Adsorption and temperature programmed desorption of NO,NO + O2, NO2 and NO + NO2 over CoH-ZSM-5

The NO₂, NO (O₂) adsorption and temperature programmed desorption (TPD) were studied systematically to probe into the selective catalytic reduction of NO by methane (CH₄–SCR) over CoH-ZSM-5 (SiO₂/Al₂O₃ = 25, Co/Al = 0.132–0.312). Adsorption conditions significantly affect the adsorption of NO, NO₂ and NO + O₂. Adsorbed NO species are unstable and desorbed below the reactive temperature 523 K. Increasing adsorption temperature results in the decrease of the adsorbed NO species amount. The amount of –NO_y species formed from NO₂ adsorption increases with the increase of NO₂ concentration in the adsorption process, while decreases significantly with the increase of adsorption temperature. Though NO species are adsorbed weakly on CoH-ZSM-5, competitive adsorption between NO and –NO_y species decreases the amount of adsorbed –NO_y species. Similar desorption profiles of NO₂ were obtained over CoH-ZSM-5 while they were contacted with NO₂ or NO + O₂ followed by TPD. If NO₂ was essential to form adsorbed –NO_y species, the amount of adsorbed –NO_y species for NO + O₂ adsorption should be the least among the adsorptions of NO₂, NO + O₂ and NO + NO₂ because of the lowest NO₂ concentration and highest NO concentration. In fact, the amount of adsorbed –NO_y species is between the other two adsorption processes. These indicate that the formation of adsorbed –NO_y species may not originate from NO₂.     

Adsorption of uranyl ions on kaolinite,montmorillonite, humic acid and composite clay material

Adsorption of uranyl ions onto kaolinite, montmorillonite, humic acid and composite clay material (both clays and humic acid) was studied by measuring the system response to clay suspensions (pre-equilibrated with or without uranyl) and to perturbations of the solution chemistry. Adsorption behavior of selected materials under the frame of batch experiments was tested at high uranyl concentrations (6–1170 μg/mL; 2.5 × 10^− 2 to 4.9 μM), whereas that under flow through continuous stirred reactor experiments was tested at low concentrations (1.00 × 10^− 4 to 1.18 × 10^− 4 M). Both experiments were developed at pH 4.5 and ionic strength 0.2 mM. The adsorption experiments follow a Langmuir isotherm model with a good correlation coefficient (R² > 0.97). The calculated amount of adsorbed and desorbed uranyl was carried out by numeric integration of the experimental data, whereas the desorption rates were determined from the breakthrough curve experiments. Kaolinite with highly disordered structure adsorbed less uranyl (3.86 × 10^− 6 mol/g) than well-ordered kaolinite (1.76 × 10^− 5 mol/g). Higher amount of uranyl was adsorbed by montmorillonite (3.60 × 10^− 5 mol/g) and only half of adsorbed amount was desorbed (1.85 × 10^− 5 mol/g). The molecular interactions between kaolinite, montmorillonite, humic acid, composite material and saturated uranyl ion solutions were studied by molecular fluorescence, infrared and X-ray photoelectron spectroscopy. The Stern–Volmer constant obtained for montmorillonite (2.6 × 10³ M^− 1) is higher than for kaolinite (0.3 × 10³ M^− 1). Molecular vibrations of SiO stretching and AlOH bending related to hydroxylated groups (SiOH or AlOH) of kaolinite and montmorillonite show structural changes when uranyl ions are adsorbed. X-ray photoelectron spectroscopy shows that the U 4f_7/2 core level signals occur at 380.5 eV in either kaolinite or montmorillonite that resulted from the interaction of aluminol surface sites with the (UO₂)₃(OH)₅⁺.     

