Solution Equilibria Research Articles

Catalytic Enantioselective Alkylation of Indoles with trans-4-Methylthio-β-Nitrostyrene.

The reaction of the rhodium aqua-complex (SRh,RC)-[Cp*Rh{(R)-Prophos} (OH2)][SbF6]2 [Cp* = C5Me5, Prophos = propane-1,2-diyl-bis(diphenylphosphane)] (1) with trans-4-methylthio-β-nitrostyrene (MTNS) gives two linkage isomers (SRh,RC)-[Cp*Rh{(R)-Prophos}(κ1O-MTNS)]2+ (3-O) and (SRh,RC)-[Cp*Rh{(R)-Prophos}(κ1S-MTNS)]2+ (3-S) in which the nitrostyrene binds the metal through one of the oxygen atoms of the nitro group or through the sulfur atom, respectively. Both isomers are in equilibrium in dichloromethane solution, the equilibrium constant being affected by the temperature in such a way that when the temperature increases, the relative concentration of the oxygen-bonded isomer 3-O increases. The homologue aqua-complex of iridium, (SIr,RC)-[Cp*Ir{(R)-Prophos}(OH2)][SbF6]2 (2), also reacts with MTNS; but only the sulfur-coordinated isomer (SIr,RC)-[Cp*Ir{(R)-Prophos}(κ1S-MTNS)]2+ (4-S) is detected in the solution by NMR spectroscopy. The crystal structures of 3-S and 4-S have been elucidated by X-ray diffractometric methods. Complexes 1 and 2 catalyze the Friedel–Crafts reaction of indole, N-methylindole, 2-methylindole, or N-methyl-2-methylindole with MTNS. Up to 93% ee has been achieved for N-methyl-2-methylindole. With this indole, the ee increases as conversion increases, ee at 263 K is lower than that obtained at 298 K, and the sign of the chirality of the major enantiomer changes at temperatures below 263 K. Detection and characterization of the catalytic intermediates metal-aci-nitro and the free aci-nitro compound as well as detection of the Friedel–Crafts (FC)-adduct complex involved in the catalysis allowed us to propose a plausible double cycle that accounts for the catalytic observations.

A Dynamic Combinatorial Library of Cyclic AuI2NiII Complexes with Cysteine/Penicillamine Showing Solvent-Controlled Crystallization.

A dynamic combinatorial library (DCL) is a set of molecular species existing in equilibrium in solution that can undergo self-assembly via reversible chemical bonds. Here, we report a unique DCL system that shows the independent crystallization of products from solvents with slightly different polarities. The reaction of a 1:1 mixture of [Au2(dppm)(dl-cys)2]2- and [Au2(dppm)(dl-pen)2]2- with Ni2+ in solution gave a DCL containing 10 cyclic AuI2NiII molecules of [Au2Ni(dppm)(dl-cys/dl-pen)2]. Upon crystallization, three kinds of enantiomeric pairs, homoleptic-heterochiral C/A-[Au2Ni(dppm)(d-cys)(l-cys)], homoleptic-homochiral [Au2Ni(dppm)(d-pen)2]/[Au2Ni(dppm)(l-pen)2], and heteroleptic-homochiral [Au2Ni(dppm)(d-cys)(d-pen)]/[Au2Ni(dppm)(l-cys)(l-pen)], were produced from the reaction solutions of MeOH, MeOH/H2O, and EtOH/H2O, respectively. The independent crystallization was explained by a combination of the different hydrogen-bonding interactions of the AuI2NiII molecules in the crystal and the different thermodynamic stabilities of the molecules in solution.

