Layered Double Hydroxide Adsorbent Research Articles

New insights into removal efficacy of perfluoroalkyl substances by layered double hydroxide and its composite materials

Though the use of per-and polyfluoroalkyl substances (PFAS) is strictly restricted worldwide, PFAS have been increasingly detected in aqueous environment with high human exposure risk. Effective PFAS remediation requires the simultaneous concentration and decomposition of these compounds from dilute solutions, presenting a significant challenge. The present work evaluated the suitability of layered double hydroxide (LDH) materials, promising adsorbents for anionic pollutants, for the removal of long-chain and short-chain PFAS in micro-polluted water. Additionally, it explored their potential for PFAS degradation after modification. The results suggested that LDH adsorbents have limited ability to extract short-chain PFAS such as perfluorobutane sulfonate (PFBS) from water matrices, especially in dilute solutions. Although organic modification of LDHs could enhance their uptake efficacy on PFAS, it cannot improve the decomposition of PFAS. Innovatively, a composite featuring zero-valent iron (ZVI) particles coupled with LDH was developed, in which the nanoscale ZVI core is coated with LDH to adsorb and decompose perfluorooctanoic acid (PFOA) synergistically. Characterization of the composite showed that LDH coating not only hinders the aggregation of ZVI particles, but also reduces the passivation of ZVI. The PFOA removal efficacy of the composite can be further facilitated in acid environment. By-product analysis revealed that the composite decomposed PFOA mainly through decarboxylation and formation of unstable alcohol.

Defects-rich MgFe LDH: A high-capacity adsorbent for methyl orange wastewater

Dye pollution is a common pollutant in wastewater that poses a serious threat to human health. Layered double hydroxide (LDH) is a commonly used adsorbent for dye removal. However, its adsorption efficiency is significantly limited by the limited adsorption active sites of the adsorbent. In this paper, a defects-rich MgFe LDH adsorbent for anionic dye wastewater was synthesized by a simple hydrothermal method and alkaline etching. Different analytical techniques, such as XRD, FT-IR, SEM, TEM, XPS, and N2 adsorption-desorption isotherm, were used to verify the chemical composition and surface characteristics of the materials, and the effects of pH, temperature, and contact time on the adsorption effect of methyl orange and the adsorption mechanism were analyzed. Alkaline etching of Al and Zn in the laminate generated defects that expose unsaturated coordination centers and create abundant adsorption sites, which can electrostatically attract and coordinate with dye ions. At 25°C, the adsorption capacity of MgFe LDH with Al etched and MgFe LDH with Zn etched for methyl orange dye reached 1722 mg/g and 1685 mg/g, respectively, much higher than that of MgFe LDH (544 mg/g). This work provides a promising method for the removal of dye wastewater by adsorption and a new idea for the design and development of high-performance dye wastewater adsorbents.

Efficacy of Mg-Al-layered double hydroxide nano-adsorbents for a multi-anionic mixed dye solution

Through this work, we show the efficacy of Mg-Al layered double hydroxide (LDH) as an efficient multi-anionic toxic dye adsorbent. Contrary to typical dye adsorption experiments where a single dye is usually tested for checking the potency of a particular adsorbent, eight different (anionic) dyes (comprising of anionic, reactive, azo, and acid dyes) were blended into one dye solution so that it can closely mimic a wastewater effluent of anionic dyes. With LDH adsorbent, the dye adsorption experiments depicted ∼ 100 % dye removal for all eight individual dye solutions along with the mixed dye solution in just two minutes.

Rapid and efficient removal of phosphate by La-doped layered double hydroxide/biochar from aqueous solution

Layered double hydroxide (LDH) is frequently used for phosphate removal in water, while a desirable LDH adsorbent should have sufficiently high adsorption capacity and selectivity.

