Phosphate Removal Efficiency Research Articles

Effective removal of nitrogen and phosphorus from a black-odorous water by novel oxygen-loaded adsorbents

Black-odorous water, caused by hypoxia and overloading of nitrogen and phosphorus, is ubiquitous in global urban rivers. In this study, we developed oxygen-loaded adsorbents by loading oxygen into activated carbon, Attapulgite, Phoslock, and Muscovite via vacuum-pressure swing method, and investigated their aeration and removal efficiency of phosphate, ammonia nitrogen, and total nitrogen in black-odorous water. Results showed that the addition of oxygen-loaded coal-based columnar activated carbon (OCC) or oxygen-loaded Muscovite (OM) alone could increase the dissolved oxygen (DO) concentration at the sediment–water interface to more than 6 mg·L-1 on the first day, and OCC could maintain the high level of oxidation–reduction potential (ORP) (up to + 327 mV) for 15 days. Most oxygen-loaded adsorbents remarkably reduced phosphate in water, essentially from 0.27 mg·L-1 to < 0.05 mg·L-1. Additionally, ammonia nitrogen and total nitrogen were reduced by more than 50 % by adding materials after oxygen loading treatment. The 16 s RNA results showed that Dechloromonas was dominant in abundance, and the reduction of nitrogen was mainly affected by microbial activity. Our results provided a series of oxygen-loaded adsorbent materials with potential engineering applications for rapid treatment of urban black-odorous water.

Highly efficient and selective removal of phosphate from wastewater of sea cucumber aquaculture for microalgae culture using a new adsorption-membrane separation-coordinated strategy

Highly efficient and selective removal of phosphate from wastewater of sea cucumber aquaculture for microalgae culture using a new adsorption-membrane separation-coordinated strategy

Titanium dioxide nanoparticles functionalized chitosan toward bio-based antibacterial adsorbent for enhanced phosphate capture

Developing an eco-friendly, sustainable and antibacterial adsorbent is significant for actual water treatment. Herein, a bio-based antibacterial adsorbent based on titanium dioxide (TiO2) nanoparticles functionalized chitosan (CS) was prepared through an in-situ hydrolysis strategy using titanium oxysulfate as the source of TiO2. The as-obtained CS/TiO2 nanocomposite was characterized by a variety of analytical techniques. According to the Langmuir mode, the adsorption capacity of CS/TiO2 reached 23.64 mg P g−1, almost 8 times higher than that of CS. In addition, the normalized adsorption capacity (adsorption value per Ti) of CS/TiO2 was calculated to be 102.68 mg P g−1 Ti−1, much higher than pure TiO2 (60.11 mg P g−1 Ti−1). Moreover, CS/TiO2 exhibited a highly selective capacity for phosphate removal in the presence of competing anions, and showed high stability in a wide pH range of 3.0–8.0. When the phosphate concentration was 2.0 mg P L−1, the removal efficiency of phosphate reached 99.5 % and the residual concentration was only 10 μg P L−1, which meets the USEPA standards for eutrophication prevention and control. In addition, after treatment by CS/TiO2, the phosphate concentration of two sewage water samples decreased from 1.50 and 1.0 mg P L−1 to <0.10 mg P L−1, meeting the standard of level II water based on the Environmental Quality Standard of China (GB3838–2002). Ligand exchange and electrostatic interactions are mainly responsible for phosphate adsorption by CS/TiO2. Furthermore, the CS/TiO2 nanocomposites exhibited excellent antibacterial activity, which could avoid biofouling contamination caused by microorganisms. Benefiting from the above advantages, the as-designed CS/TiO2 nanocomposite has great potential as a bio-based antibacterial adsorbent for phosphate capture or removal from wastewater.