On the interaction between calcite and dolomite: Insights from gas and aqueous geochemistry and mineralogical characterization

The current models developed to determine the pore water chemistry of clayrocks consider that Ca, Mg and Fe are controlled by equilibrium reactions with pure carbonates. However, the Ca/Mg ratios measured in pore water are not always in agreement with calculations. Here we investigated the interaction between calcite and dolomite at ambient temperature and at 80 °C. During batch experiments, despite the fast equilibration of the solution composition (within weeks), the gaseous CO2 concentration increased during several months at ambient temperature while it reached a steady state at 80 °C. The observations made at ambient temperature are apparently in conflict (metastable system). However, nanoscale characterizations proved to be useful to evidence a mineralogical evolution during the experiments. Indeed, local equilibria in solution enabled the precipitation of secondary phases despite their undersaturation with respect to the bulk solution and the dissolution of pristine phases. These results suggest that the dissolution/precipitation kinetics are slow and ongoing despite the apparent stability of the system, something usually not considered in the prediction of sedimentary facies over a geological timescale.

Intrasoil dispersed phosphogypsum utilization in a small aggregate chernozem system

Unregulated accumulation of phosphogypsum leads to dangerous geochemical flows with an avalanche effect. As a new option for the application of phosphogypsum, its dispersed placement in the small aggregate chernozem system at a depth of its modern anthropogenic illumination was described. A milling method for treating a soil layer of 30–60 cm was developed. Phosphogypsum and soil interact and agrophysical soil properties can be improved. The anthropogenic eluvial-illuvial structure of the soil profile can be eliminated. The morphological, agrophysical properties and soil moisture conditions, thermodynamic processes with Pb2 +, Cd2 + ions, the morphological parameters of the root system and the yield of sunflower after application of phosphogypsum during its utilization by dispersing in the soil layer of 30–60 cm were studied. Improved soil properties and conditions for development of the rhizosphere, passivation of heavy metals as a result of the carbonate-calcium equilibrium in the soil solution were described. The ecosphere and the agricultural production effect of phosphogypsum utilization in chernozem were substantiated.

A New Multiscale Computational Model for Low Salinity Waterflooding in Clay Bearing Sandstones

We develop a new multiscale model to compute effective properties such as relative permeability, contact angle and partition coefficients in low salinity enhanced oil recovery processes for two-phase flow in sandstones containing reactive surfaces of kaolinite clay. In this setting, we construct a three-scale approach which entails the local nanoscale description ruled by the electro-chemistry of a confined electrolyte solution containing Na+, $$Ca^{2+}$$ , $$H^+$$ , $$Cl^-$$ and $$OH^-$$ ions residing between bounded crude-oil droplets at residual saturation and clay substrate. Our analysis focuses on the case of surface complexation geochemical reactions between the ionic species of the invading water and the electrically charged kaolinite and oil–water interfaces. In this scenario, we construct a local electric double layer problem for the electric potential based on a non-symmetric Poisson–Boltzmann equation supplemented by nonlinear boundary conditions with the magnitude of the surface charge strongly dictated by the geochemical reactions. By invoking the local mechanical equilibrium of the electrolyte solution and solving numerically the nonlinear problem using the finite element method, we compute the local ionic profiles and reconstruct numerically the disjoining pressure and adsorption isotherms for each ionic species for a wide range of brine compositions and pH of the water phase. Furthermore, combining the disjoining pressure results with the Frumkin/Derjaguin wetting theory allows to compute the dependence of the contact angle on wettability, pH and salinity. Subsequently, the formal homogenization procedure is adopted to upscale the pore-scale flow and ion transport to the macroscale giving rise to a new Darcy scale coupled flow/transport model. The hyperbolic part of the nonlinear homogenized model is solved analytically in an 1D example of enhanced oil recovery.

