Controlling calcium carbonate scaling in desalination: A green approach using citric acid

Abstract

This study focuses on the deposition of calcium carbonate, adding citric acid in solution: it shows green properties and can retard scale precipitation, reducing equipment malfunctions. Three concentrations were considered ($0.520\times {10}^{-3}$, $1.041\times {10}^{-3}$, $1.561\times {10}^{-3}mol/l$), with different temperature values ($15°C$, $35°C$). Results showed that citric acid is a powerful retarding agent, enhancing this behaviour at $15°C$. Moreover, it makes nucleation more difficult because it can increase the interfacial tension between $Ca{CO}_3$ crystals and the surrounding solution. Finally, citric acid favors the formation of calcite crystals with reduced sizes, whose morphological characteristics hinder their growth.