Minggu, 18 April 2010

Adsorption of Methylene Blue by Activated Carbon


1.1 Background

Today, the purification system to eliminate the color and organic content in order to get a desired substance that has several kinds of techniques. The system of textile industrial waste water treatment is intended to eliminate many colors and are commonly used are coagulation-flocculation.

Biological processes generally use the activated sludge process or a biofilter which is the processing continued with the aim to reduce the organic content of the other. Lack of coagulation-flocculation process is the high consumption of chemicals and produce chemical sludge.

Alternative to the process of coagulation-flocculation is the process of adsorption using activated carbon. The adsorption by activated carbon proved to give good results in setting aside the color and organic content, but the cost becomes very expensive to replace the saturated activated carbon. To reduce the costs involved are modified in the process using a combination of physical and biological systems, namely by incorporating activated carbon into the activated sludge aeration tank. Use of activated carbon in activated sludge aeration tank produced a better processing efficiency and cost more economical than the process of coagulation-flocculation and activated carbon adsorption process premises.

Increasing removal efficiency of dyes and other organic and low cost of this system is due to reduced use of carbon micro-organisms. Nevertheless until now bioregenerasi mechanism is still not able to clearly articulated. With a background operation described above, to be more aware of dye adsorption by activated carbon in more depth, we perform this experiment.

1.2 Experiment Objectives
1.2.1 Experimental Purposes

The purpose of this experiment is to study the adsorption of dyes by activated carbon.

1.2.2 Experiment objectives

The purpose of this experiment are:

1. Determining the appropriate adsorption model for adsorption in methylene blue by activated carbon.

2. Determine the adsorption capacity of methylene blue adsorption by activated carbon.

1.3 Principle Experiment

The principle of this experiment is to determine the appropriate model for the adsorption of methylene blue adsorption by activated carbon by measuring the concentration of methylene blue solution after adsorption of activated carbon with varying initial concentration and stirring time for 30 minutes, through measurement of absorbance and wavelength using a spectrophotometer.
Benefits Experiment

The benefits derived after the experiment were students better understand the method of dye adsorption by activated carbon, not only through theory, in addition, mhasiswa more adept in the use of laboratory equipment, in this case specializes in spektronik 20D +, and also magnetic stirrer.


Molecules and atoms can be attached to the surface in two ways. In fisisorpsi (short of physical adsorption), there are van der Waals interaction between adsorpat and substrate. Intermolecular van der Waals forces have a long distance, but weak, and the energy released when particles terfisiorpsi have the same order of magnitude with the enthalpy of condensation. Energy quantity as small as this can be adsorbed and removed as the lattice vibrations of thermal motion. Molecules that bounced on the surface like rocks will slowly lose energy and eventually adsorbed padapermukaan that, in a process called accommodation. Fisorpsi enthalpy can be measured by noting the increase in temperature of the sample with a known heat capacity, and typical values around 20 kJ mol-1. The change in enthalpy is not small enough to produce the termination of the bond, so that the molecule retains its identity terfisisorpsi, although the molecule can be distorted by the exchange (Atkins, 1997).

Adsorption or absorption is the formation of the gas layer on the surface of solids or liquids occasionally. In the process of adsorption there are substances that are absorbed at the surface of another substance called the adsorbate, while the surface of a substance that can absorb another substance called the adsorbent. Adsorption or absorption of different absorption or absorption, because the absorption process of the absorbed substances penetrate into the absorbent material. In chemical absorption is the entry of gas into a solid or solution, or the entry of liquids into solids. While the physics, absorption is the change in energy electromagnetic radiation, sound, particle beam, etc. into other energy forms, if passed on a medium. When a photon is absorbed will be a transition to the excited states keadan (Daintith, 1994).

Absorption is the process of separating substances from a gas mixture by way of binding material on the surface of the liquid absorbent, followed by dissolution. Solubility of gases to be absorbed can be caused only by physical forces (on the physical absorption) or in addition to those styles as well as by chemical bonds ( on chemical absorption). Gas components that can be entered into a chemical bond will be dissolved first, and also with a higher speed. Because it outperformed chemical absorption of physical absorption (Rahayu, 2009).

