Kinetics Of Leaching Research Articles

Kinetics and toxicological potential of heavy metal leaching from asphalt pavements

The leaching of heavy metals from asphalt pavement has attracted increasing attention due to its associated environmental risks. Comprehending the leaching process is crucial for ensuring the safe utilization of asphalt pavement. This study investigates heavy metal leaching kinetics from asphalt pavements using tank-leaching tests and dynamic simulations employing both first and second-order kinetic models. Furthermore, this study reveals the toxicological potential of heavy metal leaching from asphalt pavement by assessing its temporal metal accessibility based on the obtained kinetic attributes. Six distinct asphalt mixtures were prepared and tested, each exhibiting two different gradations. The findings demonstrated that both kinetic models effectively elucidated the leaching process. Notably, the relatively stable final leaching stages primarily adhered to first-order kinetics, while the second-order kinetics provided a superior description of the more intricate initial leaching stages. In terms of toxicological potential, the results indicated that recycled waste-incorporated asphalt pavements, specifically bottom ash-incorporated asphalt and asphalt rubber, exhibited excessive heavy metal leaching for varying durations, ranging from several days to months under specific conditions. This study has provided valuable insights into the metal leaching kinetics of asphalt pavements and their associated toxicological impact, significantly advancing the current understanding of the consequences of heavy metal leaching from asphalt pavements.

Vanadium Leaching Kinetics from Calcification-Roasted Vanadium Slag in Ammonium Carbonate

Vanadium Leaching Kinetics from Calcification-Roasted Vanadium Slag in Ammonium Carbonate

Kinetics of nitric acid leaching of bornite and chalcopyrite

The paper presents a study of the process of nitric acid dissolution of the natural minerals chalcopyrite and bornite. The influence of various parameters, including temperature, nitric acid concentration and particle sizes, on this process was examined. Based on the data obtained, the values of apparent activation energy (57.41 and 42.98 kJ/mol for chalcopyrite and bornite, respectively), empirical orders with respect to nitric acid (1.62 and 1.57 for chalcopyrite and bornite, respectively) and with respect to particle size (–1.16 and –2.53 for chalcopyrite and bornite, respectively) were calculated using the shrinking core model. Generalized kinetic equations for the dissolution process of both minerals were derived. Based on the calculations performed, it was suggested that the dissolution processes of chalcopyrite and bornite under these conditions are limited by internal diffusion.

Mechanism and kinetic study of rare earth extraction from allanite by direct acid leaching

Direct acid leaching was conducted to recover rare earth elements (REEs) from an allanite ore assaying 9,861.4 ppm of REEs. The effects of operational variables, such as acid type, sulfuric acid (H2SO4) concentration, temperature, solid/liquid (S/L) ratio, and particle size, on the total REE (TREE) recovery were systematically examined. The REE mineralogy and the involved leaching mechanisms were investigated by electron microscopy characterization and residue re-leaching tests. It was found that approximately 80% of REEs was extracted using 1 M H2SO4 at 75 °C for 2 h. Increasing temperature significantly improved the REE extraction, while changing acid type, H2SO4 concentration, and particle size did not cause noticeable influences on the extraction efficiency. The low fraction of Si leached (<4.0%) suggested that the extraction did not significantly alter the crystal structure of the dominant minerals. The leaching kinetics of REEs was fast within the first 10 min, followed by a much slower stage (i.e., 10–120 min). The kinetic modeling results showed that both stages were likely controlled by both chemical reaction and diffusion, implying a mixed control mechanism. The activation energies for REE leaching using 1 M H2SO4 were determined to be 20.3 kJ/mol for the 0-10 min stage and 10.8 kJ/mol for the 10-120 min stage. The residue re-leaching results suggested that the initial fast leaching kinetics was caused by the preferential dissolution of metamict allanite, while the following slower leaching stage was due to the dissolution of difficult-to-leach REE-bearing minerals, such as well-crystallized allanite.

