Lanthanum Modification Research Articles

Converting large-scale waste paper fibers into lanthanum-modified cellulose carbon aerogel adsorbents for efficient phosphorus removal

This study presents the synthesis of a novel lanthanum-modified cellulose-based carbon aerogel (La-CCA) from waste printing paper, aimed at addressing the issue of phosphate pollution in aquatic environments. The objective was to develop an effective and sustainable adsorbent to mitigate eutrophication caused by excess phosphates in water bodies. La-CCA exhibited a remarkable phosphate adsorption capacity, peaking at 44.32 mg/g under optimal conditions, demonstrating its efficiency as an adsorbent. The novelty of this work lies in the use of waste paper as a raw material, coupled with lanthanum modification, which enhanced adsorption performance through multiple mechanisms, including electrostatic interactions, ligand exchange, and inner-sphere complexation. The study also discussed the retention of the microfibrous structure of cellulose, contributing to the material’s stability and functionality. Comprehensive analyses including zeta potential, FTIR, and XPS elucidate the underlying adsorption mechanisms. La-CCA was demonstrated to be easily separable from solutions with minimal lanthanum leaching, particularly under conditions above pH 3.0, underscoring its potential for practical applications in phosphate removal from nutrient-enriched waters.

Performance and mechanism of lanthanum-modified MnO2 for defluoridation from water: The role of MnO2 crystal forms

MnO2 has a large potential for defluoridation, however, the influences of its crystal forms on the performance and mechanism of defluoridation are unknown. The research systematically investigated the defluoridation performance and mechanism of a total of eight materials with different crystal forms of MnO2 (α, β, γ, δ) before and after lanthanum modification, separately. It was indicated that the largest Langmuir adsorption of α-MnO2 and La-γ-MnO2 for fluoride achieved 5.04 mg/g and 42.39 mg/g, correspondingly. The surface hydroxyl group and lanthanum loading of the material proved to be the major contributors to defluoridation. For the adsorption performance of eight materials on fluoride, pH was a significant influencing factor, with the highest adsorption performance at pH 5 ∼ 6. The eight materials showed consistent selectivity for fluoride adsorption in the existence of different anions, with the order of influence on the removal efficiency: CO32–> NO3–> SO42–> Cl–. The studies of FTIR, XPS, and variation of solution pH further illustrated that the adsorption mechanism of the eight materials on fluoride was the ion-exchange interaction and the complexation reaction. In addition, the effect of crystal forms on the adsorption of fluoride ions was further elaborated by DFT analysis. Finally, this study provided an in-depth discussion of the parameters of the dynamic process as well as the nature of the penetration curves by applying the Thomas, Clark, and BDST models.

Classical to Relaxor Ferroelectric Transformation of Lanthanum Modified BaTi0.91Sn0.09O3 Ceramics

Lead-free Ba1-xLaxTi0.91Sn0.09O3 (BLTS) ceramics with x = 0, 0.01, 0.03 and 0.05, were prepared by the traditional solid-state sintering method with calcination and sintering temperatures of 1200 °C for 2 h and 1400 °C for 4 h, respectively. X-ray diffraction (XRD) measurements revealed that all the BLTS ceramics had pure perovskite structures with no detectable impurities. When x = 0 and 0.01, the ceramics exhibited coexisting orthorhombic (O) and tetragonal (T) phases, while the orthorhombic (O), tetragonal (T) and cubic phase (C) were detected in the BLTS ceramics with x = 0.03 and 0.05, which the Rietveld refinement analysis confirmed. Furthermore, increasing x in the BLTS ceramics led to a large decrease in the average grain size (from 45.7 to 0.9 µm). A significant decrease in the remnant polarization (P r) accompanied by very slim hysteresis loops were observed for higher La (x ≥ 0.03) levels. This demonstrates that BLTS ceramics transition from classical ferroelectric to relaxor ferroelectric behavior due to changing occupancy of the A-site to La3+ from Ba2+.

