Adsorption-desorption Capacity Research Articles

Zeolite enhances leaf photosynthesis and fruit quality in tomato through greenhouse CO2 enrichment

Elevated CO2 concentration has been widely acknowledged as a leading factor to global climate change, while deficient CO2 serves as a crucial limiting factor in modern greenhouse production. Harnessing the existing excessive CO2 to promote agriculture production is significant but filled with challenges. To this end, we proposed a concentration gradient-regulated CO2 enrichment system for capturing CO2 into greenhouses, which requires suitable CO2 sorbents with sufficient CO2 desorption capacity and high hydrophobicity at ambient temperature and pressure. Zeolites with different framework types and cations were detected by CO2 desorption and cyclic stability test under simulated agricultural production conditions. The results indicate that larger pore volume cooperated with higher Si/Al ratio and weaker alkali cations may be critical determinants for balancing high CO2 adsorption-desorption capacities and hydrophobicity in crop-cultivated environments. H-SSZ-13 zeolite is identified as the potential sorbents and exhibits exceptional CO2 release abilities and cyclic stability in tomato-grown environment. Long-term application of H-SSZ-13 zeolite to tomato plants significantly stimulated photosynthetic processes, particularly the Calvin-Benson cycle, culminating in notable improvements in plant growth, fruit yield and quality. This investigation provides a promising solution to develop a carbon-neutral CO2 enrichment system for both sustainable and productive greenhouse production.

SO2 capture and detection with carbon microfibers (CMFs) synthesised from polyacrylonitrile.

SO2 emissions not only affect local air quality but can also contribute to other environmental issues. Developing low-cost and robust adsorbents with high uptake and selectivity is needed to reduce SO2 emissions. Here, we show the SO2 adsorption-desorption capacity of carbon microfibers (CMFs) at 298 K. CMFs showed a reversible SO2 uptake capacity (5 mmol g-1), cyclability over ten adsorption cycles with fast kinetics and good selectivity towards SO2/CO2 at low-pressure values. Additionally, CMFs' photoluminescence response to SO2 and CO2 was evaluated.

Resolving Molecular Size and Homologues with a Self-Assembled Metal–Organic Framework Photonic Crystal Detector

Traditional environmental photonic sensing based on the balanced reflection of a photonic structure can hardly be applied to distinguish molecular size and homologues, since the refractive index change introduced by these analytes can be too similar to be unambiguously distinguished. Here, a sensing method based on the pore size selectivity and organics adsorption–desorption capacity of self-assembled ZIF-8 photonics crystal is demonstrated, which can tell apart different molecular sizes, homologues, and organics with similar structures and physical properties. Specificity is improved by the inherent relationships between the pore size of ZIF-8 metal–organic frameworks and the associated molecular diffusion rates in the pores, so that the combination of the observed peak shift and recovery time are unique to each analyte. Using this method, selective detection of molecular size is also demonstrated in the case of linear vs cyclic molecules, since only the former can penetrate inside the ZIF-8 pores to induce a large wavelength shift. The reflection peak shift caused by the linear molecules was found to be about 30–40 nm, an order of magnitude larger compared to those for the cyclic molecules. A relationship between the diffusion rate of linear molecules in ZIF-8 pore and the recovery time of photonic crystal reflective peak is further established, linking the recovery time and the linear molecular diffusion coefficient. Finally, different linear molecules are identified by their associated recovery time to detect homologues or organics with similar refractive index.

Modulating the electronic structures derived by neighbouring hetero-diatomic FeCoN6-Gra for prominent electrocatalysis of arsenious acid

Single atom catalysts (SACs) have been widely studied in the field of electrocatalytic reduction, but in the complex multi-step proton-electron reactions, the metal active site is easy to be weakened or even poisoned. Therefore, how to improve the adsorption-desorption capacity and rapid surface reaction to obtain superior electrocatalytic performance remains a great challenge. We indicate the electron synergism of neighbouring Fe and Co diatoms on graphene (FeCoN6-Gra) to promote the electrocatalytic reduction of arsenious acid (As(III)), which is superior to single-atomic catalysts containing only Fe or Co. It is found that the new electron allocation mechanism associated with the injection of Co is beneficial to trigger the two-site adsorption and effectively regulate electron transport between surface sites and As(III). Moreover, the dynamic migration of As(III) driven by Co atom during the reduction process is emphasized, which contributes to break the As-O bond, thus achieving efficient catalysis of the diatomic model.