Hierarchical flower-like MgAl layered double hydroxide microparticles as phosphate porter for its recovery from phosphate-contaminated water

Layered double hydroxide (LDH) represents an important class of adsorbents for phosphate (P) recovery from water, but the scale application remains challenged by the scarcity of LDH adsorbents with balanced adsorption capacity and settling performance. Herein we developed the three-dimensional MgxAl100-x-LDH microparticles (∼4 μm) with hierarchical flower-like structure and controlled compositions, which delivered fast P adsorption (equilibrium time < 5 min), large P adsorption capacities (108.8 mg g−1 by Mg60Al40-LDH) and better settling performances than the nanoscale LDH counterpart. The mechanistic study revealed that the robust adsorption performance of MgAl-LDH was attributed to the efficient anion exchange of P with the intercalated anions (Cl− and CO32−) in LDH. Owing to the exchangeability of intercalated P with the concentrated CO32− in aqueous solution, we demonstrated that almost all the P adsorbed in LDH could be recovered in 1.0 M Na2CO3 solution, and the cumulative P in solution could reach a concentration of 4.5 g/L after batches of recovery experiments. The Mg60Al40-LDH was further coupled with magnetic particles for P removal from natural lake water. The composite afforded high efficiencies in P removal and adsorbent separation from water (settling time: ∼10 min), but inadequate adsorption selectivity towards P especially in the presence of SO42− and dissolved organic matters. This work is expected to provide a new platform for both the efficient P recovery and adsorbent collection from wastewater.

La–Ca/Fe–LDH-coupled electrochemical enhancement of organophosphorus removal in water: Organophosphorus oxidation improves removal efficiency

Metal ions or metal (hydrogen) oxides are widely used as active sites in the construction of phosphate-adsorbing materials in water, but the removal of soluble organophosphorus from water remains technically difficult. Herein, synchronous organophosphorus oxidation and adsorption removal were achieved using electrochemically coupled metal–hydroxide nanomaterials. La–Ca/Fe–layered double hydroxide (LDH) composites prepared using the impregnation method removed both phytic acid (inositol hexaphosphate, IHP) and hydroxy ethylidene diphosphonic acid (HEDP) acid under an applied electric field. The solution properties and electrical parameters were optimized under the following conditions: organophosphorus solution pH = 7.0, organophosphorus concentration = 100 mg L−1, material dosage = 0.1 g, voltage = 15 V, and plate spacing = 0.3 cm. The electrochemically coupled LDH accelerates the removal of organophosphorus. The IHP and HEDP removal rates were 74.9% and 47%, respectively in only 20 min, 50% and 30% higher, respectively, than that of La–Ca/Fe–LDH alone. The removal rate in actual wastewater reached 98% in only 5 min. Meanwhile, the good magnetic properties of electrochemically coupled LDH allow easy separation. The LDH adsorbent was characterized using scanning electron microscopy with energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction analysis. It exhibits a stable structure under electric field conditions, and its adsorption mechanism mainly includes ion exchange, electrostatic attraction, and ligand exchange. This new approach for enhancing the adsorption capacity of LDH has broad application prospects in organophosphorus removal from water.

RETRACTED: Controlled synthesis of porous Zn/Fe based layered double hydroxides: Synthesis mechanism, and ciprofloxacin adsorption

• porous Zn/Fe LDH exhibited appreciable adsorption capacity. • Successful decomposition of H 2 O 2 present between the LDH layers. • Introduction of pores in the layers enhanced the surface area and adsorption activity. • Successfully reusable for consecutive 6 cycles adsorption cycles. Present work include the designing of a novel porous Zn/Fe layered double hydroxide (LDH) based adsorbent using a combination of three methods, namely, co-precipitation, hydrothermal, and thermal treatment. The Zn/Fe LDH was synthesized by co-precipitation followed by hydrothermal method. The LDH was then intercalated with H 2 O 2 and its decomposition under the thermal treatment created oxygen bubbles that pierce holes in the layered structure of the LDH by local pressure build-up. Major techniques used for assessing the morphology and surface area characteristics of the LDH and porous LDH were Scanning electron microscope (SEM) and Brunauer-Emmet-Teller (BET). The intercalation of H 2 O 2 and its later decomposition triggered by thermal treatment lead to the introduction of pores in the LDH layers that increased the surface area from 108.863 m 2 /g to 168.923 m 2 /g. The synthesized adsorbent was utilized for the removal of an antibiotic; ciprofloxacin (CIP) from the aqueous solution. The porous Zn/Fe LDH adsorbent was featured with an admirable CIP adsorption capacity of 344.83 mg/g at pH 6.5 and temperature 298 K. The adsorption of CIP onto porous Zn/Fe LDH adsorbent followed the Freundlich isotherm model and pseudo-second-order kinetic model. The temperature increase negatively affected the adsorption rate. The adsorption mechanism of CIP onto porous Zn/Fe LDH was also projected and established, and Cπ- metal interactions, hydrogen bonding, and electrostatic interactions, were found to be the major interactive forces. The thermodynamic study revealed the exothermic and spontaneous nature of the adsorption experiments. Overall, the synthesized adsorbent is sustainable in terms of its usability and non-toxic nature.

