Equilibrium-Based Modeling of Chemical Sorption on Soils and Soil Constituents

Schulthess, Cristian P.; Sparks, Donald L.

doi:10.1007/978-1-4612-3144-8_2

Cited by 25 publications

(17 citation statements)

References 93 publications

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“…Th e debate was mostly over whether the adsorption of ions was a physical or chemical process. Th e struggle to defend ion exchange to describe soil chemical reactions went on for years (Th omas, 1977), and even today the details of how ion-exchange reactions should be interpreted and modeled are still being debated (Schulthess and Sparks, 1991).…”

Section: The Early Yearsmentioning

confidence: 99%

“…Irving Langmuir (1916) derived an equation 58 yr later that described the adsorption isotherm. Although a single adsorption reaction model is not the same as a single ion-exchange reaction model, it can be shown that the Langmuir equation also applies to this kind of ion-exchange reaction if the aqueous concentration of one of the ions is kept constant (Schulthess and Sparks, 1991).…”

Section: The Early Yearsmentioning

confidence: 99%

“…Th is is not to say that it cannot be derived. Henry (1922) derived the Freundlich equation by assuming that free surface energy is linearly related to the fraction of surface coverage (Schulthess and Sparks, 1991). Th e primary problem with using this equation is that it does not elucidate what the reaction mechanism happens to be, and this problem exists even if the predicted curve fi ts the data perfectly.…”

Section: Adsorption and Ion-exchange Modeling Empirical Modelsmentioning

confidence: 99%

“…First, it was originally based on a simple adsorption reaction rather than a simple ion-exchange reaction. Although the Langmuir equation can be derived as a special case of an ion-exchange reaction where the concentration of one of the ions involved (such as pH) is kept constant (Schulthess and Sparks, 1991), it is routinely used and interpreted based on its original assumption. Specifi cally, it is used to represent a single ion-adsorption reaction.…”

Section: Langmuir Modelmentioning

confidence: 99%

“…Gans (1913) proposed a simple ion-exchange equilibria model for ions of similar charge. Th is equilibria model yields an equation that can be easily reduced to the Langmuir equation if the aqueous concentration of one of the ions is kept constant (Schulthess and Sparks, 1991). Th e primary problem with this equation is that it assumes only one ion-exchange reaction.…”

Section: Ion-exchange Modelsmentioning

confidence: 99%

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Historical Perspective on the Tools That Helped Shape Soil Chemistry

Schulthess

2011

Soil Science Society of America Journal

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SSSA 75 th Anniversary Paper T he tools of soil chemistry include instruments, mathematics, models, and software. Th ere is also the mind and imagination. Th roughout the history of our science, we have been shift ing away from a very labor-intensive laboratory environment, where long hours of concentration on tedious tasks was the norm. Th is change in the way we work has been accelerating, particularly since the 1950s. We are accomplishing more work but with less eff ort and more time to contemplate what the data are trying to tell us. Th e essence of our research activity has changed dramatically.Numerous laboratory tools have been used in soil chemistry during the last 200 yr, and the major changes that have occurred are highlighted here. It is hoped that the picture presented will help us decide how to better train our students for the future. By knowing how we have changed in the past and how we appear to be changing in the present, we can perhaps trace the path that we are taking, at least in the near future.Eight major themes are addressed here:1. Th e early years reviews the research environment of the 1800s up to the early 1900s. It marks the beginning years of soil chemistry that shaped many of our ideas for the decades that followed.2. Th e age of electronics covers the early part of the 1900s and the origins of the fi rst portable meters on the market.3. Spectroscopy is at the core of most of our modern methods of analysis. While the development of only a few tools are described here, the impact of spectroscopy on our current research activity cannot be understated.

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Section: The Early Yearsmentioning

confidence: 99%

Section: The Early Yearsmentioning

confidence: 99%

Section: Adsorption and Ion-exchange Modeling Empirical Modelsmentioning

confidence: 99%

Section: Langmuir Modelmentioning

confidence: 99%

Section: Ion-exchange Modelsmentioning

confidence: 99%

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Historical Perspective on the Tools That Helped Shape Soil Chemistry

Schulthess

2011

Soil Science Society of America Journal

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Estimating dissolved phosphorus losses from legacy sources in pastures: The limits of soil tests and small‐scale rainfall simulators

et al. 2021

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A legacy of using P fertilizers on grazed pastures has been enhanced soil fertility and an associated, increased risk of P loss in runoff. Rainfall simulation has been extensively used to develop relationships between soil test P (STP) and dissolved P (DP) in runoff as part of modelling efforts scrutinizing the impact of legacy P. This review examines the applicability of rainfall simulation to draw inferences related to legacy P. Using available literature, we propose a mixing layer model with chemical transfer to describe DP mobilization from pasture soils where readily-available P in the mixing layer is rapidly exhausted and contact time controls DP concentrations responsible for subsequent DP mobilization. That conceptual model is shown to be consistent with field monitoring data and then used to assess the likely effect of rainfall simulation protocols on DP mobilization, highlighting the influence of soil preparation, scale and measurement duration, and, most importantly, hydrology that can facilitate the physical transport of P into, and out of, surface flow. We conclude that rainfall simulation experimental protocols can have severe limitations for developing relationships between DP in runoff and STP, that are subsequently used to estimate legacy P contributions to downstream water resources.

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Nitrate removal from aqueous solutions by adsorption onto hydrogel‐rice husk biochar composite

Afjeh

Marandi

Zohuriaan‐Mehr

2020

Water Environment Research

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In the present study, we investigated the performance of hydrogel-rice husk biochar composites, as low-cost, alternative, and biocompatible adsorbents for separating nitrate ions from aqueous solutions. Hydrogel-biochar composite was synthesized at dosages of 2.5%, 3.6%, 4.8%, and 9.6% weight ratios of biochar. The composite was characterized by several common methods including FTIR, SEM, TEM, TGA, and DSC. In addition, the effect of contact time, initial concentration of nitrate ions, and solution pH were considered. The maximum removal of nitrate was about 34.3% at acidic pH (pH = 3) using 0.02 g of adsorbent in 25 ml of nitrate solution with the initial concentration (20 mg/L) and temperature of 25°C for 60 min. Based on the findings, 5% biochar in the composite was the optimal dosage. Adsorption kinetic study revealed that this process followed the first-order kinetic model. The experimental equilibrium adsorption data were tested by the Temkin isotherm model with R 2 > 0.97. Based on the thermodynamic studies, the adsorption process was endothermic and spontaneous. Overall, the results suggested that the obtained composite can be specifically employed for removal of contaminations from aqueous solutions. © 2020 Water Environment Federation • Practitioner points• Hydrogel-biochar composite provides a biocompatible and cost-effective adsorbent. • Hydrogel-biochar composite was applied to eliminate nitrate from aqueous solutions. • Nitrate removal increased in the synthesized composite upon elevation of the weight ratio of biochar to 0.2 g.

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Equilibrium-Based Modeling of Chemical Sorption on Soils and Soil Constituents

Cited by 25 publications

References 93 publications

Historical Perspective on the Tools That Helped Shape Soil Chemistry

Historical Perspective on the Tools That Helped Shape Soil Chemistry

Estimating dissolved phosphorus losses from legacy sources in pastures: The limits of soil tests and small‐scale rainfall simulators

Nitrate removal from aqueous solutions by adsorption onto hydrogel‐rice husk biochar composite

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