Enhanced Phosphate Adsorption Research Articles

Nanoconfinement of MgO in nitrogen pre-doped biochar for enhanced phosphate adsorption: Performance and mechanism

Advanced metal-doped biochar with superior phosphate (P) adsorption capacity plays a crucial role in combating eutrophication, depending on the rational design of the biochar structure for uniform and nanoscale dispersion of metal oxides. Herein, the nanoconfinement of magnesium oxide (MgO) was successfully attained in nitrogen pre-doped biochar (Mg/N-BC). The well-dispersed MgO was confined within nanoscale structure of Mg/N-BC, delivering P adsorption capacity of 108.41 mg g−1 and adsorption rate of 18.01 mg g-1h−1. More importantly, its adsorption performance at equilibrium 0.5 mg P/L was 17.70 times higher. Results suggested the decrease in pore size was positively correlated with the increase of N, confirming the role of N pre-doping in structure shaping and MgO confinement. The enhanced P adsorption was attributed to the well-dispersed MgO nanoparticles within the biochar. This study introduced a facile synthesis approach for biochar-incorporated nanoscale MgO, offering a new strategy for enhanced P removal.

Expansion of d-spacing of boehmite for enhanced phosphate adsorption via hydrogen bond network

The optimization of the interlayer water content to increase the d-spacing of layered materials has recently attracted interest in pollutant removal. Several studies have explored phosphate adsorption onto boehmite considering its high surface area; however, the influence of its d-spacing on the adsorption performance remains unexplored. Therefore, our study aimed to investigate the impact of the synthesis pH of boehmite on the d-spacing and adsorption performance of phosphate ions. For this purpose, boehmite samples were synthesized under various pH conditions at 100°C to be tested for phosphate adsorption. As a result of this mild synthesis condition, the number of reactive hydroxyl groups in boehmite samples ranged from 7.02 – 9.02mmol/g, nearly four times higher than the reported boehmites. Boehmite prepared under acidic conditions exhibits a relatively high interlayer water content and an enlarged d-spacing from 0.640 to 0.996nm, resulting in superior phosphate adsorption (215mg/g) within one minute. We also confirmed that phosphate adsorption increased the binding energy states of aluminum and oxygen in boehmite, indicating a robust hydrogen bond network with phosphate ions in the inner space. In contrast, the adsorption decreased the binding energy for other types of boehmite, indicating charge interaction. Competitive adsorption tests also showed the strong affinity of boehmite for phosphate ions, even in the presence of fluoride ions. These findings highlight the importance of the interlayer water molecules in controlling the d-spacing of boehmite, indicating their critical role in removing anions from water.

Enhanced phosphate adsorption using Zr-Al and Ce-Al binary oxide nanoparticles

In addressing eutrophication resulting from phosphate accumulation, multi-metallic oxides often outperform single-metallic oxides in phosphate adsorption capacity. While alumina is abundant, its stability in acidic or alkaline environments is limited. Contrastingly, zirconium and cerium oxides demonstrate superior acid and base resistance, alongside specific phosphate affinity. This study focuses on the synthesis of Zr-Al and Ce-Al binary oxide nanoparticles through a sol-gel approach for phosphate removal from aqueous solutions, evaluating their efficiency through batch experiments. By judiciously adjusting the Zr/Al and Ce/Al ratios, binary oxide nanoparticles with distinct structures, grain sizes, surface characteristics, and phosphate adsorption properties were fabricated. Results indicate that Zr(3)Al(10) and Ce(3)Al(10) nanoparticles exhibit optimal phosphate adsorption properties among Zr-Al binary oxide variants and Ce-Al binary oxide counterparts, respectively. Kinetic data conform to the pseudo-second-order model for phosphate adsorption on Zr(3)Al(10) and Ce(3)Al(10), while equilibrium adsorption isotherms align with the Langmuir model. Phosphate adsorption capacities reached 83 mg/g for Zr(3)Al(10) and 210 mg/g for Ce(3)Al(10), positioning them as potent adsorbents. Coexisting anions minimally influence phosphate adsorption on Zr(3)Al(10) and Ce(3)Al(10) nanoparticles, indicating high selectivity towards phosphate, whereas Ca2+ and Mg2+ ions notably enhance phosphate adsorption. Mechanistically, phosphate adsorption on both nanoparticles follows electrostatic attraction, ligand exchange, and inner-sphere complexation, with surface-OH groups playing a pivotal role. Leveraging the advantageous properties of their parent materials, Zr-Al and Ce-Al binary oxide adsorbents exhibit synergistic effects, enhancing their potential for phosphate removal.

