In the chapter Environmental Chemistry in our textbook it's given that Powder of Kernel of Tamarind seeds can be used for water treatment as a substitute for alum.

But if I understand correctly, alum ionizes in water and these ions neutralize the electrical double layer surrounding colloidal particles. How does a substance like 'Powder of Kernel of Tamarind seeds' produce the same effect?

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    $\begingroup$ The key is to know the composition and behaviour of this powder what is mostly unknown to chemists. My understanding is that alum hydrolyzes, forming colloidal hydroxide, which adsorbs these colloidal particles. The powder may form organic colloids of similar properties, settling later down as aluminium hydroxide does. $\endgroup$
    – Poutnik
    Feb 7, 2021 at 8:07
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    $\begingroup$ mostly unknown to chemists – better expression may be "unknown to most chemists". $\endgroup$
    – Poutnik
    Feb 7, 2021 at 11:35
  • $\begingroup$ Alum is a flocculating agent which causes suspended solids, like fine clay particles, to form aggregates and precipitate. $\endgroup$
    – MaxW
    Feb 7, 2021 at 13:18
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    $\begingroup$ In my understanding,, Al^3+ in near neutral environment hydrolyzes faster than it gets chance to interact with colloids. $\endgroup$
    – Poutnik
    Feb 7, 2021 at 16:42


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