Preparation of Vermiculite Nanoparticles Using Thermal Hydrogen Peroxide Treatment

Abstract

Powdered natural Mg-vermiculite (Letovice, Czech Republic), with the formula (Mg0.35K0.02Ca0.01) (Mg2.39Fe0.51(3+)Fe0.02(2+)Al0.08) (Si2.64Al1.33Ti0.03) O10(OH)2 x 4.97H2O and particle size < 5 microm, was used for the investigation of exfoliation after hydrogen peroxide and/or microwave treatment (600 W). A sample heated in the microwave oven for 40 min exhibits a 11% mass loss and reduction of the 001 peak intensity in the X-ray diffraction pattern. The basal 001 peak intensity of untreated Mg-vermiculite sample (/001 = 100%) drops to 35% in the microwave treated sample. Only the sample treated for 5 h at 80 degrees C fully rehydrated after 120 min at room temperature. A more pronounced reduction of the 001 peak intensity (to 8%) was observed after hydrogen peroxide treatment of the sample at 25 degrees C. The combination of a five-hour hydrogen peroxide treatment at 80 degrees C and subsequent microwave heating leads to an effective extinction of the 001 diffraction in the XRD pattern. The 001 diffraction profile becomes very diffuse with peak intensity less than 1%. The degree of reduction of the 001 diffraction intensity also depends on the time and temperature of hydrogen peroxide treatment and on the peroxide concentration. An even more pronounced reduction of the peak intensity is caused by exfoliation of particles to nano-domains coupled with a randomization of the c-axes.

Porous Layered Double Hydroxides Synthesized using Oxygen Generated by Decomposition of Hydrogen Peroxide

“…Dehydration was performed to enhance the diffusion of H 2 O 2 and water molecules back into the interlayer. Water removal from a layered system has been mentioned as a crucial step to accomplish quantitative intercalation of H 2 O 2 30 . The LDH-H 2 O 2 suspension was annealed in the MW reactor for 2 h in an open vessel until all hydrogen peroxide had completely decomposed.…”

Vermiculite: Structural Properties and Examples of the Use

“…These interactions disrupt the electrostatic equilibrium between the layers and the interlayer cations. Weiss et al [60] studied exfoliation of Mg-vermiculite after thermal, microwave and/or hydrogen peroxide treatments. A stronger than hydrogen peroxide oxidation agent potassium persulfate (K2S2O8) used Matějka et al [61] to delaminate/exfoliate Mg-vermiculite.…”

Highly Hydrophobic Polydimethylsiloxane-Coated Expanded Vermiculite Sorbents for Selective Oil Removal from Water

“…Vermiculite, a clay mineral, can be expanded by thermal or chemical processes to produce a highly porous and lightweight material. The advantages of vermiculite include its chemical inertness, non-toxicity, natural abundancy, and pore-structure controllability, thus providing an opportunity to create ecologically friendly, low-cost sorbents [19][20][21]. Until now, a surface of expanded vermiculite (eVMT) had been commonly modified by impregnation with polymers [22], carnauba wax [23] and porous carbon formed by carbonization of polyglycerol [24] in order to verify the possibility of its use as an oil sorbent.…”