Magnetic-field-regulated Ni-Fe-Mo ternary alloy electrocatalysts with enduring spin polarization enhanced oxygen evolution reaction

The oxygen evolution reaction (OER) constrains the efficiency of water splitting. The catalytic activity of electrocatalysts is mostly determined by the electronic structure, which is expressed as the electron transfer property and the reactant adsorption–desorption capacity. Ferromagnetic electrocatalysts exhibit promising applications in OER. However, an external magnetic field is indispensable for the electron spin polarization of ferromagnetic materials. Here, Ni-Fe-Mo ternary alloy nanowire electrocatalysts were prepared via a magnetic field-assisted self-assembly method in an aqueous-solution system at a mild temperature (65 °C). These Ni-Fe-Mo ternary alloy electrodes feature a spin polarization-dependent OER catalytic performance, which is attributed to ferromagnetic regulation. Ni0.8Fe0.15Mo0.05 possesses the maximum ferromagnetism compared to other electrodes (Ni0.8Mo0.2 and Ni0.8Fe0.2) and improved substantially OER activity. The regulated OER activity is assigned to the favorable adsorption of oxygen-containing intermediates (OH*) due to Ni-Fe-Mo composition-dependent, and the accelerated kinetics of OER with enduring spin polarization. The Ni-Fe-Mo ternary alloy nanowires with higher magnetic properties contribute to in situ spin polarization at the surface. This magnetic field-assisted synthesis approach provides a new strategy to realize electrodes with enduring spin polarized.

Porous bimetallic cobalt-iron phosphide nanofoam for efficient and stable oxygen evolution catalysis

Developing oxygen evolution reaction (OER) catalysts with high activity and long-term stability is critical to achieving efficient hydrogen production from water electrolysis. Herein, a porous bimetallic cobalt-iron phosphide (CoFe-P) nanofoam is synthesized via a novel one-pot glucose-blowing followed by oxidization and then phosphidization process. The CoFe-P nanofoam presents a porous nanostructure which contributes to contact with electrolytes and release of generated gas during electrocatalytic reactions. As OER catalysts in alkaline, the bimetallic porous CoFe-P nanofoam exhibit a lower overpotential (258 mV@10 mA cm−2) as well as outstanding stability (70 h@100 mA cm−2), which surpasses the RuO2 and is comparable to many high-performance Co and Fe-based catalysts. It is demonstrated that the surface of CoFe-P undergo a reconstruction process and form new high active (CoxFe1−x)OOH. Density functional theory (DFT) calculations reveal that the elevated activity is caused by the bimetal Co and Fe optimizing the d-band center (Ed) energy levels and thus balancing the adsorption–desorption capacities for OER intermediates. This work through constructing porous bimetallic nanofoam offers a feasible strategy to facilitate the reaction activity and prolong the long-term stability of OER.

Effect of firing temperature on humidity self-regulation functionality in a ceramic tile composition

The effect of sintering temperature on the humidity regulating capacity of a ceramic composition based on the mineral gibbsite has been studied. The humidity self-regulation functionality is due to the presence of mesopores in the material.In this work, it has been found that the adsorption-desorption capacity decreases drastically with sintering temperature, preserving a certain regulating activity up to temperatures as high as 1200 °C. The variation of the regulating capacity with temperature is consistent with the transformation of gibbsite from transition alumina to alpha alumina, which leads to a sharp decrease of the mesopore volume which can be determined from mercury porosimetry and especially nitrogen gas adsorption. The adsorption-desorption curves fit well to a pseudo-second order kinetic model and it is found that the equilibrium moisture is proportional to the specific surface area while the sorption rate constant depends on permeability for water diffusion through the porous structure.

