1. Industrial Field

　　Metal Treatment:

　　As a rust remover (removing rust from steel surfaces) and a polishing agent (e.g., electrolytic polishing of aluminum alloys);

　　Used to adjust pH values in electroplating solutions, or as a complexing agent to promote the deposition of metal ions.

　　Chemical Synthesis:

　　Preparation of oxalate esters (e.g., dimethyl oxalate, used in the production of polyester fibers) and oxalates (e.g., ferrous oxalate, a precursor for lithium battery cathode materials); as an intermediate in organic synthesis (e.g., synthesis of pharmaceuticals and dyes).

　　Cleaning Agents:

　　Removing scale from tiles and toilets (forming soluble complexes with Ca2+), or cleaning metal salt residues from laboratory glassware.

　　2. Pharmaceutical and Biological Fields

　　Analytical Reagent: Used for the standardization of standard solutions, or as a complexometric titrant to determine metal ion concentrations.

　　Pharmaceutical Intermediate: Involved in the synthesis of certain drugs (e.g., antibiotics, sulfonamides).

　　3. Other Uses

　　Agriculture: Oxalic acid solution can be used as a herbicide (disrupting plant cells), but its use is restricted due to toxicity;

　　Natural Occurrence: Oxalic acid is widely found in plants such as spinach, amaranth, and cocoa (excessive consumption may increase the risk of stones; blanching is required to remove some oxalic acid)