COPPER LOADED MAGNETIC HYDROCHAR DERIVED FROM COCONUT HUSK FOR CATALYTIC REDUCTION OF 4-NITROPHENOL

Tengku Shafazila Tengku Saharuddin; Nuraqilah Abdul Kadir; Nadia Farhana Mohd Zamry; Farah Wahida Harun; Lailatun Nazirah Ozair; Salma Samidin; Fairous Salleh

Tengku Shafazila Tengku Saharuddin Faculty of Science and Technology, Universiti Sains Islam Malaysia, Bandar Baru Nilai, 71800, Nilai, Negeri Sembilan, Malaysia.
Nuraqilah Abdul Kadir Faculty of Science and Technology, Universiti Sains Islam Malaysia, Bandar Baru Nilai, 71800, Nilai, Negeri Sembilan, Malaysia.
Nadia Farhana Mohd Zamry Faculty of Science and Technology, Universiti Sains Islam Malaysia, Bandar Baru Nilai, 71800, Nilai, Negeri Sembilan, Malaysia.
Farah Wahida Harun Faculty of Science and Technology, Universiti Sains Islam Malaysia, Bandar Baru Nilai, 71800, Nilai, Negeri Sembilan, Malaysia.
Lailatun Nazirah Ozair Faculty of Science and Technology, Universiti Sains Islam Malaysia, Bandar Baru Nilai, 71800, Nilai, Negeri Sembilan, Malaysia.
Salma Samidin Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia (UKM), 43600, UKM, Bangi, Selangor, Malaysia.
Fairous Salleh Department of Chemical Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Malaysia.

Keywords: Magnetic hydrochar, catalytic reduction, 4-nitrophenol, hydrothermal carbonisation

Abstract

4-nitrophenol (4-NP) is a hazardous pollutant that poses significant risks to human health and the environment. One promising approach to address this contaminant is the use of hydrochar derived from biomass sources. In this study, hydrochar was produced through hydrothermal carbonisation of coconut husks. The synthesised hydrochar was then integrated with magnetite and further loaded with Cu to form Cu magnetic hydrochar (Cu-MHC). The properties and catalytic performance of the Cu-MHC were examined by synthesising with varying copper loadings (1 %, 5 %, and 10 %). Various factors influencing the degradation of 4-NP into 4-aminophenol (4-AP) using sodium borohydride (NaBH₄) as the reducing agent were investigated, including the effects of copper loading, catalyst dosage, and the initial concentrations of 4-NP. The catalytic performance was compared across different copper loadings against that without copper (MHC) and showed that MHC achieved 13.25 %, while 1 % Cu-MHC reached 15.38 % in 3 minutes. A significant improvement was observed at 5 % Cu-MHC with 95.92 %, followed by 10 % Cu-MHC at 92.62 % in 3 minutes. From the results, 5 % Cu-MHC is the most effective catalyst for the reduction of 4-NP and was further characterized using x-ray diffraction (XRD), field emission scanning electron microscope with energy dispersive x-ray spectroscopy (FESEM-EDX) and transmission electron microscope (TEM). The results showed that 30 mg of 5 % Cu-MHC could effectively degrade 0.12 mM 4-NP (98 %) within 3 minutes. TEM analysis revealed predominantly spherical nanoparticles with diameters between 15 and 20 nm, highly distributed across the hydrochar. FESEM-EDX mapping confirmed the presence of copper and describe well distribution of copper on the surface of magnetic hydrochar nanocomposite. This is further supported by the absence of Cu peaks in the XRD spectra, which may indicate a high dispersion of copper species on the magnetite hydrochar, which contributes to the efficient catalytic reduction of 4-NP.