operation oaxaca: the operation.

theory/practical procedure to make filter (007)

Carlos Manuel Jarquín Sánchez
4 min readFeb 3, 2024

this is carlos.

i’ve completed the basics.

although i will focus more on the problem.

and what is it that i want to correct.

all i know is that i want to make a filter similar to lifestraw, but for heavy metal ions.

something that people can use… not just for industrial applications.

i have the first half of the operation complete.

this will be an extra layer of protection to shield the mango peel.

take a look.

that extra layer was the previous water filter i made.

it was alginate and calcium chloride.

it’s good.

but in the real world, the economics don’t align.

and economics first. then everything else.

but mango, yes.

agricultural waste is abundant.

but what was the procedure for the alginate, you may ask?

got you.

i’ll tell you that first.

then we proceed to the mango attempt.

made from the sea 🌊

i made three versions of this junk before i got it to partially hydrophobe itself.

granted, i did not have a lab, i did it in the garage lol.

i just followed the golden rule:

use what you got.

i’ll go in-depth about each version of the old filter.

here we go.

btw, the ingredients to make the filter…

i have it on a literal piece of paper, i had to figure it out on the go lmao.


the strongest beads had:

2% or 2.25% concentration of giant kelp powder (C6-H7-Na-O6)

2 grams of kelp powder in 100 ml of distilled H2O

2.25 grams of kelp powder in 100 ml of distilled H2O

stir until partially dissolved.

to add color (so you can see the beads):

insert mccormick food coloring, of whatever choice.

i added five drops, but i recommend three…

it is a lot once you begin to stir.

if you stir manually, it will take ~25 minutes for complete dissolution.

if you use a blender, it will take ~5 minutes for complete dissolution.

if you stir manually, use metal spoons.

once the kelp powder, food coloring, and water have been mixed,

to create an oozing, highly-viscous fluid:

you’ll make a 4% or 5% calcium chloride solution. (CaCl2)

that was what worked best for me.

it will be 20 grams of CaCl2 in 500 ml of distilled H2O

or 25 grams of CaCl2 in 500 ml in distilled H2O

this does not require a blender,

you can stir manually for ~5 minutes and you’re good to go.


to get the beads to maintain form after squishing them with tweezers,

simply add the right amount to allow a colloidal solution.

colloidal solution → free-flow spreading of a solid in a liquid.

our solid is the powder, the liquid is the food coloring & water.

if we add too much, we interrupt equal dispersion,

and we’re left with chunks of powder in the liquid.

if we add too little, we won’t create enough dispersion for the perlas to have mechanical strength.

the strongest perlas were 2% kelp powder & 5% CaCl2 concentrations.


to create the perlas,

repeat the v1 + v2 steps.

once that’s done,

get some polybutyl methacrylate.

it’s the hydrophobe powder required to make the beads hydrophobic.

be careful with this chemical. it may irritate your skin if you touch it.

i used 10 grams of the powder and mixed it with the giant kelp powder.

in full honesty, i would suggest using 5 grams.

i left powder residue in the solution, not equal dispersion. :\

then i stirred manually for ~15 minutes.

i used the following for under $400 to make it:

plastic syringe
kn-95 mask
three plastic cups (didn’t have glass beakers)
metal spoons
arrowhead distilled water

the calcium chloride was bought on amazon.com (1 packet)

the sodium alginate was bought on scipoly.com (2 containers)

ok, now, the big reveal.

for the mango peel procedure, here is what i would do:

the mangoes would be purchased at a local convenience store or farmer’s market.

then we would peel the outer layer, or the peel.

cut that peel into pieces that are somewhat equal to the beads size.

most likely, 0.03 - 0.05 cm² in size.

and we would add hydroxyl/carboxyl groups to create anionic behavior on the mango peel.

heavy metals are cationic (positively charged). hydroxyl/carboxyl is anionic (negatively charged). and opposites attract.

distilled/deionized water will be used.

and an oven to dry the pieces of the mango peel.

we don’t want any compounds that could affect the outcome of their metal-ion adsorption abilities.

random questions:

at what temperatures?

how much would it cost, approximately?

what other chemicals may i need for an effective answer?

is this even the best solution to the problem?

and what is the ever-evolving problem?

tbh, idk.

all i know is this:

use what i got. and i will find my answers.


gunna go send a few emails now.

see if i can infiltrate a lab or two hahaha.



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