Cu-Ca-Al-layered double hydroxide modified by itaconic acid as an adsorbent for anionic dye removal: Kinetic and isotherm study

Here, for the first time, Cu-Ca-Al-based layered double hydroxide (LDH) was prepared using a facile co-precipitation method. Itaconic acid (ITA) was used as a biodegradable and green organic molecule to modify the LDH and then physicochemical properties of the ITA-modified LDH (LDH-ITA) were studied using FTIR, FE-SEM, TEM, XRD, and TGA techniques. Then the synthesized LDH and LDH-ITA were applied as novel adsorbents for the removal of Congo red as a model of an anionic dye from aqueous media. Several parameters such as the solution pH, contact time, adsorbent amount, and initial concentration of the dye on the adsorption process were monitored and kinetic and isotherm studies were conducted to gain a more in-depth insight into the adsorption mechanism in the process. The results demonstrated that the adsorption of Congo red onto both the LDH and LDH-ITA adsorbents followed the pseudo-second-order kinetic model. Also, isotherm investigations revealed that the Freundlich model provided the best fit with the equilibrium data of both adsorbents. Maximum adsorption capacities of 81 and 84 mg g−1 for Cong red were obtained using Cu-Ca-Al-LDH and LDH-ITA adsorbents, respectively, surpassing those values obtained for most adsorbents reported in the previous studies.

Phosphorus and humic acid extraction from fermentation liquor of ferric phosphate sludge via layered double hydroxides: Efficiency and interaction mechanism

Iron salts are increasingly employed in wastewater treatment worldwide, generating ferric phosphate sludge with low phosphorus (P) bioavailability. The fermentation of ferric phosphate sludge effectively transfers P from the solid phase to the liquid phase and simultaneously releases high contents of ferrous cations (Fe2+) and humic acids (HA) into the sludge liquor. This study aimed to extract P from simulated and real sludge fermentation liquor via Mg/Al layered double hydroxide (LDH), evaluate the impact of co-existed Fe and explore the interaction mechanism between phosphate and HA adsorption. The Fe influence experiments explored the suitable organic matter concentration range for the LDH adsorbent to extract P without the concurrent precipitation of iron compounds. Thus, the residual ferrous species in sludge liquor can be reused as a flocculant. Moreover, the analysis of the adsorption kinetics of phosphate at 25, 35, and 55 °C showed that increasing temperature accelerated the phosphate adsorption rate but had minor effects on the P adsorption capacity. HA and phosphate were jointly adsorbed onto Mg/Al LDH. Investigations on isotherm, kinetics, and mechanism suggested that phosphate anions have a competitive advantage in the ion exchange process but are hindered by large-molecular-weight HA in surface adsorption because of limited adsorption sites. Subsequent adsorption experiments in sludge liquor and nutrient release test confirmed the possibility of using Mg/Al LDH to simultaneously recover P and organic matters from sludge fermentation liquid based on its stable P adsorption performance and intercalated anion slow-release property.

Phosphorus recycling potential by synthetic and waste materials enriched with dairy wastewater: A comparative physicochemical study

Recovery of the essential macro-nutrient phosphorus (P) from P-rich waste streams is of global interest, with dwindling sources of P fertilizers threatening food security. We present a comparative physicochemical study of potential P adsorbents: two types of synthetic layered double hydroxide (LDH) and two recycled water treatment residuals (WTRs). Adsorbents were mixed with dairy WW, pre-clarified with either nanocomposites or centrifugation. LDHs practically removed all P (and higher N and organic C). In contrast, WTRs removed 50–80% P. WW-treated WTRs, particularly Fe-WTR, displayed substantially higher P lability than WW-treated LDHs, and inorganic P-loaded forms (e.g., 90 vs. 0.5 mg P kg−1). Adsorbent analyses with SEM, PXRD, FTIR, and 31P solid-state NMR contributed structural and chemical insights. Adsorbents mixture with dairy WW led to chemical and structural alterations, including Ca absorption and co-precipitation with P. Yet, high porosity and predominating adsorbed P species indicated rapid surface adsorption reactions onto the LDHs. The WTRs presented multiple sorption pools, including amorphous oxides, calcite and silicate surfaces, and disequilibrium with Ca-P minerals, accounting for weak P sorption. In addition, it appears Fe-based WTR was most sensitive to organic compounds’ impact. Thus, WW-treated WTRs can be employed as labile P sources, while LDH adsorbents can be employed as excellent purifiers for polluted streams.