Cellulase immobilization on zeolitic imidazolate frameworks for boosting cellulose hydrolysis at high solids loading

This study investigates the cellulase immobilization onto zeolitic imidazolate frameworks (ZIFs) to enable efficient cellulose hydrolysis at high solids loading. Different ZIF carriers (ZIF-8, ZIF-8-NH2, Fe3O4@ZIF-8, and Fe3O4@ZIF-8-NH2) were prepared and characterized. The resulting ZIF-immobilized cellulases were subsequently analyzed for their loading capacity and enzyme activity, as well as their biochemical properties such as temperature stability, pH stability, storage stability, enzyme leaching, and enzyme kinetics. Results revealed that the cellulase immobilized on Fe3O4@ZIF-8-NH2 exhibited an exceptional loading capacity of 359.89 mg/g and a relative enzyme activity of 69.39%. Remarkably, at a solid loading of 15% (w/w) and an enzyme dosage of 5 FPU/g cellulose, the Fe3O4@ZIF-8-NH2 immobilized cellulase demonstrated a 20.44% higher hydrolysis yield compared to the free cellulase. Furthermore, this immobilized enzyme system displayed robust reusability, retaining 71.03% of its initial activity even after 10 cycles of reuse. A proposed mechanism of enhanced enzymatic hydrolysis by ZIF-immobilized cellulases was also presented. These findings have significant implications for the future application of ZIF-immobilized cellulases in efficient and cost-effective lignocellulosic bioconversion.

Leaching kinetics and reactivity evaluation of fly ash based on the synergistic effect of alkali and sulfate

This work evaluates the reactivity of various minerals of fly ash based on the backscattered electron images analysis (BSE-IA) method and discusses the influencing factors and kinetics of Si and Al selective leaching of fly ash in alkali solution and alkali-sulfate composite solution, respectively. The relationships among the physicochemical properties, dissolution behavior, and reactivity of fly ash have been revealed. There are three typical phases in fly ash, namely the Si–Al phase, Ca–Si–Al phase, and Fe phase. The Ca–Si–Al phase is more soluble and preferentially participates in the reaction process than the other two phases. The dissolution process is greatly affected by temperature. Alkali and sulfate have a compound synergistic effect and SO42− further promotes the dissolution of Si and Al mainly by changing the gel property wrapped on the surface of fly ash particles. The leaching kinetics results indicate that the internal diffusion controls the reaction process. The research method and system in this work can be applied to other solid waste, providing reference significance for quickly exploring its reaction activity. Moreover, the synergistic effect of alkali and sulfate can be used to establish an alkali-sulfate composite cementitious system, guiding the application of fly ash as a supplementary cementitious material.

Oxidative leaching of rhenium from grinding waste of rhenium-containing superalloys

The study investigated the feasibility of oxidative leaching rhenium in the presence of hydrochloric acid from machining waste (grinding waste) derived from products made of ZhS-32VI, a nickel-based heat-resistant alloy containing rhenium. This was achieved through agitation leaching process. The grinding waste fraction size of –0.071 mm, which accounted for the highest yield (49.2 wt.%), was utilized in the experiments. The rhenium leaching process was conducted in two variations: in the first option, grinding waste was mixed with a hydrochloric acid solution at ~100 °C, followed by the addition of hydrogen peroxide to the leaching solution after it had cooled; in the second option, leaching was performed using a hydrochloric acid solution with the gradual addition of hydrogen peroxide solution. The highest degree of rhenium leaching (91.0 %) was achieved in the first option. In this case, the initial concentration of hydrochloric acid was 8 M, and the molar ratio of the added reagents was ν(HCl): ν(H2O2) = 2.7 : 1.0. The kinetics of nickel leaching using a 6 M hydrochloric acid solution at 70 °C, with a solid-to-liquid phase ratio of 1 g : 50 ml, was also examined. The analysis of the kinetic data, processed using the “contracting sphere,” Ginstling–Brounshtein, and Kazeev–Erofeev models, indicates that the nickel leaching process occurs within the kinetic region. Additionally, the kinetics of rhenium leaching from the solid residue obtained after the hydrochloric acid leaching of nickel from grinding waste was investigated. Employing the same kinetic models to analyze the data, it was determined that the limiting stage of this process involves the diffusion of hydrogen peroxide within the rhenium-containing solid residue.

Separation of La/Ce in rare earth polishing powder waste via Two-Stage hydrochloric acid leaching and corresponding leaching mechanism

Rare earth polishing powder waste (REPPW) usually contains lanthanum (La) and cerium (Ce) with content over 50 %, thus its recovery is important for the cyclic utilization of rare earth. In the traditional acid leaching process, La and Ce are simultaneously leached and required further separation. Based on their leaching behavior difference, a two-stage hydrochloric acid leaching process was proposed in this study to recover and primarily separate La and Ce in REPPW. With the optimal operation conditions, La enriched solution with a relative purity of 91.11 % and Ce enriched solution with a relative purity of 92.85 % were obtained and their recovery ratio were 59.47 and 85.15 %, respectively. After precipitation and calcination, products of La2O3 with purity of 83.67 % and CeO2 with purity of 93.38 % were obtained. Besides, individual leaching kinetics of La and Ce in low-acid leaching were studied using various shrinking core models. Based on the analysis of phase components and micromorphology evolution of REPPW during the leaching process, the leaching mechanism of REPPW was determined. Combined the leaching regularity with the fitting results, the leaching process of La was controlled by interfacial transfer and product layer diffusion, and the Ce was by product layer diffusion. The apparent activation energies of the LaOF and CeO2 leaching reactions were 89.97 kJ/mol and 79.03 kJ/mol, respectively.

