Carbon from agricultural waste as an adsorbent in the removal of chromium and nickel ions from aqueous solution
The objectives of this study were to produce carbon from sugarcane bagasse and rice straw by pyrolysis technique as an adsorbent for heavy metal removal and to determine the optimum condition with respect to contact time, pH of solution, adsorbent doses, particle sizes of adsorbent, initial metal...
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| Format: | Thesis |
| Language: | English |
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| Online Access: | http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/22188/1/Page%201-24.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/22188/2/Full%20Text.pdf |
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| Summary: | The objectives of this study were to produce carbon from sugarcane bagasse and rice
straw by pyrolysis technique as an adsorbent for heavy metal removal and to determine
the optimum condition with respect to contact time, pH of solution, adsorbent doses,
particle sizes of adsorbent, initial metal concentration and temperature. Also adsorption
isotherm and adsorption kinetic behavior of nickel(II) and chromium(VI) removal by each
adsorbent will be determined.
Sugarcane bagasse and rice straw are inexpensive and locally available agricultural
waste. The raw materials were pyrolized at different temperatures ranging from 300 – 700
oC for 30 minutes with the average heating rate of 30 oC/minute.
The adsorbents were characterized for the yield, density, pH, ash content, moisture
content, surface area and porosity by using BET surface area and porosity analyzer,
functional groups by using Fourier Transform Infrared, surface morphology by using
Scanning Electron Microscope and element and chemical composition by using Energy
Dispersive X-ray.
Adsorptions were found to be effected by pyrolyzing temperature and surface area. The
adsorbents that produced at 700 oC have been chosen for this adsorption study because it
produced the highest percentage of removal.The maximum removal efficiency of Ni(II) on
RSC and SBC as 85.65% and 21.79 %, respectively and Cr(VI) on RSC and SBC as 61.81
% and 76.10 %, respectively.
The operation parameters included contact time (15 – 210 minutes), pH of solution (1.0 –
10.0), temperature (25, 30, 45 and 55 oC), particle sizes of adsorbents (1.18 mm, 600 µm,
300 µm and 150 µm), adsorbents doses (0.04, 0.10, 0.20, 0.40, 0.6 and 1.0 g) and initial
concentrations of adsorbates (10, 25, 50, 75 and 100 mg/L). The experimental tests were
conducted in batch process. The contact time, amount of adsorbent, temperature, particle
size of adsorbent and initial concentration of the metal ions solutions affect the adsorption
efficiency but most importantly depended on the pH of solution.
The experimental isotherms data were analyzed by using Langmuir and Freundlich
equation. The applicability of adsorption was described by using the Freundlich and
Langmuir adsorption isotherm. It was found that Langmuir isotherm model fit well the
data for nickel(II) and chromium(VI). The measured high linearity of correlation
coefficient, R2 and the values dimensionless separation factor, RL indicated a favorable
adsorption of both Ni(II) and Cr(VI) onto RSC and SBC, respectively. While, the
adsorption kinetics, pseudo-first order model, pseudo second order model and intra particle diffusion model were analyzed on the experimental kinetics data. It was found that
the pseudo second order kinetic model described the adsorption kinetic of both adsorbent
well. The performance of both adsorbent in the removal of nickel(II) and chromium(VI)
were also compared. It was found that the adsorption capacity of rice straw carbon on
nickel(II) was high may be due to the present of surface oxygen groups, surface charge,
high silica content and the properties of nickel. While, the adsorption capacity of
sugarcane bagasse carbon on chromium(VI) was high was caused by the high surface
area of the adsorbent, surface charge and the properties of chromium. |
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