Absorbent is a liquid that can dissolve the material to be absorbed on the surface, both physical and chemical reactions. Often also referred to as the absorbent washer fluid. Terms of absorbent (Rahayu, 2009):
Has the power to dissolve the materials that absorbed as much as possible (the need for less liquid, smaller equipment volumes).
Has a low vapor pressure
Not corrosive.
Has a low viscosity
Thermal stable.

The types of materials that can be used as the absorbent is water (for the exhaust gases can dissolve, or for the separation of dust particles and liquid droplets), sodium hydroxide (for gases which can react as acids) and sulfuric acid (for gas- gas which can react as a base) (Rahayu, 2009).

Important heterogeneous reaction is the reaction on the catalyst surface, such as (Sukardjo, 1985):

a. The process of making contact on the H 2 SO 4

b. Haber process in the manufacture of NH 3

c. Oxidation of NH 3 on the making of HNO 3

d. Manufacture of methanol, etc.

Heterogeneous catalysts typically rely on at least one adsorbed reactants and modified into a form that can react immediately. Often these modifications in the form of fragmentation of reactant molecules. Reaction to this process occurs at the surface of the catalyst (Sukardjo, 1985).

The closing level of the surface is usually expressed as the closure terfraksi (θ). Θ adsorption rate is the rate of change of surface closure, and can be determined by observing changes in the closure of terfraksi against time (Atkins, 1997).

Adsorption is terjerapnya a substance (molecule or ion) on the surface of the adsorbent. Entrapment mechanism can be divided into two, namely, adsorption of the physics (fisisorpsi) and chemical adsorption (kemisorpsi). In the process of binding force fisisorpsi adsorbate by the adsorbent is a style of van der Waals forces. Very weakly bound molecules and the energy emitted at a relatively low physical adsorption of about 20 kJ / mol (Kisliuk, 1957).

The adsorption model approach was used Langmuir and Freundlich adsorption models (batch) and Thomas (continuous).
In the Langmuir isothermal model assumed that the maximum adsorption is proportional to the saturation of a single layer of molecules of solute (copper (II)) in particle penjerap materials, energy and constant entrapment did not occur between the field of substance adsorbed on the surface.
Freundlich equation applies to the process of entrapment that took place in a dilute solution, isothermal and usually to explain the adsorption on the surface with a heterogeneous entrapment of heat .. Value 1 / n usually ranges from 0.2 to 0.7 with a parabolic-shaped curve (Haryanto, 2008).

Adsorbate with the adsorbent interaction strength is influenced by the nature of the adsorbate and adsorbennya. Symptoms commonly used to predict which components are more strongly adsorbed by the adsorbent polarity adsorbatnya. If adsorbennya are polar, the polar component will be bound more strongly than the less polar components. The strength of interaction is also influenced by the nature of the weakness of the hard-adsorbate or adsorbent. Intractability for cations associated with the term power Polarizing cation, namely the ability of a cation to anion in polarizing a bond. Cations that have a large cation Polarizing power tends to be hard. Polarizing properties of a large cation power possessed by metal ions with size (radius), small and large loads. On the contrary nature of the low cation Polarizing power possessed by metal ions with large size but small payload, so the ions are considered weak. While the notion hard to anion anions associated with the term polarisabilitas namely, the ability of an anion to experience the polarization caused by the electric field of the cation. Anion is the anion is very hard in small size, big loads and high electronegativity, conversely a weak anion is owned by the anions with large size, small loads and low elektronegatifitas. Hard metal ions bind strongly with hard anions and weak metal ions bind strongly with the weak anion (Atkins, 1997).

Among the main techniques to measure θ, is the flow method. In this method, the sample itself as a pump, for removing particles from gas adsorption. Therefore, one can use techniques that are memonitori gas flow rate entering and exiting the system, where the difference is the rate decision by the sample gas. The integration resulted in the closing rate at each stage terfraksi. In flash desorption, the sample we suddenly heated (electrically) and the resulting increase in pressure is interpreted with respect to the quantity contained in the original sample. This interpretation may be confused with the desorption of compounds (Atkins, 1997).