Ultrasound-assisted extraction of Sn from tinplate scraps by alkaline leaching: Novel acoustoelectric synergy effect underlying intensifying mechanism

Clean and fast extraction of tin from the surface of tinplate scraps is of great significance for the efficient utilization of waste resources. However, the dense tin layer causes the low efficiency of conventional leaching process. To improve Sn leaching efficiency, the ultrasound technique was adopted to extract Sn from tinplate scraps by alkaline leaching in this study. In the NaOH-H2O2 leaching system, metallic tin and alloyed tin in Fe-Sn alloy located on the surface of tinplate scraps can be oxidized and transferred to soluble Na2SnO3, while the iron in Fe-Sn alloy was oxidized to oxides which were chemically inert in alkaline solution. The differences in chemical solubility of Sn and Fe, and solubleness of stannate and iron oxides gave rise to the selective separation of Sn from the tinplate scraps. The effects of the leaching parameters on the Sn leaching behaviors in conventional and ultrasound-assisted leaching processes were compared. The conventional leaching temperature and time were significantly reduced during the ultrasound-assisted leaching process. Almost all of Sn can be extracted after conventional leaching at 1 mol/L NaOH, temperature of 80 ℃ and time of 60 min, however the same Sn leaching effect can be achieved by ultrasound-assisted leaching at 60 ℃ for 30 min with ultrasound power of 60% (360 W). Sn leaching kinetics based on the plate model demonstrated the reaction rate constant of the ultrasound-assisted leaching was 70% higher than that of the conventional leaching. A novel acoustoelectric synergy effect underlying intensifying mechanism by ultrasound irradiation was proposed in this study. Eventually, this work provided a rapid and clean tin extraction method from tinplate scraps via the ultrasound-assisted alkaline leaching treatment.

Selective extraction of nickel and cobalt from disseminated sulfide flotation cleaner tailings using alkaline glycine-ammonia leaching solutions

Millions of tons of nickel-bearing tailings, derived from disseminated sulfide resources, has been or are being dumped as waste and the recovery of metals from these tailings is insignificant. There are no economic hydrometallurgical processes to recover valuable metals from such wastes due to their low metal recovery, their alkaline high-magnesium mineralisation, and high reagent requirement. This study presents a novel alkaline process of glycine leaching to extract nickel and cobalt from such tailings. The outcomes of the experimental tests of using an alkaline glycine-based lixiviant system to extract nickel and cobalt from a float tailing material containing 0.79 % Ni and 0.02 % Co respectively are presented in this study. A comparison between using ammonia and sodium hydroxide as pH modifiers was conducted and the leaching performance of glycine-ammonia has been found to be superior based on both metal extractions and leaching kinetics. The use of resin-in-leach (RIL) to recover Ni and Co from glycine-ammonia leaching solution enhanced Ni extraction by ∼ 10 %. Grinding of the float tailing sample to a P80 of 15 µm enhanced both Ni and Co extraction by 10–15 %. Increasing the temperature to 45 °C considerably enhanced the metal leaching at which the highest Ni and Co extractions were achieved at 88 % and 90 %, respectively. Controlling dissolved oxygen (DO) levels during the leaching significantly increased the leaching kinetics and decreased the leaching time from 48 to 24 h. QEMSCAN analysis confirmed the selectivity of the alkaline glycine-based system to leach Ni, Co and Cu over impurities such as Fe, Mn and Mg. Two conceptual block diagram flowsheets were proposed for Ni and Co extraction from the float tailings using an alkaline glycine-based leaching process, where the Ni in the original ore is mineralised in an ultramafic, highly disseminated form of pentlandite in a magnesium-rich alkaline gangue matrix.

Battery metal recycling by flash Joule heating.