Characterization and Evaluation of Ca/Al LDHs Adsorbents Synthesized by a One-Step Hydrothermal Method for Congo Red Removal

We investigated the fabrication of Ca/Al layered double hydroxide (LDHs) via a one-step hydrothermal approach with slow hydrolysis of urea at a low temperature without further annealing required. The as-synthesized Ca/Al LDHs nanostructures obtained were defined using Fourier transforms infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), powder X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results demonstrated that Ca/Al LDHs exhibit excellent adsorption performance on Congo red anionic dyes in aqueous solution. The adsorption capacity of the Ca/Al LDHs toward Congo red was found to be 59.41 mg/g.

Simultaneous Elimination of Dyes and Antibiotic with a Hydrothermally Generated NiAlTi Layered Double Hydroxide Adsorbent.

In this study, a hydrothermal route was used to design a novel NiAlTi layered double hydroxide. The material so-obtained was characterized using various physiochemical techniques such as X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis for structural analysis, scanning electron microscopy, transmission electron microscopy for morphological analysis, and so on. The material so-obtained was further applied for wastewater remediation and was found to be an efficient, cost-effective, and reusable adsorbent. Organic contaminants such as dyes and antibiotics were used as pollutants to carry out the removal study. NiAlTi LDH was found to be an excellent adsorbent for the removal of anionic dyes and antibiotics. Excellent performance was shown by NiAlTi LDH at a broad pH range from 4 to 10 for anionic dyes (orange II and methyl orange), but tetracycline removal was predominantly maximum at pH = 9. Further, the kinetic studies also revealed that the adsorption process of both organic contaminants obeyed a pseudo-second-order model. In addition, the Langmuir isotherm adsorption model fitted the experimental results for both types of pollutants very well. The attained maximum adsorption capacity was superb for both organic dyes and antibiotics (1250 mg/g for MO, 2000 mg/g for OII, and 238.09 mg/g for TC). NiAlTi LDH was also capable of simultaneous elimination from a mixture of antibiotics and dyes. Further, NiAlTi LDH also showed outstanding stability and reusability, making it one of the most promising materials for large-scale wastewater remediation contaminated by dyes and antibiotics.

Preparation of polymer functionalized layered double hydroxide through mussel-inspired chemistry and Kabachnik–Fields reaction for highly efficient adsorption

A novel method for the fabrication of phosphorylated layered double hydroxide (LDH) based adsorbents was proposed, in which polydopamine and α-amino phosphonate chains were anchored onto the pristine LDH nanosheets by a combinatorial procedure of mussel-inspired chemistry and Kabachnik-Fields (KF) reaction. The modified LDH adsorbents were characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). Various adsorption conditions, including contact time, pH, Cu2+ concentrations, and solution temperature was further investigated. Kinetics results revealed that the pseudo-second-order model can provide a better depiction of adsorption data. The modified LDH exhibited a better adsorption capacity towards Cu2+ owing to the introduction of oxygen-containing groups. Adsorption isotherms showed that the adsorption data can be well represented by the Langmuir isotherm model. The maximum adsorption capacity was calculated to be 105.44 mg g−1. Thermodynamic results indicated that the adsorption features of Cu2+ on phosphorylated LDH nanocomposites were spontaneous and endothermic. The electrostatic attraction was proposed as the dominant adsorption mechanism. In summary, this work not only brings about a discovery of surface modification of LDH-based materials via an effective and versatile combinatorial method, but also provides new avenues to architecturally construct various multifunctional hybrid materials for many high-value applications, such as advanced oxidation technology, oxygen reduction reaction, photocatalyst, supercapacitor.