Adsorption is the collection of the solute on the surface of the media and is the type of adhesion which occurs in solid or liquid substances in contact with other substances. There are a number of things that influence the effectiveness of adsorption that is one of them is kind of adsorban. One of the common adsorban applied in drinking water treatment is the activated carbon. Charcoal is used to eliminate the odor, color and taste of water including heavy metals ions (Cahyana, 2009).


3.1 Experimental Equipment

The tools used in these experiments was 100 mL erlenmeyer flask, multimagnetik stirer, 300 mL beaker, 500 mL beaker, pipette drops, burette, stirrer rod, stative, 50 mL measuring flasks, measuring 10 mL flask, tube brush, Buchner funnel, digital balance, spektronik 20 b +, stopwatch, and diaphgram pumpe vacuum.

3.2 Experimental Materials

The materials used in these experiments was methylene blue, aluminum foil, tissue rolls, filter paper, Whatman 41 filter paper and soap.

3.3 Experimental Procedure

Prepared 5 pumpkins measure 50 mL of a clean and dry.
Diluted solution of methylene blue concentration of 100 ppm to 2 ppm, 4 ppm, 6 ppm, 8 ppm and 10 ppm in 50 mL measuring flask as the sample solution.
Diluted solution of methylene blue concentration of 10 ppm to 0.5 ppm, 1 ppm, 2 ppm, 4 ppm and 8 ppm in the 50 mL measuring flask as a standard solution.
Prepared 5 erlemeyer fruit clean and dry.
Weighed as much as 2 g of active carbon with a meticulous and precise.
Entered solution with the concentration of methylene blue concentration of 2 ppm, 4 ppm, 6 ppm, 8 ppm and 10 ppm in each erlemeyer.
Activated carbon is also incorporated into these erlemeyer and covered with aluminum foil.
The solution is stirred using a magnetic stirer for 30 minutes.
All solutions are filtered in a Buchner funnel.
Absorbance of each solution was measured using spektronik 20 b + and recorded.
Also measured the concentration of methylene blue solution of 0.5 ppm, 1 ppm, 2 ppm, 4 ppm and 8 ppm using spektronik 20 b + and recorded.
Concentration determined via standard curves after adsorption.


4.1 Observation Results

4.2 Discussion

Adsorption is the collection of the solute on the surface of the media and is the type of adhesion which occurs in solid or liquid substances in contact with other substances. Activated carbon, or often also called activated charcoal, is a type of carbon that has a very large surface area. This could be achieved by activating the carbon or charcoal, with just one gram of activated carbon, would be obtained if a material has a surface of 500m2 . Normally the activation is only intended to enlarge the surface area, but some efforts are also associated with increased ability of activated carbon adsorption itself.

These experiments used activated carbon as adsorban methylene blue which is a dye that serves as the adsorbate. Methylene blue used was 100 ppm of methylene blue and methylene blue as an example of 10 ppm as a standard solution that serves as a comparison sample absorbance of the solution.

Activated carbon which has weighed so wrapped in aluminum foil does not absorb carbon obtained by other substances that can affect changes in the mass of the substance. For example the ability of activated carbon to absorb water because it is hygroscopic.

The dilution of methylene blue in order to obtain different concentrations. When mixing erlenmeyer covered with aluminum foil so that condensation does not terpecik out erlenmeyer and prevents interference from outside so the solution is not contaminated by substances that may affect the adsorption ability of methylene blue by activated carbon. Stirring carried out for 30 minutes because it was considered as good enough time for the adsorption solution. Stirer Stirring the solution using magnetic stirring to be done at the same time. This is so that the absorption of the color of the solution with different concentrations require the same time. In addition, mixing with stirer done to the effectiveness of time.

After stirring filtering is then performed using a Buchner funnel in order to expedite the process so it does not need to ppenyaringan settling for one hour as shown in the previous procedure. Solution is obtained and then measured absorbance with spektronik 20 D +. Measurement process begins by using the blank solution in this case distilled water as a solvent in the dilution. Measurement of solution absorbance at 590 nm wavelength. Any solution to be measured wavelength must begin with calibrating device with a blank. Kuvet used must remain clean and dry before you put in spektronik, and no finger marks that stick out kuvet, because it will result in an error reading wavelength. Standard solution was also measured absorbance to the results obtained can be seen the increase or decrease in absorbance value.