Synthesis and characterization of pH-sensitive glucomannan-poly(acrylic acid) hydrogels for 5-aminosalicylic acid controlled delivery systems

In this study, glucomannan-poly(acrylic acid) hydrogels were synthesized under different conditions. The hydrogels consist of glucomannan and acrylic acid and are crosslinked by N,N-methylene-bis-(acrylamide). The structure and morphology of the hydrogels were investigated by using Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM). The swelling ratio, biodegradation and pH-sensitive properties, relationship between hydrogel swelling rate and 5-ASA adsorption-desorption capacity, influence of medium pH on 5-ASA desorption, and 5-ASA adsorption kinetics were studied. The swelling ratio of the synthesized hydrogel samples is 16.70–56.21 times. This ratio is low in the pH 1.0 media and increases significantly in the pH 7,4 media. The hydrogels are biodegradable in the presence of cellulase (400 U·mg–1) in a pH 7.4 phosphate buffer at 37 °C (69.8% after ten days; the cellulase concentration 1.5 g·L­–1). The hydrogels exhibit high adsorption and desorption capacities for 5-ASA. The adsorption kinetics follows the pseudo-first-order model. These hydrogels can be applied to smart drug delivery systems.

Promotional catalytic activity and reaction mechanism of Ag-modified Ce0.6Zr0.4O2 catalyst for catalytic oxidation of ammonia

Ce1-xZrxO2 composite oxides (molar, x = 0-1.0, interval of 0.2) were prepared by a cetyltrimethylammonium bromide-assisted precipitation method. The enhancement of silver-species modification and catalytic mechanism of adsorption-transformation-desorption process were investigated over the Ag-impregnated catalysts for low-temperature selective catalytic oxidation of ammonia (NH3-SCO). The optimal 5 wt.% Ag/Ce0.6Zr0.4O2 catalyst presented good NH3-SCO performance with >90% NH3 conversion at temperature (T) ≥ 250°C and 89% N2 selectivity. Despite the irregular block shape and underdeveloped specific surface area (∼60 m2/g), the naked and Ag-modified Ce0.6Zr0.4O2 solid solution still obtained highly dispersed distribution of surface elements analyzed by scanning electron microscope-energy dispersive spectrometer (SEM-EDS) (mapping), N2 adsorption-desorption test and X-ray diffraction (XRD). H2 temperature programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS) results indicated that Ag-modification enhanced the mobility and activation of oxygen-species leading to a promotion on CeO2 reducibility and synergistic Ag0/Ag+ and Ce4+/Ce3+ redox cycles. Besides, Ag+/Ag2O clusters could facilitate the formation of surface oxygen vacancies that was beneficial to the adsorption and activation of ammonia. NH3-temperature programmed desorption (NH3-TPD) showed more adsorption-desorption capacity to ammonia were provided by physical, weak- and medium-strong acid sites. Diffused reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments revealed the activation of ammonia might be the control step of NH3-SCO procedure, during which NH3 dehydrogenation derived from NHx-species and also internal selective catalytic reduction (i-SCR) reactions were proposed.

Sustainable electrochemical synthesis of natural starch-based biomass adsorbent with ultrahigh adsorption capacity for Cr(VI) and dyes removal

In order to achieve the recovery and utilization of gelatin (Gel) extracted from leather solid wastes, a renewable, eco-friendly and low-cost honeycomb biomass adsorbent based on oxidized corn starch-gelatin (OCS-G) was synthesized by one-pot reaction equipped with sustainable electrochemical synthesis system. The prepared biomass adsorbent was characterized using BET, FTIR, SEM, XRD, TGA, EDS, XPS, and other analysis technologies. The results demonstrated that the OCS-G has been successfully prepared, and the OCS-G’s maximum decomposition temperatures and specific surface area reached 366.4 °C and 30.48 m2 g−1, respectively. Then, the prepared OCS-G was used as a biomass absorbent to remove potassium dichromate (Cr(VI)), methylene blue (MB) and methyl orange (MO) from aqueous solutions. The effects of initial concentration (C0), adsorption time, and pH on the Cr(VI), MB and MO adsorption were investigated. The results revealed that the OCS-G showed ultrahigh adsorption properties for Cr(VI) (581.4 mg g−1), MB (1551.5 mg g−1) and MO (1107.2 mg g−1). The adsorption process of the OCS-G on Cr(VI), MB and MO followed the pseudo-second-order and the Langmuir adsorption model. Meanwhile, according to the desorption/regeneration experiments, the OCS-G with high specific surface area had good adsorption–desorption capacity and reusability. As a renewable, eco-friendly and low-cost biomass adsorbent with ultrahigh adsorption capacity, the OCS-G can be effectively used for wastewater treatment.

SO2 capture and detection using a Cu(II)-metal-organic polyhedron.