Enhanced Phosphate Adsorption by Cerium-Doped Porous Boron Nitride Nanosheets

Enhanced Phosphate Adsorption by Cerium-Doped Porous Boron Nitride Nanosheets

Structural insights into amino-modified defective UiO-67: Enhancing phosphate adsorption through multiple active sites synergistic interactions

Zirconium-based Metal-Organic Frameworks (Zr-MOFs) have attracted significant attention for phosphate removal due to their large specific surface area and abundant active sites. In this study, amino-modified Zr-MOFs were synthesized and used for phosphate removal, with a focus on investigating the relationship between the physicochemical structure of the amino-modified Zr-MOFs and phosphate adsorption, as well as the role of the amino groups. A series of amino-modified Zr-MOFs (UiO-67) were synthesized and characterized, with particular emphasis on the variant with one amino group functionalization on a defect-rich framework, designated as DUN. The results reveal that amino modification of defective UiO-67 (DUN) increases the number of phosphate adsorption sites per unit mass and specific surface area, thereby enhancing phosphate adsorption capacity, which is significantly higher than that of other synthesized UiO-67 variants. The role of amino group not only enhances the affinity for phosphate and the adsorption efficiency at low phosphate concentrations but also accelerates the phosphate adsorption rate. Through comprehensive characterization and DFT simulations, the superior performance of DUN is primarily attributed to the synergistic effects of its structural defects, carboxyl groups, and introduced amino functionalities. The defects at Zr nodes in DUN contribute significantly to phosphate adsorption by providing Zr-OH groups and oxygen vacancies. Concurrently, the carboxyl groups present in the DUN's ligand linkers engage in hydrogen bonding interactions with phosphate. The amino groups, a novel addition to the DUN structure, not only provide additional adsorption sites but also significantly enhance the strength of the existing hydrogen bonds and the Zr-O-P coordination interactions. This study sheds light on the intricate relationship between the physicochemical structure of Zr-MOFs and their phosphate adsorption capacity, providing a theoretical basis and practical approach for developing efficient Zr-MOF-based adsorbents for water purification.

Facile and scalable synthesis of long-life porous MgO-nanofiber functionalized biochar adsorbent from magnesite for phosphate recycling

The recycling of phosphate from wastewater using regenerable and highly efficient MgO-modified biochar for Mg-P fertilizer application is of great interest. However, the practical application of MgO-modified biochar for the removal and recycling of phosphate is hindered by its short-recycled service-life. Herein, a facile yet scalable method is proposed to fabricate porous MgO nanofiber-functionalized biochar (PMgNF-BC) with enhanced phosphate adsorption and regeneration performances from wastewater using waste biomass and magnesite. The as-prepared PMgNF-BC exhibited the maximum phosphate adsorption capacities of 594.53, 661.57, and 725.43 mg/g at 298.15 K, 308.15 K and 318.15 K, respectively. More importantly, PMgNF-BC demonstrated excellent regeneration performance with the removal efficiency of 84.2 % after eight regeneration cycles. Furthermore, the regenerated PMgNF-BC exhibited the well-preserved fiber shape of MgO on BC, enabling splendid regeneration performance. This work validates PMgNF-BC as a sustainable adsorbent for recycling phosphorus from wastewater, addressing the urgent need for synthesizing biochar with high regeneration performance.

Porous red mud ceramsite for aquatic phosphorus removal: Application in constructed wetlands

