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Adsorptive removal of naphthalene (NAP) and phenanthrene (PHE) was reported using NH2-UiO-66(Zr) metal-organic frameworks. The process was optimized by response surface methodology (RSM) using central composite design (CCD). The fitting of the model was described by the analysis of variance (ANOVA) with significant Fischer test (F-value) of 85.46 and 30.56 for NAP and PHE, respectively. Validation of the adsorption process was performed by artificial neural network (ANN), achieving good prediction performance at node 6 for both NAP and PHE with good agreement between the actual and predicted ANN adsorption efficiencies. The good reusability of the MOF was discovered for 7 consecutive cycles and achieving adsorption efficiency of 89.1 and 87.2% for the NAP and PHE, respectively. The performance of the MOF in a binary adsorption system was also analyzed and the adsorption efficiency achieved was 97.7 and 96.9% for the NAP and PHE, respectively.

The experimental adsorption of Anthracene (ANT), a model polycyclic aromatic hydrocarbon (PAHs) was optimized using central composite design (CCD) of response surface methodology (RSM). MIL-88(Fe) and NH2-MIL-88(Fe) Metal-organic frameworks (MOFs) were employed as the potential adsorbents. The model was described as the significant according to the analysis of variance (ANOVA) for the statistical fittings of R2 (0.991 and 0.992), and adequate precision (43.55 and 47.82) with the lack of fit F-values (2.15 and 1.59) for the MIL-88(Fe) and NH2-MIL-88(Fe) respectively. The highest adsorption efficiency achieved were 99.55 and 95.67% for the MIL-88(Fe) and NH2-MIL-88(Fe) respectively based on the RSM optimized conditions. The pseudo-second-order kinetic model has been described as the best mechanism for the adsorption process.

Metal-organic frameworks (MOFs), MIL-88(Fe) and NH2-MIL-88(Fe) were synthesized using microwave-assisted solvothermal technique. BET analysis has shown the porous nature of the MOFs, possessing surface areas with corresponding pore volumes of 1240 m2g−1 and 0.7 m3 g−1, 941 m2 g−1 and 0.6 m3 g−1 for MIL-88(Fe) and NH2-MIL-88(Fe), respectively. Other characterizations were also conducted using scanning electron microscopy (SEM), powdered X-ray diffraction (XRD) and Fourier transformed infrared (FTIR) spectroscopy. The MOFs were evaluated for application as adsorbents for the removal of pyrene (PYR) in aqueous solution. The removal efficiency achieved by MIL-88(Fe) was 99.7% while for NH2-MIL-88(Fe) was 96.0% within 40 minutes. Both MOFs has shown good removal of the PYR even after 5 consecutive uses. The adsorption isotherm was studied and favoured more by the Langmuir model, while the kinetics was found to follow pseudo-second-order model. The process was thermodynamically exothermic and spontaneous. Thus, the MOFs studied exhibited favourable features as potential adsorbents for the removal of PYR in wastewater.

Mesoporous silica nanoparticles (MSN) were successfully synthesized using different types of ionic liquids (ILs) with different length of side alkyl chain as the template. The formed MSN were characterised by FTIR, XRD and BET. In this study, ILs of long alkyl chains of cation was found to decrease the pore size of the MSNs thus, increasing the surface area. FTIR spectroscopy affirmed the formation of SiO2 while the broad peak in the X-ray diffractogram conveyed that the silica of MSNs is amorphous.