The SO2 adsorption-desorption capacity at room temperature and 1 bar of the metal-organic polyhedron MOP-CDC was investigated. In addition, the qualitative solid-state absorption-emission properties of this material (before and after SO2 exposure) were measured and tested, and it demonstrated remarkable capability for SO2 detection. Our results represent the first example of fluorimetric SO2 detection in a MOP.

Facile sol-gel synthesis of calcium oxide nanoparticles for effective removal of Ni(II) from aqueous solution

ABSTRACT In this study, nanoparticles of calcium oxide (CaO-NPs) were prepared via the sol-gel technique and introduced as a highly efficient adsorbent for removing Ni(II) from aqueous media. The prepared adsorbent was characterised via SEM, TEM, FTIR, XRD, and TGA. The pHzpc and surface area were also determined. XRD pattern exposed a polycrystalline nature of the adsorbent. SEM analysis showed that the adsorbent possesses enhanced surface porosity highlighting its potential capacity for adsorption. TEM analysis confirmed the crystallisation of adsorbent with a simple cubic structure. The FTIR spectrum displayed that the adsorbent surface comprises mostly (–OH and C=O) groups which are principally accountable for the adsorption of Ni(II). A series of batch adsorption experiments were done to study the effect of several parameters as pH, adsorbent dose, time of contact, initial concentration of adsorbate, temperature, ionic strength, and presence of interfering ions on the removal of Ni(II) ions from aqueous solutions using CaO-NPs. Maximum removal was obtained with 200 mg of adsorbent after 90 min contact time at pH 7 and 25°C as optimal conditions. The adsorption process was fitted well with Langmuir isotherm model and pseudo-second-order kinetic model, showing that the adsorption of Ni(II) ions on CaO-NPs was monolayer coverage with 166.67 mg/g capacity of adsorption. Thermodynamic studies revealed a spontaneous and endothermic adsorption process. The regeneration study using Na2EDTA indicated that the prepared adsorbent has a high renewal potential without notable loss in its performance. Moreover, the prepared adsorbent proved its good applicability and performance by successful application of the suggested procedure for the recovery of Ni(II) added to some real water samples. Accordingly, the obtained results showed that CaO-NPs can rapidly and efficiently remove Ni(II) from aqueous solutions. Also, CaO-NPs adsorbent is eco-friendly, easy to produce, cost-effective, non-toxic, and with good adsorption-desorption capacity. Therefore, this study will contribute to ecological cleaning and wastewater treatment.

Pd Nanoparticles Coupled to NiMoO4-C Nanorods for Enhanced Electrocatalytic Ethanol Oxidation.

The interfacial interaction including chemical bonding or electron transfer and even physisorption in composite electrocatalysts has a considerable effect on electrocatalytic oxidation reaction. Herein, we report a tremendously enhanced catalytic activity and excellent durability for the ethanol electro-oxidation reaction in NiMoO4-C-supported Pd composites (Pd/NiMoO4-C) compared to the commercial Pd/C (10%) catalyst. The X-ray powder diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy measurements disclose that the strong electron transfer between NiMoO4 nanorods and Pd nanoparticles likely induces the formation of more electrochemical active centers and improves the adsorption-desorption capacity of reactants and corresponding intermediates. In addition, the Pd/NiMoO4-C composite exhibits superior specific activity for ethanol oxidation compared to the Pd/NiMoO4 catalyst with physically incorporated carbon black, which further reveals that the stronger anchoring effect between Pd and C and higher electrical conductivity in Pd/NiMoO4-C composites are also conducive to promote the ethanol oxidation reaction. These discoveries provide an effective and simple method for the design of advanced electrocatalysts and provide more insights into optimizing the electronic interaction between the catalyst and support in general.

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.