Organics and Nutrient Transformation in a Microbial Fuel Cell Influenced by Antibiotics

AbstractThe present research focuses on the effect of the highly toxic and broad‐spectrum bacteriostatic antibiotic pollutant, tetracycline (TC) as a sole electron donor and co‐electron donor on the operational efficacy of a microbial fuel cell (MFC) in terms of nutrient and pollutants removal. It is observed that the removal efficiency of the MFC increases by the gradual increase in TC concentration (5–30 mg L−1). The maximum removal efficiency (59%), voltage production (372 mV), power density (81.4 mW m−2), and current density (232.5 mA m−2) are achieved in the MFC with 25 mg L−1 of TC. Moreover, the influential role of TC as a co‐substrate is also investigated using three substrates viz, acetic acid, sucrose, and albumin. The current results suggest that chemical oxygen demand (COD) removal efficiency, coulombic efficiency, and voltage output of each substrate are inversely proportional to the amount of TC and are in the order of acetic acid &gt; sucrose &gt; albumin. The nutrient removal efficiency of the MFC decreases with an increase in TC concentration, i.e., when TC is increased from 10 to 50 mg L−1, the nitrogen removal efficiency decreases from 78% to 38%, the sulfur removal efficiency decreases from 79% to 32%, and the phosphorous removal efficiency decreases from 72% to 24%. The results suggest that an MFC can be upgraded for large‐scale biological processes for antibiotic pollutant removal. Moreover, the adverse effect of TC in power generation of an MFC can serve as a biosensor for biological wastewater treatment processes to detect the antibiotic toxicity.

Understanding the process of phosphate removal in Fe0/H2O systems using the methylene blue method

The removal mechanisms of contaminants in Fe0/H2O are still poorly understood, and characterized by contradictory findings. Therefore, the present study aims to improve the understanding of the processes involved in phosphate removal in Fe0/H2O system. Herein, the methylene blue method (MB method) is used to trace the dynamics within the investigated systems. The MB method utilizes the differential adsorptive affinity of MB onto sand and sand coated with iron corrosion products to evaluate the degree of Fe0 corrosion in Fe0/H2O systems. The extent of MB discoloration and phosphate removal in various Fe0-based systems was characterized in parallel quiescent batch experiments for two weeks and two months. Parallel experiments with Orange II (O-II) as a model contaminant allowed an improved discussion of the results. The investigated systems were: (i) Fe0 alone, (ii) MnO2 alone, (iii) sand alone, (iv) Fe0 + sand, (v) Fe0 + MnO2, and (vi) Fe0 + sand + MnO2. Additional experiments were conducted to test the influence of Fe0 type, Fe0 and sand mass loadings on dye discoloration and phosphate removal in Fe0/sand system. Each system was characterized by: (i) pH value, (ii) Fe concentration, (iii) dye discoloration (MB, O-II), and (iv) phosphate concentration. Results showed that the MB method was capable of tracing the extent of iron corrosion in the various investigated systems and clarified the role of in-situ generated iron corrosion products (FeCPs) in the removal of phosphate. The suitability of mixing sand aggregates with Fe0 for efficient phosphate removal is demonstrated through the MB method. Overall, the appropriateness of the MB method to characterize the dynamics of Fe0/H2O systems is validated.

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.

Terbium-based metal organic framework and its immobilized nanofibrous membrane for selective detection and efficient removal of phosphate

The detection and removal of phosphate were advantageous means to predict and mitigate eutrophication of aquatic ecosystems. In this study, a luminescent rod-like terbium-based metal organic frameworks (MOFs) had been synthesized successfully via facile hydrothermal reaction for convenient and efficient detection and adsorption of phosphate. Specifically, the Tb-based MOFs (Tb-BTC) exhibited high selectivity for sensing of phosphate through fluorescence quenching mechanism with the quenching constant values (Ksv) of 1.18 × 104 M−1 and low limit of detection (LOD) of 2.97 μM. Simultaneously, Tb-BTC also possessed superior adsorption ability for phosphate based on Langmuir isotherm model and pseudo-second-order kinetic model determining that the maximum adsorption capacity reached up to 222.2 mg/g with equilibrium time of 30 min. More significantly, Tb-BTC nanoparticle could be stably integrated into polyacrylonitrile (PAN) nanofibers for constructing hierarchically hybrid nanofibrous membrane (PAN/TB) through electrospinning to further improve its operability and recoverability. And the obtained customized membrane maintained selective detection for phosphate with visual LOD of 3 × 10−4 M and good capture of phosphate with the maximum adsorption capacity of 111.3 mg/g, respectively. Therefore, this study provided prospective candidate for detection and removal of phosphate making contribution at a certain level to predict and attenuate water eutrophication.

