Page 15 - Shaping A Sustainable Future

Subsequently, we proceeded to assist the management conductivity results. The CMC was established by
in finding a solution to minimize environmental impacts. identifying the intersection point of both conductivity
We researched the best methods to minimise the trends before and after the CMC was reached.
amount of dishwashing detergent required to clean the
dishes effectively.

Proposed Eco-Solutions Figure 2: Detergent used by the
coffee shop - TP 706 dishwashing
liquid
From our research, we found that dishwashing
detergents contain surfactants. Surfactants function
by breaking down the interface between water and
oil, facilitating the removal of oily food grime attached In the experiment, dishwashing detergent concentrations
to the surfaces of the dirty dishes when soaked in a of 2.5 ml/, 5 ml/l, 7.5 ml/l, 10 ml/l, 12.5 ml/l, 15 ml/l,
dishwashing detergent and water solution. 17.5 ml/l, 20 ml/l, 22.5 ml/l and 27 ml/l were prepared
by dissolving the measured detergent volume into 1L
Usually, dishwashing detergent and water solution will of water. To investigate the influence of oil on CMC,
reach a Critical Micelle Concentration (CMC). This is different amounts of domestic cooking oil ranging from
when the solution interface is saturated with surfactants 0g, 1g and 10g were added to the solution. Subsequently,
micelles, and no more surfactants micelles can be the conductivity measurements of the solutions were
attached. plotted against detergent concentration.

Hence, the minimum concentration of surfactants The oil and detergents used in the experiment
(dishwashing detergent) needed is derived from the CMC were obtained from the coffee shop to ensure the
of the dishwashing detergents used. Using detergent reproducibility of the results. Refer to Figure 3 to
concentrations at the correct CMC for dishwashing will identify the CMC value for dishwashing detergent with
achieve the optimal result at the minimum possible 1g oil added and Annex B for the rest of the CMC graphs.
detergent concentrations. This will minimise the
amount of dishwashing detergent being used, thereby
conserving water, achieving cost savings and reducing
wastewater discharge.

There are different methods available to determine
the CMC of a dishwashing detergent. Refer to Figure
2 for the dishwashing detergent used in the coffee
shop. Conductivity is the most common method
used to determine CMC. To find the CMC value of the
dishwashing detergent used by the coffee shop, various
concentrations of dishwashing detergent solution Figure 3: Identification of the CMC for dishwashing
were prepared. A CMC graph was plotted using the detergent (1g oil added)

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