Yen Ping Tan

A novel heterogeneous catalyst composite (CuS-FeS/SiO₂) derived from rice husk silica was engineered following pyrolysis, chemical precipitation, and chemical redox technique. The resulting catalyst was applied to the conversion of palm fatty acid distillate to biodiesel. The presence of CuS and FeS on the catalyst was verified using X-ray diffraction and Fourier transform infrared spectroscopy, nitrogen physisorption, scanning electron microscopy (FESEM) with energy dispersive X-ray (EDS) spectroscopy, and temperature-programmed desorption of NH₃ (TPD-NH₃), inductively coupled plasma-atomic emission spectrometry (ICP-AES), and TGA; a specific surface area of approximately 40 m²·g⁻¹ was identified. The impact of independent variables, i.e., reaction temperature, reaction duration, methanol:oil ratio and catalyst concentration were evaluated with respect to the efficacy of the esterification reaction. The greatest efficiency of 98% with a high productivity rate of 2639.92 µmol·g⁻¹·min⁻¹ with k of 4.03 × 10⁻⁶ mole·S⁻¹ was achieved with the following parameters: temperature, 70 °C; duration, 180 min; catalyst loading, 2 wt.%; and methanol to oil ratio, 15:1. The CuS-FeS/SiO₂ catalyst showed relatively high stability indicated by its ability to be reused up to five times.

In our current work, we have established a novel approach in the synthesis of a new adsorbent by using choline chloride and urea (DES)/orthophosphoric acid (H₃PO₄) as our activating agent and palm kernel shell (PKS) as our precursor. The resulting activated carbon (DES/H₃PO₄-6002:3) was used to adsorb Pb(II) from aqueous solution. Characterization of DES-H₃PO₄-6002:3 by nitrogen adsorption/desorption isotherm measurements, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) demonstrated good micropores structure and high surface area that makes DES/H₃PO₄-600 2:3 a suitable alternative for liquid phase adsorption. The fundamental batch experiment of DES/H₃PO₄-600 2:3 was investigated by different parameters (such as concentration, pH, temperature and absorbent dose). The results obtained indicated that Langmuir model and pseudo-second-order equation best fit the data, indicating that the adsorption was controlled by chemical reaction and monolayer uptake. In addition, the fabrication of DES/H₃PO₄ AC exhibits good potential for Pb(II) ions uptake, including its high adsorption capacity (97.1 mg/g) and good recyclability. The future potential of this works lies in the identification of alternatives to environmental benign synthesis AC and reuse of Pb(II) ion–laden biosorbent after heavy metal uptake.