A Recyclable Magnetic Aminated Lignin Supported Zr-La Dual-Metal Hydroxide for Rapid Separation and Highly Efficient Sequestration of Phosphate

The application of lignin-based adsorbents in the efficient removal of phosphate from wastewater has attracted much attention and been intensively studied in recent years. However, most currently reported lignin-based adsorbents are difficult to recover and recycle. Herein, we have developed a recyclable, nanostructured bio-adsorbent, poly(ethyleneimine) (PEI)-modified lignin (LG) integrated with Fe3O4 and Zr-La dual-metal hydroxide (LG-NH2@Fe3O4@Zr-La), by the Mannich reaction followed by the chemical coprecipitation method. Multilayer adsorption existed on the surface of LG-NH2@Fe3O4@Zr-La based on the isotherm fitting curve, and its adsorption capacity reached 57.8 mg P g-1, exhibiting a higher phosphate uptake than most reported metallic oxide-based composites. The adsorption process was dominated by inner-sphere complexation of ligand-exchange and electrostatic interactions. Moreover, LG-NH2@Fe3O4@Zr-La exhibited excellent selectivity against coexisting anions, and the adsorption was more efficient under acidic conditions. When the phosphate concentration was 2.0 mg P L-1, the removal efficiency of phosphate reached 99.5% and the residual concentration was only 10 μg P L-1, which meets the United States Environmental Protection Agency (USEPA) standard for eutrophication prevention. In addition, the LG-NH2@Fe3O4@Zr-La displayed excellent reusability, maintaining 91.8% of removal efficiency after five cycles. Importantly, owing to the magnetic properties of the loaded Fe3O4, the resulting composite could be separated within 30 s under an external magnetic field. Thus, the separable and recyclable biobased magnetic adsorbent developed in this work exhibited promising application in phosphate capture from real sewage. This research study provides a new perspective for lignin valorization in lignocellulose biorefineries and establishes an approach for developing an economical and efficient bio-adsorbent for phosphate removal from wastewater.

Oxygen defects of MgLa-LDH enhancing electrostatic attraction and inner-sphere complexation during phosphate adsorption from wastewater

The introduction of oxygen defects toward constructing new binding sites is a promising strategy for improving the adsorption performance of layered double hydroxide (LDH). Here, a facile and novel method for adjusting the abundance of oxygen defects by regulating the preparation pH values of MgLa-LDH was used to enhance phosphate efficient adsorption. The MgLa-LDH with high-defect-degree (ML-11) presented a larger adsorption capacity and faster mass-transfer than that of low-defect-degree LDH (ML-10). Particularly, the adsorption capacity (121.56 mg/g) and initial adsorption rate (16.25 mg/g⋅min) of ML-11 were 1.8 times and 2.6 times higher than those in ML-10 in neutral condition, respectively. Characterization results confirmed that oxygen defects played a vital role in phosphate adsorption. The promotion mechanism of oxygen defects on phosphate absorption included the enhancing electrostatic attraction via increasing surface electron density, boosting M-OH groups generated by oxygen defects, and reducing adsorption energy. Compared with ML-10, ML-11 had similar or even better resistance of coexisting anions, and regeneration performance. Furthermore, the performance of ML-11 was verified in fixed-bed column experiment with real wastewater, and the treatment bed volume of it (978.6 BV) was higher than that in ML-10 (509.7 BV). The oxygen defects method can provide a promising choice for improving the material properties of efficient phosphate removal.

Salinity affects the efficiency of a brackish aquaponics system of sea bass (Dicentrarchus labrax) and rock samphire (Crithmum maritimum)

Brackish aquaponics using euryhaline fish and halophyte plants may be a sustainable method of functional food production. In addition, they could have a great potential as high nutritional, commercial and pharmaceutical value. This study investigated the effect of three different salinity levels (8 ppt, 14 ppt and 20 ppt) on the growth performance of sea bass (Dicentrarchus labrax) and rock samphire (Crithmum maritimum), the first-time production of essential oil and the nutrient-removal efficiency of rock samphire in a brackish aquaponic system. A total of 135 sea bass (weight 8.2 ± 0.15 g, length 9.5 ± 0.33 cm) and 54 rock samphire individuals (height 7.7 ± 0.20 cm) were distributed in the nine aquaponics systems (rearing temperature 20 ± 0.2οC). The seabass growth performance was significantly higher (p < 0.05) at 8 and 14 ppt salinity group than in 20 ppt, and FCR was significantly better at 8 and 14 ppt than in the 20 ppt (p < 0.05) salinity group. Rock samphire at 8 ppt showed significantly better growth and survival than those at 20 ppt (p < 0.05). Nitrate and phosphorous removal efficiencies were significantly higher at 8 and 14 ppt than at 20 ppt. Heat shock proteins (HSPs) and mitogen-activated protein kinases (MAPK) were differentially expressed, showing tissue-specific responses. The highest yield of essential oils was obtained at a salinity of 14 ppt (0.31 ± 0.03 mL per 100 g of dry plant weight). Seabass and rock samphire can have satisfactory growth performance in a tailored-made brackish aquaponic system and under the frame of sustainability and usage of saline water.