Strong adsorption of arsenic species by amorphous zirconium oxide nanoparticles

A novel oxide adsorbent of amorphous zirconium oxide (am-ZrO₂) nanoparticles was synthesized by a simple hydrothermal process for effective arsenic removal from aqueous environment. Due to their high specific surface area (327.1 m²/g), large mesopore volume (0.68 cm³/g), and the presence of high affinity surface hydroxyl groups, am-ZrO₂ nanoparticles demonstrated exceptional adsorption performance on both As(III) (arsenite) and As(V) (arsenate) without pre-treatment at near neutral condition. At pH ～ 7, the adsorption kinetic is fast and the adsorption capacity is high (over 83 mg/g for As(III) and over 32.4 mg/g for As(V), respectively). Under low equilibrium arsenic concentrations (C_e at 0.01 mg/L, the maximum contaminant level (MCL) for arsenic in drinking water), the amount of arsenic adsorbed by am-ZrO₂ nanoparticles is over 0.92 mg/g for As(III) and over 5.2 mg/g for As(V), respectively. The adsorption mechanism of arsenic species onto am-ZrO₂ nanoparticles was found to follow the inner-sphere complex mechanism. Testing with arsenic contaminated natural lake water confirmed the effectiveness of these am-ZrO₂ nanoparticles in removing arsenic from natural water. The immobilized am-ZrO₂ nanoparticles on glass fiber cloth demonstrated an even better arsenic removal performance than dispersed am-ZrO₂ nanoparticles in water, paving the way for their potential applications in water treatment facility to treat arsenic contaminated water body without pre-treatment.     

Decomposition of activated CO2 species on Ni(110): Role of surface diffusion in the reaction mechanism

Chemisorption and decomposition of CO₂ on Ni(110) surface have been studied by means of spin-polarized density functional theory calculations. Several possible CO₂/Ni(110) conformations with similar adsorption energies were found. The bonding nature of the adsorbed CO₂ was further analyzed on the basis of partial density of states (PDOS) and effective bond order (EBO) results, indicating the enhanced charge transfer and significant activation of the CO bond. Climbing image nudged elastic bound calculations provide an insight into CO₂/Ni(110) → CO/Ni(110) + O/Ni(110) reaction mechanism. All computed reaction pathways can be separated into two stages: 1) surface diffusion of CO₂ to the one energetically favored conformation; 2) breakage of the coordinated C–O bond. The total reaction barrier (relative to the energy of CO₂/Ni(110)) was found about 0.44 eV.     

Correlation between eletrokinetic mobility and ionic dyes adsorption of Moroccan stevensite

This study aims at establishing a correlation between the electrical charge of Moroccan stevensite particles and ionic dyes adsorption. The electrophoretic mobility, (U_e), of the stevensite particles in water, was measured at pH 2.5–12 by microelectrophoresis. At pH between 2.5 and 8, U_e remained constant (U_e = ? 1.6 10^? 8 m²/(V s)), as resulting from the permanent charge of the clay mineral planar surfaces. At pH > 8, the magnitude of electrophoretic mobility increased (U_e = ? 2.7 10^? 8 m²/(V s)) due to the deprotonation of silanol groups on the surfaces. The anionic Orange G adsorption at the clay mineral–water interface was negligible whereas the methylene blue cations were strongly adsorbed due to the electrostatic attraction.     

A DFT study of methanol oxidation on Co3O4

By means of spin polarized density functional theory with the GGA + U framework, the reaction mechanism of CH₃OH oxidation on the Co₃O₄ (110)-B and (111)-B surfaces has been investigated. Adsorption situation and a part of reaction cycle for CH₃OH oxidation are clarified. Our results indicated that: i) U value can affect the calculated energetic result significantly; ii) CH₃OH can adsorb with surface lattice oxygen atom (O_2f/O_3f) to form CoO bond directly, and the adsorption of CH₃OH and its decomposition products on (110)-B is more stable than on (111)-B, which means CH₃OH prefers Co^3 + better than Co^2 +; iii) on the (110)-B surface, CH₃OH can form CO₂, H₂O and adsorbed H atom. But on the (111)-B surface, CH₃OH can just form formaldehyde (CH₂O) and adsorbed H atom, this means oxidative capacity of (110)-B (Co^3 +) is higher than (111)-B (Co^2 +). The possible reasons corresponding to the high oxidative of (110)-B come from both Co^3 + and O_2f: Co^3 + tends to bind adsorbed species for further decomposition and O_2f tends to bind more hydrogenation atom involved in methanol due to its low-coordinates number compared to that of O_3f.     

