水草情迷

看完SUPER兄介紹的網頁，有些不明白的地方，請各位指教。
什麼是螯合 (連讀都唔識讀)。
什麼是EDTA。

EDTA is one of the 螯合 agent.

螯合 agent can increase the solubility of iron or other trace elements into water. In the example of Iron. Iron (Ferrous) EDTA can be ready dissolving in water and which make Iron available for plants to use. Without EDTA, Iron will be easily oxidized to become Ferric Oxide or hydroxide (Rust) which is NOT soluble in water and Plant cannot absorb them.

Usually most of the Iron in commercial fertilizers are 螯合 (chelated), else they won't last long. E.g. TMG use EDTA and DTPA

EDTA stands for ethylenediaminetetraacetic acid:
(CH2N(CH2COOH)2)2

EDTA in water would become anion (negatively charged ion) and is a strong chelator to divalent metal ions.

即係包住個 Fe2+ ion , 唔比 D oxidizing agent 埋佢身
一但 Fe2+ oxidized 成 Fe3+ 就冇用嫁啦 , 加多多都冇用 , 因為草唔吸 Fe3+

多謝各位的解答，特別是ARKI兄的解答很傳神。另外，還想問：EDTA可否把三價鐵還原為二價鐵？

Simon,
The answer is no.

EDTA is not a 還原 agent. Actually the Fe2+ in EDTA will gradually oxidized to Fe3+ and become less usable. Therefore most of the Iron fertilizers are preferred to be store in dark location and use when fresh.

0吾知大家点配EDTA呢,仲有点样防止酸效应呢.THANKS!

DEAR KB-Z,
0吾知大家点配EDTA呢, YOU MEAN WHERE TO BUY?

仲有点样防止酸效应呢. THANKS! THEY ARE WEAK ACID, NOT MUCH EFFECT ON PH IF AMOUNT IS NOT MUCH.

I think I better define it as weak base , since it salt of weak acid. In the case of bracking the Fe 2+ ion , the charge on the oxygen will be used to bond to the iron ion , but attracting the hydrogen ion in water . So , the pH change will not be important (or increase a bit due to free EDTA salt).
All the above are just my " PREDICTION" without physical data and please correct me in case my prediction is wrong .

DEAR ARKI,
YOUR PREDICTION IS RIGHT,
IN MY CASE, I PUT ENOUGH EDTA-FE TO RAISE THE CHELATED IRON FROM 0.25 TO 1MG/L THE PH DROPS FROM 6.1 TO 6.0, AND COME BACK TO 6.1 AFTER FEW HOURS.

系0吾系就0甘放入去啊。定系配成溶液，系又点配呢。THANKS！

DEAR KB-Z,
DO NOT 系0吾系就0甘放入去啊, WILL BE TOO MUCH.
。定系配成溶液，系又点配呢。SEE THE POST OF "PPMD"

Dear begineer,

How's your plant doing with your Fe-EDTA ?

dear alex,
after dose my tank with edta-fe, pmdd, basf 10-4-7 for about a week, plants getting greener, short pearl growing at double speed, some green spot comes out.