focuses on understanding NPs interaction with weathering sequence of minerals in freshwater under varying geochemical conditions. Primary mineral feldspar and weathering originated secondary minerals, i.e., kaolinite and gibbsite, were investigated for interaction with NPs under batch mode under relevant environmental conditions. Minerals-NPs interaction was also investigated in natural water samples. Results showed that the amorphous nature, small particle size, and positive surface charge of gibbsite resulted in multi-fold sorption of NPs (108.1 mg/g) compared to feldspar (7.7 mg/g) and kaolinite (11.9 mg/g). FTIR spectroscopy revealed hydrogen bonding and complexation as major players in gibbsite-NPs interaction suggesting the possibility of their co-precipitation. The continuous adsorption-desorption and limited sorption capacity of feldspar and kaolinite can be attributed to their negative surface charge, larger size, crystalline nature, and physical sorption. Therefore, both minerals may co-transport and enhance the mobility of NPs.

Topics: Adsorption; Aluminum Silicates; Kaolin; Microplastics; Minerals; Potassium Compounds

Many hirundine species construct their nests by carrying mud particles from adjacent areas. This study aimed to investigate for the first time the materials that mud-nesting hirundines choose for nest construction from a mineralogical and sedimentological perspective. For this purpose, we sampled nests of three sympatric species, namely the Barn Swallow (Hirundo rustica), the Red-rumped Swallow (Cecropis daurica) and the House Martin (Delichon urbicum), from southeastern Europe. Our results showed that all species tend to use clay minerals as a cement and especially smectite and illite and if these minerals are not present in the adjacent area, they use halloysite, kaolinite or chlorite. The amounts of clay minerals in the nests are generally low indicating that the studied species can accurately identify the properties of the nesting materials. Most of the non clay minerals that they use are the common, easily accessible colourless or white minerals with low specific gravity values such as quartz, feldspars and calcite. Grain size distribution analysis revealed that the amount of clay sized grains in the mud nests of all three species is relatively low, while the amount of larger grain particles decreases when the size of the non clay minerals is small. The Red-rumped Swallow showed an increasing preference for larger grain size particles and quartz, the Barn Swallow for finer grain size particles and calcite, and the preferences of the House Martin are in between the other two species. The three hirundine species present different nest building strategies and depending on the nest architecture, each of them seems to show preference for specific minerals and specific grain sizes.

Topics: Aluminum Silicates; Animals; Calcium Carbonate; Chlorides; Clay; Construction Materials; Kaolin; Nesting Behavior; Potassium Compounds; Quartz; Swallows

The flocculation efficiency of a cationic polyelectrolyte with quaternary ammonium salt groups in the backbone, namely PCA5 was evaluated on zirconium silicate (kreutzonit), kaolin, K- feldspar and zinc oxide (ZnO) suspensions prepared either with each pollutant or with their mixture. The effect of several parameters such as settling time, polymer dose and the pollutant type on the separation efficacy was evaluated and followed by optical density and zeta potential measurements. Except for ZnO, the interactions between PCA5 and suspended particles led to low residual turbidity values (around 4% for kreutzonit, 5% for kaolin and 8% for K-feldspar) as well as to the reduction of flocs settling time (from 1200 min to 30 min and 120 min in case of kaolinit and K-feldspar, respectively), that meant a high efficiency in their separation. The negative value of the zeta potential and flocs size measurements, at the optimum polymer dose, point to contribution from charge patch mechanism for the particles flocculation. A good efficiency of PCA5 in separation of paraffin oil (a minimum residual turbidity of 9.8%) has been also found.

Topics: Aluminum Silicates; Flocculation; Kaolin; Oils; Paraffin; Polyamines; Polyelectrolytes; Polymers; Potassium Compounds; Quaternary Ammonium Compounds; Silicates; Water; Water Pollutants, Chemical; Water Purification; Zinc Oxide; Zirconium

Infrared spectroscopy has been employed in a study of the degradation of heritage Sydney sandstone used in St. Mary's Cathedral in Sydney, Australia. Spectra were used to characterise the clay components taken from weathered and unweathered sandstone blocks removed from the Cathedral as part of a restoration programme. Two types of kaolin clays - kaolinite and its polymorph, dickite - have been identified. A higher amount of dickite present in the clay of weathered sandstone indicated that a kaolinite-to-dickite transformation occurs upon weathering. X-ray photoelectron spectroscopy was also used to confirm the presence of a more thermally stable polymorph of the kaolinite in the sandstone.

Topics: Aluminum Silicates; Clay; Color; Construction Materials; Kaolin; Minerals; New South Wales; Oxidation-Reduction; Potassium Compounds; Quartz; Silicon Dioxide; Spectroscopy, Fourier Transform Infrared; Spectrum Analysis; Weather; X-Rays

The quantitative mineralogical analysis of small samples (less than 20 mg) of china clay has been investigated using x ray diffractometry to determine kaolinite, mica, quartz, and feldspar. A method has been developed and applied to the quantitative analysis of airborne dust samples and of other small discrete samples. Determinations were made either on samples after collection on a membrane filter or on samples after deposition from aqueous suspension on to a silver substrate. Quantitative analysis was hindered by preferred orientation of the kaolinite and of the mica particles that occurs when using these methods of specimen preparation. Quartz and feldspar were determined direct from prepared calibration graphs. Preferred orientation of the mica particles leads to serious interference with the most sensitive quartz x ray diffraction peak which, if not recognised, will result in an overestimation of the quartz content. Kaolinite and mica were determined from the ratio of their most intense x ray diffraction peak areas to overcome the preferred orientation effects observed for these two minerals. During the investigation, the opportunity arose for comparative measurements of quartz contents of airborne dust samples with the Occupational Medicine and Hygiene Laboratories of the Health and Safety Executive. The mass of specimen examined varied between 0.8 mg and 20 mg and the quartz contents varied between 0.1% and 1.2%. The comparative results were in good agreement.

Topics: Air Pollutants, Occupational; Aluminum Silicates; Kaolin; Particle Size; Potassium; Potassium Compounds; Quartz; X-Ray Diffraction