A Study On Bio Solid Cleaning Agents Biology Essay


Using waste from palm oil tree is one of the green technology applications. Green product derive from plant will decrease the chemical usage and certified 'halal'. Bio-solid cleaning agent from dodecanoic acid in bio-oil from EPFB was produce, test the properties and compare to commercial cleaning agent. Samples were variation of mole ratios of NaOH to dodecanoic acid. Cold process of fatty acid saponication with alkali was the best method. The dodecanoic acid reacts with NaOH solution at 40-50°C until an emulsion was formed. Others ingredients were added at this point (moisturizer, bar-hardening, deodorant, fragrance oil, filler, and antioxidants). pH value, lathering ability, erosion rate, biodegradability, and cleaning ability was test for every sample and compare to commercial product. This bio-solid cleaning agent have pH of 9.08, slightly lower lathering ability, lower erosion rate (3.2g/min), high biodegradability (60%), and same cleaning ability as the commercial cleaning agent.

Keywords: bio-solid cleaning agent, dodecanoic acid, bio-oil, green technology, biodegradability.

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In recent decades, the world has struggled with shortages of fossil fuels, pollution, and increased global energy requirements due to fast population growth, fast technological developments, and higher living standards. These factors have led to world population transition, migration, hunger, environmental (especially air and water pollution) problems, deteriorating health and disease, terrorism, energy and natural resources concerns, and wars. Also, problems with energy supply and use are related not only to global unrest, but also to such environmental concerns as air pollution, acid precipitation, ozone depletion, forest destruction, and the emission of radioactive substances. These issues must be taken into consideration simultaneously if human it is to achieve a bright energy future with minimal environmental impact.

Numerous studies conducted on the green material products are published in various scientific journals. A study carried out in the United State on 2002 found a lot of opportunities and challenges of sustainable bio-composites from renewable resources in the green materials world [1]. Another recent study in Canada proved that development of by-products from industrial waste is concerned, has perhaps never been diametrically opposed to the environmental interest of society. Indeed, market institutions, such as does found in Victorian England, seemed to have proven effective at focusing manufacturers' long term economic and environmental benefits [2].

In this study, the functional group that will be substitute using functional group in bio-oil is fatty acid. In bio-oil, fatty acid exists in a certain percentage. From catalytic pyrolysis of empty fruit bunches, area percentage of dodecanoic acid is 1.61 percent and tetradecanoic acid is 0.76 percent [3]. In slow pyrolysis, dodecanoic acid has 30.92 percent relative and tetradecanoic acid has 4.87 percent relative [4]. Acids are found to be 2.32 percent using catalytic process of empty fruit bunch [5]. In rice husk pyrolysis, the bio-oil produces has formic acid with 7.69 weight percent [6]. Bio-oil production from fast pyrolysis of waste furniture sawdust in a fluidized bed has acetic acid with 13.7 percent area [7]. Saponified, palm, olive, rapeseed and castor oils were pyrolysed (at 750 â-¦C for 20 s) by pyrolysis gas chromatography yield fatty acid component [8].

Soap is chemically defined as the alkali salt of fatty acids. In general parlance, the term "soap" has taken on a more functional definition, by which any cleansing agent, regardless of its chemistry, is considered as soap. Soap is manufactured by the saponification process, by which triglycerides (fats and oils) or fatty acids are transformed into the corresponding alkali salt mixtures of fatty acids. There are three ways to produces soap. The first reaction is direct neutral fat saponification (Equation 1). Oils and fats are directly saponified with alkali in a boiled or semiboiled kettle process.


CHOOC C11H23 + 3NaOH → 3 C11H23COONa + CHOH (Equation 1)


The resulting mixture of soap and glycerin is treated with salt to precipitate the soap, which is then separated from the glycerin solution, washed, and dried. The second reaction that will be use in this study is fatty acid saponification (Equation2). The fatty acid distillates are neutralized.