The staggering accumulation of end-of-life lithium-ion batteries (LIBs) and the growing scarcity of battery metal sources have triggered an urgent call for an effective recycling strategy. However, it is challenging to reclaim these metals with both high efficiency and low environmental footprint. We use here a pulsed dc flash Joule heating (FJH) strategy that heats the black mass, the combined anode and cathode, to >2100 kelvin within seconds, leading to ~1000-fold increase in subsequent leaching kinetics. There are high recovery yields of all the battery metals, regardless of their chemistries, using even diluted acids like 0.01 M HCl, thereby lessening the secondary waste stream. The ultrafast high temperature achieves thermal decomposition of the passivated solid electrolyte interphase and valence state reduction of the hard-to-dissolve metal compounds while mitigating diffusional loss of volatile metals. Life cycle analysis versus present recycling methods shows that FJH significantly reduces the environmental footprint of spent LIB processing while turning it into an economically attractive process.

Hydrothermal Leaching Kinetics of Vanadium from an Iron Vanadate Mineral Using Oxalic Acid

Hydrothermal leaching vanadium using oxalic acid is a novel method reported recently to overcome the serious environmental problems caused by traditional extracting processes. In view of its promising application potential, the hydrothermal leaching kinetics of vanadium from a concentrate mainly composed of Fe3−xVxO4 mineral via oxalic acid were investigated in this study. Firstly, the effects of the temperature and concentration of oxalic acid on the leaching behavior of vanadium were studied by measuring the leaching efficiency of vanadium at various times. Then, by fitting the measured leaching efficiency data to the proposed kinetic model, the leaching mechanism was analyzed and the rate-controlling step of the leaching process, the apparent activation energy, and the order of the chemical reactions were determined. Finally, a kinetic model was proposed to describe the present investigated leaching process. Detailed results are as follows: (1) an interfacial chemical reaction was the rate-controlling step of the present hydrothermal leaching process within temperatures ranging from 363 to 403 K, and the leaching efficiency was less than 85%; (2) the apparent activation energy of the interfacial chemical reaction was 45.6 kJ/mol; (3) the order of the interfacial chemical reaction to the concentration of oxalic acid was around 1.66.

Impact of accelerated weathering on the leaching kinetics of stabiliser additives from microplastics

The release of additives from microplastics is known to harm organisms. In the environment, microplastics are exposed to weathering processes which are suspected to influence additive leaching kinetics, the extent and mechanism of which remain poorly understood. We examined the impact of weathering on stabiliser additive leaching kinetics using environmentally relevant accelerated weathering and leaching procedures. Nine binary polymer-additive formulations were specifically prepared, weathered, analysed, and evaluated for their leaching characteristics. Cumulative additive release (Ce) varied widely between formulations, ranging from 0.009 to 1162 µg/g. Values of Ce generally increased by polymer type in the order polyethylene terephthalate < polyamide 6 < polyethylene. The change in leaching kinetics after accelerated weathering was incongruous across the nine formulations, with a significant change in Ce only observed for three out of nine formulations. Physicochemical characterisation of the microplastics demonstrated that additive blooming was the primary mechanism influencing the leaching response to weathering. These findings highlight the dependency of additive fate on the polymer type, additive chemistry, and the extent of weathering exposure. This has significant implications for risk assessment and mitigation, where the general assumption that polymer weathering increases additive leaching may be too simplistic.

The accelerated recovery of silver using the nitrite-copper novel system: Development of the kinetic model

This research presents a systematic-kinetic analysis of silver leaching from pure metallic silver using the NO2-Cu2+ novel system, with the aim to maximize the silver recovery and decrease the massive consumption of reagents. The effect of pH, nitrite ions concentration, cupric ions concentration, temperature and stirring rate on silver leaching kinetics and recovery was evaluated. The thermodynamic and leaching results showed that a decrease of pH from 5.4 to 4.5 increases remarkably the silver leaching kinetics, while the parasite precipitation of copper hydroxysulfate species is inhibited. The silver leaching kinetics is also favored when nitrite and copper concentrations are increased up to 1.5 and 0.2 M, respectively. The fundamental kinetic analysis revealed that silver leaching mechanism from its metallic form with this system was incomplete and follows the next kinetic model: t = [ 10-0.52pH [NO2–]1.2 [Cu2+]0.522.63 × 109e-56,900/RT][ 1–3(1-x)2/3 + 2(1-x)], where the diffusion of fluid species through a non-conventional ash layer is the rate determining step of the leaching process. Finally, the dissolved silver can be easily recovered in its metallic form (high purity > 99%) using a simple cementation step, which permits the recycling of the leaching solution.