Advanced removal of phosphate from water by a novel lanthanum manganese oxide: Performance and mechanism

A novel lanthanum manganese oxide (La0.96Mn0.96O3, LMO) was synthesized for advanced phosphate removal to alleviate water eutrophication process. The adsorbent had a specific surface area of 18.51 m2/g with pH at point of zero charge of 6.6; exhibited excellent phosphate adsorption capacity of 168.4mg/g; performed well in a wide pH range from 3 to 10. The phosphate removal was not interfered by coexisting ions. The adsorbent remained 94.8% of its initial adsorption efficiency after reused for four times. Phosphate adsorption process conformed to pseudo-second-order model (R2=0.992) and Langmuir model (R2=0.935). Ligand exchange and electrostatic interaction played important roles in phosphate removal. In addition, the actual sewage secondary effluent was used to further verify the phosphate removal performance of LMO. For practical water treatment, the LMO showed high phosphate removal efficiency of 83.4% and low residual P of 0.1mg/L. LMO is a potential candidate for low-concentration phosphate removal in real water environment.

Modification of sand with Fe-Zn oxides: an alternative strategy to improve adsorption of phosphate from artificial wastewater treatment

ABSTRACT In this work, Fe-decorated quartz sand (FS), Fe-Mn bimetallic cation-decorated quartz sand (FMS) and Fe-Zn bimetallic cation-decorated quartz sand (FZS) were synthesised from ordinary quartz sand (QS). Iron, iron-manganese and iron-zinc oxides were stably formed on the surfaces of FS, FMS and FZS, respectively. The specific surface area of FZS (1.0497 m2/g) increased to more than 320% against that of QS (0.2482 m2/g). The obtained samples were evaluated for the removal of phosphate from artificial wastewater. Parameters that can affect adsorption process include solution phosphate concentration, pH and retention time, which were investigated by bath adsorption experiments. Under the optimal experimental conditions (pH value 4.0, initial concentration of phosphate 15 mg/l, temperature 25°C, retention time 150 min and adsorbent dose 5 g), the removal efficiency of phosphate by FS was higher than that of QS, FS and FMS and the maximum phosphate adsorption capacity (qmax) provided by FZS is 0.18 mg/g. Furthermore, the kinetics of phosphate adsorption fit well with the pseudo-second-order model, indicating that adsorption of phosphate on the Fe-Zn co-decorated quartz sand occurred through chemisorption, and the Langmuir adsorption isotherm model (R2 = 9944) is more suitable for adsorption capacity prediction than the Freundlich adsorption isotherm model (R2 = 0.9427). The results show that quartz sand can be modified effectively, which has great practical application potential in water treatment.

Preparation of novel Ce (IV)-based MOF/GO composite and its highly effective phosphate removal from aqueous solution

In this study, a cerium- Metal-Organic Framework /Graphene Oxide (Ce-MOF/GO) composite material with highly efficient phosphate removal was synthesized via a solvothermal method. The physiochemical properties and removal mechanism of phosphate on composite material were analyzed by Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET). The influencing parameters such as, effect of reaction time, solution pH, initial concentration, adsorbent dosage, and temperature on the adsorption capacity of the adsorbent were investigated. The kinetic and isothermal adsorption data were consistent with the pseudo-second-order model and the Langmuir adsorption isotherm model. The result shows that the maximum adsorption capacity of Ce-MOF/GO-2% composite for phosphate removal was 308. 64 mg g-1, which is higher than that of Ce-MOF. The adsorbent shows excellent reusability and after four adsorption/regeneration cycles, still maintains (92%) adsorption capacity.

