Co‐aggregation of mixture components of montmorillonite, kaolinite and humus

Abstract

Soil particle aggregation is closely related to soil quality and pollutant migration in the environment. Soil is a naturally complex system with multi-components, including different organic and inorganic particles. However, current studies with respect to particle aggregation by dynamic light scattering (DLS) have centred on single-component particles. Therefore, the application of DLS to mixture components is an important issue in soil science research. In this study, montmorillonite (Mont), kaolinite (Kaol) and humic acid (HA) particles were mixed in different mass ratios to form two-and three-mixture components, and then the aggregation kinetics of the mixture components in KNO 3 solutions were studied by DLS. The results showed that (a) for any given mixing ratio of two-and three-mixture component particles, there was only one critical coagulation concentration (CCC) value observed for the mixture components; (b) the CCCs of the two-mixture components aggregation were always between the CCC values of each single component in the mixture, and the CCC values of the three-mixture components aggregation were always between those of the two-components aggregation. Based on those experimental results we concluded that, for mixture components aggregation, all the components would participate in the aggregation with equal probability, and the aggregation should be driven by the average DLVO forces of the mixture components. Therefore, for the mixture components of natural soil, the soil particle aggregation would be a co-aggregation process, and the DLS technique would thus be a useful tool to study the real soil aggregation. Meanwhile, HA would decrease soil particle aggregation by increasing the DLVO/XDLVO repulsive forces, rather than promoting soil particle aggregation. Highlights• The aggregation of mixture colloids analysed by DLS is an important issue in soil science research.• There was only one CCC for mixture colloids with different colloidal components.• The aggregation of mixture colloids (soil) is a co-aggregation process.• HA will decrease soil particle aggregation by increasing the DLVO/XDLVO repulsive forces.

Insight into Hofmeister effects on aggregation of 2:1 and 1:1 type clay minerals

“…Mt and Ka used in the experiment were supplied by Wu Hua Tian Bao Mineral Resources Co. Ltd. (Inner Mongolia, China) and Xuzhou Mineral Resources Co. Ltd. (Jiangsu, China), respectively. Both Mt and Ka were characterised by X‐ray diffraction (XRD, XD‐3, Beijing Purkinje General Instrument Co. Ltd., Beijing, China) and the details of the measurements and XRD spectrum are given in our previous publication (Zhang et al, 2021). The specific surface area of Mt and Ka were measured using the combined determination method (H. Li et al, 2011), and the surface charge number Mt and Ka at pH = 6 were estimated by measuring the adsorption quantity of a base cation (K + ) at pH = 6 (Supplementary Material S1) and further shown in Table 1.…”

Editorial for special issue on “Recent innovations in soil physical, chemical and biological analysis” (2nd National Symposium on soil analysis)

“…The analysis of humic substances, as a stable pool of soil organic matter, is still widely considered of pivotal importance in the global carbon cycle. In particular, humic substances remain central to studies of modelling interactions between soil particles (e.g., Zhang et al, 2022). Their extraction from soils and subsequent analysis are usually complicated, which has limited research on humic substances in soils.…”

Optimization of Sumatera Bentonite by Ammonium-impregnated as a Coagulant for Cassava Wastewater Treatment

“…Furthermore, the expanded layer on NH-B provides numerous active sites in the bentonite layer and supports the neutralization and the bridging step in floc formation (see Figure 3b) (Sarkar and Dana, 2022;Figure 4. Turbidity Level on Different Coagulant Levels Used According to the literature, the coagulation will affect the pH final of the wastewater treated Yaghmaeiyan et al, 2022;Zhang et al, 2022). The EDX graph compared element amount in SB and NH-B as the peak height (see Figure 3c-d).…”