Innovative co-treatment technology for effective disposal of electrolytic manganese residue

Electrolytic manganese residue (EMR) stockpiles contain significant amounts of Mn2+ and NH4+-N which pose a risk of environmental pollution. For EMR safe disposal, an innovative approach is proposed that involves direct sodium silicate-sodium hydroxide (Na2SiO3–NaOH) collaborative technology. This approach utilises Na2SiO3 and NaOH as the solidifying agent and activator, respectively, to treat EMR without hazardous effects. The study also provides insights into the kinetics of Mn2+ leaching under the effect of Na2SiO3–NaOH. Leaching efficiency was determined by varying parameters such as stirring rate, reaction temperature, pH of the initial solution, Na2SiO3 concentration, and reaction time to investigate the efficacy of this method. The study indicates that the co-treatment technology of Na2SiO3–NaOH can achieve maximum solidification efficiencies of 99.7% and 98.2% for Mn2+ and NH4+-N, respectively. The process can successfully solidify Mn2+ by synthesising Mn(OH)2 and MnSiO3 in an alkaline environment under optimal conditions including stirring rate of 450 rpm, initial solution pH of 8, test temperature of 40 °C, test time of 420 min, and Na2SiO3 content of 5%. The findings of this study have confirmed that surface chemistry plays a vital role in regulating the test rate and the proposed equation accurately describes Mn2+ leaching kinetics. Overall, the co-treatment technology involving Na2SiO3–NaOH is a viable solution for EMR resource utilisation without compromising environmental safety. This method has the potential to be implemented for other waste streams with comparable compositions, ultimately promoting the sustainable management of waste.

Understanding CO2 mineralization and associated storage space changes in illite using molecular dynamics simulation and experiments

Clay minerals have the potential to capture anthropogenic CO2 emissions permanently and safely. Understanding the kinetics of cation leaching and carbonate formation, as well as changes in clay structure, has resource and environmental implications. However, metadynamics mechanism and relevant structural changes in representative clay minerals exposed to supercritical carbon dioxide (scCO2) are rarely studied in current research. In this work, ReaxFF molecular dynamics simulation in combination with scCO2‒H2O‒illite experiments at 10 MPa and 333 K were carried out to investigate the mechanisms of mineralization and structure alteration under geological conditions. The results show that interlayer K+ cations were leached out due to surface non-bridging oxygen protonation, subsequently bonding with HCO3− and forming K2CO3 molecules at the surface. Upon analyzing the chemical and structural results of experiments, carbonate precipitation and accumulation reduce storage space and modify the composition of illite, but the octahedral and tetrahedral sheets of the illite are structurally stable. The efficiency of mineralization is typically dominated by the exposed surface, where sufficient cations can be provided to enhance interactions at the illite/liquid interface. In comparison to a decrease in plane porosity of 27.3%, the mineralization degree with values between 15.22% and 33.12% is comparable and acceptable. These findings present a non-structural mechanism in clay minerals that might have critical influence on CO2 geo-sequestration in shale gas reservoirs.

The Effect of Process Conditions on Sulfuric Acid Leaching of Manganese Sludge.

Manganese sludge, an industrial waste product in the ferroalloy industry, contains various components and holds significant importance for sustainable development through its valorization. This study focuses on characterizing a manganese sludge and investigating its behavior during sulfuric acid leaching. The influence of process conditions, including temperature, acid concentration, liquid to solid ratio, and leaching duration, was examined. The results revealed that Mn, Zn, and K are the main leachable components, and their overall leaching rates increase with increasing temperature, liquid to solid ratio, and time. However, the acid concentration requires optimization. High leaching rates of 90% for Mn, 90% for Zn, and 100% for K were achieved. Moreover, it was found that Pb in the sludge is converted to sulfate during the leaching, which yields a sulfate concentrate rich in PbSO4. The leaching process for Mn and Zn species appears to follow a second or third order reaction, and the calculation of rate constants indicated that Mn leaching kinetics are two to five times higher than those for Zn. Thermodynamic calculations were employed to evaluate the main chemical reactions occurring during leaching.