C11H23 COOH + NaOH → C11H23 COONa + H2O (Equation 2)

The soap bases obtained by the above two processes have a fatty acid contents of 63 to 75%. They are then continuously dried to a final mass of 78 to 80% fatty acid content. These processes account for more than 95% of world soap production. The third method, which is rarely use is fatty acid methyl ester saponification.

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C11H23COOCH3 + NaOH → C11H23COONa + CH3OH (Equation 3)

The methyl esters are obtained by catalytic transesterification of triglycerides with methanol or direct catalytic esterification of fatty acids with methanol. The end product of this process has higher fatty acid content, at the expense of a more costly process. For economic as well as for toxicology and ecology reasons, the process must be carried out in sealed equipment with recycling of methanol [9].

In this study, we will be using the second method to substitute fatty acid with dodecanoic acid because the by-product is water and safe to be done in the lab. For the first method, the triglycerides cannot be obtained directly from bio-oil. For the third method, even thought the methyl ester is available component in bio-oil, the by-product obtained is methanol. The experiment must be done in sealed equipment which is not available in the lab. Methanol is also highly toxic and flammable which can be a risk during the experiment.

The desired benefits of the finished soap product are governed by a professional selection of appropriate surfactant cleansing raw materials (in this case soap) and of manufacturing process and by the marriage between the two [9]. In this study, the parameters that will be tested were pH value, lathering ability, erosion rate after hand washing, and biodegradability.


2.1 Reagents and solutions

Dodecanoic acid was obtained from pyrolysis of empty palm fruit bunch (EPFB). NaOH pellet was dilute in water for different ratios to dodecanoic acid to be reacts as base. Others ingredients were glycerin as moisturizer, sodium chloride for bar hardening, triclosan for deodorant, fragrance oil (rose), filler(starch), and dye for colouring.

2.2 Experimental procedure

2.2.1 Cleaning Agent Production

Table 1: Sample of Dodecanoic Acid


Moles Ratios of to NaOH Dodecanoic Acid

Mass of NaOH

(g) in 100mL of water

Mass of Dodecanoic Acid






















Table 2: Ingredient in Cleaning Agent


Mass Percentage (%)

Mass/ Volume



55.575 g



3.000 mL



1.308 g



0.654 g

Fragrance oil





2.615 g

This procedure was obtained from "Preparation of Soap" [10].10g of NaOH pellets was diluted in 100 ml of distilled water in a 150mL beaker. The mixture of NaOH pellets and water were stirred, until the solution was clear. The sample of dodecanoic acid was prepared in a 250ml beaker. The beaker was then placed on the hot plate with low heat and with occasional stirring until the temperature rises between 40-50oC. The dodecanoic acid was removed from the hot plate and the NaOH solution was added to the sample with continuous stirring. The sample and NaOH mixture was stirred continuously until an emulsion was formed. The mixture was let cool with occasional stirring until an emulsion, which does not separate, was formed. Others ingredients was added at this point (Refer Table 2). The emulsion was poured into a mould for the reaction to run. The cleaning agent was left to age for about two days. The experiment was repeated for different moles of NaOH.

2.2.2 Cleaning Agent Properties Testing Determination of pH

pH meter (bench-top) was used to measured the cleaning agent pH. The pH meter was first calibrated. The standard operating procedure was as in Instruction Manual HI 8417 - HI 8519 - HI 8520 - HI 8521 Microprocessor Bench-Top pH Meters. 0.5g of the cleaning agent sample was placed into a test tube. Forceps was used to handle the cleaning agent sample until the pH has been determined. 10 mL of distilled water was added to the test tube and stopper the test tube. The test tube was shacked to dissolve the cleaning agent in the water. The pH of the solutions were determined and recorded. The test was repeated for Sample B, C, D, E, X, and Y. Lathering Ability

Procedure obtained from "Preparation of Soap" [10] state that 0.5g of the cleaning agent sample was placed into a test tube. 10 mL of distilled water was added to the test tube and stopper the test tube. The test tube was shacked vigorously for 25 times. Observations of the lathering abilities were recorded. Test tubes were allowed to sit until the liquid below the cleaning agent bubbles appear clear (about one minute). The volume of lather formed was recorded. The test was repeated for Sample B, C, D, E, X, and Y.