Red mud (RM) and spent oyster mushroom substrate (SOMS), by-products of industrial and agricultural production, can be recycled for polluted freshwater purification, bringing about a win-win situation. In this study, unacidified RM and RM acidified with oxalic acid (O-RM) and hydrochloric acid (H-RM), respectively, were mixed with SOMS to produce a porous ceramsite as a potential constructed wetlands (CWs) substrate. The results showed that the O-RM, H-RM, and RM ceramsites displayed fine compressive strengths of 7.75 ± 1.14, 8.40 ± 1.30, and 8.84 ± 0.69 MPa after calcining at 950 °C for 30 min, respectively. The phosphorus adsorption capacities of H-RM, O-RM, and RM ceramsite at a solid-liquid ratio of 25 g/L were 1.18 mg/g, 0.88 mg/g, and 1.06 mg/g, respectively. Toxicity release experiments showed that the ceramsites did not cause secondary environmental pollution, except for arsenic (ranging from 0.210 to 0.238 mg/L). The H-RM ceramsite was tested in a tidal flow-vertical flow CW (TF-VFCW) with Iris pseudacorus L. and Canna indica L plants. In the TF-VFCW, the average chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), total nitrogen (TN), and total phosphorus (TP) removal rates were 81.01, 90.25, 66.90, and 77.32 %, respectively. Plant growth had less impact on COD and NH4-N removal but had greater limited TN and TP removal. Scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction analysis confirmed that acid pretreatment and the incorporation of SOMS significantly increased the surface and interior porous structures of the ceramsite and enhanced phosphate adsorption by the polyhydroxyl aluminum-iron complex ions. Bacteroides and Campylobacter used the energy produced during polyhydroxyalkanoic acid (PHA) catabolism to absorb phosphorus. Therefore, the synergistic effect of the substrate, plants, and microorganisms achieved the removal of phosphorus from CWs and offered effective and environmentally friendly recycling of RM and SOMS.

A novel Ce/Fe bimetallic metal-organic framework with ortho-dodecahedral multilevel structure for enhanced phosphate adsorption

The synthesis of novel Ce/Fe bimetallic metal–organic frameworks (Ce/FcDA/FA-MOFs) via an innovative hydrothermal method is reported. This method utilizes Ce as the central metal and 1,1′-ferrocene dicarboxylic acid (FcDA) and formic acid (FA) as ligands. Optimization of hydrothermal time, feed ratio, and the addition of FA yielded Ce/FcDA/FA-MOFs with ideal ortho-dodecahedral hierarchical configurations. Comprehensive characterization via FT-IR, XRD, SEM, EDS, XPS, and N2 adsorption/desorption analyses elucidated the influence of FA on morphology and chemical structure. Phosphate adsorption tests on Ce/FcDA/FA-MOFs revealed sustained strong selectivity and adsorption capacity, even in the presence of coexisting anions and variations in pH. Kinetic, thermodynamic, and isothermal simulations indicated spontaneous, efficient, and heat-absorbing phosphate adsorption properties on Ce/FcDA/FA-MOFs. Fitting parameters from the Langmuir adsorption model demonstrated a maximum adsorption capacity of up to 530.25 mg g−1, attributed to physical/chemical adsorption during the reaction. Furthermore, investigation into the adsorption mechanism of Ce/FcDA/FA-MOFs on phosphate through FT-IR, XRD, and XPS analyses of the adsorbed samples revealed a complex process involving the electrostatic mutual attraction of outer-sphere entities and ligand exchange in the inner-sphere. This study advances our understanding of Ce/FcDA/FA-MOFs as effective adsorbents for phosphate and contributes to the development of environmentally sustainable materials with potential applications in water treatment.

Nanoscale MgO confined in magnetic biochar via two-step pyrolysis for enhanced phosphate adsorption

The confinement of nano-MgO within magnetic biochar represents a promising strategy to enhance phosphate (P) adsorption performance. Nevertheless, the inherent agglomeration tendency of MgO within magnetic biochar has been identified as a significant impediment to its P adsorption efficiency. In this study, the nano-MgO was confined within magnetic biochar via a novel two-step pyrolysis process involving KHCO3 and HNO3 activation. This novel fabrication process resulted in a reduction in pore size and an increase in the negatively charged surface, facilitating the controlled formation of nano-MgO. The results demonstrated a uniform dispersion of nano-MgO crystals, with their size reduced to less than 10 nm. The P adsorption capacity reached 83.06 mg/g, which was 2.98 times higher than that of biochar via one-step pyrolysis. The mechanism study suggested that the chemical reaction was the driving force in P adsorption on biochar. Collectively, this research provides a feasible path to the successful confinement of nano-MgO in magnetic biochar, resulting in enhanced P adsorption performance.

Efficiency and mechanism of phosphate adsorption and desorption of a novel Mg-loaded biochar material.