Experimental study on the stability of graphitic C3N4 under high pressure and high temperature

The stability and decomposition of graphitic C₃N₄ (g-C₃N₄) were studied in the pressure and temperature range of 10–25 GPa and up to 2000 °C by multi-anvil experiments and phase characterization of the quenched products. g-C₃N₄ was found to remain stable at relatively mild temperatures, but decomposes to graphite and nitrogen at temperatures above 600–700 °C and up to 15 GPa, while it decomposes directly to diamond (plus nitrogen) above 800–900 °C and between 22 and 25 GPa. The estimated decomposition curve for g-C₃N₄ has a positive slope (~ 0.05 GPa/K) up to ~ 22 GPa, but becomes inverted (negative) above this pressure. The diamond formed through decomposition is characterized by euhedral crystals which are not sintered to each other, but loosely aggregated, suggesting the crystallization in a liquid (nitrogen) medium. The nitrogen release from the graphitic CN framework may also play an important role in lowering the activation energy required for diamond formation and enhancing the grain growth rate. No phase transition of g-C₃N₄ was found in the studied P–T range.     

A new processing aid for dry-pressing: A copolymer acting as dispersant and binder

PVX copolymers containing both carboxylate (COO⁻) and hydroxyl groups (vinyl alcohol) are synthesized with the objective to ensure the double function of dispersant and of binder for dry-pressed green parts.Carboxylate groups are responsible for strong adsorption of copolymers onto alumina surface and can promote sufficient electrostatic repulsive forces to achieve a good state of dispersion, similar to that obtained with a classical ammonium polymethacrylate (PMA-NH₄⁺) for a proportion of carboxylic groups in the copolymer larger than 35%. On the other hand, hydroxyl groups confer higher mechanical strength than PVA to the green pressed parts (4.2 MPa for 1.5 wt.% PV35 (35% COO⁻) versus 1.8 MPa for 1.5 wt.% PVA, with and without PEG as plasticizer, in the case of samples pressed at 120 MPa).The high density of the green parts obtained with soft PV35 copolymer and the good adsorption of this compound onto alumina surface lead to a high mechanical strength of the pressed compacts. After addition of 1.5 wt.% PV35, the amount adsorbed (0.7 wt.%) confers a high cohesion to the spray-dried granules and the non-adsorbed copolymer (0.8 wt.%) reinforces adhesion between granules through interdiffusion of the low T_g polymeric films.Then, synthesized PVX copolymers have proved to be efficient dispersants for aqueous suspensions of alumina and also efficient binders for dry-pressing, even for concentrations as low as 1.5 wt.%.     

Introduction of copper nanoparticles in chitosan matrix as strategy to enhance chromate adsorption

In this study, copper nanoparticles (CuNPs) were incorporated to chitosan (CHI) matrix as strategy to enhance the chromate adsorption by CHI membrane. The CuNPs were synthesized using NaBH₄ as the reducing agent. Dispersive X-ray Absorption Spectroscopy (DXAS) was used to monitor the in situ reduction of Cu(II). The influence of the presence of CuNPs on the hygroscopic behavior was also evaluated. DXAS technique showed that the adsorbed Cu(II) was reduced to Cu(I) (63%) and Cu(0) (37%) species, at the end of the reduction reaction (using NaBH₄, after ∼30 min). The hygroscopic behavior of the proposed sorbent was more influenced by CuNPs when the water vapor adsorption was conducted under synthetic air atmosphere. A decrease in the energy of interaction among the water molecules adsorbed on the monolayer was observed. The chromate adsorption study has shown a higher equilibrium concentration of adsorbed chromium species when the CHI membrane containing CuNPs was used as sorbent. The CuNPs offered a second active adsorption site, which was characterized by a higher coefficient of affinity (12 L mmol⁻¹, against 0.18 L mmol⁻¹ reported for CHI). The enhanced adsorption of chromium in the presence of CuNPs was associated to the redox reaction between the CuNPs and chromate anions.     

Low-temperature synthesized nitrogen-doped iron/iron carbide/partly-graphitized carbon as stable cathode catalysts for enhancing bioelectricity generation

