Adsorption Of Urea Research Articles

A gentle strategy to design amine-functionalized cellulose aerogel with tunable graft density for urea adsorption

The development of efficient adsorbent materials to remove urea from dialysate is an effective way to solve the bottleneck limiting the development of a wearable artificial kidney. Three methods were used to fabricate amine-functionalized cellulose aerogels aiming to screen for excellent structures favorable for urea adsorption. The influence of APTES addition on the structure and adsorption performance of the adsorption materials was investigated. The kinetics and thermodynamics of urea adsorption were evaluated, and adsorption mechanisms were also discussed. Results indicate that the material prepared by the gentle method was still able to maintain a large specific surface area, large pore volume and low crystallinity. Amine-functionalized cellulose aerogels retain the original hydroxyl adsorption sites, and the amino or silanol hydroxyl as new adsorption active sites are also introduced. Furthermore, proper APTES graft density plays a critical role in the urea adsorption. The equilibrium adsorption capacity of urea on HA-N-NCA-10 is increased by 156%.

MXene Nanosheets Functionalized with Cu Atoms for Urea Adsorption in Aqueous Media

MXene Nanosheets Functionalized with Cu Atoms for Urea Adsorption in Aqueous Media

Surface Engineering over Metal-Organic Framework Nanoarray to Realize Boosted and Sustained Urea Oxidation.

Facilitating C─N bond cleavage and promoting *COO desorption are essential yet challenging in urea oxidation reactions (UORs). Herein a novel interfacial coordination assembly protocol is established to modify the Co-phytate coordination complex on the Ni-based metal-organic framework (MOF) nanosheet array (CC/Ni-BDC@Co-PA) toward boosted and sustained UOR electrocatalysis. Comprehensive experimental and theoretical investigations unveil that surface Co-PA modification over Ni-BDC can manipulate the electronic state of Ni sites, and in situ evolved charge-redistributed surface can promote urea adsorption and the subsequent C─N bond cleavage. Impressively, Co-PA functionalization can impart a negatively charged catalyst surface with improved aerophobicity, not only weakening *COO adsorption and promoting CO2 departure, but also repelling CO3 2- approaching to deactivate Ni species, eventually alleviating CO2 poisoning and enhancing operational durability. Beyond that, improved hydrophilic and aerophobic characteristics would also contribute to better mass transfer kinetics. Consequently, CC/Ni-BDC@Co-PA exhibits prominent UOR performance with an ultralow potential of 1.300V versus RHE to attain 10mA cm-2 , a small Tafel slope of 45mV dec-1 , and strong durability, comparable to the best Ni-based electrocatalysts documented thus far. This work affords a novel paradigm to construct MOF-based materials for promoted and sustained UOR catalysis through elegant surface engineering based on a metal-PA complex.

Controlled synthesis of Mo and Ni codoped Co2P as environmentally friendly catalyst for urea, freshwater and seawater oxidation

The thermodynamic equilibrium potential of urea electrolysis (0.37 V) is lower than that of conventional water electrolysis (1.23 V). In this paper, the urea oxidation reaction performance of Ni-Co2P was regulated and enhanced by doping with different quantity of Mo. The growth characteristics of Mo doping Ni-Co2P were characterized and analyzed to reveal the electrochemical properties of the target catalysts, and finally the electrochemical performance tests were carried out. The experimental results show that MoNi-Co2P-0.12 electrode exhibits superior catalytic activity and durability at an iR compensation of 90. What is noteworthy is that at a current density of 10 mA cm−2, the MoNi-Co2P-0.12 catalyst showed an ultra-low voltage of 1.244 V with a small Tafel slope (79.52 mV dec−1) and stable catalysis for over 12 h, which is one of the best catalytic activities reported to date. Experimental results show that the increased activity of the MoNi-Co2P-0.12 catalyst is attributable to synergic catalytic effect of Mo and Co, electron regulation and exposure of more active sites. Density functional theory (DFT) calculations demonstrate the doping of Mo can increase the urea adsorption energy of the MoNi-Co2P material compared with the Ni-Co2P material, and is also conducive to the improvement of the conductivity of the MoNi-Co2P material. This work provides new research into the use of cheap transition metal catalysts as an alternative to precious metal catalysts for urea electrolysis.

