IRON IMPREGNATED RICE HUSK ASH ADSORBENT FOR CYANIDE REMOVAL FROM CASSAVA PROCESSING EFLLUENT

  • M.S. Olakunle
  • O.A. Ajayi
  • H.S. Ajoge
Keywords: Adsorption, Cyanide, Effluent, Impregnation, Calcination, Response Surface Methodology (RSM).

Abstract

Rice husk (RH) was calcined and the resultant ash (RHA) was impregnated with Fe, (Fe-RHA). Both were used to adsorb cyanide from simulated cyanide solution and effluent from cassava processing. X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR), and Scanning Electron Microscope (SEM) were used to characterize the RH, RHA and Fe-RHA, while UV spectrophotometer was used to monitor the cyanide concentrations. BET results for surface area, pore volume and pore width are 552 m2/g, 0.625 cm3/g, and 3.17 nm, respectively for RHA while those for Fe-RHA are 475.6 m2/g, 0.2253 cm3/g, and 2.128 nm respectively. The optimum conditions for the synthesis of Fe-RHA when response surface methodology was employed were 0.075 mol/L, 630 oC, and 11minutes respectively for impregnation ratio, calcination temperature, and calcination time. Batch adsorption processes for cyanide removal were carried out by contacting RHA and Fe-RHA adsorbents with effluents A (juice extracted from cassava tubers), B (effluent from cassava processing plant), and C (effluent from cassava processing plant after sedimentation). The adsorption efficiencies when RHA adsorbent was used were: 45.10%., 40.09% and 58.18% respectively for effluents A, B, and C. Similarly, 64.71%, 60.37%, and 63.03% respectively when Fe-RHA adsorbent was used. The analysis of the adsorption data using the Langmuir and Freundlich models showed that Langmuir model is suitable with adsorption capacity of 4.2 mg/g with a correlation coefficient (R2) of 0.9924. Pseudo-second-order kinetic model has been found most applicable when first, second, and intra-particle kinetic models were used to fit the data.

Author Biographies

M.S. Olakunle

Department of Chemical Engineering, Ahmadu Bello University, Zaria, Nigeria

 

O.A. Ajayi

Department of Chemical Engineering, Ahmadu Bello University, Zaria, Nigeria

 

 

H.S. Ajoge

Department of Chemical Engineering, Kaduna Polytechnic, Kaduna, Nigeria

 

Published
2020-09-01