Adsorption performance of activated carbon synthesis by ZnCl2, KOH, H3PO4 with different activation temperatures from mixed fruit seeds

ABSTRACT In this study, new activated carbons (ACs) were synthesized from a mixture of lemon and orange seeds (LOS) for toxic metal removal from aqueous solutions. Adsorbents have been produced by chemical activation with different activation agents (with H3PO4, ZnCl2 and KOH) and activation temperature (600°C, 700°C, 800°C). The elemental analysis, FT-IR, XRD and SEM analyses were performed to determine the characterization of the ACs. A series of batch adsorption experiments were done to research the influence of various parameters such as pH, adsorbent dosage, contact time, temperature, the complexing agents on the toxic metal ions (Cu(II), Cr(III) and Ni(II)) removal capacity of ACs. Adsorption equilibration time was 60 min, the adsorption capacity was 118.02 mg/g for Ni(II) ions, 146.03 mg/g for Cr(III) ions and 150.45 mg/g for Cu(II) ions. The adsorption of toxic metal ions was observed as a maximum at pH = 5 on AC-ZnCl2 (600°C) produced under N2 atmosphere. The adsorption process was fitted with a Langmuir isotherm model and a pseudo-second-order kinetic equation, showing the metal ions adsorption on AC was monolayer coverage. Thermodynamic studies show that the adsorption is endothermic and spontaneous in nature. AC produced from the LOS mixture has not been encountered in the literature. A simple, easy-to-apply method has been developed for a new adsorbent prepared from a mixture of LOS with environmentally friendly, easy to produce, reusable, cost-effective, non-toxic and with good adsorption-desorption capacity. Therefore, this study will contribute to the world economy in terms of environmental and wastewater cleaning.

Novel Porous Carbon Material for the Detection of Traces of Volatile Organic Compounds in Indoor Air.

A highly sensitive and selective silicon-based microanalytical prototype was used to identify a few ppb of volatile organic compounds (VOCs) in indoor air. Herein, a new nonactivated tannin-derived carbon synthesized by an environmentally friendly method, DM2C, a MIL-101(Cr) MOF, and a DaY zeolite were selected for the preconcentration of BTEX compounds (i.e., benzene, toluene, ethylbenzene, and xylenes). Integrating a small amount of these nanoporous solids inside a miniaturized preconcentration unit led to excellent preconcentration performance. By taking advantage of the high adsorption-desorption capacities of the DM2C adsorbent, concentrations as low as 23.5, 30.8, 16.7, 25, and 28.8 ppb of benzene, toluene, ethylbenzene, ortho- and para-xylene, respectively, were detected in a short analysis time (∼10 min) even in the presence of 60% relative humidity at 25 °C. The DM2C showed excellent stability over a period of 4 months and more than 500 tests, as well as repeatability, which makes it a very reliable adsorbent for the detection of trace VOCs in indoor air under realistic conditions in the presence of humidity.

Comparative Study of Zn2Ti3O8 and ZnTiO3 Photocatalytic Properties for Hydrogen Production

In the present work, zinc titanates (ZTO) as photocatalysts were synthesized, characterized, and evaluated aiming to study their photocatalytic properties for hydrogen production under visible-light irradiation and employing MeOH (methanol) and TEOA (Triethanolamine) as sacrificial agents. ZTO were synthesized by modified Pechini method. Characterization of materials consisted in TGA, XRD, TEM, EELS, BET, and UV–Vis. Surface interaction studies consisted of FT-IR spectroscopy and determination of MeOH and TEOA adsorption–desorption capacities on the ZTO by TGA. Zinc titanates were evaluated as photocatalyst for H2 production using an artificial visible light and monitored by GC. TGA results led to establish calcination temperatures of 550 °C (Zn2Ti3O8) and 700 °C (ZnTiO3) to reach their crystalline phases. XRD analysis of sample cds-ZTO found cubic Zn2Ti3O8 and traces of the ZnO crystalline phase, while p-ZTO exhibited a mixture of cubic and hexagonal ZnTiO3 crystalline phases. Surface area for cds-ZTO was 88 m2/g, while ZnTiO3 had 13 m2/g. Photocatalytic H2 production for cds-ZTO and p-ZTO using TEOA as sacrificial agent showed the highest photocatalytic activities generating 548 and 441 µmolH2/h.gcat. TEOA adsorption–desorption capacity was found superior on cds-ZTO and p-ZTO than that for MeOH on both samples.