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This procedure was obtained from Ginn et al [11]. The cleaning agent bars was weighed before the experiment. The cleaning agent was used to wash hands for 1 minute. The cleaning agent was allowed to dry at room temperature for 24 hr and reweighed. The difference of cleaning agent weight before and after washing was recorded. The test was repeated for Sample B, C, D, E, X, and Y. Biodegradability

The biodegradability of green cleaning agent was compared to commercial cleaning agent. The samples were subject to the testing guidelines prepared by the Organization of Economic and Cooperative Development of the United Nations (OECD 301D closed bottle test) method over 28 days. Samples were prepared by dissolving 5 g of cleaning agent into 150 ml of distilled water. The cleaning agent solution was then added with 150ml waste water sample into the BOD bottle. Dissolved oxygen meter (Model YSI 58) was used to record the dissolved oxygen (DO). The meter was first calibrated using saturated air. The initial DO was recorded for every bottle. Final DO was recorded for every four day until day 28. BOD was calculated using this formula:

(Equation 4)

Biodegradability percentage was determined using:

(Equation 5)

ThOD (theoretical oxygen demand) was defined as the calculated amount of oxygen required to oxidize a compound to its final oxidation products. Cleaning Ability

Hands with dirt and cooking oils were washed with water. If the dirt and oil did not come off, the cleaning ability test was preceded. Wash hands with green cleaning agent for about 1 minute. Observation was recorded. The experiment was repeated using commercial cleaning agent.


3.1 Cleaning Agent Production

Five samples of bio-solid cleaning agent were produced in this experiment. Table 3 shows the cleaning agent that had been produced. Only Sample A and Sample B appeared in solid form. Sample C, D, and E appeared as sludge. The reason is because soap could not form at lower pH. Soap exists as alkali substance and the lower pH will make the soap appear as sludge. According to U.S Patent 4,100,097 [12], normal alkali metal soap has a pH about 10; it is not possible to provide a bar which depends primarily on soap for its cleansing action and which also provide an acid or neutral pH. Acid or neutral bar can only be practical reality with the advent of synthetic detergents. The pH test and lathering ability test was run to all sample but the other tests was only run to Sample A, B, X, and Y. Sample X and Y were sample from commercial cleaning agent.

Table 3: Cleaning Agent Sample Produce







Cleaning Agent




sample 4.jpg

sample 5.jpg


Solid form

Solim form

Sludge with little water

Sludge with some water

Sludge with a lot of water

3.2 pH Test

Figure 1 shows the results of pH values for Sample A, B, C, D, E, X, and Y that had been prepared. Increasing the concentration of NaOH will increase the pH value. The higher pH at higher mole of NaOH was due to the presence of unreacted NaOH in the mixture. Cleaning agent produced from the higher mole of NaOH gave the higher pH value. This result obtained is the same with result of Awang et. al [13]. Awang stated that increasing the mole ratio of NaOH to dihydroxystearic acid (DHSA) decreased Total Fatty Matter (TFM), while pH and free caustic alkalinity increased. Cleaning agent Sample A and B appear as solid cleaning agent, and were used for further analysis.

Figure 1: pH value for cleaning agent samples

3.3 Lathering Ability

Foam is an important aspect of detergent products and surfactants were mainly responsible for its generation. One important property is the foam generation. The factors that affect this property were the concentration of hardness ions [14]. A common misconception is that soap increases the water's surface tension, soap actually does the opposite, decreasing it to approximately one third the surface tension of pure water [15].In Figure 2, all the foam volumes increased gradually with the increasing ratio of base added. Commercial cleaning agent, Sample X has the higher foam volume which was 32 ml. Sample Y has second highest foam volume which was 27 ml. The lowest foam volume was produce by Sample E which only 3 ml. The highest lathering ability for bio-solid cleaning agent was Sample B which posses almost the same foam volume with commercial cleaning agent Sample Y.