Ca–La layered double hydroxide (LDH) for selective and efficient removal of phosphate from wastewater

Adsorption showed advantages in removing phosphorus (P) at low concentrations. Desirable adsorbents should have sufficiently high adsorption capacity and selectivity. In this study, a Ca–La layered double hydroxide (LDH) was synthesized for the first time by using a simple hydrothermal coprecipitation method for phosphate removal from wastewater. A maximum adsorption capacity of 194.04 mgP/g was achieved, ranking on the top of known LDHs. Adsorption kinetic experiments showed that 0.02 g/L Ca–La LDH could effectively reduce PO43–P from 1.0 to <0.02 mg/L within 30 min. With the copresence of bicarbonate and sulfate at concentrations 17.1 and 35.7 times of that of PO43–P, the Ca–La LDH showed promising selectivity towards phosphate (with a reduction in the adsorption capacity of <13.6%). In addition, four other (Mg–La, Co–La, Ni–La, and Cu–La) LDHs containing different divalent metal ions were synthesized by using the same coprecipitation method. Results showed much higher P adsorption performance of the Ca–La LDH than those LDHs. Field Emission Electron Microscopy (FE-SEM)-Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR), and mesoporous analysis were performed to characterize and compare the adsorption mechanisms of different LDHs. The high adsorption capacity and selectivity of the Ca–La LDH were mainly explained by selective chemical adsorption, ion exchange, and inner sphere complexation.

Influence of key cations and anions on phosphate removal by Fe(0) electrocoagulation

The electrocoagulation technology is efficient for the removal of phosphate. The removal efficiency of phosphate in the secondary effluent is higher than that of in the synthetic wastewater. In order to identify the key factors for promoting the removal of phosphate in Fe(0) electrocoagulation (EC), this study investigated typical coexisted substances in the secondary effluent, including Ca2+, Mg2+, NH4+, HCO3−, SO42−. The results indicated that Ca2+ and Mg2+ were the key factors promoting the removal of phosphate by Fe(0) EC both under normal (5–6 mg/L) and low dissolved oxygen (DO) (≤ 1 mg/L) conditions. Under low and normal DO conditions, the phosphate removal efficiency increased from 28 % to 98 % ± 2 % (in 5 min) at 10 mA/cm2 with the addition of Ca2+ (0.2–20 mM) or Mg2+ (0.2–2 mM) but decreased to approximately 70 % with the addition of a Mg2+ of 20 mM. Under low and normal DO conditions, the aggregation time of iron oxide flocs decreased from 10 min to 5 min when the concentration of Ca2+ increased from 0 to 20 mM and Mg2+ increased from 0 to 2 mM. The aggregation stability of flocs was not sufficient when the Mg2+ concentration was 20 mM at 5 mA/cm2. Our results confirmed that Fe(0) EC was suitable for the removal of phosphate in the secondary effluent, especially containing moderate amounts of Ca2+ and Mg2+ regardless of the concentration of DO.

Multi-stage precipitation for the eco-friendly treatment of phosphogypsum leachates using hybrid alkaline reagents

The leachate of waste phosphogypsum (PG) contains substantial amounts of phosphate, sulfate, and fluoride, which poses an immense threat to the safety of the aquatic ecosystem. In this study, a multi-stage precipitation approach is proposed to treat PG leachates using hybrid alkaline reagents including barium hydroxide (Ba(OH)2) and quicklime (CaO). To avoid potential environmental impacts, hazardous environmental contaminants are removed from the PG leachates by adding alkaline reagents in a specific order. The multi-stage precipitation approach achieves nearly 100% removal efficiencies for phosphate, fluoride, and metal ions as well as satisfactory removal efficiencies for sulfate and ammonia nitrogen (93.6% and 94.8% respectively). The compositions of generated mineral precipitates are comprehensively investigated by analytical techniques including X-ray diffraction (XRD), transmission electron microscope (TEM), etc. The main precipitated mineral phases are barite (BaSO4), brushite (CaHPO4·2H2O), and hydroxyapatite (Ca5(PO4)3OH). This is further proven by the geochemical modeling using Visual MINTEQ, in which the precipitation of mineral phases is calculated. Furthermore, a straightforward economic analysis indicates the proposed method has a lower cost of the use of alkaline reagents. Overall, this study establishes an effective and eco-friendly approach for the treatment of waste PG leachates to remove hazardous environmental contaminants and recover valuable precipitates.