Absorbance value should increase with increasing solution concentration was measured. In data obtained results in accordance with the theory. Decrease in concentrations to be influenced by the nature of highly polar methylene blue. The more polar a compound, the more strongly adsorbed.

Methylene blue also has a very high molecular weight compounds that cause is easily adsorbed. In addition, adsorban used the activated carbon which is a very good adsorban and shape in the form of powder can cause the magnitude of adsorption was happening because it has a broad surface.

From the calculation, the value of the effectiveness of adsorption for the initial concentration of 2 ppm is 0.0441 mg / g, for the initial concentration of 4 ppm is 0.0282 mg / g, for the initial concentration of 6 ppm is 0.1534 mg / g, for initial concentration 8 ppm is 0.1695 mg / g, and for initial concentration of 10 ppm is 0.3239 mg / g. From the Langmuir isothermal curves obtained value of y = 4.34 x + 27.307 with R 2 = 0.0147 value. The value of adsorption capacity (Qo) of 0.2304 mg / g adsorbent and its adsorption energy value (b) equal to 0.1589 L / mg. Freundlich isothermal curves obtained on the value of y = -0.7459 x + 0.7054 with a value of R 2 = 0.7124. The value of adsorption capacity (K) of 0.1971 mg / g adsorbent and the adsorption intensity (n) equal to -1.3406 mg / L. From the two curves show different values of R, where R values for Freundlich method is closer to 0.9 than the Langmuir method, whereas according to theory should be the method of Langmuir adsorption Methylene blue is more fulfilling than Freundlich method. This might be due to weighing is not analytical.


5.1 Conclusion

The conclusion from this experiment are:
Adsorption model corresponding to the methylene blue adsorption by activated carbon is the Freundlich adsorption model.
For the method of Langmuir adsorption capacity (K) is 0.2304 mg / g asorben and adsorption energy (b) was 0.1589 L / mg. For the method of Freundlich adsorption capacity (K) is 0.1971 mg / g of adsorbent and adsorption intensity (n) is -1.3406 mg / L.

5.2 Suggestion

For the laboratory should be equipped with a fan so that lab can run smoothly. For the experiment, should not the only solution of methylene blue are used but other dyes that can be compared to the results and knowledge praktikan increases.


Atkins, PW, 1997, Chemical Physics, grants, Jakarta.

Cahyana, GH, Activated Carbon Adsorption (online), http://gedehace.blogspot.com, diaksese May 1, 2009, at 8:30 pm.

Dainith, J., 1994, A Complete Dictionary of Chemistry, grants, Jakarta.

Haryanto, Great Sugiharto., 2008, Use of Soil Lime as Penjerap Copper (II) in the Waste Water Craft Copper Industry, Gelagar Engineering Journal, vol. 19, no. 1.

Kisliuk, P., 1957, The sticking probabilities of gases chemisorbed on the surfaces of solids, Journal of Physics and Chemistry of solids, vol. 3, pp. 95-101.

Rahayu, Suparni Setyowati., Absorption (online), accessed August 23, 2009.

Sukardjo., 1985, Chemical Physics, Literacy Development, Jakarta.

Taba, P., and Paulina, St., 2006, Practical Guide of Physical Chemistry, Physical Chemistry Laboratory Science, State UH, Makassar.

3 komentar:

  1. hi!!! i'm a doing a research on activated carbon and wanted to know the source of this information so i can cite it, please if you could inform me, please write me back at nhila_bj@hotmail.com
    thank you in advance

  2. Erlenmeyer flask is one of the most important & common lab equipment and these erlenmeyer flasks consider first choice for holding liquid mixtures and information you shared is good.

  3. Of the many benefits of charcoal, the greatest use as activated carbon. That is, the carbon structure with modified charcoal freed from the bonds of other elements so that the surface and active center becomes widespread.price of activated carbon