Thermodynamic Study on the Protonation and Complexation of the Neuroleptic Drug, Gabapentin with Na+, Ca2+ and Mg2+ at Various Temperatures and Ionic Strengths

The current work investigates the protonation constants of gabapentin (GP), 2-[1-(aminomethyl)cyclohexyl]acetic acid and the stability constants for the binding of GP to Ca2+ and Mg2+ in a wide range of temperature and ionic strength conditions [283.15 ≤ T/K ≤ 318.15 and ionic strengths of NaCl(aq), 0.12 ≤ I/mol·dm−3 ≤ 4.84]. The pH-potentiometric titration method was applied for gathering experimental data and determination of solution equilibrium constants. The ΔpK method was used for the determination of calcium and magnesium stability constants due to the low values which were predicted. A Debye–Huckel type equation, Specific Ion Interaction Theory, Pitzer and van’t Hoff equations were used for the modeling of ionic strength and temperature effects. Two species, ML and MHL, were found according to the best model for Ca2+ and Mg2+. Both protonation processes are exothermic based on the enthalpy values at 298.15 K and infinite dilution. A case study has been performed taking into account the speciation of GP in seawater.

Vapor-Liquid Equilibrium Measurements of Polymeric Solutions – A Review

The nature of the molecule of the substance depends heavily on its physico-chemical properties. An accurate and reliable measurement of physical properties is therefore, essentially needed as a framework to gain a comprehensive understanding of the molecular behavior. Of these properties, saturated pressure is one of the most important thermophysical properties in the design of products, equipment, and processes in various chemical industries. In this review, various techniques that have been utilized in measuring the vapor-liquid equilibrium (VLE) for polymeric solutions are discussed.Keywords: VLE, polymer, measurements, pressure.

An environmental-friendly process for dissociating toxic substances and recovering valuable components from spent carbon cathode

Spent carbon cathode (SCC), a hazardous solid waste discharged from the aluminum electrolysis industry, has a serious environmental pollution risk. This study aims to explore an environmental friendly process for dissociating toxic substances and recovering valuable components from SCC. Parameters of molten salt-assisted roasting and water leaching were optimized. A possible dissociation mechanism of toxic substances was proposed. Results showed that 99.12% of cyanide was decomposed and 96.63% of fluoride was leached under optimal conditions. The recovery route of fluoride was designed according to the solution equilibrium chemical calculation and the difference in solubility and particle size between the recovered products. Exhaust gas with a high concentration of CO and CO2 was used for the carbonation of the leaching solution to recover cryolite. Effects of reaction conditions on precipitation mass and phase composition of recovered cryolite were investigated in detail. Characterization results indicated that the crystallinity and particle size of cryolite recovered under optimal conditions were extremely similar to those of commercial products. Finally, NaF and Na2CO3 were separated and recovered via evaporative crystallization combined with selective filtration. This proposed process with circular economy and green chemistry characteristics is expected to recover valuable components while minimizing environmental hazards of SCC.

Removal of Ni(II) ions from wastewater by raw and modified plant wastes as adsorbents: A review

Adsorption may be used to process significant metal particles in contaminated wastewater by various methods. The authors looked at various adsorbents for the expulsion of Ni(II) particles from an aquatic environment by different researchers. This paper aims to gather scattered open knowledge on a large variety of potentially persuasive adsorbents for the removal of Ni(II) particles. The present work on the usage of nickel by various natural/modified adsorbents was studied profoundly, for example, natural/modified agricultural waste, agricultural activated carbon, algae, fungal and, aquatic plant biomasses. This performance was assessed for removal efficiency and the sorbent capacity of used natural/waste materials in the system processes. Isotherm and kinetic studies results were obtained from pH solution equilibrium contact time, adsorbent dose, initial metal concentration, and temperature of various adsorbents toward the Ni(II) particles to be examined. A documented analysis of reputed published papers revealed that industrial solid waste products, natural materials, and biosorbents have extraordinary Ni (II) adsorption ability from wastewater.