Phosphate removal is complicated by the need for resource recovery. Biochar shows promise for efficient phosphate adsorption, but it must be modified to enhance its adsorption capacity. In this work, magnesium (Mg)-loaded biochar was synthesized through a two-step dipping and calcination process, and the MgBC600 product was used to adsorb phosphate from simulated water and biogas slurry wastewater. The phosphate adsorption capacity of Mg-loaded biochar was 109.35mg/g, which was 12 times higher than that of unmodified biochar. The R2 of the Langmuir and pseudo-second-order kinetic models were 0.988 and 0.990, respectively, which fitted the phosphate adsorption process of MgBC600. Phosphate adsorption by MgBC600 was a spontaneous and endothermic process. The adsorption mechanism study showed that phosphate adsorption was controlled by the formation and electrostatic attraction of MgHPO4. In addition, 98% of chemically adsorbed phosphate was released after regeneration. Using phosphate-adsorbed MgBC600 as a soil amendment, Arabidopsis thaliana was 1.47 times higher than that in the biochar-only group, demonstrating that this is a promising strategy for enhancing phosphate adsorption efficiency and adsorbent recycling.

Enhanced phosphate adsorption and desorption characteristics of MgO-modified biochars prepared via direct co-pyrolysis of MgO and raw materials

Biochar modified by metal ions—particularly Mg—is typically used for the effective recovery of phosphorous. In this study, MgO-modified biochars were synthesized via the direct co-pyrolysis of MgO and raw materials such as rice straw, corn straw, Camellia oleifera shells, and branches from garden waste, which were labeled as MRS, MCS, MOT, and MGW, respectively. The resulting phosphate (PO) adsorption capacities and potential adsorption mechanisms were analyzed. The PO adsorption capacities of the biochars were significantly improved after the modification with MgO: MRS (24.71 ± 0.32 mg/g) > MGW (23.55 ± 0.46 mg/g) > MOT (15.23 ± 0.19 mg/g) > MCS (14.12 ± 0.21 mg/g). PO adsorption on the modified biochars was controlled by physical adsorption, precipitation, and surface inner-sphere complexation processes, although no electrostatic attraction was observed. Furthermore, PO adsorbed on modified biochars could be released under acidic, alkaline, and neutral conditions. The desorption efficiency of MRS was modest, indicating its suitability as a slow-release fertilizer.Graphical

Performance of novel pillared eggshell-bentonite clay bio-composite for enhanced phosphate adsorption from aqueous media

Modified clay mineral is a potential technique for phosphorus adsorption and has received much attention in the high phosphate pollution witnessing regions. In the present work, an iron-pillared eggshell-modified bentonite clay bio composite (IP-ESMB) is used to test the adsorption of phosphate from the aqueous medium. The characteristics of the prepared IP-ESMB bio composite were analyzed using XRF, SEM, EDX, FTIR, XRD, BET, TG and DTG analysis to study its physicochemical characteristics. The diffusion process, electrostatic interaction, and ion exchange mechanisms work in concert to remove the phosphate ions effectively at a pH of 3.0. The adsorption capacity is influenced by the initial phosphate concentrations, adsorbent dose (2 g/L), contact time (50 min), temperature (303 K) and pH (3.0) of the solution. Kinetic studies revealed that the pseudo-second-order model best described the experimental data. The Langmuir isotherm model provided the best fit for the equilibrium isotherm data of the IP-ESMB, and the determined Q0 value was found to be 60.51 mg/g at pH 3.0 and 30 0C. The reaction was endothermic and spontaneous, according to thermodynamic analysis, with overall changes in enthalpy (ΔH0) and entropy (ΔG0) of 10.08 KJmol-1 and 0.09 KJmol−1K−1, respectively. It is also found that the IP-ESMB bio composite has excellent reusability over several adsorption cycles. Designing an adsorption reactor provides another means of calibrating the performance of the created bio-composite during factorial operations. This study confirms that to curb eutrophication in a natural water system, the present modified clay mineral can efficiently act as a green adsorbent.

Optimized Ca-Al-La modified biochar with rapid and efficient phosphate removal performance and excellent pH stability

Biochar-based adsorbents for phosphate removal from wastewater has gained increasing attention and achieved significant progress. However, there is still much room for the enhancement on adsorption performance in terms of removal rate, adsorption capacity and pH application range. Herein, novel Ca-Al-La modified biochar adsorbents in this study were synthesized for enhancing phosphate adsorption in wastewater. The synthesis parameters of adsorbents were optimized by using the response surface methodology (RSM). The Ca-Al-La modified biochar adsorbent synthesized under the optimal conditions (CAL-MBC) exhibited superior adsorption capability towards phosphate. Specifically, CAL-MBC achieved a rapid removal rate to reach the adsorption equilibrium within 1 h, a maximum phosphate adsorption capacity of 152.9 mg/g, and excellent pH stability within a broad pH range of 3.0–11.0. The adsorption mechanisms involving electrostatic interaction, precipitation and inner-sphere complexation via ligand exchange were responsible for the excellent adsorption performance of phosphate on CAL-MBC. This study verifies CAL-MBC as a promising metal modified biochar adsorbent to enhance phosphate removal from wastewater.