Improved high-temperature sintering resistance and light alkanes oxidation activity by La modification on Co3O4 nanocatalyst

In order to improve low-temperature activity and high-temperature sintering resistance of cobalt-based catalyst in catalytic degradation of emitted light alkanes, a strategy of lanthanum modification on Co3O4 nanocrystalline is proposed in this work, aiming at efficiently degrading methane emitted from the oil and natural gas industry. The La-Co3O4 nanocatalysts were prepared by co-precipitation method, and the effects of La-doping on the structural features and catalytic activity of Co3O4 catalyst for methane oxidation were investigated. The results show that the addition of lanthanum forms a composite catalyst containing La2O3 phase and Co3O4 phase, and the interaction increases the active species, which can significantly improve the low-temperature activity of the catalyst. Among them, 5 % La-Co3O4-F catalyst shows the best catalytic activity with 48 °C decrease of the temperature of 90 % methane conversion (T90) compared with pure Co3O4. Furthermore, with thermal ageing treatment at 750 °C for 100 h, Lanthanum modification can significantly slow down the agglomeration growth and the decrease of specific surface area of cobalt oxide in long-term running, and the formation of perovskite structure (LaCoO3) on Co3O4 nanocrystal surface increases the mobility of lattice oxygen, further inhibiting the sintering deactivation of Co3O4 catalyst. The catalyst doped with 5 % La still showed better performance after thermal ageing, which is 127 °C lower than T90 of pure Co3O4. Moreover, this advantage of La doping can also be observed in the catalytic oxidation of other typical hydrocarbons such as ethane and propane. This work provides a promising strategy toward the design of advanced non-precious metal oxide catalysts for practical catalytic oxidation application with excellent high-temperature sintering resistance.

Rare earth lanthanum pinning effect for corrosion resistance ultraefficient microwave absorption FeCo@rGO composites

Magnetic metal absorbers exhibit remarkable microwave absorption capacity. However, their practical application is severely limited due to their susceptibility to corrosion, particularly in marine environments. To address this challenge, we propose a novel approach involving the modification and control of FeCo/rGO microwave absorbers using rare earth lanthanum (La). This strategy aims to achieve both high-performance microwave absorption and enhanced resistance to marine corrosion. In this study, we employ a La2O3 modifying control strategy to refine the FeCo magnetic particles and coat them with CoFe2O4 on the surface, leveraging the pinning effect of in situ generated La2O3. This process enhances the interface polarization of the absorbers, thereby improving their electromagnetic performance and marine corrosion resistance. Consequently, the La2O3 modified FeCo@rGO composites exhibit broadband absorption, covering a wide frequency range of 6.11 GHz at 1.55 mm. Notably, the electromagnetic properties of the La2O3 modified FeCo@rGO absorbers remain stable even after prolonged exposure to a 3.5 wt% NaCl solution, simulating marine conditions, for at least 15 days. Furthermore, we perform first-principle calculations on FeCo and FeCoO to validate the corrosion resistance of the La2O3 modified FeCo@rGO composites at the atomic level. This comprehensive investigation explores the control of rare earth lanthanum modification on the size of magnetic metal particles, enabling efficient electromagnetic wave absorption and marine corrosion resistance. The results of this study provide a novel and facile strategy for the control of microwave absorbers, offering promising prospects for future research and development in this field.

Adsorption of Phosphate and Heavy Metals by Lanthanum Modified Zeolite and Its Performance in Sediment Inactivation

Due to the large scale of mining and smelting activities, considerable amounts of heavy metals are discharged into the environment and accumulate in the sediment of rivers and lakes. The combined pollution of heavy metals and the intrinsic phosphorus in sediment calls for novel remediation technologies. In this study, lanthanum-modified zeolite (LMZ) was employed as an inactivation agent for the immobilization of phosphorus, zinc, and lead in sediments. The adsorption capacities as well as the inactivation performance of LMZ for P, Zn, and Pb were investigated, and the adsorption mechanisms were explored via desorption experiments, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The results indicated that the adsorption maximums of LMZ for P, Zn, and Pb were 53.76, 27.70, and 123.45 mg·g-1, respectively. Pre-adsorption of Zn and Pb had a negligible effect on the P adsorption by LMZ, whereas the adsorption of Zn and Pb were inhibited significantly by the pre-adsorption. P, Zn, and Pb in the sediment were transformed to more stable or less bioavailable forms by dosing 0.83% and 1.66% weight percentages of LMZ. It was found that P, Zn, and Pb were adsorbed through the formation of inner-sphere complexes. Further, desorption experiments and XRD patterns suggested that electrostatic attraction and surface precipitation also contributed to the adsorption of Zn and Pb, respectively.

