Amine-modified silica for removing aspirin from water

Abstract

The synthesis and structural characterisation (Fourier transform infrared, FTIR spectrometry, scanning electron microscopy, SEM and energy-dispersive X-ray, EDX) of amino-modified silicates (unloaded L1, and aspirin-loaded, L2) are reported. The optimal conditions for the extraction of aspirin from water by the modified silicate material were determined as a function of the mass of the extracting agent and the pH of the aqueous solution. The optimum mass was found to be 0.08–0.10 g with 99.9% removal of aspirin. Maximum extraction of aspirin by the material was observed at pH 4. The kinetics, the removal capacity of the material, as well as its recycling, were investigated. The results indicate that (i) the process is fast and (ii) the removal capacity for the drug is greater than that of previously reported materials and (iii)the modified silicate can be easily recycled. These data along with the low cost involved in the production of the material led to the conclusion that the modified silicate has the required potential for industrial use. Molecular simulation calculations suggest that one unit of aspirin interacts with one unit of the modified silicate L1 through hydrogen bond formation between the amine functional group of the silicate and the oxygen donor atoms of aspirin. Final conclusions are given.

One-Pot Synthesis of Amine-Functionalized Nano-Silica via Sol-Gel Assisted by Reverse Micelle Microemulsion for Environmental Application

“…The possible reason for the undetected band at 3400 cm −1 of the N-H stretching vibrations is the strong interaction between the terminal NH 2 of the aminopropyl groups and the unreacted surface hydroxyls on the silica [ 19 ]. A similar observation was reported in the literature with no detection of N-H stretching vibrations of amine-modified silica [ 20 , 21 , 22 ]. The weak band centered at around 1450 cm −1 appeared and was assigned to the NH 2 deformation mode of the amine group [ 20 ].…”

Adsorption and Release Properties of Drug Delivery System Naproxen-SBA-15: Effect of Surface Polarity, Sodium/Acid Drug Form and pH

“…Whereas no residual methanol solvate fraction is present in the neat SBA-15 carrier, a relatively large amount of NaNAP in the crystalline methanol solvate form is found for the SBA-15-CH 3 system. This finding derived from 23 Na MAS NMR data is relatively consistent with 13 C CP/MAS NMR spectrum. Similarly, as in the previous case, in SBA-15 + NaNAP systems, the recorded solidstate NMR spectra (Figure 5) revealed the presence of various fractions of the active compound.…”

“…Extensive structural transformation of naproxen sodium salt is further demonstrated in 23 Na MAS NMR spectra (see Figure 6).…”

“…The strength of the spin-locking fields had a B 1 ( 13 C) field nutation frequency of 62.5 kHz. The number of scans was 10-20 k. Single-pulse 23 Na MAS NMR spectra were acquired at a spinning frequency of 18 kHz with a pulse width of 1.0 µs (30 • flip angle); excitation field intensity B 1 ( 23 Na) of 83.3 kHz; recycle delays of 2 s; and the number of scans 256-1024 depending on the signal-to-noise ratio. 1 H MAS NMR spectra were acquired using the standard pulse scheme with a repetition delay of 4 s, and a number of scans of 4.…”

“…The aminopropyl functional group is a frequently used molecule in grafting for the preparation of DDS. For example, works [21][22][23] focus on studies concerning amino-functionalized mesoporous silica surfaces used to store drugs. These studies showed that amine modification influences the loading capacity of drugs such as aspirin and ibuprofen due to intermolecular interactions.…”