Heterostructured NiSe2/MoSe2 electronic modulation for efficient electrocatalysis in urea assisted water splitting reaction

Efficient heterogeneous catalysts play a very important role in the value-updated green hydrogen production from urea-containing wastewater. Herein, NiSe2/MoSe2 heterostructured catalyst with optimized interfacial electron redistribution and urea adsorption energies via a strong built-in electric field was demonstrated effective for the urea-assisted water splitting reactions. Efficient catalytic performance was found on NiSe2/MoSe2 hybrid microsphere owing to the combined merits such as the unique structure features, the strong synergetic coupling effects, the increased active sites, and the high amount of intrinsic Ni3+ species. Excellent urea oxidation activity was found to drive 10 mA cm−2 at the potential of 1.33 V when loaded on the glassy carbon electrode, and a cell voltage of 1.47 V was required in the NiSe2/MoSe2||Pt/C urea-water electrolyzer to drive 10 mA cm−2, about 220 mV less than that of water electrolysis, indicating a less energy consumption technique during the electrolysis. The spectroscopic and theoretical analysis revealed the effective synergy of the Ni–Se bond and Mo–Se bond that would be promising for efficient catalyst system construction.

One-Step Hydrothermal Preparation of a Corncob-Derived Porous Adsorbent with High Adsorption Capacity for Urea in Wastewater: Sorption Experiments and Kinetics Study.

With rapid industrial development, the massive generation of nitrogenous wastewater poses a serious threat to both human beings and the ecosystem. Bio-based adsorbents are considered promising adsorption materials for many applications. However, their complex preparation procedures, large energy consumption, and difficulty of microstructure control hinder their practical applications. In this study, a new corncob-derived porous adsorbent (CPA) with excellent urea adsorption capacity in wastewater was prepared by the one-step hydrothermal process. The effects of the hydrothermal process conditions on the urea adsorption capacity of the CPA were evaluated and optimized using the response surface methodology, and a kinetic analysis of the CPA was also carried out. Our findings showed that the adsorption process of urea by the adsorbent followed the Langmuir isotherm and pseudo-second-order kinetic models. The high adsorption capacity for urea was attributed to the abundant porous structure and the hydrogen bonds formed between the adsorbent and the amine group in urea, which made it more conducive to the adsorption of urea. Therefore, we believe that CPA could be a promising adsorbent for urea removal in wastewater.

Modulation Strategies for the Preparation of High-Performance Catalysts for Urea Oxidation Reaction and Their Applications.

Compared with the traditional electrolysis of water to produce hydrogen, urea-assisted electrolysis of water to produce hydrogen has significant advantages and has received extensive attention from researchers. Unfortunately, urea oxidation reaction (UOR) involves a complex six-electron transfer process leading to high overpotential, which forces researchers to develop high-performance UOR catalysts to drive the development of urea-assisted water splitting. Based on the UOR mechanism and extensive literature research, this review summarizes the strategies for preparing highly efficient UOR catalysts. First, the UOR mechanism is introduced and the characteristics of excellent UOR catalysts are pointed out.Aiming at this, the following modulation strategies are proposed to improve the catalytic performance based on summarizing various literature: 1) Accelerating the active phase formation to reduce initial potential; 2) Creating double active sites to trigger a new UOR mechanism; 3) Accelerating urea adsorption and promoting C─N bond cleavage to ensure the effective conduct of UOR; 4) Promoting the desorption of CO2 to improve stability and prevent catalyst poisoning; 5) Promoting electron transfer to overcome the inherent slow dynamics of UOR; 6) Increasing active sites or active surface area. Then, the application of UOR in electrochemical devices is summarized. Finally, the current deficiencies and future directions are discussed.

The synthesis of Cr and P codoped NiMoO4 nanospheres as efficient catalyst for urea oxidation and oxygen evolution reaction

