The first peak in the powder diffraction pattern of a mesoporous MCM material with 30 pores

The first peak in the powder diffraction pattern of a mesoporous MCM material with 30 Å pores recorded with a wavelength λ of 1.54 Å is at 2.2° 2θ. Estimate the thickness of the silica walls. A hexagonal material has a = b ≠ c, α = β = 90, ɣ = 120; Bragg’s law states λ = 2d_hklsinθ.