Attapulgite Powder Research Articles

Hydrocracking of benzyloxybenzene as a lignite-related model compound over a novel solid acid

A novel solid acid was prepared by impregnating trifluoromethanesulfonic acid (TFMSA) onto attapulgite powder (AP). Benzyloxybenzene (BOB) was used as a lignite-related model compound to evaluate the catalytic activity of TFMSA/AP for cleaving Calk–O bridged bonds in lignites. The results show that BOB was mainly hydrocracked to toluene, phenol, and (ethoxymethyl)benzene over TFMSA/AP in ethanol without adding gaseous hydrogen. In addition, ethanol participated in and significantly facilitated BOB hydrocracking. Based on the kinetic investigation, BOB hydrocracking over TFMSA/AP is absent of mass transfer limitations with the apparent activation energy of only 19.4kJmol−1, which is far smaller than the dissociation energy (209.2kJmol−1) of Calk–O bridged bond in BOB. The proton transfer directly from TFMSA/AP and/or via ethanol dehydrogenation to the oxygen atom of BOB could be the crucial step for BOB hydrocracking over TFMSA/AP.

Tribological behaviors and wear mechanisms of ultrafine magnesium aluminum silicate powders as lubricant additive

The ultrafine attapulgite powders (UAP) were prepared using natural attapulgite powders (NAP) by the ball-milling dispersion method. The tribological behaviors of surface-modified NAP and UAP dispersed into mineral base oil were investigated. SEM, EDS, XPS and a microhardness tester were utilized to analyze the tribofilm formed on the worn surfaces. It is found that both the additives can improve the friction-reduction and anti-wear properties of the base oil. A tribofilm mainly composed of FeO, Fe2O3, FeOOH and SiO formed on the worn surface lubricated with oil containing NAP and UAP. And the content of iron oxides and SiO formed on the worn surface lubricated with oil containing UAP is much higher, which is responsible for the better friction-reduction and anti-wear properties of UAP.

Effect of natural attapulgite powders as lubrication additive on the friction and wear performance of a steel tribo-pair

Tribological properties of the surface-modified attapulgite powders as additive to lubricating oil for mated steel contact were investigated. The results indicated that the attapulgite powders exhibit good performance in reducing wear and friction coefficient. Such effect can be attributed to the formation of a smooth and compact tribo-film composed of multiple oxides on the worn surface.

Influence of different dry milling processes on the properties of an attapulgite clay, contribution of inverse gas chromatography

The effect of dry milling processes on the surface properties of an attapulgite clay, also called palygorskite, was investigated by carrying out experiments with different types of grinding devices. Ground products were then characterized by size measurement, scanning electron microscopy, X-ray diffraction, adsorption–desorption of N2 and inverse gas chromatography at infinite dilution (IGC-ID) as well as finite concentration conditions (IGC-FC). These analyses were performed to evaluate the changes in particle size distribution, morphology, crystallinity and surface properties of attapulgite powder, respectively. Among the tested dry grinding devices, grinding in an air jet mill (Alpine 50 AS) and a vibratory ball mill (Pulverisette 0) led to the most significant particle size reduction. SEM photomicrographs showed that a breakage of the fibrous structure took place during dry grinding. Moreover, long grinding in Pulverisette 0 resulted in the complete destruction of fibre morphology followed by agglomeration. XRD analysis showed that whatever the grinding process, the microstructure of the attapulgite was not affected. IGC confirmed that only grinding in Pulverisette 0 affected the surface properties notably. In this case, the most significant decreases were observed in the dispersive component of the surface energy (164 to 116mJ/m2) and in the specific surface area obtained with the octane probe (114.5m2/g to 62.6m2/g) by IGC-ID and IGC-FC, respectively. At the same time, a modification of the distribution functions of the adsorption energies (DFAE), giving information about surface heterogeneity, was noticed.

Removal of Cd(II) from Aqueous Solution by Electrospun Nylon 6 Nanofibrous Nonwoven Containing Attapulgite

The attapulgite powders modified by silicane coupling agent are loaded onto the surface of nylon 6 nanofibers by immersing the nylon 6 electrospun fiber nonwoven in a bath containing modified attapulgite dispersion under ultrasonicating. The nylon6 nanofibrous nonwoven containing attapulgite nano particles was explored as “nano adsorbent” to remove Cd (II) ions from Cd (II) aqueous solution. The effects of various parameters on adsorption properties, such as contact time, pH values of Cd (II) solution and initial Cd (II) concentration were investigated.

Effect of Heat Treatment on Properties of Mineral Attapulgite

Mineral attapulgite powders were heat treated at different temperature from 100°C to 800°C. The effect of heat treatment on properties of attapulgite were studied by particle size distribution, surface free energy, and water vapor adsorption performance. The results show that the medium particle size and surface free energy of attapulgite increase and hygroscopic capacity promptly reduce with the increase of heat temperature .The medium particle size of the raw palygorskite is 3.09 μm, and it becomes 14.12 μm after heat treatment at 800 °C. The surface free energy, polarity component and dispersion component of the natural attapulgite are 45.16mN•m-1, 13.92mN•m-1, 31.24mN•m-1, respectively, and they become 116.22 mN•m-1，116.22 mN•m-1，0.0 mN•m-1 after heat treatment at 800°C. Moreover, the hygroscopic capacity of attapulgite in 24h decreases from 17.1 % to 5.6% after heat treatment at 800°C.