Removal of Nitrate and Phosphate by Starch and Lanthanum Modified Montmorillonite

<p>Unqualified treatment of the discharge of wastewater contains a large number of nitrogen and phosphorus and other nutrients, such wastewater into the water environment is easy to lead to eutrophication of water bodies, and cause harm to human health. In order to prepare a cost-effective, efficient and environmentally friendly adsorbent material for nitrogen and phosphorus removal, lanthanum modified montmorillonite(La4-Mt), starch modified montmorillonite(St6-Mt) and starch and lanthanum modified montmorillonite(St6-La4-Mt) were used in this paper to investigate the removal effect and adsorption mechanism of the three modified materials on nitrogen and phosphorus. The mechanism of modification and the properties of the modified montmorillonite were characterised by zeta potential and scanning electron microscopy (SEM) analysis. The test results show that：After the introduction of starch and lanthanum, the adsorption of both nitrogen and phosphorus by the modified montmorillonite was significantly enhanced. The mechanism of PO43- removal by La4-Mt and St6-La4-Mt, materials prepared from La-loaded montmorillonite, is due to the binding of La3+ to OH- in solution to produce La(OH)3, which in turn removes the oxygenate PO43- and NO3- from solution by electrostatic gravitation. The mechanism of removal of oxygenates by St-loaded montmorillonite St6-Mt and St6-La4-Mt is that St itself is an electropositive natural polymeric organic substance, and by reducing the electronegativity of the system, St reduces the electrostatic repulsion between the system and the oxygenates and improves the effect of oxygenate removal, thus achieving the purpose of nitrogen removal and phosphorus removal.</p>

Comparison of fluorine removal performance and mechanism of spheroidal magnesium oxide before and after lanthanum modification.

Firstly, spherical magnesium oxide was synthesized by simple magnesium salt and specific reaction conditions. Then, lanthanum-modified spherical magnesium oxide (LSMO) was prepared by impregnation of lanthanum salt. The adsorption mechanism of the adsorbent was investigated by XRD, SEM, XPS, and FT-IR. Through the study of fluorine removal performance, for the solution with fluoride ion concentration of 10mg·L-1, the fluorine removal efficiency of lanthanum-modified spherical magnesium oxide (15LSMO) (93.1%) with 15% impregnation mass ratio is higher than that of SMO (82.7%). In addition, in the pH range of 2-11 or in the presence of interfering ions, the fluoride removal effect of 15LSMO still meets the fluoride removal efficiency of more than 90%. The research enhanced the profound insights into the effect and mechanism of fluorine removal of lanthanum modified materials.

Achieving simultaneous removal of nitrogen and phosphorus in sediment via combined adsorption and oxygen supplement

Nutrients released from lake sediments contribute to the total nutrient load of an aquatic ecosystem. In this study, we used the oxygen-loaded lanthanum modified zeolites (LOZ) for absorbing internal phosphorus (P) and nitrogen (N) meanwhile with potential to trigger biological transformation of the nutrients. The results showed that the lanthanum modification of the zeolites manifested both the P and N adsorption in comparison to the pristine zeolites (enhanced by 129.13 % for PO43−-P and 27.53% for NH4+−N, respectively). In addition, lanthanum modified zeolites also exhibited the excellent oxygen-loading capability (0.73 mmol/g) than the pristine one. Apart from the blocking of P and N, the LOZ application over surface sediment substantially improved the benthic and aquatic DO level as the DO concentration in overlying water was 3–5 mg/L and diffused to 12 mm depth of sediment. The increased oxygen level in sediment favored the phosphate and Fe oxy(hydr)oxides combination and reduced FeS formation with subsequent decline in PO43−-P release from sediments. The improvement of water DO level also induced the microbial community shifts and promoted the abundance of nitrifiers in the surface sediment while denitrifiers in the deeper layer. Consequently, the release of total phosphorus and total nitrogen from the sediment to overlying water was reduced by 80% and 92%, respectively. Thus, the application of LOZ to sediment was beneficial to not only the anaerobic and aerobic processes that involved in nitrogen removal, but also the inactivation of phosphate. The study delivered positive outcomes regarding the control of internal nutrients release with a quick, efficient and sustainable remediation approach to rehabilitate polluted water systems.