Low efficiency of oxygen reduction reaction (ORR) across cathode interfaces constitutes an obstacle to the bioelectricity generation in microbial fuel cells (MFCs). Advances in the property of carbon-based catalysts for ORR will have far-reaching implications for MFCs. Melamine is used as both carbon and nitrogen sources for preparing nitrogen-doped Fe-species/partly-graphitized carbon (Fe-species/NPGC) catalysts at relatively low temperature (640–700 °C). Main crystalline phases in Fe-species/NPGC-x (x = 640, 650, 660 and 700) change from iron carbide (Fe₃C) to α-Fe as temperature increases. The OCO groups and structurally-bonded nitrogen (Fe-bonded N, pyridinic N and pyrrolic N) in PGC skeleton are favorable for improving electrical conductivity and catalytic activity. Single chamber MFCs with Fe/Fe₃C/NPGC-650 generate power density of 1323 mW m⁻², which is higher than those of Fe-species/NPGC-x (x = 640, 660 and 700) and Pt/C (1191 mW m⁻²). Minimum power density decline (1.75%) is achieved by Fe/NPGC-660, which is far lower than that (17.11%) of Pt/C. The highest coulombic efficiency (30%) is obtained by Fe/Fe₃C/NPGC-650 due to the sufficient active-sites (embedded Fe₃C or FeN species) and easy charge transport across the triphase interfaces, which are conducive to “capture–consume” the electrons for catalyzing ORR.     

The effects of the surface oxidation of activated carbon,the solution pH and the temperature on adsorption of ibuprofen

A commercial microporous–mesoporous granular activated carbon was modified by oxidation with either H₂O₂ in the presence or absence of ultrasonic irradiation, or NaOCl or by a thermal treatment under nitrogen flow. Raw and modified materials were characterized by N₂ adsorption–desorption measurements at 77 K, Boehm titrations, pH measurements and X-ray photoelectron spectroscopy. Ibuprofen adsorption kinetic and isotherm studies were carried out at pH 3 and 7 on raw and modified materials. The thermodynamic parameters of adsorption were calculated from the isotherms obtained at 298, 313 and 328 K. The pore size distribution of carbon loaded with ibuprofen brought out that adsorption occurred preferentially into the ultramicropores. The adsorption of ibuprofen on pristine activated carbon was found endothermic, spontaneous (ΔG° = −1.1 kJ mol⁻¹), and promoted at acidic pH through dispersive interactions. All explored oxidative treatments led mainly to the formation of carbonyl groups and in a less extent to lactonic and carboxylic groups. This then helped to enhance the adsorption uptake while decreasing adsorption Gibbs energy (notably −7.3 kJ mol⁻¹ after sonication in H₂O₂). The decrease of the adsorption capacity after bleaching was attributed to the presence of phenolic groups.     

Adsorption of glycine on montmorillonite in aqueous solutions

Glycine was adsorbed on the surface of montmorillonite from aqueous solutions of variable glycine concentrations (0.001–0.3 mol L^− 1) and pHs (2–12) at room temperature. The reaction products were characterized using X-ray diffraction and attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy. The results indicate that adsorption is highly pH dependent, increasing at acidic pHs. Glycine adsorption is dominated by complexation of the carboxylate group of zwitterionic glycine onto the edge surface at low concentrations of glycine. When the edge surface is saturated, the adsorption occurs by cation exchange in the interlayer space. ATR-FTIR results point to an adsorption by hydrogen bonding between the NH₃⁺ group and the basal oxygen of the interlayer surface. The dependence of glycine adsorption with its aqueous concentration fits for a Freundlich equation. The measure of the desorbed interlayer cations shows that the 68% of the K⁺ was exchanged with glycine. The K⁺–glycine exchange reaction produces a decrease of the smectite interlayer space from 14.5 to 12 Å and an arrangement of the smectite layers. Intercalated glycine is present as both glycinium and zwitterionic forms. Since only glycinium contribute to structural charge balance, total adsorbed glycine can exceed K⁺ released. These findings are of relevance for the evaluation of distribution and reactions of free amino acids in natural environments.     

A model study for the breaking of cyanogen out of CNx within DFT

To explain the nitrogen low rate in CVD CN_x layers, and their amorphisation, a release of gaseous species containing N was proposed. Previous modelling studies based on local density functional theory use pyrite type CN₂ as starting model to assess the release of molecular nitrogen. This model is completed here to investigate another mechanism of release of cyanogen as another gaseous species. The theoretical pyrite-like C₂N wherein C and N atoms form dumbbells in octahedral sites of a carbon face-centred sub-lattice is proposed as likely to model it. It demonstrates a good compressibility (B₀ = 272 GPa) and a mechanical instability, which supports both release of atoms and the amorphisation of layers. However, the variation of interatomic distances under strain leads to propose the formation of a radical species CN. This is enforced by the consideration of the chemical bonding and its evolution in the model with the E_COV and ELF functions. The release of nitrogen in molecular cyanogen is consequently substituted by a mechanism which implies a CN radical species, which is likely to recombinate at the CVD layers surfaces.     