Influence of parent material on organic phosphorus fractions in vineyard soils in Santa Catarina, Brazil

Phosphorus (P) is an essential element for vineyard productivity. This study assessed the influence of parent material on organic P fractions in vineyard soils of basaltic and rhyodacitic origin. The experiment was conducted in four municipalities located in mountainous regions in Santa Catarina, Brazil: Urubici, São Joaquim, Campos Novos, and Água Doce. Disturbed soil samples were collected between grapevine rows at depths of 0.00–0.05, 0.05–0.10, 0.10–0.20, and 0.20–0.40 m. Soil chemical attributes (pH in H2O, Ca2+, Mg2+, Al3+, P, K+, and H + Al), total organic carbon (TOC), available and residual P, labile P (extracted with sodium bicarbonate), moderately labile P (extracted with sulfuric acid), and moderately resistant P (extracted with sodium hydroxide) were determined. Soil parent material influenced the dynamics of phosphorus in vineyard soils. Both P forms (available and solution equilibrium P) and P organic fractions (labile, moderately labile, and moderately resistant P), are affected by the parent material. Basaltic soils had higher TOC, available and residual P, and moderately labile and moderately resistant P, whereas rhyodacitic soils showed higher labile P. The high levels of moderately labile and moderately resistant P fractions in basaltic soil were attributed to its high TOC, available P, and residual P contents. Parent material was found to influence organic P fractions in vineyard soils.

GFP fluorescence tagging alters dynamin-related protein\xa01 oligomerization dynamics and creates disassembly-refractory puncta to mediate mitochondrial fission

Green fluorescent protein (GFP)-tagging is the prevalent strategy to monitor protein dynamics in living cells. However, the consequences of appending the bulky GFP moiety to the protein of interest are rarely investigated. Here, using a powerful combination of quantitative fluorescence spectroscopic and imaging techniques, we have examined the oligomerization dynamics of the GFP-tagged mitochondrial fission GTPase dynamin-related protein 1 (Drp1) both in vitro and in vivo. We find that GFP-tagged Drp1 exhibits impaired oligomerization equilibria in solution that corresponds to a greatly diminished cooperative GTPase activity in comparison to native Drp1. Consequently, GFP-tagged Drp1 constitutes aberrantly stable, GTP-resistant supramolecular assemblies both in vitro and in vivo, neither of which reflects a more dynamic native Drp1 oligomerization state. Indeed, GFP-tagged Drp1 is detected more frequently per unit length over mitochondria in Drp1-null mouse embryonic fibroblasts (MEFs) compared to wild-type (wt) MEFs, indicating that the drastically reduced GTP turnover restricts oligomer disassembly from the mitochondrial surface relative to mixed oligomers comprising native and GFP-tagged Drp1. Yet, GFP-tagged Drp1 retains the capacity to mediate membrane constriction in vitro and mitochondrial division in vivo. These findings suggest that instead of robust assembly-disassembly dynamics, persistent Drp1 higher-order oligomerization over membranes is sufficient for mitochondrial fission.

Tautomeric Equilibrium in Condensed Phases.

We present an ab initio molecular dynamics (MD) investigation of the tautomeric equilibrium for the aqueous solutions of glycine and acetone under realistic experimental conditions. Metadynamics is used to accelerate proton migration among tautomeric centers. Due to the formation of complex water-ion structures involved in the proton dynamics in the aqueous environment, standard enhanced sampling approaches may face severe limitations in providing a general description of the phenomenon. Recently, we have developed a set of collective variables (CVs) designed to study protons transfer reactions in complex condensed systems [Grifoni, E. Proc. Natl. Acad. Sci. U.S.A. 2019, 116, 4054 4057]. In this work, we applied this approach to study proton dissociation dynamics leading to tautomeric interconversion of biologically and chemically relevant prototypical systems, namely, glycine and acetone in water. Although relatively simple from a chemical point of view, the results show that even for these small systems, complex reaction pathways and nontrivial conversion dynamics are observed. The generality of our method allows obtaining these results without providing any prior information on the dissociation dynamics but only the atomic species that can exchange protons in the process. Our results agree with literature estimates and demonstrate the general applicability of this method in the study of tautomeric reactions.

A Photochemical/Thermal Switch Based on 4,4′‐Bis(benzimidazolio)stilbene: Synthesis and Supramolecular Properties.