Sludge-based biochar with lanthanum modification for phosphate recovery from wastewater streams

Sludge based biochar granules were prepared and modified with lanthanum for effective phosphate recovery from wastewater and anaerobic digestion liquid.

Phosphorus Binding by Lanthanum Modified Pyroaurite-like Clay: Performance and Mechanisms

In situ immobilization of phosphorus (P) by using P binding agents is a facile and effective strategy for eutrophication control. Currently, the most successful commercial agent (Phoslock, a lantha...

Effects of Lanthanum Modified Bentonite and Polyaluminium Chloride on the Environmental Variables in the Water and Sediment Phosphorus Form in Lake Yanglan, China

The application of lanthanum modified bentonite (Phoslock®) and polyaluminium chloride (PAC) is popular in the restoration of European temperate lakes; however, the effects of the application on the concentrations of phosphorus (P) in both the water and the sediments have been poorly evaluated to date. We studied the effects of the application of Phoslock® + PAC on the concentrations of total phosphorus (TP), particulate phosphorus (PP), soluble reactive phosphorus (SRP), total suspended solids (TSS) and chlorophyll a (Chla) in the water, and different P forms in the sediments, in an isolated part of Lake Yanglan. The results showed that the concentrations of TP, PP, SRP, TSS and Chla decreased significantly after the addition of Phoslock® + PAC. Moreover, the concentrations of labile-P, reductant-soluble-P and organic-P in the sediments were also significantly decreased after the Phoslock® + PAC application. However, the concentrations of both the stable apatite-P and residual-P in the sediments after application of Phoslock® + PAC were much higher than the pre-addition values, while the concentrations of metal-oxide-P did not differ significantly between the pre- and post- application conditions. Our findings imply that the combined application of Phoslock® and PAC can be used in the restoration of subtropical shallow lakes, to reduce the concentrations of P in the water and suppress the release of P from the sediments.

Inactivation of lead and zinc in sediment using lanthanum modified zeolite

Access accumulation of zinc and lead in sediment would be harmful to human beings. In the present study, Lanthanum Modified Zeolite (LMZ) was developed with fly ash and its binding capabilities toward zinc and lead were investigated. The Langmuir adsorption maximum of LMZ for Zn2+ and Pb2+ were 22.78 and 105.26 mg/g, higher or at least comparable to adsorbents developed in recent studies. Dosing LMZ to polluted sediment could transfer zinc and lead from environmental available forms to refractory form, and higher dosage would enhance the immobilization performance.

INTERACTION OF LANTHANE AND LUTETIUM AT TEMPERATURE 1500–1600°C

Materials based on La2O3–Lu2O3 system are promising candidates for a wide range of applications, but the phase relationship has not been studied systematically previously. To address this challenge, the subsection of the phase diagram for 1500 and 1600 °C have been elucidated. The samples of different compositions have been prepared from nitrate acid solutions by evaporation, drying and heat treatment at 1100, 1500 and 1600 °C. The phase relations in the binary La2O3–Lu2O3 system at 1500 and 1600 °C were studied from the heat treated samples using X-ray diffraction analysis and scanning electron microscopy in the overall concentration range. The X–ray analysis of the samples was performed by powder method using DRON-3 at room temperature (CuKa radiation). It was established that in the binary La2O3–Lu2O3 system there exist fields of solid solutions based on hexagonal (A) modification of La2O3, cubic (C) modification of Lu2O3, and with perovskite–type structure of LaLuO3 (R) with rhombic distortions. The systematic study that covered whole composition range excluded formation of new phases. The systematic study that covered whole composition range excluded formation of new phases. The boundaries of mutual solubility and concentration dependences the lattice parameters for all phases have been determined. The solubility of Lu2O3 in the hexagonal А–lanthanum modification is ~ 9 mol. % at 1500 and 1600 °С. The solubility of La2O3 in the cubic C–Lu2O3 is ~ 4 mol. % at 1500 and 7 mol. % at 1600 °С.