The design of reasonable and efficient electrocatalysts is imperative in large scale water splitting applications. In this paper, NiMoO4 nanospheres doped with Cr and P were constructed by hydrothermal method and phosphating process as electrocatalysts for water splitting, and the doping of Cr and P effectively modulated the electronic structure, which led to an increase in the active sites and an increase in the intrinsic activity of each site. Notably, Cr/P–NiMoO4@NF presented excellent urea oxidation reaction (UOR) performance (1.312V @ 10 mA cm−2) and oxygen evolution reaction (OER) performance (overpotential 309 mV @ 10 mA cm−2) in electrolytes of 1 M KOH and 1 M KOH with 0.5 M urea because of the doping effect of Cr and P. The experimental analysis showed that the improvement of electrochemical performance was mainly reflected in the accelerated electron transfer rate, increased exposure of reaction sites and improved metal properties and so on. For Cr/P–NiMoO4@NF, after a long time UOR and OER stability test, some changes have taken place in the appearance of the sample, which increases the contact area and provides more active sites, making the catalytic performance of the sample have no too obvious attenuation. Density functional theory calculation shows that the Cr/P–NiMoO4 material exhibits higher urea adsorption energy, indicating that urea is preferentially adsorbed on its surface. The Cr/P–NiMoO4 material shows more state density near the Fermi level, indicating that the introduction of Cr and P enhances the conductivity of the Cr/P–NiMoO4 material. This work provides a novel idea for the research and exploitation of low cost and robust UOR and OER electrocatalysts.

Improving the adsorption performance of urea by using polyhydroxy groups to modify two-dimensional Ti3C2Tx

Wearable artificial kidney can provide continuous dynamic dialysis for uremia patients. For the sake of practical application, the critical step is to find an adsorbent that can effectively remove urea and have excellent biological compatibility. The layered Ti3C2Tx (DL-Ti3C2Tx) with high specific surface area and good dispersion was prepared by a two-step etching method. From the first principles calculation, urea can be adsorbed by different groups (−F, –O, –OH) on the surface of Ti3C2Tx, among which –OH has the greatest binding energy to urea. Therefore, DL-Ti3C2Tx was modified with different alkali solutions (KOH, NaOH, LiOH) to introduce –OH on the surface, which can increase the adsorption capacity of urea. The experimental results showed that DL-Ti3C2Tx (LiOH-Ti3C2Tx) after treated by LiOH had the highest urea adsorption efficiency, and the urea removal rate of LiOH-Ti3C2Tx was still higher than 92% when the urea concentration was 500 mg/L. In the Simulated dialysate, Ti3C2Tx treated with three kinds of alkali solutions still maintained a good adsorption efficiency for urea, and still had a certain adsorption capacity after recycling for four times. Biocompatibility experiments showed that Ti3C2Tx in different concentrations did not cause hemolysis of erythrocyte, and had no obvious damage to vascular endothelial cells. This study greatly improves the urea adsorption efficiency of MXene, which has a broad application prospect in the selection of adsorbent for wearable artificial kidney.

Controlled synthesis of CoVP as robust electrocatalysts for water, seawater and urea oxidation

Urea electrolysis has more advantages in energy saving and environmental protection as well as wastewater treatment. A series of CoVM (M = P, S and Se) catalytic materials with a nanosphere morphology composed of nanoneedles were successfully synthesized by one-step hydrothermal and tube furnace phosphating process. Based on the principle of electronic regulation, the polyvalent state of V can effectively provide the electronic and environmental structure required for Co, the catalytic activity of the electrode was significantly improved by increasing the charge transfer of the electrode. CoVP electrode shows excellent and efficient catalysis in the anodic reaction of water, seawater and urea electrolysis. At the current density of 10 mA cm−2, it only needed the overpotential of 270 mV for oxygen evolution reaction (OER) and only needed potential of 1.30 V for urea oxidation reaction (UOR). Experimental results show that the increased activity is attributed to the rapid charge transfer rate, the exposure of more active sites and the enhanced conductivity due to the synergistic catalysis of CoP and V3P. Density functional theory (DFT) calculation shows that the CoP material exhibits higher urea adsorption energy, which promotes catalysis. The V3P material shows a higher density of states near the Fermi level, indicating that it has better conductivity. The synergistic catalysis of the two enhanced the catalytic activity of the CoVP material. This study provides a new idea for the synthesis of catalytic electrode materials in the anodic oxidation aspect of urea electrolysis, and provides a further understanding for the improvement of catalytic performance of relatively non-toxic catalysts.

Indirect urea electrooxidation by nickel(III) in alkaline medium: From kinetic and mechanism to reactor modeling

AbstractThis study consists in the determination of two kinetic laws of urea oxidation (UO) and electrooxidation (UEO) in alkaline media on nickel(III). Two kinds of active sites were examined, the first one derived from a Ni(OH)2 powder and the second from a massive nickel electrode. Partial orders of nickel(III) (two for UO and five UEO) enable to conclude about (i) the urea adsorption on two nickel(III) sites and (ii) that a multistep oxidation of urea occurs involving five nickel(III) site electroregenerations. A multipathway mechanism is also proposed to explain UEO facilitated by the nickel(III)/nickel(II) mediation system, and to predict the by‐products' formation previously identified (). At last, a model combining the UEO kinetic law previously established, with diffusive and convective transport phenomena was developed. A consistent correlation (maximum deviation of 6%) between laboratory electrolysis results with the model' predictions was obtained under different operating conditions, enabling the validation of this model.

