Influence of surface functionalization and particle size on the aggregation kinetics of engineered nanoparticles

► We studied the effect of capping agent on gold nanoparticles aggregation kinetics. ► pH, NaCl and natural organic matter concentrations effects were investigated. ► The long-chain capped gold nanoparticle showed steric repulsion with higher CCC. ► The pKa of the capping agent leads the aggregation kinetics. ► Natural organic matter is not always a stabilizing agent.