Adsorption of chlortetracycline from aquaculture wastewater using modified zeolites

In this study, lanthanum modified zeolite (La-Z) was used to adsorb chlortetracycline (CTC) from aquaculture wastewater. La-Z was characterized by SEM, TEM, EDS, XRD, FTIR and BET. The effects various factors on the adsorption of CTC by La-Z were investigated, including the lanthanum modification concentration on zeolites, the dosage of La-Z, solution pH and reaction time. Orthogonal experiments were performed to determine the optimal adsorption conditions. Adsorption kinetics were studied by quasi-first-order model, quasi-second-order model, Weber-Morris, Boyd and Bangham models, while isotherms were analyzed by the Langmuir and Freundlich models. The removal rate reached 98.4%, when the modified concentration was 0.02 mol/L, the adsorbent dosage was 0.04 g, the initial concentration of CTC was 5 mg/L, the adsorption time was 20 min, and the pH was 7. The initial CTC concentration had the greatest influence on the adsorption process. The kinetic results showed a significant linear correlation between the experimental results and the quasi-second-order kinetic model. From the results of the internal diffusion model, it was found that the La-Z adsorption rate was controlled by both internal diffusion and external diffusion, in a multi-step process. The adsorption isotherm conforms to the Langmuir model, with the maximum adsorption quantity reaching 127.55 mg/g. Thermodynamic analysis showed that the adsorption process was an endothermic process of entropy increase, which occurs spontaneously.

Lanthanum modification of crystalline phases and residual glass in augite glass ceramics produced with industrial solid wastes

The effects of La2O3 on microstructure and properties of the CaO-MgO-SiO2-Al2O3 glass ceramics, made from Bayan Obo West Mine tailing and fly ash, were investigated. Results showed that La2O3 additions up to 2 wt% promoted augite crystallization. Above this concentration, La2O3 suppressed augite crystallization by rather forming lanthanum oxyapatite that acted as a barrier for the growth of augite. Also Cr ions, the key element for the augite nuclei, were enriched in lanthanum oxyapatite. The La3+ cations were found to partially substitute for Ca2+ at the M2 structural sites in clinopyroxene (augite). Nano crystalline clusters, containing La3+, Na+, Ca2+, Mg2+ and Fe3+ in augite-like proportions, were found uniformly dispersed in the residual glassy phase. The glass ceramic with 2 wt% La2O3 shows optimum mechanical properties and chemical durability. The bending strength and Vickers hardness are 238 MPa and 7.57 GPa, acid and alkali-resistance are 97.5% and 98.9%, respectively.

A simple method to improve the adsorption properties of drinking water treatment residue by lanthanum modification

The loading of La can substantially enhance the adsorption capability of drinking water treatment residue (DWTR) for better recycling. Normally, the modification was based on incubation of DWTR and La solution at a certain ratio, following by solid-liquid separation and drying processes. This study attempted to simplify La loading procedures by adopting high ratio of DWTR and La solution to eliminate the solid-liquid separation, aiming to promote the potential actual production. According to the results of the short- (2 d) and long-term (30 d) P adsorption tests, the N2 gas sorption and desorption analysis, the X-ray photoelectron spectroscopy analysis, and the metal fractionation, the substantial enhanced adsorption capability of the modified DWTR was maintained and the La loading mechanisms to DWTR changed little after eliminating solid-liquid separation processes during modification; typically, La loading increased the initial P adsorption rates from 1.00 (raw DWTR) to 6.08 and 6.03 mg g-1 d-1 for the modified DWTR with and without the separation processes. Furthermore, the DWTR before and after modification had little unfavorable effect on the survival of snail Bellamya aeruginosa, while eliminating the separation processes tended to reduce the bioavailability of Al, Fe, and La in the modified DWTR. These results demonstrated that solid-liquid separation was not the key step for DWTR modification and that the developed simple modification method was feasible for La loading to DWTR, promoting the beneficial recycling in environmental remediation.