Stilbene derivatives are well-recognised substructures of molecular switches based on photochemically and/or thermally induced (E)/(Z) isomerisation. We combined a stilbene motif with two benzimidazolium arms to prepare new sorts of supramolecular building blocks and examined their binding properties towards cucurbit[n]urils (n=7, 8) and cyclodextrins (β-CD, γ-CD) in water. Based on the 1 H NMR data and molecular dynamics simulations, we found that two distinct complexes with different stoichiometry, i. e., guest@β-CD and guest@β-CD2 , coexist in equilibrium in a water solution of the (Z)-stilbene-based guests. We also demonstrated that the bis(benzimidazolio)stilbene guests can be transformed from the (E) into the (Z) form via UV irradiation and back via thermal treatment in DMSO.

Pattern-free generation and quantummechanical scoring of ring-chain tautomers.

In contrast to the computational generation of conventional tautomers, the analogous operation that would produce ring-chain tautomers is rarely available in cheminformatics codes. This is partly due to the perceived unimportance of ring-chain tautomerism and partly because specialized algorithms are required to realize the non-local proton transfers that occur during ring-chain rearrangement. Nevertheless, for some types of organic compounds, including sugars, warfarin analogs, fluorescein dyes and some drug-like compounds, ring-chain tautomerism cannot be ignored. In this work, a novel ring-chain tautomer generation algorithm is presented. It differs from previously proposed solutions in that it does not rely on hard-coded patterns of proton migrations and bond rearrangements, and should therefore be more general and maintainable. We deploy this algorithm as part of a workflow which provides an automated solution for tautomer generation and scoring. The workflow identifies protonatable and deprotonatable sites in the molecule using a previously described approach based on rapid micro-pKa prediction. These data are used to distribute the active protons among the protonatable sites exhaustively, at which point alternate resonance structures are considered to obtain pairs of atoms with opposite formal charge. These pairs are connected with a single bond and a 3D undistorted geometry is generated. The scoring of the generated tautomers is performed with a subsequent density functional theory calculation employing an implicit solvent model. We demonstrate the performance of our workflow on several types of organic molecules known to exist in ring-chain tautomeric equilibria in solution. In particular, we show that some ring-chain tautomers not found using previously published algorithms are successfully located by ours.

Kinetic and thermodynamic studies on the adsorption of Cu2+ ions from aqueous solution by using agricultural waste-derived biochars

AbstractIn this study, it was aimed to investigate the adsorption properties of the biochars obtained by pyrolysis of hazelnut and walnut shells for removal of copper ions from aqueous solutions. The characterization of raw biomasses and also biochars were performed using TGA-DTG, FT-IR, BET, SEM, partial and elemental analysis techniques. The optimum conditions were determined by investigating the effect of adsorption parameters (initial concentration, temperature, adsorbent amount, pH, contact time and mixing speed) for efficient removal of copper ions from aqueous solution by batch adsorption experiments carried out under different conditions. The highest adsorption efficiencies were recorded as 82 and 86% respectively for hazelnut and walnut shell biochars at pH 4, Co = 15 ppm, adsorbent dosage = 3 g/L and mixing speed = 600 rpm. Experimental results showed that the adsorption efficiency for copper ions increased with the increase of temperature (T = 45 °C) in studies only using biochar obtained from hazelnut shell. While the time of equilibrium in the aqueous solution containing copper ions was determined to be 75 min for walnut shell char, this duration was 30 min for hazelnut shell char. The experimental results were investigated in terms of Langmuir, Freundlich and Temkin isotherm models. Together with the calculated thermodynamic parameters, the adsorption mechanism was explained. In order to determine the kinetic model of the adsorption process, the experimental data were applied to pseudo first-order, pseudo second-order and intra-particle diffusion models, and the model constants were investigated.

Synthesis, Spectroscopic, and Structural Characterization of Organyl Disulfanides and a Tetrasulfanide.

