Investigating Humic Acid Adsorption from Aqueous Solution using UiO-66 Functionalized with Amine Group

Natural Organic Matters (NOMs) are pollutants that exist in many drinking water resources, cause many problems in drinking water treatment processes, and have adverse effects on human health. For this reason, these substances must be removed from drinking water via a proper method. Metal Organic Frameworks (MOFs) are novel adsorbents that have been widely considered in recent years. In this study, Uio-66 functionalized with NH2 was synthesized and applied for humic acid adsorption (as a natural organic matter) removal from water.

The present study was conducted in a batch reactor and on a laboratory scale. Firstly, the characteristics of the synthesized adsorbent were investigated. Then, the effect of different parameters such as pH, adsorbent dosage, and initial concentration of humic acid on adsorption process was also investigated. Additionally, isotherms and kinetics of humic acid adsorption on Uio-66-NH2 adsorbent were determined. The data analysis and isotherms comparisons were conducted using linear regression and determination coefficient.

In this study, the analysis confirmed the structure and properties of the fabricated nanoparticles. The adsorbent surface area was 673.4 m2/g. The results also showed that the optimal pH for adsorption of humic acid was in the range of 5 to 7, the optimal dose of adsorbent was 0.8 g/L, and the maximum adsorption of humic acid was 2.2 mg/g of adsorbent.

Based on the findings of the present research, humic acid adsorption isotherm on the adsorbent was in accordance with the Langmuir isotherm model and its adsorption kinetics followed the pseudo-second-order kinetic model. The current study revealed that by optimization of the condition, the adsorbent can be used for organic matter removal.