Green and Efficient Al-Doped LaFexAl1–xO3 Perovskite Oxide for Enhanced Phosphate Adsorption with Creation of Oxygen Vacancies

La-based metal oxide materials are environmentally friendly and show promise for phosphate adsorption. A series of Al-doped perovskite oxides, such as LaFexAl1-xO3, were prepared using a facile citric acid-assisted sol-gel method. The characterization results demonstrated that with optimized Al doping, there was a significant increase in the specific surface area and increased defect content of perovskite oxide LaFexAl1-xO3. Adsorption experiments showed that the performance of phosphate removal by LaFexAl1-xO3 was largely enhanced due to the improved adsorption capacity, which is maximum eight times higher compared with control perovskites prepared under neutral conditions. The mass transfer rate for adsorption was considerably boosted with phosphate removal within the initial 15 min. Spectroscopy analysis and density functional theory calculation results showed that the process of phosphate removal by the Al-doped perovskite oxides LaFexAl1-xO3 involved electrostatic interactions, an inner-sphere complex, and surface oxygen vacancies, among which the creation of oxygen vacancies caused by the Al doping was the predominant mechanism for reducing the bonding barrier during adsorption and generating adsorption sites. The results enable the development of a green and efficient perovskite adsorbent with a La-based perovskite material for phosphorus removal.

Enhanced phosphate adsorption studies on several metal-modified aluminum sludge: preparation optimization, adsorption behavior, and mechanistic insight.

To solve the problems such as water eutrophication caused by excess phosphorus, the potential residual value of aluminum sludge was fully exploited and its phosphate adsorption capacity was further improved. In this study, twelve metal-modified aluminum sludge materials were prepared by co-precipitation method. Among them, Ce-WTR, La-WTR, Y-WTR, Zr-WTR, and Zn-WTR showed excellent adsorption capacity for phosphate. The adsorption performance of Ce-WTR on phosphate was twice that of the native sludge. The enhanced adsorption mechanism of metal modification on phosphate was investigated. The characterization results showed that the increase in specific surface area after metal modification was 9.64, 7.5, 7.29, 3, and 1.5 times, respectively. The adsorption of phosphate by WTR and Zn-WTR was in the accordance with Langmuir model, while the others were more following the Freundlich model (R2 > 0.991). The effects of dosage, pH, and anion on phosphate adsorption were investigated. The surface hydroxyl groups and metal (hydrogen) oxides played an important role in the adsorption process. The adsorption mechanism involves physical adsorption, electrostatic attraction, ligand exchange, and hydrogen bonding. This study provides new ideas for the resource utilization of aluminum sludge and theoretical support for preparing novel adsorbents for efficient phosphate removal.

Pyrolysis of Ca/Fe-rich antibiotic fermentation residues into biochars for efficient phosphate removal/recovery from wastewater: Turning hazardous waste to phosphorous fertilizer

Ca/Fe-rich antibiotic fermentation residues (AFRs), a type of hazardous waste, can be regarded as recyclable biomass and metal resources. However, concurrent detoxification and reutilization of biomass and metals resources from AFRs have never been reported before. In this study, Ca/Fe-rich vancomycin fermentation residues were pyrolyzed into biochar to adsorb phosphate for the first time. The residual vancomycin and antibiotic resistance genes were completely decomposed during pyrolysis. The resultant Ca/Fe-rich biochar exhibited excellent performance at adsorbing phosphate without further modifications. The process had rapid kinetics and a maximum adsorption capacity of 102 mg P/g. Ca and Fe were the active sites, whereas different mechanisms were observed under acidic and alkaline conditions. Surprisingly, HCO3− enhanced phosphate adsorption with an increase of adsorption capacity from 43.9 to 71.0 mg/g when HCO3− concentration increased from 1 to 10 mM. Furthermore, actual wastewater could be effectively treated by the biochar. The phosphate-rich spent biochar significantly promoted seed germination (germination rate: 96.7 % vs. 80.0 % in control group, p < 0.01) and seedling growth (shoot length was increased by 57.9 %, p < 0.01) due to the slow release of bioavailable phosphate, and thus could be potentially used as a phosphorous fertilizer. Consequently, the hazardous waste was turned into phosphorous fertilizer, with the additional benefits of detoxifying AFRs, reutilizing biomass and metal resources from AFRs, controlling phosphate pollution, and recovering phosphate from wastewater.