Role of phosphorus in carbon matrix in desulfurization of diesel fuel using adsorption process

Adsorptive removal of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (DMDBT) from model diesel fuel with 20 ppmw total concentration of sulfur was investigated on polymer-derived carbons with incorporated heteroatoms of oxygen, sulfur and phosphorus. The materials before and after exposure to model diesel fuel were characterized using adsorption of nitrogen, thermal analysis, potentiometric titration, XPS and elemental analysis. The selectivities for DBT and DMDBT adsorption were calculated with reference to naphthalene. The results indicated that the presence of phosphorus, especially in the form of pyrophosphates and P₂O₅, increases the capacity and selectivity for removal of dibenzothiophenes. It also affects the adsorption mechanism. Phosphorus suppresses oxidation reactions of DBT and DMDBT. Owing to a possible location of bulky phosphorus groups in pore with sizes between 1 and 3 nm thiophenic molecules are strongly adsorbed there via dispersive forces. Acidic environment also enhances adsorption via acid–base interactions. Physical adsorption mechanism and stability of surface make these carbons attractive candidates for thermal regeneration.     

Activity of Mo(II) allylic complexes supported in MCM-41 as oxidation catalysts precursors

[Mo(η³-C₃H₅)X(CO)₂(NCCH₃)₂] (X = Br, 1a; X = Cl, 1b) complexes reacted with the bidentate ligand RNC(Ph)–C(Ph)NR, R = (CH₂)₂CH₃ (DAB, 2) affording [Mo(η³-C₃H₅)X(CO)₂(DAB)] (X = Br, 4a; X = Cl, 4b), which were characterized by elemental analysis, FTIR and ¹H and ¹³C NMR spectroscopy. The modified silylated ligand RNC(Ph)C(Ph)NR, R = (CH₂)₃Si(OCH₂CH₃)₃ (DAB–Si, 3), was used to immobilize the two complexes in MCM-41 (MCM) mesoporous silica. The new materials were characterized by powder X-ray diffraction, N₂ adsorption analysis, FTIR and ²⁹Si and ¹³C CPMAS solid state NMR spectroscopy. Both the materials and the complexes were tested in the oxidation of cyclooctene and styrene and behaved as active catalyst precursors for cyclooctene and styrene epoxidation with TBHP (t-butylhydroperoxide), leading selectively to epoxides with high conversions and TOFs. Although the homogeneous systems reach 100% conversion of cyclooctene and slightly less for styrene, the loss of catalytic activity in the heterogeneous systems is small, with a 98% conversion of styrene achieved by the chloride containing material.     

Density functional theory study on adsorption of thiophene on TiO2 anatase (0 0 1) surfaces

In order to develop a fundamental understanding of the adsorption mechanism of thiophenic compounds on TiO₂-based adsorbents for ultra-deep desulfurization of liquid hydrocarbon fuels, a density functional theory (DFT) study was conducted on the adsorption of thiophene over the TiO₂ anatase (0 0 1) surface. The perfect, O-poor (with oxygen vacancies), and O-rich (with activated O₂ on the surface) anatase (0 0 1) surfaces were built, and the interaction of thiophene molecule with these surfaces was examined. The adsorption configuration and adsorption energy on the different surfaces and sites were estimated. The results showed that thiophene may be adsorbed on both the perfect and O-poor surfaces through an interaction between the Ti cations on the surface and the S atom in thiophene, whereas on the O-rich surface through an interaction of the activated O atoms (the dissociatively or associatively adsorbed O₂) on the surface with the S atom in thiophene to form a sulfone-like surface species. The adsorption of thiophene on the O-rich surface is significantly stronger than adsorption on the perfect and O-poor surfaces on the basis of the calculated adsorption energies. The results indicate that the activated O₂ on the TiO₂ anatase (0 0 1) surface may play an important role in the adsorption desulfurization over the TiO₂-based adsorbents, and increased concentration of the activated O₂ on the surface may result in improvement of the adsorption capacity of the adsorbents.     