Recovery of phosphates from anaerobic MBR effluent using columns of eggshell and seagrass residues and their final use as a fertilizer

The combination of a submerged anaerobic membrane bioreactor (SAnMBR) and two biowaste adsorption columns (eggshell (EGSL) and seagrass (SG)) was studied for the first time to evaluate the recovery of phosphates from wastewater. Reject wastewater from anaerobic sludge dewatering process was fed into the SAnMBR and the results showed a COD removal of 50%. The phosphate removal efficiency was low and as such, the effluent from SAnMBR was then passed through two columns containing thermally treated eggshell and seagrass residues for further phosphate removal. The final effluent analysis confirmed that phosphates could be additionally removed resulting in over 95% recovery (flow rate 0.3 L d−1), for both biowaste materials. The ammonium and COD removal after the adsorption columns was low, indicating the high selectivity towards phosphates. Moreover, the solid residues after adsorption were evaluated as soil conditioners on Lepidium sativum and Sinapis alba seeds. The SG end product exhibited high GI values for both seeds tested indicating a positive effect on plant growth, while the EGSL end product negatively affected the seed germination. The fractionation analysis of phosphorus showed that inorganically bound phosphorus (IP) was the major phosphorus fraction in EGSL and SG end product, accounting for 92.6 and 95.7% of TP, respectively. The results of this study suggest that the SG and EGSL could be effectively reclaimed as selective adsorbents towards phosphates in combination with a SAnMBR and the SG solid residues after adsorption can be directly applied for agricultural purposes, contributing to the development of a zero-waste technology.

Recyclable Magnesium-Modified Biochar Beads for Efficient Removal of Phosphate from Wastewater

Although ball milling is effective for biochar modification with metal oxides for efficient phosphate removal, the recyclability of the adsorbent as well as the precursors for modification, still need to be optimized. Herein, a magnesium-modified biochar was first prepared with the precursor of MgCl2·6H2O through the solvent-free ball milling method. After that, recyclable biochar beads were fabricated with the introduction of sodium alginate and Fe3O4. The beads were proved to have excellent adsorption performance for phosphate with a saturated capacity of 53.2 mg g-1, which is over 12 times higher than that of pristine biochar beads. Although the particle size reduction, surface area, and O-containing group increments after milling are beneficial for adsorption, the remarkable promotion in performance should mainly result from the appropriate formation of magniferous crystals on biochar, which greatly accelerates the electrostatic interactions as well as precipitation for adsorption. The beads also exhibited excellent magnetism-driven recyclability, which greatly avoids secondary contamination and broadens the application field of the adsorbent.

One-pot synthesis of novel flower-like LaCO3OH adsorbents for efficient scavenging of phosphate from wastewater.

Phosphorus removal from wastewater has been considered as an effective method to control eutrophication and mitigate phosphorus deficiency. Phosphate adsorption using lanthanum-based materials has awakened much attention and triggered extensive research. In this study, novel flower-like LaCO3OH materials were synthesized via a one-step hydrothermal method and evaluated for phosphate removal from wastewater. The adsorbent with flower-like structures prepared at the hydrothermal reaction time of 4.5h (BLC-4.5) exhibited the optimum adsorption performance. BLC-4.5 had a rapid removal rate with more than 80% of the saturated adsorbed phosphate removed within 20min. Furthermore, the maximum phosphate adsorption capacity of BLC-4.5 was as high as 228.5mg/g. Notably, the La leaching amount of BLC-4.5 was negligible in the pH range of 3.0-11.0. BLC-4.5 outperformed most of the reported La-based adsorbents in terms of removal rate, adsorption capacity, and La leaching amount. Moreover, BLC-4.5 had broad pH adaptability (3.0-11.0) and high selectivity for phosphate. BLC-4.5 also displayed excellent phosphate removal efficiency in actual wastewater and great recyclability. The potential adsorption mechanisms of phosphate on BLC-4.5 were precipitation, electrostatic attraction, and inner-sphere complexation via ligand exchange. This study demonstrates that the newly developed flower-like BLC-4.5 reported here is a promising adsorbent for the effective treatment of phosphate in wastewater.

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.