Key Role of Lanthanum Oxychloride: Promotional Effects of Lanthanum in NiLaOy /NaCl for Hydrogen Production from Ethyl Acetate and Water.

The hydrogen economy is accelerating technological evolutions toward highly efficient hydrogen production. In this work, the catalytic performance of NiO/NaCl for hydrogen production via autothermal reforming of ethyl acetate and water is further improved through lanthanum modification, and the resulted 3%-NiLaOy /NaCl catalyst achieves as high as 93% H2 selectivity and long-term stability at 600 °C. The promoting effect is caused by the strong interactions between lanthanum and NiO/NaCl, by which LaNiO3 and a novel LaOCl phase are formed. The key role of LaOCl in promoting low-temperature hydrogen production is highlighted, while effects of LaNiO3 are well known. The LaOCl (010) facet possesses high adsorption capacity toward co-chemisorbing ethyl acetate and water. LaOCl strongly interacts with ethyl acetate and H2 O in the form of hydrogen bonding and coordination effect. The interactions induce tensions inside ethyl acetate and H2 O, activate the molecules, and hence decrease the energy barrier for reaction. In situ Fourier transform infrared spectroscopy (FTIR) reveals that LaOCl along with NaCl enhances the adsorption ability of NiO/NaCl. Moreover, LaOCl improves the dispersion of Ni species in NiO-LaNiO3 -LaOCl nanosheets, which possess abundant active sites. The effects together promote hydrogen evolution. Furthermore, the NiLaOy /NaCl catalyst can be easily reborn after deactivation due to the water solubility of NaCl.

Mechanism of As(Ⅴ)Removal from Water by Lanthanum and Cerium Modified Biochars

Loaded lanthanum or cerium biochars were prepared by one step pyrolysis of La (NO3)3-laden or Ce (NO3)3-laden rice hulls and were employed for enhancing the adsorption of As (Ⅴ) from water. In contrast with BC and Ce-BC in this study, La-BC had better adsorption capacity in the acidic condition. The maximum adsorption capacity could reach 20.1 mg ·g-1. With increased pH, the adsorption capacity of La-BC was reduced. The highest adsorption capacity reached 39.1 mg ·g-1 (pH=5) and the lowest was 17.6 mg ·g-1 (pH=9). The resulting La-BC with As (Ⅴ) adsorption was characterized by SEM-EDS, FTIR, and XPS. There were two types of active adsorption sites for As (Ⅴ), oxygen-rich functional groups and lanthanum oxide. Although Ce-BC had oxygen-rich functional groups and cerium oxide, it was unable to participate in the adsorption of As (Ⅴ) from water.

Glycerol hydrogenolysis over ruthenium supported on lanthanum modified ZrO2 catalysts

2Ru/x%La-ZrO2 catalysts with different lanthanum contents (x = 0.0, 0.5, 1.0, 2.5, 5.0 10.0) were prepared by the deposition precipitation method and were characterized by XRD, BET surface area, CO chemisorption, CO2-TPD, NH3-TPD, TEM and XPS to determine the effect of lanthanum modification on the catalyst. Then these catalysts were used in the hydrogenolysis of glycerol in the aqueous phase at 190 °C for 8 h. It was found that the lanthanum modification could significantly improve the catalytic efficiency and the 2Ru/1.0%La-ZrO2 catalyst had the highest glycerol conversion and the strongest C–C cleavage ability. The comparison of the catalytic performances of individual catalysts with their physico-chemical characteristics led to the conclusion that the formation of Ruδ− particles, the better dispersion and the improvement of surface acidity and alkalinity had the highest potential for the improvement of the catalytic efficiency. Under the optimized reaction conditions, the reaction over the 2Ru/1.0%La-ZrO2 catalyst obtained the highest EG selectivity 55% and a good conversion of glycerol in less reaction time.