Enhancing phosphate removal performance in water using La–Ca/Fe–LDH: La loading alleviates ineffective stacking of laminates and increases the number of active adsorption sites

Increasing the number of adsorption sites in layered bimetallic hydroxide (LDH), which is frequently used for phosphate removal in water, is a crucial step in enhancing phosphate adsorption. In this study, we investigate whether lanthanum (La) metal loading can improve the phosphate adsorption capacity of LDH. Based on Ca/Fe–LDH prepared through coprecipitation, a La–Ca/Fe–LDH composite is fabricated by La loading through impregnation. The adsorption capacity of La–Ca/Fe–LDH is 11.4% higher than that of Ca/Fe–LDH. The magnitude of adsorption and accelerated rate of adsorption of La–Ca/Fe–LDH satisfy the quasi-second-order kinetic and Langmuir isothermal equations. When comparing La–Ca/Fe–LDH to Ca/Fe–LDH, the adsorption capacity increased by 3.3%–328.39% in the pH range of 3–11; additionally, the resistance to pH influence and coexisting ion interference was considerably enhanced. However, under the coexistence of Cl−, NO3−, CO32−, SO42−, and F−, the adsorption capacity increased by 20.59%–27.6%. After three cycles of desorption, the phosphate removal abilit till increased by 11%, and the magnetic property was suitable for separation. The improvement of La–Ca/Fe–LDH adsorption capacity is attributed to the relief of ineffective stacking of LDH laminates and increased number of adsorption sites. The primary causes of adsorption are ion exchange, electrostatic attraction, and ligand exchange. In this study, a novel technique for enhancing LDH adsorption capability is proposed. This technique has numerous potential applications related to adsorbents in water treatment.

Enhanced Phosphate Adsorption by Mg-Stirred Leaf Biochar in a Complex Water Matrix via Active MgO Facet Exposure

Enhanced Phosphate Adsorption by Mg-Stirred Leaf Biochar in a Complex Water Matrix via Active MgO Facet Exposure

Production of magnetic biochar-steel dust composites for enhanced phosphate adsorption

In this study, a new low-cost magnetic composite comprising biochar-steel dust wastes was fabricated by the facile co-pyrolysis method at different proportions of steel dust wastes. The performance of the magnetic composite was investigated for the adsorption of phosphate from water. The physicochemical characteristics of the magnetic composite indicate an effective coupling of the steel dust into a biochar matrix leading to improved crystallinity, surface heterogeneity, and functional groups (CO, CC, and metal oxides). The proportion of the steel dust significantly influenced the adsorptive characteristics of the magnetic biochar-steel dust composite. The synergistic effect of the biochar and steel dust facilitated enhanced phosphate adsorption compared to the pristine biochar and steel dust. Pseudo-second order model well-described the kinetics of the phosphate adsorption, while the isotherm results showed better fitting with the Redlich Peterson model (R2 > 0.999). The maximum monolayer adsorption capacity of 175.23 mg/g was achieved at pH 4, 240 min, and 25 °C, higher than many other similar magnetic adsorbents. The magnetic biochar composite exhibited excellent phosphate removal with just ~10% reduction in the presence of co-existing ions (SO42−, CO32− and HCO3−). The high reusability performance of the magnetic composite for up to five cycles implies that the composite possessed great potential for low cost and sustainable remediation of phosphate from water streams.

An in situ grown amorphous ZrO2 layer on zeolite for enhanced phosphate adsorption.

Zeolite supported amorphous metal oxide nanolayers with high specific surface area, abundant adsorption sites, and excellent reusability hold a bright prospect in the efficient removal of contaminants, yet it is proven to be still challenging to precisely regulate and control their synthesis. Herein, we reported a facile synthetic strategy for rational design and achieving the uniform and firm in situ growth of an amorphous ZrO2 layer decorated on the surface of zeolite (ZEO@AZ) for enhanced phosphate adsorption. The Langmuir isotherm model and pseudo-second order kinetic equation well described the adsorption process towards phosphate solution, and the synthetized ZEO@AZ exhibited an excellent maximum adsorption amount of 24.98 mgP g−1. Furthermore, the adsorption of phosphates on ZEO@AZ was confirmed to be chemisorption, endothermic and spontaneous. This approach for fabricating amorphous metal oxide nanolayers on a robust matrix may provide a new route for constructing composites with superb phosphate adsorption performance.