Reductive leaching behaviour of manganese and cobalt phases in laterite and manganese ores

The reductive leaching behaviour of manganese (Mn) and cobalt (Co) in a laterite and a pure manganese ore was investigated by varying and optimising various leaching parameters for the recovery of Mn and Co. The effect of different reducing agents (FeSO4, Na2SO3), sulfuric acid concentration, reductant/ore mass ratio, leaching time, and reaction temperature on the dissolution of Mn and Co from the laterite and manganese ores were studied. Furthermore, the kinetics of Mn and Co leaching from laterite ore was studied. The Mn and Co recovery from both ores increased with increasing H2SO4 concentration, reductant/ore mass ratio, leaching time, and reaction temperature. Based on the manganese and cobalt extraction efficiency, FeSO4 was the best reductant among the two evaluated reductants. The optimum leaching of Mn and Co from the laterite ore occurred at a H2SO4 concentration of 0.51 M, a reductant/ore mass ratio of 2.7, a leaching time of 5 h, and a reaction temperature of 363.15 K. For the manganese ore the optimum leaching of these elements at the same temperature occurred at a higher H2SO4 concentration of 1.02 M, a reductant/ore mass ratio of 2.4, and a shorter leaching time of 2 h. The results from the optimization studies showed that the leaching trends of Mn and Co phases in the manganese ore are similar to those of the Mn and Co phases in the laterite ore. Moreover, Co was co-leached together with Mn suggesting a degree of correlation of cobalt to manganese mineral phases in both, the laterite, and the manganese ores. The kinetics of the reductive leaching of Mn and Co for the laterite ore could well be described by the Avrami model reflected by high correlation coefficient values of R2 > 0.95. The leaching of Mn and Co occurred rapidly at the initial leaching stage but gradually slowed down with prolonged leaching time. This was indicated by the modal parameter (n) values that were <1, at varying reaction temperatures. The experiments showed further that Mn and Co leaching in laterite ore is a diffusion-controlled reaction, which was indicated by the apparent activation energy of 11.7 kJ mol−1 and 11.1 kJ mol−1, respectively.

Impacts of Nanobubbles in Pore Water on Heavy Metal Pollutant Release from Contaminated Soil Columns.

This study investigated the release of heavy metals from polluted soil under the pore water flow containing nanobubbles (NBs) to simulate natural ebullition. Three types of NBs (CH4, H2, and CO2) were generated in water and characterized, including bubble size, zeta potential, liquid density, and tension. The flow rate used in column tests was optimized to achieve proper soil fluidization and metal desorption or release. The leachate chemistries were monitored to assess the effect of NBs on conductivity, pH, oxidation-reduction potential (ORP), and dissolved oxygen (DO). The results showed that NBs in the pore water flow were significantly more effective in releasing Pb compared to DI water, with CO2 NB water being the most effective and H2 NB water being the least effective. CO2 NB water was also used to rinse column soil contaminated with four different metals (Pb, Cu, Zn, and Cr), which exhibited different leaching kinetics. Moreover, a convective-dispersion-deposition equation (CDDE) model accurately simulated the leaching kinetics and explained the effects of NBs on the key parameters, such as the deposition rate coefficient (Kd), that affect the released metal transport. The findings could provide new insights into soil pollutant release under ebullition and soil remediation using water wash containing NBs.

Hydrothermal Leaching of Amylose from Native, Oxidized and Heat-Treated Starches

The kinetics of amylose leaching in hot, excess water from native, oxidized-by-potassium permanganate and heat-treated potato starch at temperatures of 62–90 °C was investigated in isothermal conditions. For the first time, it was proposed to describe the kinetic data by the Kroger–Ziegler equation. It was found that for native starch in the range of 62–70 °C, the activation energy of the amylose leaching process is 192.3 kJ/mol, and at a temperature of 80–90 °C, it decreases to 22 kJ/mol. Similar patterns were established for modified starches. In the kinetic mode, the activation energy was 102.5 kJ/mol for oxidized starch and 44.7 and 82.5 kJ/mol for heat-treated starches at a temperature of 135 °C for 2.5 and 5 h. In the diffusion mode, it was: 18.7 kJ/mol for oxidized and 16.2 and 18.9 kJ/mol for heat-treated starches for 2.5 and 5 h, respectively. It is shown that the consideration of amylose leaching as a heterogeneous pseudochemical process makes it possible to explain the change in the activation energy with increasing temperature by the transition of the leaching process from the kinetic to the diffusion mode. As such a pseudochemical process, it is proposed to consider the breaking of multiple hydrogen bonds between amylose macromolecules. The change in the activation energies of amylose extraction from modified starches is explained by the change in the degree of amylose polymerization. Thin-layer chromatography was used to compare the molecular weight distributions of the resulting modified amylose samples. FTIR spectroscopy and thermal methods of analysis were used to study the transformations of starch during heat treatment.