Various room-temperature-stable monoorganylpolysulfanides of the form [X][RSn] (X = [PPh4]+, [PNP]+, [NEt4]+; R = Ph, t-Bu, n ≥ 2) were synthesized in a simple and versatile one-step process starting from sodium thiolates and elemental sulfur. The compounds were characterized by X-ray crystal structure analysis, NMR spectroscopy, microelemental analysis, and electrospray mass ionization spectrometry including collision-induced dissociation experiments. While these salts are well-defined species as crystals, they undergo complex equilibria in solution. In one case, compounds ranging from n = 1-8 have been observed in solution. Structural features, dynamics in solution, as well as thermochromic properties of one of the compounds, [PPh4][PhS2], are investigated in detail by temperature- and pressure-dependent X-ray crystal structure analysis. The experimental data are complemented by periodic boundary density functional theory calculations on the crystal structures, as well as energy decomposition analyses.

New palladium (II) complexes with 1‐phenyl‐1H‐tetrazole‐5‐thiol and diphosphine Synthesis, characterization, biological, theoretical calculations and molecular docking studies

This paper reports the syntheses and spectral investigations of the new complexes [Pd(k1‐S‐ptt)2(k2‐dppmS2)] (1), [Pd(k1‐S‐ptt)2(k2‐dppp)] (2a), [Pd(k1‐N‐ptt)2(k2‐dppp)] (2b), [Pd(k1‐S‐ptt)2(k2‐dpppS2)] (3), [Pd(k1‐S‐ptt)2(k2‐dppb)] (4), [Pd(k1‐S‐ptt)2(k2‐dppf)] (5a) and [Pd(k1‐N‐ptt)2(k2‐dppf)] (5b), derived from 1‐phenyl‐5‐thiol‐1H‐tetrazole (Hptt) and diphosphine (dppmS2, dppp, dpppS2, dppb and dppf) as co‐ligand. The Hptt ligand acts as monodentate through the thiolato sulfur atom in complexes 1, 3 and 4. While in complexes 2 and 5, the Hptt ligand also acts as monodentate through the nitrogen of heterocyclic ring, or sulfur of thiol group after deprotonation, as two linkage isomers. Theoretical calculations on the all complexes were performed, isomers based on 2a, 2b and 5a, 5b reveal that each pair of isomers is isoenergetic. For the 2a and 2b complexes the energy difference was 19.92 kcal mol−1, while for the 5a and 5b complexes the difference was 11.78 kcal mol−1. These differences are relatively small and suggest that the linkage isomers may be in equilibrium in solution. The reasons for the adoption of these different coordination modes are not clear but steric factors are likely to be a major contributory factor. Further, in vitro anti‐bacterial activity and molecular docking analysis has been carried out to study the activity of the compound.

Facile Synthesis, Characterization, and Adsorption Insights of Lanthanum Oxide Nanorods

This study synthesized lanthanum oxide (La2O3) nanorods to develop a practical approach for the removal of arsenic from groundwater. La2O3 nanorods were synthesized by a simple hydrothermal process followed by calcination at 500 °C and were characterized by spectroscopic and microscopic techniques. To evaluate the adsorption mechanism of La2O3 nanorods, adsorption parameters including solution pH, temperature, equilibrium isotherms, and kinetics for arsenic were studied. The results suggested that the arsenic uptake was a rate-limiting, monolayer adsorption interaction on the La2O3 nanorods homogeneous surface. In addition, it was found that the adsorptive removal behavior of La2O3 for As(V) was sensitive to the initial pH and temperature, and the maximum uptake amount of as prepared La2O3 was found to be 260.56 mg/g of As(V) at pH 6.0 and 25 °C. Furthermore, the uptake capacity of La2O3 nanorods for As(V) increased with temperature. The resultant thermodynamic parameters (ΔG0, ΔH0, and ΔS0) suggested an endothermic adsorption of As(V) on La2O3. The adsorption capacity of La2O3 was higher than that of several reported nanocomposites, suggesting its practical applicability and novelty for As-contaminated wastewater treatment.