In situ topologically induced metastable phase Ni/r-Ni(OH)2@C heterostructures with abundant oxygen vacancies as efficient bifunctional electrocatalysts for energy-saving hydrogen production

To simultaneously accelerate both sluggish hydrogen evolution reaction (HER) and urea oxidation reaction (UOR) kinetics, strongly coupling of transition metal hydroxides of high UOR activity with the transition metals of low hydrogen adsorption barrier for highly active HER is a promising strategy. Herein, a tractable hydrothermal protocol and a partial in-situ topological reduction strategy are developed to synthesize hcp Ni/r-Ni(OH)2 nanosheets containing abundant oxygen defects with an ultrathin carbon layer, which are utilized as the new bifunctional catalysts for both HER and UOR. As for HER, the surface electronic structure of Ni is optimized by introducing the oxygen defects coupling with hcp Ni with excellent electronic structure, which greatly enhances the dissociation ability of H2O and reduces the Ni-H bond strength, thus acquiring the optimized H* Gibbs free energy (∆GH*). As for UOR, abundant interfaces and the electron transfer between transition metal hydroxides/transition metal are favorable to regulate the urea adsorption. As expected, the hcp Ni/r-Ni(OH)2/C electrocatalyst shows good activity for HER (70.7 mV @ 10 mA cm−2), UOR (1.36 V @ 10 mA cm−2), and urea electrolysis (1.45 V @ 10 mA cm−2). This facile strategy provides a novel way to design high-performance electrocatalysts towards urea splitting, which can utilize to generate hydrogen as well as eliminate urea in water.

Synthesis of an IRMOF-1@SiO2 Core-Shell and Amino-Functionalization with APTES for the Adsorption of Urea and Creatinine Using a Fixed-Bed Column Study.

Kidney dysfunction is a clinical disease that disables the kidneys to remove the waste products and uremic toxins from the circulation and may lead to fatal kidney failure. Hemodialysis is advantageous in this circumstance since it prevents the accumulation of waste products in the body and facilitates the removal of uremic toxins. However, hemodialysis cannot entirely remove some uremic toxins, such as urea and creatinine. In this paper, a high-performance fixed-bed column for urea and creatinine removal was offered. As a result, a MOF layer was built on SiO2, which was then amino-functionalized using APTES. Numerous assays were used to characterize the final adsorbent. The adsorption of urea and creatinine was evaluated in batch and continuous conditions. Thus, it was demonstrated that the adsorption behavior of A(0.2)-IRMOF-1@SiO2 followed the Langmuir isotherm, and it exhibited the maximum adsorption capacity. The batch experiment determined that urea and creatinine had an adsorption capacity of 1325.73 and 625.00 mg·g-1, respectively. The adsorption capacity was increased, which was due to the presence of amino groups (APTES) on the MOF surface. The continuous operation was evaluated using the A(0.2)-IRMOF-1@SiO2 fixed-bed column. Thomas and Nelson's models were examined to achieve a better understanding of the adsorption behaviors. The A(0.2)-IRMOF-1@SiO2 fixed-bed column successfully removed 92.57% of urea and 80.47% of creatinine. The separation factor for urea in comparison to creatinine was 2.40 in the A(0.2)-IRMOF-1@SiO2 fixed-bed column.

Fabrication and characterization of novel PES-based nanocomposite hollow fiber membranes for the hemodialysis process

