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2 years ago in Environmental Chemistry , Geochemical Modeling By Simanghi
How do I use the NICA-Donnan model for heavy metal interactions with natural organic matter?
My background is in analytical chemistry, and I now need to model Cd and Pb binding to dissolved organic matter in my soil solutions. The NICA-Donnan model is cited as the standard, but the literature is theoretical. What software do I actually use, and what input data do I need to gather from my samples to get started?
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By Vishal Answered 1 year ago
The most straightforward path is to use the free software Visual MINTEQ. I've trained many students on it. Your first step is to fully characterize your water chemistry: you need accurate measurements of pH, major ions (Ca2+, Mg2+, Na+, K+), anions, and most importantly, your total dissolved organic carbon (DOC). Within Visual MINTEQ, you select the NICA-Donnan framework for organic matter. The model has default parameters for generic humic acids, but for better accuracy, I would recommend trying to determine your specific site's organic matter proton binding (from a titration) if possible. Start by modeling a single metal at a time to calibrate your approach.
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