Phosphorus-rich biochar produced through bean-worm skin waste pyrolysis enhances the adsorption of aqueous lead

In China, more than 10,000 tons of bean-worm, which is rich in protein (68.5%) and essential amino acids (52.8%), is consumed annually. Thus, a large amount of bean-worm skin waste is generated, and is often indiscriminately disposed of, potentially causing environment problems. In this study, bean-worm skin (BWS) waste was pyrolyzed at 500 °C to produce biochar (BWS-BC), and the surface properties of BWS and BWS-BC were characterized using various spectroscopic techniques. Pb(II) adsorption properties of BWS and the corresponding biochar as a function of solution pH, contact time, and equilibrium concentration of Pb(II) were examined using adsorption isotherm, kinetics and thermodynamics studies. The maximum Pb(II) adsorption capacities based on the Langmuir isotherm model were calculated as 45 and 62 mg g−1 for BWS and BWS-BC, respectively, which were comparable to the values obtained for biochars derived from other agro-wastes. The adsorption feasibility, favorability and spontaneity of Pb(II), as derived from the thermodynamic parameters, indicated that chemisorption and precipitation (e.g., hydroxypyromorphite) were the main adsorption mechanism in case of BWS and BWS-BC, respectively. Thus, conversion of BWS to biochar for Pb(II) adsorption can be considered as a feasible, promising and high value-added approach for BWS recycling.

Chemical Soil-Biological Engineering Theoretical Foundations, Technical Means, and Technology for Safe Intrasoil Waste Recycling and Long-Term Higher Soil Productivity

The amelioration and remediation technology was developed on the basis of research of phosphogypsum and utilization in the Haplic Chernozem of South-European facies (Rostov Region). Phosphogypsum was utilized via dispersed application into a soil layer of 20–45 cm with intrasoil milling of this layer. The phosphogypsum utilization doses were 0, 10, 20, and 40 t ha–1. The Pb analytical content in soil solution was studied in the model experiment. The soil solution Pb thermodynamic forms were calculated. The mathematical chemical–thermodynamic model ION-2 was developed to calculate the real soil solution (water extract) calcium-carbonate equilibrium (CCE) ion forms, considering the ion pair association. The associated ion pairs CaCO30, CaSO40, MgCO30, MgSO40, CaHCO3+, MgHCO3+, NaCO3–, NaSO4–, CaOH+, and MgOH+ were accounted for in soil solution equilibrium macroion form calculation. The procedure for the microelement ion [including heavy metals (HMs)] equilibrium concentration in the soil solution coefficient kas calculation was proposed to account for the real soil solution CCE, macroions, and HM (including Pb) association. The Pb2+ ion in soil solution was mostly bound to associates PbOH+, Pb(OH)20, PbCO30, Pb(CO3)22–, and PbHCO3+. The calculation of CCE and ion association in soil solution revealed 14.5–21.5 times HM passivation compared to HM water-soluble values. The calculated HM activity in the soil solution in the example of the Pb2+ ion was less than 4% after phosphogypsum application in the target amelioration layer of 20–45 cm. The studied phosphogypsum doses were substantiated as environmentally safe. This was because the real soil solution CCE provided HM ion form association and consequent passivation. The dry steppe soil remediation after phosphogypsum application was justified as highly probable. The intrasoil milling chemical soil-biological engineering technology was developed for simultaneous soil amelioration and remediation on the basis of the biogeosystem technique (BGT*) transcendental methodology. The BGT*-based technology was tested in the long-term field experiments and is capable of ensuring the priority geophysical micro- and macroaggregate structure via intrasoil milling and mixing of soil illuvial and transitional horizons. This helps synthesize soil multilevel architecture, providing intrasoil-dispersed environmentally safe recycling of wastes of different origin. Addressing the environment safety concerns, a new decision of the intrasoil milling device was proposed for phosphogypsum and other substance application to soil.