Effect of salinity on formaldehyde interaction with quartz sand and kaolinite colloid particles: batch and column experiments

Formaldehyde (FA) is a highly reactive compound that is used extensively in medicine, agriculture and industrial processes as a disinfectant for killing bacteria and fungi. Therefore, the probability of FA release in the environment, with subsequent surface and ground water contamination is significant. In this study, the effect of salinity on the interaction of FA with quartz sand and kaolinite colloid particles under static and dynamic conditions was examined. Emphasis was given to salinity fluctuations, as related to typical saltwater intrusion cases commonly encountered in coastal cultivated agricultural lands. All bench scale experiments were performed under controlled conditions at room temperature. The data from the batch experiments were adequately fitted with a linear sorption isotherm. The transport of FA through columns packed with quartz sand under different salinity concentrations was also investigated. Formaldehyde was analyzed spectrophotometrically according to the Hantzsch reaction. The results of this study indicated that FA has a weak affinity for sand, but a relatively strong affinity for kaolinite colloid particles. Salinity was shown to have minor effects on FA transport.