In the hemodialysis process, membrane filtration is used to clean blood. Urea and creatinine are two significant substances that should be removed from the blood during hemodialysis, which takes a great deal of time. To decrease the hemodialysis process time, in this study, we fabricated novel polyethersulfone nanocomposite hollow fiber membranes with silica and amine-modified silica nanoparticles via the non-solvent induced phase separation (NIPS) method. Membranes have been evaluated in a membrane contactor system by two modes of contact with fresh sweeper fluid (retentate process) and recycled sweeper fluid (circulated process) to remove urea and creatinine from a synthetic blood-like solution. Fourier transform infrared (FTIR) was carried out along with pure water flux, contact angle, mechanical strength, field emission electron microscope test (FESEM), and X-ray diffraction (EDX) to characterize the synthesized nanoparticles and fabricated membranes. The results revealed that modification of membranes by silica and amine-modified silica nanoparticles increased the urea and creatinine removal rate from the feed as the modified membranes’ separation mechanisms were adsorption and diffusion. Furthermore, removal of urea and creatinine were higher in the retentate process than the circulated process. The membrane samples containing 1.5% amine-modified silica nanoparticles had the highest urea and creatinine removal rate compared to the other modified membranes containing fewer or higher amine-modified silica and/or silica nanoparticles in the both retentate and circulated processes. The adsorption kinetics showed that the adsorption of urea and creatinine on the surface of the silica and amine-modified silica nanoparticles were consistent with the pseudo-second kinetic model, meaning rapid and possibly irreversible adsorption.

Phase transition in V-doped cobalt hydroxide for efficient oxygen evolution and urea oxidation reaction

In this work, many kinds of V doped Co(OH)2 electrodes were in situ synthesized on Ni foam by a one-step typical hydrothermal process. It is worth noting that the phase transition composition of the V doped Co(OH)2 material can be modulated by the difference of the amount of the V introduced. Different crystal phase compositions show different water oxidation activities. It is worth noting that the V2–Co(OH)2/NF electrode shows better oxygen evolution performance (Overpotential of 320 mV@50 mA cm−2) compared with Co(OH)2/NF (450 mV@50 mA cm−2), V1–Co(OH)2/NF (340 mV@50 mA cm−2) and V3–Co(OH)2/NF (350 mV@50 mA cm−2) electrodes. The experimental results show that not all doping can improve the electrochemistry performance of electrodes, such as the oxidation of urea. Density functional theory calculation further proves that the doping of the V is favorable to the adsorption of water and inhibits the adsorption of urea. This study provides a new idea for the development of efficient overall water splitting catalysts.

Unusual hcp Ni with metal and non-metal dual doping modulation to realize boosted urea oxidation

Modulating cost-competitive metallic Ni-based electrocatalysts with favorable surface electronic configuration to boost urea oxidation reaction (UOR) is crucial to urea-related technologies, yet dauntingly challenging due to limited tailoring methods. Herein we put forward a novel N-doping induced phase transfer strategy to construct anomalous metastable hcp Ni with metal Co and non-metal N dual doping engineering (hcp-CoNi-N/C) for manipulating electronic state and catalytic response toward the UOR. Impressively, the hcp-CoNi-N/C can deliver prominent UOR performance with an exceptionally low potential of 1.310 V vs. RHE to attain 10 mA cm−2 and fast reaction kinetics (34.0 mV dec–1), standing out among the best UOR catalysts reported to date. The combined experimental analysis and theoretical calculations disclose that unconventional hcp phase design coupled with metal and non-metal dual doping engineering enables electron density manipulation and creates a charge-polarized surface favorable for urea adsorption and C–N bond cleavage, thereby substantially promoting urea decomposition. Meanwhile, such synergistic phase and doping engineering can boost mass transfer kinetics via tailoring the wetting characteristics. This study offers a new paradigm to craft advanced metallic Ni-based UOR catalysts through unusual metastable phase design synergistic with multiple doping engineering.

Directed Urea‐to‐Nitrite Electrooxidation via Tuning Intermediate Adsorption on Co, Ge Co‐Doped Ni Sites

AbstractThe electrochemical urea oxidation reaction (UOR) is an alternative to electrooxidation of water for energy–saving hydrogen (H2) production. To maximize this purpose, design of catalysts for selective urea‐to‐nitrite (NO2–) electrooxidation with increased electron transfer and high current is practically important. Herein, a cobalt, germanium (Co, Ge) co‐doped nickel (Ni) oxyhydroxide catalyst is reported first time that directs urea‐to‐NO2– conversion with a significant Faradaic efficiency of 84.9% at 1.4 V versus reversible hydrogen electrode and significantly boosts UOR activity to 448.0 mA cm−2. Importantly, this performance is greater than for most reported Ni‐based catalysts. Based on judiciously combined synchrotron‐based measurement, in situ spectroscopy and density functional theoretical computation, significantly boosted urea‐to‐NO2– production results from Co, Ge co‐doping is demonstrated that optimizes electronic structure of Ni sites in which urea adsorption is altered as NO‐terminal configuration to facilitate CN cleavage for *NH formation, and thereby expedites pathway for urea to NO2– conversion. Findings highlight the importance of tuning intermediate adsorption behavior for design of high‐performance UOR electrocatalysts, and will be of practical benefit to a range of researchers and manufacturers in replacing conventional water electrooxidation with UOR for energy‐saving H2 production.