Efficient removal of iodide anion from aqueous solution with recyclable core-shell magnetic Fe3O4@Mg/Al layered double hydroxide (LDH)

Magnetic Mg/Al layered double hydroxides (LDH) with three cationic ratios (Mg/Al = 2:1, 3:1, and 4:1) were successfully synthesized and utilized for the first time in an iodide adsorption study. The effects of the Mg/Al ratio of LDH on iodide adsorption were investigated, and physicochemical properties of synthetic LDHs depending on Mg/Al ratio were confirmed by XRD, TEM, ICP-OES, VSM, Zeta-potential, and BET analyses. The ferrimagnetic property was well preserved even after a coating of LDH on magnetite irrespective of the Mg/Al ratio. Among the three Mg/Al ratios, the calcined Fe3O4@4:1 Mg/Al LDH exhibited excellent performance for iodide removal with 105.04 mg/g of the maximum iodide adsorption capacity due to its wide interlayer spacing and largest BET surface area. In the presence of competing carbonate anions, the Fe3O4@4:1 LDH showed removal rate of >80% at a dosage of over 3 g/L solid to liquid ratio. The recyclability test of Fe3O4@4:1 LDH showed that the removal performance for iodide is maintained at >80% even during the first to the fourth cycles. These results demonstrated that the magnetic Mg/Al LDH adsorbent can be effectively utilized for remediation of radioactive iodide anions with high efficiency and economics.

A new biocompatible ternary Layered Double Hydroxide Adsorbent for ultrafast removal of anionic organic dyes

It would be of great significance to introduce a new biocompatible Layered Double Hydroxide (LDH) for the efficient remediation of wastewater. Herein, we designed a facile, biocompatible and environmental friendly layered double hydroxide (LDH) of NiFeTi for the very first time by the hydrothermal route. The materialization of NiFeTi LDH was confirmed by FTIR, XRD and Raman studies. BET results revealed the high surface area (106 m2/g) and the morphological studies (FESEM and TEM) portrayed the sheets-like structure of NiFeTi nanoparticles. The material so obtained was employed as an efficient adsorbent for the removal of organic dyes from synthetic waste water. The dye removal study showed >96% efficiency for the removal of methyl orange, congo red, methyl blue and orange G, which revealed the superiority of material for decontamination of waste water. The maximum removal (90%) of dyes was attained within 2 min of initiation of the adsorption process which supported the ultrafast removal efficiency. This ultrafast removal efficiency was attributed to high surface area and large concentration of -OH and CO32− groups present in NiFeTi LDH. In addition, the reusability was also performed up to three cycles with 96, 90 and 88% efficiency for methyl orange. Furthermore, the biocompatibility test on MHS cell lines were also carried which revealed the non-toxic nature of NiFeTi LDH at lower concentration (100% cell viability at 15.6 μg/ml). Overall, we offer a facile surfactant free method for the synthesis of NiFeTi LDH which is efficient for decontamination of anionic dyes from water and also non-toxic.

Selective removal of heavy metal ions in aqueous solutions by sulfide-selector intercalated layered double hydroxide adsorbent

Remaining largely under-appreciated, a majority of metal ion sorbents are limited in their target selectivity. In this work, a 3D sulfide intercalated NiFe-layered double hydroxide (NFL-S) hierarchical sorbent has been synthesized for selective heavy metal removal. The intercalation of sulfurated groups in the interlayer of the layered double hydroxide (LDH) nanosheets endows NFL-S as a selective heavy metal ion filter; the selectivity of NFL-S for heavy metals is in the order of Pb2+ > Cu2+ ≥ Zn2+ > Cd2+> Mn2+, and NFL-S has high kd values for Pb2+ (∼106 mL/g) and Cu2+ (∼105 mL/g). Scanning electron microscopy, X-ray photoelectron spectroscopy and powder X-ray diffraction were used to analyze the composition of the as-prepared nanoadsorbent. The selective adsorption behavior was systematically studied using batch experiments, and the performance was evaluated through kinetic and isotherm studies. Moreover, the adsorption mechanism of heavy metals by NFL-S through surface complexation was also investigated, which shows great potential for water decontamination.