Multi-walled carbon nanotubes modified with iron oxide and manganese dioxide (MWCNTs-Fe3O4−MnO2) as a novel adsorbent for the determination of BPA

Multi-walled carbon nanotubes modified with iron oxide and manganese dioxide (MWCNTs-Fe3O4−MnO2) was synthesized by using iron oxide (magnetic agent) and manganese dioxide (surface enhancer agent) to further approach in a magnetic solid-phase extraction (MSPE) coupled with high performance liquid chromatography (HPLC) method for the determination of bisphenol A (BPA) in plastic bottled drink samples. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX), Fourier-transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), and BET surface area measurement (BET) were used to characterized the materials. MWCNTs-Fe3O4MnO2 are more effective for BPA adsorption than other materials which compared in this study. The binding performances of sorbent were evaluated by static and kinetic adsorption experiments. The data were well fitted to the Langmuir isotherm model and pseudo-second-order model, which the maximum adsorption capacity (qmax) and the contact time of initial concentrations to achieve equilibrium were found to be 132.9 mg g−1 and 150 min, respectively. After adsorption, MWCNTs-Fe3O4−MnO2 can be conveniently and quickly separated from the media by an external magnetic field, and adsorption-desorption capacity can remain at least 6 times of usage. Several parameters affecting the extraction efficiency were investigated. Under optimal conditions, the sorbent was successfully applied to MSPE followed by HPLC determination of BPA in real sample. The limit of detection (LOD) and limit of quantification (LOQ) values of MSPE-HPLC was 0.092 ng mL−1 and 0.167 ng mL−1, respectively. Spiked recoveries ranged from 94.9 to 103.4% for four real samples, with relative standard deviations of less than 6.7%. It was concluded that the synthesized MWCNTs-Fe3O4−MnO2 could be used as an efficient adsorbent for the determination of BPA in different plastic bottled drink samples.

Research of Scale Inhibitors in Downhole Equipment

The article is devoted to the problem of salt deposition in the West-Agan field of Western Siberia in various types of oil equipment during the extraction and transportation of petroleum products, as well as research and identification of the most effective inhibitors. The article is devoted to the problem of salt deposits in various types of oil equipment during the extraction and transportation of petroleum products. Salinity (scale) adversely affects the surface of pipes, the working parts of pumps, installations in contact with formation waters. When this occurs, the parts are jammed or break. The article describes methods for solving the problem of scaling using inhibitors. The possibility of SIs supplying in the reservoir with the aim of its subsequent removal in the composition of the reservoir fluid [1-4]. The data on the adsorption-desorption capacity of scale inhibitors on core samples were studied. Adsorption was tested under dynamic conditions on the FDS-210 filtration unit, filled with a core from the West Agan field. The core was saturated with a scale inhibitor through pumping a 1% solution through it. Desorption of inhibitors was modeled by passing the bottom-water model through the cell under the same pumping conditions. The results of processing the experimental data are obtained; the figures are shown in the form of the dependence of the Freundlich equation relating the magnitude of adsorption to the current concentration of inhibitors, as well as the profile of the removal of Descum-2 scale inhibitors H-3611-Descum-4 and OEDPK. The paper presents the results of modeling the removal of Descum-2 inhibitors of the mark H-3611-A, Descum-4 of the mark S and OEDFC in the form of a table. The use of the studied inhibitors on the West Agan field allows to increase the duration of the maintenance-free period of the well equipment.

Effect of organic matter on phosphorus adsorption and desorption in a black soil from Northeast China

Phosphorus (P) adsorption–desorption in soil is an important internal cycle related to soil fertility problems, as well as for determining the environmental fate of P. Soil organic matter (SOM) has been identified as an important factor affecting the adsorption–desorption of soil P through different mechanisms. In this study, humic acids were added to change the SOM content in black soil. Following an incubation period of 30 days, the changes in soil P adsorption–desorption capacity were studied. The results indicated that increased SOM led to increases in the soil available P and the P activation coefficient. All soil treatments fitted well with both Langmuir and Freundlich equations. The P adsorption and desorption characteristics were analyzed using the Langmuir equation as a local isotherm. The maximum adsorption capacity of P increased with the increase in SOM, but the P bonding energy and maximum buffering capacity first decreased, and then increased, with the lowest values obtained with a SOM content of 75.3 mg kg−1. Both the maximum desorption capacity of P and the ratio of soil P desorption showed a fluctuating trend, which were the greatest when the SOM content reached 75.3 g kg−1 in black soil, showing an improved ability to release P. Thus, the addition of organic matter could efficiently enhance P availability by reducing the strength of P adsorption and the maximum phosphate buffering capacity and increasing the desorption of P to some extent, with the greatest P availability obtained at a SOM content of 75.3 g kg−1.