Say it with flowers!

Ajita Banerjee

Mumbai generates waste to the tune of 7025 tons per day. The waste consists of 5025 tons of biodegradable and recyclable material. Flowers offered to the gods in temples form a sizeable amount of this waste. My students and I (as a facilitator) decided to analyze this floral waste and see if we could put these flowers to better use and in the process help conserve the environment. On collecting the floral waste from a few temples we found that it mainly consists of Calendula officinalis or marigold flowers.

Work plan

Drying and grinding of calendula flowers

  1. First, we sorted the flowers and washed them with chlorine water to sanitize them.
  2. Then we dried them in the oven at 40ºC. We crushed them with mortar and pestle sieved them and stored them in airtight boxes.
  3. Our experimentation started with the dry powder. We prepared extracts of orange marigold and yellow marigold in water, in ethanol 70%, in coconut oil and stored them.
  4. Next we studied the pigments under the spectrophotometry machine to observe the different wavelengths of the pigments through UV rays.
  5. We found that the main pigment was lutein (C40H56O2). We calculated the length of its path using the formula
  6. The path length was 10.45 mg/litre.
  7. We also studied the pigments using the Paper Chromatography technique (analytical method used to separate colored chemicals or substances).
  8. We prepared dye from orange and yellow marigold. To improve the colour and texture we used different mordants (dye fixatives) like CuSO4 (Copper sulfate) 10% and 20%, K2Cr2O7 (Potassium dichromate) 10% and 20%.
  9. We used the dye to colour white cotton cloth and thread. We made soap with the help of the extract and dry powder.
  10. Our next endeavour was to test the pesticidal property of calendula extract in water on different fungi like Aspergillus flavus, Aspergillus parasiticus, Mucor or Rhizopus stolinifier, white mould or sclerotinia sclerotiorum and on activated yeast that is Saccharomyces crevisiae.

Wavelengths under the spectrophotometry machine
Our observations were as follows

  1. By drying the floral waste, its volume reduced remarkably. One kg of flower was reduced to 136 gms of dry powder, which we stored in an air tight box.
  2. We prepared the extracts in ethanol 70%, water, coconut oil and performed our experiments with these extracts.
  3. We determined the pH value of the extract in water and we did a litmus test as well. The pH value was 2. This solution, we realized, could be used as an indicator as in an acidic medium it turned yellow and in basic medium it turned brown.
  4. The pigment lutein was observed between 414 nM (nanomolar) to 669 nM under the spectrophotometer. Lutein has immense pharmacological properties.
  5. Dyeing of cloth
  6. Calendula extract in water as a dye gave excellent results. Cotton cloth turned yellow ochre or brown based on the mordants used. We also tried dyeing the cloth for different time intervals from 30 minutes to 24 hours. Extract in ethanol did not give positive results.
  7. Soap that was made with the help of soap base, extract and dry calendula powder had a pleasant smell and moisturizing effect.
  8. The pesticidal property of the extract really enthralled us. Yellow marigold in water was inhibiting the growth of Aspergillus flavus. Orange marigold in water was inhibiting the growth of Aspergillus parasiticus.
  9. We also turned some of the waste flowers into compost which could be used as fertilizer.
Soap made from calendula extract and powder

This floral waste could be used as wealth if proper methodology is followed. These types of tasks interest students and in future they could become entrepreneurs and utilize such waste for the betterment of the society.

We would like to thank the Institute of Chemical Technology, Mumbai for guiding us in our various experiments.

The author has been a teacher of science from 1980. She currently teaches at Shree Amulakh Amichand Bhimji Vivdhalakshi Vidyalaya, Matunga, Mumbai. She can be reached at

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