Evaluation and characterisation of metal sorption and retention by drinking water treatment residuals (WTRs) for environmental remediation

Drinking water treatment residuals (WTRs) are wastes generated when water is clarified using aluminium or iron salts. They are increasingly being considered as a resource with potential reuse value, particularly in relation to soil or water remediation. Adsorption–desorption capacity of Al-based (Al-WTR) and Fe-based (Fe-WTR) materials was investigated here for Pb and Zn, both separately and in combination, as a preliminary trial to assess their utility for immobilising contaminant metals in environmental settings. Maximum adsorption observed at the highest test solution concentrations imposed (400 mg/L) was similar for each WTR type and each metal; Al-WTRs sorbed Zn at 3579 mg/kg and Pb at 4025 mg/kg, while Fe-WTRs sorbed Zn and Pb at 3579 mg/kg and 3980 mg/kg, respectively. Equilibrium adsorption data were tested against Langmuir, Freundlich, and Temkin isotherm models, which indicated a substantial reserve capacity for further Pb sorption and that multiple sorption mechanisms were involved. Subsequent desorption tests with 0.001 M CaCl2 solution indicated that > 89.76% of sorbed metal remained sorbed. When in solution together, both metals were strongly sorbed by WTRs, but a slight preference for Pb was observed. The results indicate that WTRs would be very effective immobilising agents if placed in contaminated soil or if used to treat contaminated waters.

Soil Nitrogen Sorption Using Charcoal and Wood Ash

This paper reviews the use of charcoal and wood ash in acid soils as adsorbents to improve N availability at the same time improving their soil fertility and crop productivity. Soil acidification poses a major challenge in agricultural sustainability and it is serious in highly weathered soils such as Ultisols and Oxisols which are noted for nutrient deficiency and Al and Fe ions toxicities. Understanding sorption mechanisms and isotherms is important for the improvement of soil N availability particularly inorganic N. However, understanding the sorption mechanisms in relation to charcoal and wood ash as absorbents in the literature is difficult because the soil amendments vary depending on their raw materials or sources of origin. Therefore, one of the objectives of this review is to provide recent research findings and theory development on the role of charcoal and wood ash in agriculture. Furthermore, this review focuses on how charcoal and wood ash improve N availability through physical, chemical and biological processes in mineral acidic soils. Balanced application and good understanding of the role of charcoal and wood ash as soil amendments have potential benefits to improve N availability and crop productivity.

Açaí Biochar and Compost Affect the Phosphorus Sorption, Nutrient Availability, and Growth of Dioclea apurensis in Iron Mining Soil

Organic materials, such as biochar and organic compost, can reduce P sorption mechanisms and improve soil fertility, benefiting the reclamation of areas impacted by mining. This study evaluated how the chemical properties of Fe mining soil, the adsorption of P onto this substrate, and the growth of the native plant Dioclea apurensis, were affected by the application of açaí biochar (BC), organic compost (OC), and different P doses. Substrate collected from mining soil piles was incubated for 30 days with BC or OC. Each mining substrate with or without the addition of BC or OC received five doses of P (0, 40, 80, 120, and 240 mg∙kg−1 P). The addition of BC or OC promoted an increase in pH and nutrient availability (P, K, Ca, and B) in Fe mining soil. However, plants grown in the unamended mining soil (W) showed higher growth. The maximum P adsorption capacity decreased as a function of the addition of BC. We conclude that the application of BC reduced P sorption, while the application of either OC or BC altered the chemical properties of the soil and caused contrasting effects on P dynamics in Fe mining soil, and these treatments also affected plant growth.

Chromatographic Method for Evaluation of Polymeric GC Stationary Phases Ageing Using the Novel Non-Cross-Linked Poly(3-(Tributoxysilyl)Tricyclononene-7) as the Model Stationary Phase

The chromatographic properties and thermal stability are investigated for the polymeric stationary phase based on the norbornene polymer. It was shown that without additional cross-linking, poly(3-(tributoxysilyl)tricyclononene-7) demonstrates properties similar to liquid chromatographic stationary phases. It was also found to be more thermally stable than previously studied trimethylsilyl- and trimethoxysilyl- derivatives. The long-term heating at 170 °C resulted in an increase of mass transfer rate between stationary and mobile phases which could be observed as a decrease of parameter C of Van Deemter equation. This effect is rather unusual, as the polymeric stationary phases tend in decrease of the layer volume and porosity while ageing. Additionally, the values of thermodynamic parameters of sorption are calculated for the polymeric stationary phase: enthalpy of sorption varied −28 to −37 kJ/mol, entropy change was −41 to −51 J/mol K. The compensation curves were plotted for the alkanes, arenes, and alcohols, and the parameters of compensation plot were calculated, demonstrating the different sorption mechanisms both for hydrocarbons and oxygen-containing compounds, and different classes of organic compounds.

Physisorption and Chemisorption Mechanisms Influencing Micro (Nano) Plastics-Organic Chemical Contaminants Interactions: A Review

Microplastics, which serve as sources and vector transport of organic contaminants in both terrestrial and marine environments, are emerging micropollutants of increasing concerns due to their potential harmful impacts on the environment, biota and human health. Microplastic particles have a higher affinity for hydrophobic organic contaminants due to their high surface area-to-volume ratio, particularly in aqueous conditions. However, recent findings have shown that the concentrations of organic contaminants adsorbed on microplastic surfaces, as well as their fate through vector distribution and ecological risks, are largely influenced by prevailing environmental factors and physicochemical properties in the aquatic environment. Therefore, this review article draws on scientific literature to discuss inherent polymers typically used in plastics and their affinity for different organic contaminants, as well as the compositions, environmental factors, and polymeric properties that influence their variability in sorption capacities. Some of the specific points discussed are (a) an appraisal of microplastic types, composition and their fate and vector transport in the environment; (b) a critical assessment of sorption mechanisms and major polymeric factors influencing organic contaminants-micro (nano) plastics (MNPs) interactions; (c) an evaluation of the sorption capacities of organic chemical contaminants to MNPs in terms of polymeric sorption characteristics including hydrophobicity, Van der Waals forces, π–π bond, electrostatic, and hydrogen bond interactions; and (d) an overview of the sorption mechanisms and dynamics behind microplastics-organic contaminants interactions using kinetic and isothermal models. Furthermore, insights into future areas of research gaps have been highlighted.