Interfacial Engineering of Ni3N/Mo2N Heterojunctions for Urea-Assisted Hydrogen Evolution Reaction

The urea oxidation reaction (UOR) is considered as an alternative to the oxygen evolution reaction for high-efficiency hydrogen production. However, an urea molecule is relatively complex, containing both electron-donating amino (−NH2) and electron-withdrawing carbonyl (C═O) groups, and understanding the influence of different functional groups on the adsorption behavior is conducive to the rational design and preparation of high-performance UOR catalysts. Herein, we report a simple synthesis of the Ni3N/Mo2N heterostructure and a systematic investigation of urea-assisted electrolytic hydrogen production. Both temperature-programmed desorption and theoretical calculations decipher that −NH2 and C═O groups of the urea molecule are more easily adsorbed on Ni3N and Mo2N, respectively. Meanwhile, the Ni3N/Mo2N heterostructure could combine and enhance the advantages of individual components, optimizing the adsorption of urea. Besides, this heterostructure is also beneficial to improving the hydrogen evolution reaction performance. As expected, in the two-electrode urea-assisted water electrolyzer utilizing Ni3N/Mo2N as bifunctional catalysts, hydrogen production can readily occur at an evidently lower voltage (1.36 V@10 mA cm–2), which is much lower than that of traditional water electrolysis, as well as 7 times higher hydrogen production rate is achieved.

Enhanced electrocatalytic activity of sulfur and tungsten co-doped nickel hydroxide nanosheets for urea oxidation

Ni(OH)2 is regarded as one of the most promising electrocatalyst candidates for urea oxidation reaction due to its structural diversity and low cost, however the inferior electrocatalytic activity severely limits its application. Herein, tungsten and sulfur species are successively doped into Ni(OH)2 nanosheets (S,W-Ni(OH)2) and synergistically promote the electrocatalytic activity towards urea electro-oxidation. Compared with Ni(OH)2 without doping or Ni(OH)2 doping with only one species, S,W-Ni(OH)2 exhibits faster reaction kinetic, larger ECSA, smaller charge transfer and urea adsorption resistance, which should guarantee the enhanced electrocatalytic activity. Potential dependent impedance measurements indicate that tungsten doping can prevent the electrocatalyst from being poisoned and sulfur doping will further enhance the charge transfer and urea adsorption ability. Therefore, simultaneously introducing sulfur and tungsten species into Ni(OH)2 should offer a promising way for designing efficient Ni-based electrocatalysts towards urea electro-oxidation.

Application of Natural and Calcined Oyster Shell Powders to Improve Latosol and Manage Nitrogen Leaching.

Excessive N fertilizer application has aggravated soil acidification and loss of N. Although oyster shell powder (OSP) can improve acidic soil, few studies have investigated its ability to retain soil N. Here, the physicochemical properties of latosol after adding OSP and calcined OSP (COSP) and the dynamic leaching patterns of ammonium N (NH4+-N), nitrate N (NO3--N), and Ca in seepage, were examined through indoor culture and intermittent soil column simulation experiments. Various types of N fertilizer were optimized through the application of 200 mg/kg of N, urea (N 200 mg/kg) was the control treatment (CK), and OSP and COSPs prepared at four calcination temperatures-500, 600, 700, and 800 °C-were added to the latosol for cultivation and leaching experiments. Under various N application conditions, the total leached N from the soil followed ammonium nitrate > ammonium chloride > urea. The OSP and COSPs had a urea adsorption rate of 81.09-91.29%, and the maximum reduction in cumulative soil inorganic N leached was 18.17%. The ability of COSPs to inhibit and control N leaching improved with increasing calcination temperature. Applying OSP and COSPs increased soil pH, soil organic matter, total N, NO3--N, exchangeable Ca content, and cation exchange capacity. Although all soil enzyme activities related to N transformation decreased, the soil NH4+-N content remained unchanged. The strong adsorption capacities for NH4+-N by OSP and COSPs reduced the inorganic N leaching, mitigating the risk of groundwater contamination.