Should "constitutional" be changed to "constituent" in the following sentence? Or do both of them give the same meaning?
The spectra indicate the removal of constitutional water from the octahedral sheets
Constituent means "being part of a whole" whereas constitutional means "having to do with a constitution." Constitution has various different meanings including the base laws of a country, the durability or mental state of a person, the durability or makeup of an object, and possibly more.
"Constitutional" and "constituent" are not interchangeable terms. "Constituent" could have several meanings. It could refer to an essential component (i.e., not a contaminant) that is a chemical ingredient, or it could refer to anything present in the sample in question.
Constitutional has a very specific meaning. Constitutional water, or water of constitution, in not a chemical ingredient, but is held as an essential part of its physical structure, such as enabling crystals to form their shape.
It refers to something with characteristics sort of in between a chemical ingredient and a catalyst. A catalyst serves a function in initiated a chemical reaction but isn't itself part of the reaction (it may be remain present in the result, but as a "contaminant" rather than an essential component). Like a catalyst, constitutional water isn't a chemical component, but unlike a catalyst, it plays a critical role in the physical properties and must be present in order for the material to have that physical form.