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International Journal of ChemTech Research CODEN (USA): IJCRGG, ISSN: 0974-4290, ISSN(Online):2455-9555 Vol.9, No.12, pp 688-694, 2016
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Characterization of activated carbon that’s synthesis from green bean peels by using H2SO4 agent: Implementation in reactive blue dye removal
Hassanin M. Ali
Department of Chemical Engineering, Babylon University Al-Hilla 51002 PO, box 4, Iraq
Abstract : In this article used green bean peels (GBPs) that collected from Iraqi markets to synthesis activated carbon (AC). H2SO4 agent using in one step chemical activation method. The effect of volume (15, 25, 35 ml) and concentration (4, 6, 8 molarity) of H2SO4 on the activated carbon (AC) yield was studied by removal reactive dye blue from wastewater. Adsorption using synthesis activated carbon has been proven by calculated the dye removal efficiency and the amount of adsorbed dye. Activated carbon (AC) was characterized by laser particles size, XRD and FTIR. The best volume and concentration of H2SO4 using in this study are (15 ml volume) and (4 molarity concentration) that investigated by % efficiency of dye removal (90.3%) and the amount of adsorbed dye (11.31 mg/gm).
Keywords : GBPs, Sulfuric acid, Reactive dye Blue.
The great importance of the activated carbon (AC) is as an absorbent in the separation and purification processes to reduce environmental pollution in the air, water and soil. Activated carbon capacity of absorption does not depend on the AC surface area only, but also on (i) the internal structure of the pores, (ii) characteristic of the surface, and (iii) functional groups provide on the surface of the adsorbent. These criterions depend on the method used in the preparation and the precursor used also. Therefore, an appropriate adsorbent characterization is decisive to the separation and adsorption processes. It prefers to use local raw materials and cheap and which contain a small amount of ash and high amount of carbon in the preparation of activated carbon process to reduce the cost of the massive production1. Synthesis of activated carbon from agricultural waste deals from many researchers including broad bean peels2, date palm fronds3-5, apple pulp and apple peel6, rice husk7,8, pistachio hull9, pistachio shell and apricot stone10, hard cortex of apricot stones11, spent tea leaves12, banana peel13, pineapple peel21, dates kernels22, residues of trimming peach trees22, corn stalks22, eucalyptus bark23, leaves of anthacephalous cadamba24 etc. Synthesis ACs used two common activation methods physical and chemical. In this method , which relies on the activation physicist where the preparation of activated carbon from any source containing carbonaceous material and the extent of high temperatures 700-1100 ° C and using an inert gas , while the next stage is activation by using agents like steam, O2 and carbon dioxide. While, chemical activation method used lower temperature 400-700 ºC to carbonized the precursor materials by utilized activating chemical agent. In chemical method the activation and carbonization happens together. There are some benefits of chemical over physical activation method. Considering that the chemical method has a low cost process and since it’s occur through a one step and at lower temperature range thus the produced activated
carbon has a higher carbon yields and better pores structure3. Many workers have applied the method of chemical activation to synthesis the ACs. Several chemical activating agents are used by researchers such as zinc chloride (ZnCl2) 3,24, phosphoric acid (H3PO4) 4,6,7,22, potassium hydroxide (KOH) 8, calcium chloride (CaCl2) 14, sulfuric acid (H2SO4) 15,21, sodium hydroxide (NaOH) 16, hydrochloric acid (HCl) 17,24, (FeCl3) 20, nitric acid 23 etc.. Wastewater outflow from industries have different pollutant like dyes 18. Many methods can be used for clearing of dyes from the medium including chemical, biological and physical processes; one of these methods is adsorption 19. The goal of this research is to synthesize and characterization of activated carbon from green bean peels (GBPs) and test it for clear reactive dye blue from aqueous solution.
2. Experimental
2.1. Materials
GBPs (Figure 1) were collected from Iraqi market. GBPs were thoroughly washed by tap water to remove the impurities and dust. Microwave (LG, China) using to dried the washed GBPs for 20 min. to remove the moisture content. The result sample was mill by hand into powder. H2SO4 98% (J. T. Baker, Belgium) analytical grad chemical was used for activation. Distilled water was used for prepared solution and washing.
Figure 1. Green bean peels GBPs
2.2. Preparation of Activated Carbon
To prepare ACs, added different volumes 15, 25, 35 ml of H2SO4 solution to the GBPs powder. Also using Different concentrations such as 4, 6 and 8 M of H2SO4 solutions that prepared by dissolving H2SO4 in distilled water. 5 gm of GBPs powder was mixed with 15 ml, 4 M H2SO4 solution at room temperature and transfer the sample to the furnace (Kendro, Hanau, D-63450, Germany) at 110oC for 2 h and after that carbonized the sample in the same furnace at 400oC for 3 h. The result sample was washed by distilled water to remove the remain H2SO4 until reach PH 7 then dried the sample in microwave for 20 min to remove moisture.
2.3. Analytical methods
Concentrations of dye were obtained by using a double-beam UV spectrophotometer (Jenway, 6800, China). Measurements were getting at the λmax values (600 nm) against a blank of distilled water. Calibration curve (Figure 2) must be obtained from Absorbance values and standards dye concentrations and using it to convert the absorbance to the concentration.