Figure 2: Foam volume (ml) versus sample

3.4 Erosion from Hand washing

Figure 3 show the result for erosion by actual hand washing. The lowest erosion rate is Sample B which is approximately 3.2 g /min. This is good because the cleaning agent can last longer. Commercial cleaning agent X has the highest erosion rate; the cleaning agent will not be very lasting. From the previous result discussed, Sample X has the highest foam volume. The foam was high thus the erosion rate for the cleaning agent is high too. Customer may be happy to use cleaning agent with lots of foam but they will have to buy more cleaning agent in a year. This will increase the cost. For bio-solid cleaning agent, it has much lower erosion rate rather than commercial cleaning agent. Thus, customer will save more money.

Figure 3: Erosion rate (g/min) for each sample

3.5 Biodegradability

The biodegradability of bio-solid cleaning agent produce (Sample A and B) were compared to commercial cleaning agent (Sample X and Y) and DHSA cleaning agent (typical green bio-solid cleaning agent) from Awang et al., [13]. The samples were subject to the OECD 301D closed bottle test method over 28 days. Refering to Figure 4, sample A, B and DHSA bio-solid cleaning agent degraded more than 60% but commercial cleaning agent (Sample X and Y) only 30%. Thus, the latter is not readily biodegradable. Biodegradability of bio-solid cleaning agent was proven higher than the commercial cleaning agent. This is a very good finding because it means that the bio-solid cleaning agent is safe for the environment. Higher biodegradability means that the substance will not stay long in the waste water. Commercial cleaning agent takes longer times to biodegrade and will pollute the water.

Figure 4: Biodegradability Percentage (%) vs Days

3.6 Cleaning Ability

The dirty hand was tested by washing using tap water. When the dirt did not come off, it was wash using cleaning agent sample. The bio-solid cleaning agent posses the same cleaning ability compared to commercial cleaning agent as seen in Figure 5a and Figure 5b. The hydrophilic properties of cleaning agent are the factor that the dirt comes off. The hydrophobic end of a soap avoids water, so the hydrophobic ends of many soap molecules will collect together with their hydrophilic heads pointing out in to the aqueous solution, and their hydrophobic tails clustered together in a little hydrophobic microenvironment. This clustering is called a micelle, and these little balls often surround a particle of grease or dirt, thus maintaining the hydrophobic core of the micelle [16].


Figure 5a: Cleaning ability of commercial Figure 5b: Cleaning ability of bio-solid

cleaning agent cleaning agent

3.7 Costing

Bio-solid cleaning agent production is slightly expensive than normal cleaning agent production because it involve a new technology. The price may reduce after some times. From Table 4, price per bar of bio-solid cleaning agent from this experiment is RM1.35. If the production is run on a bigger scale, the price will also be reduced. Since this study only involved small production of soap, it is quite expensive.

Table 4: Costing of bio-solid cleaning agent production

Chemicals Name

Pack Size

Price per pack (RM)

Amount use per bio-solid cleaning agent

Price per cleaning agent (RM)




7.500 g





3.000 mL





1.308 g





0.654 g





2.615 g


Dodecanoic Acid





Essential Oil



0.01 mL





0.05 mL



RM 1.35


The bio-sold cleaning agent from dodecanoic acid saponification was synthesized. The cleaning agent was sodium dodecanoate. Sample B was the best sample that posse a good properties of a bio-solid cleaning agent. The bio-solid cleaning agent has slightly lower pH rather than commercial soap. The pH of Sample B was 9.08 lower than both commercial cleaning agent sample (9.93 and 10.20). The lathering ability was slightly lower than commercial cleaning agent. The highest lathering ability for bio-solid cleaning agent was Sample B which posses almost the same foam volume (26ml) with commercial cleaning agent Sample Y. Erosion rate after hand washing were higher than commercial cleaning agent which was 3.2 g/min of washing. Biodegradability of bio-solid cleaning agent was more than 60 % which was higher than commercial cleaning agent (30%). The percentage of dodecanoic acid in this cleaning agent is 80% of its total mass. The results were sufficiently promising to warrant further investigation.