Deposition of carbon nitride films using an electron cyclotron wave resonance plasma source

Hydrogenated amorphous carbon nitride (a-C:N:H) has been synthesised using a high plasma density electron cyclotron wave resonance (ECWR) technique using N₂ and C₂H₂ as source gases, at different ratios and a fixed ion energy (80 eV). The composition, structure and bonding state of the films were investigated and related to their optical and electrical properties. The nitrogen content in the film rises rapidly until the N₂/C₂H₂ gas ratio reaches 2 and then increases more gradually, while the deposition rate decreases steeply, placing an upper limit for the nitrogen incorporation at 30 at%. For nitrogen contents above 20 at%, the band gap and sp³-bonded carbon fraction decrease from 1.7 to 1.1 eV and ∼65 to 40%, respectively. The transition is due to the formation of polymeric CN, CN and NH groups, not an increase in CH bonds. Films with higher nitrogen content are less dense than the original hydrogenated tetrahedral amorphous carbon (ta-C:H) film but, because they have a relatively high band gap (1.1 eV), high resistivity (10⁹ Ω cm) and moderate sp³-bonded carbon fraction (40%), they should be classed as polymeric in nature.     

Solar-light-induced photocatalytic decomposition of two azo dyes on new TiO2 photocatalyst containing nitrogen

The photocatalytic decolourisation of two azo dyes—Reactive Red 198 and Direct Green 99—in an aqueous solution by the artificial visible light radiation was investigated. The industrial metatitanic acid (H₂TiO₃) obtained directly from the sulphate technology installation was N-doped and used as photocatalyst. H₂TiO₃ was calcinated at different temperatures, ranging from 300 to 500 °C, for 4 or 20 h, respectively, in an ammonia atmosphere. The UV–vis/DR spectra of the modified catalysts exhibited an additional maximum in the vis region (λ ≈ 476.8 nm, E_G = 2.60 eV for catalysts calcinated for 4 h and λ ≈ 479.5 nm, E_G = 2.59 eV for catalysts calcinated for 20 h, which may be due to the presence of nitrogen in TiO₂ particles. The chemical structure of the modified photocatalysts was investigated using FTIR/DRS spectroscopy and the presence of nitrogen was confirmed. A photocatalytic activity of the investigated catalysts was determined on the basis of a decomposition rate of azo dyes. The decomposition of Reactive Red 99 increased with increasing the calcination temperature of photocatalysts, whereas the activity of the prepared photocatalysts towards Direct Green 198 degradation was as follows: 300–20 h < 400–20 h < 500–20 h < 300–4h < 400–4 h < 500–4 h. Both, the calcination time and temperature had no influence on the amount of nitrogen-doped into TiO₂ structure. The inversely proportional linear dependence between the decomposition rates of azo dyes and the intensity of the band attributed to the hydroxyl groups for both dissociated water and molecularly adsorbed water was observed. With increasing temperature of calcinations, the amount of the hydroxyl groups decreased, whereas the decomposition of azo dyes increased.     

The effect of Co doping on the magnetic and magnetocaloric properties of Pr0.7Ca0.3Mn1−xCoxO3 manganites

In this work, we report the effect of low amount of cobalt doping at the Mn-site on the magnetic and magnetocaloric properties of Pr_0.7Ca_0.3Mn_1−xCo_xO₃ (0≤x≤0.1) powder samples. Our samples, elaborated using the solid–solid reaction method at high temperature, are single phase and crystallize in the orthorhombic system with Pnma space group. While the parent compound Pr_0.7Ca_0.3MnO₃ exhibits a charge order state at low temperature, the substituted samples with low amount of cobalt exhibit a paramagnetic to ferromagnetic transition with decreasing temperature. The Curie temperature T_C increases with Co content from 105 K for x=0 to 116 K for x=0.1. The maximum values of the magnetic entropy change $\left|\mathrm{\Delta }{S}_{\mathrm{M}}^{\max }\right|$ are found to be 0.8 J/kg K, 2.2 J/kg K, 3.1 J/kg K and 3.2 J/kg K in a magnetic field change of 5 T for x=0, 0.02, 0.05 and 0.1 respectively. The maximum value of the relative cooling power RCP is found to be 378.2 J/kg in the Pr_0.7Ca_0.3Mn_0.95Co_0.05O₃ at 5 T. This value of RCP is about 92% of that obtained in gadolinium metal, known as one of the most important materials for magnetic refrigeration, at the same magnetic field change of 5 T.