Acid-salt treated CoAl layered double hydroxide nanosheets with enhanced adsorption capacity of methyl orange dye

In this study, the ultra-thin CoAl layered double hydroxide (LDH) nanosheets with Cl− intercalation were prepared by a hydrothermal method following acid-salt treatment. The morphology, structure and composition information of CoAl LDHs were identified by a variety of characterization methods including SEM, XRD, XPS, FT-IR, and BET. The effects of initial adsorbent concentration, pH, competitive anions, and temperature were also measured. The fitted adsorption curves are matched well with Langmuir isotherm model and pseudo-second-order kinetic model, suggesting that the removal of methyl orange (MO) is governed by monolayer heterogeneous adsorption and chemical adsorption, respectively. The measurements of adsorption capacity at various temperatures revealed that the adsorption process is spontaneous. Co-existing anions have different negative effects on the adsorption capacity. The Co4Al1-Cl LDH adsorbent shows the maximum experimental and theoretical adsorption capacity of 801.08 and 827.50 mg g−1 (pH = 7 and T = 293 K), respectively. An adsorption mechanism called “ion exchange and expansion-extrusion” is proposed to explain the change of interlayer spacing. These results indicate that a novel avenue for designing LDH-type adsorbent has been proposed with excellent adsorption capacity for anionic dyes like MO.

Adsorption of phosphorus by using magnetic Mg-Al-, Zn-Al- and Mg-Fe-layered double hydroxides: comparison studies and adsorption mechanism.

Mg-Al, Zn-Al and Mg-Fe magnetic layered double hydroxide (LDH) adsorbents were synthesized. The adsorption effect and influencing factors of these adsorbents were explored, and the adsorption mechanism of phosphorus was studied with advanced instruments. The results showed that the best adsorption performance was observed when the molar ratio of metals was 3 for the magnetic LDH adsorbents, and the maximum adsorption amount for phosphorus was 74.8, 80.8 and 67.8mg/g for Mg-Al, Zn-Al and Mg-Fe LDHs, respectively. Pseudo-second-order kinetics could be used to describe the adsorption process of phosphorus onto the magnetic LDHs. The adsorption of phosphorus onto the magnetic LDHs was an exothermic process. Lower temperatures were favourable for adsorption, and the adsorption of phosphorus onto the magnetic LDHs was a spontaneous process. When the solid-liquid ratios were 0.10g/L, 0.10g/L and 0.05g/L for Mg-Al, Zn-Al and Mg-Fe magnetic LDHs, respectively, the highest adsorption amount of phosphorus was achieved for each magnetic LDH. The maximum adsorption amount was observed at pH values of 6.0-8.0. The inhibitory effect of HCO3- on the adsorption capacity of phosphorus onto the magnetic LDHs was the strongest at a higher HCO3- concentration level. The relative content of -OH significantly reduced after adsorption of phosphorus by the FTIR analysis, which indicated that the mechanism of phosphorus removal was mainly through the exchange between hydroxyl on the adsorbent surface and phosphorus in water. XPS studies showed that oxygen provided electrons during the adsorption of phosphorus.

Phosphorus recovery through adsorption by layered double hydroxide nano-composites and transfer into a struvite-like fertilizer

Phosphorus (P) recovery from waste streams is attracting more attention due to the twin problems of aquatic eutrophication and global phosphorus scarcity. Layered double hydroxide mineral materials are promising phosphate adsorbents due to their excellent anion-exchange abilities and large surface area. In this study, the adsorption isotherms estimated the saturation capacity of calcined layered double hydroxide (LDH) nano-composites for phosphate as 100.7 mg-P/g-adsorbent. Ion exchange is proposed as the major mechanism in the sorption process. The commonly utilized desorption method via sodium hydroxide was found to cause recrystallization of LDH particles in increased crystal size based on the dissolution-reprecipitation (D-R) mechanism. Ammonia solution was used to desorb P from LDH adsorbent. However, struvite crystallization occurred during the desorption process because struvite has a higher precipitation tendency than LDH with sufficient NH4+ ions. The comparison of P leaching behavior among P-adsorbed LDH, ammonia-treated LDH, and pure struvite samples demonstrates that ammonia desorption probably weakened the interaction between phosphate species and LDH cationic layers, thus enhancing the bioavailability of P in LDH adsorbents. The ammonia-treated LDH has a high potential to serve like struvite as a P slow-releasing fertilizer.

Use of Ca- and Mg-type layered double hydroxide adsorbent to reduce phosphate concentration in secondary effluent of domestic wastewater treatment plant

Use of Ca- and Mg-type layered double hydroxide adsorbent to reduce phosphate concentration in secondary effluent of domestic wastewater treatment plant