FTIR spectra (Alpha, Germany) were limited in the area of (4000 – 400 cm–1) and done at H2SO4 concentration (4M) and volume (15 ml). X-Ray diffractometer (Shimadzu-6000, Japan) and Laser particle size (Bettersize 2000, China) were done at H2SO4 conditions 4M and 15 ml.
Figure 2 Calibration curve of reactive blue dye.
2.4. Adsorption studies
100 mg of reactive blue dye (C45H44N3NaO7S2; Mwt. 825.97) was dissolved in 1 litter of distilled water to prepare stock solution of dye. 0.4 gm of synthesis AC was added to the 50 ml of dye stock solution then adjusted PH to 2.5 and magnetically stirred for 30 min. The sample was filtered after that using UV to analyzed dye absorbance and using calibration curve (Figure 2) to get dye concentration. Calculated the amount of adsorbed dye (Q) (mg/gm) and the efficiency of removal dye (E) by using the following equations:
(1)
(2)
Where V is the solution volume (L), Ci illustrate the initial concentration of dye (mg/L), Cf final concentration of dye (mg/L), and ms is the adsorbent mass (gm).
3. Results and Discussion
3.1. Results of dye removal
To test the performance of synthesis AC, using it to remove reactive blue dye from aqueous solution and table (1) show the efficiency of removal dye and the amount of dye adsorbed by using different concentration of H2SO4 agent with constant volume 15 ml and table 2 show its with different volume of H2SO4 agent at constant concentration (4 M).
Table 1. Efficiency of removal dye (E) and the amount of dye adsorbed (Q) for reactive blue dye at different concentration of H2SO4 with constant H2SO4 volume 15 ml (Ci= 100 mg/L, time= 30 min., V= 50 ml, ms= 0.4 gm).
Molarity of H2SO4 at 15ml |
Absorbance |
Concentration of dye (mg/L) |
Removal dye efficiency (E %) |
Amount of dye adsorbed (Q) (mg/gm) |
4 |
0.0530 |
9.75 |
90.3 |
11.31 |
6 |
0.2984 |
38.62 |
61.5 |
7.7 |
8 |
0.3017 |
39.01 |
61.1 |
7.66 |
Table 2. Efficiency of removal dye (E) and the amount of dye adsorbed (Q) for reactive blue dye at different volume of H2SO4 with constant H2SO4 concentration 4M (Ci= 100 mg/L, time= 30 min., V= 50 ml, ms= 0.4 gm).
Volume of H2SO4 (ml) at 4M |
Absorbance |
Concentration of dye (mg/L) |
Removal dye efficiency (E %) |
Amount of dye adsorbed (Q) (mg/gm) |
15 |
0.0530 |
9.75 |
90.3 |
11.31 |
25 |
0.4371 |
54.94 |
45.20 |
5.66 |
35 |
0.5890 |
72.81 |
27.37 |
3.43 |
The desired values of removal dye efficiency and the amount of dye adsorbed that we can see from table 1 and 2 are 90.3% and 11.31 mg/gm respectively at 4M concentration and 15 ml volume of H2SO4.
3.2. Results of XRD test
Figure (3) shows the XRD pattern of the prepared activated carbon after carbonization at 400 °C for 3h. It shows that the prepared sample is poor crystalline with weak peaks at 25°, 26°, and 31° which are diffracted from the planes indexed to graphite.
Figure 3. XRD of synthesis AC.
3.3. Results of FTIR test
The FTIR spectra of the prepared activated carbon after carbonization at 400 °C for 3h are shown in figures (4). Table ( 3) summarizes the interpretation of this spectrum.
Table 3. FTIR spectrum interpretation
Band (cm-1) |
Corresponding to |
1116 |
O-H (hydroxyl or carboxyl) stretching vibration and C-OH bending vibrations |
1370 |
Stretching vibration of the C-H in the carbonyl |
2360, 2220, 2181 |
OH stretching of HSO4 group |
875–750 |
aromatic C–H out-of-plane bending vibrations |
1554 |
stretching vibration of benzene ring skeleton |
3614 |
Free OH stretching |
3862-3737 |
vibration absorption spectra of OH |
450-750 |
in-plane and out-of-plane aromatic ring deformation vibrations |
602 and 674 |
out-of-plane C-H bending mode |
Figure 4. FTIR spectrum of synthesis AC.
3.4. Results of particles size distribution test
Figure (5) shows the result of analysis of particles size distribution for the prepared activated carbon after carbonization at 400 °C for 3h. It can be observed that the prepared sample has wide particle size distribution from around 0.5μm to 200μm with avarge particle size of around 40μm.
Figure 5. Particles size distribution of synthesis AC.
Conclusions
Activated carbon was synthesised from GBPs at different H2SO4 concentration (4, 6, 8 M) and volume (15, 25, 35 ml). The 4 M concentration and 15ml volume of H2SO4 agent are the optimum values at which the higher efficiency of dye removal 90.3% and the amount of adsorbed dye 11.31 mg/gm. For environmental and economic considerations prefers to use GBPs for the production of AC and also because it is abundant agricultural waste product. In XRD test weak peaks at 25°, 26°, and 31° which appear and diffracted from the planes indexed to graphite. For particles size distribution test the average size of particle was around 40μm.
References
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