Phosphate Ions In Water Research Articles

Amine modification over activated carbon for an effective removal of phosphate ions in water

Amine modification over activated carbon for an effective removal of phosphate ions in water

Efficient separation of phosphate ions in water using tris(hydroxymethyl)aminomethane modified polyaniline-p-phenylenediamine composite membrane

In this study, polyaniline-p-phenylenediamine (PAPD) was employed as an amino monomer to fabricate a polyaniline-p-phenylenediamine composite membrane (PAPD/PES) with a nanoparticle-like surface morphology. Additionally, we used interfacial polymerization of Tris(hydroxymethyl)aminomethane (THAM) to hydroxylate the PAPD/PES composite membrane, resulting in the formation of a TPAPD/PES composite membrane. THAM is an economical and environmentally friendly monomer, rarely used for surface modification of composite membranes through interfacial polymerization. Following the introduction of THAM, a significant abundance of hydroxyl groups appeared on the membrane’s surface, enhancing its hydrophilicity and electronegativity. This, in turn, improved both flux and rejection capabilities. Simultaneously, the introduction of THAM led to the formation of a hydration layer growing on the membrane’s surface, further enhancing its antifouling performance. The optimal polymerization concentration (0.5 mol/L) of THAM was used to synthesize the TPAPD/PES composite membrane, resulting in a flux of 84.18 L m−2 h−1 bar−1, which was 1.46 times higher than that of the PAPD/PES composite membrane before polymerization. Additionally, the phosphate rejection rate was determined to be 92.14 % (with an initial phosphate concentration of 10 mg P/L). Long-time running and operating pressure tests results confirmed the remarkable stability of the TPAPD/PES composite membrane. Furthermore, the phosphate separation property of the TPAPD/PES composite membrane was evaluated using real wastewater samples (with an initial phosphate concentration of 1.03 mg P/L) as the research object. After separation, the permeate displayed a phosphate concentration of 0.28 mg P/L, meeting the first-class A standard for urban sewage treatment in China (0.5 mg P/L). This indicates that the prepared TPAPD/PES composite membrane has significant potential for practical application.

Multifunctional Roles of Dihydrotetrazine-Decorated Zr-MOFs in Photoluminescence and Colorimetrism for Discrimination of Arsenate and Phosphate Ions in Water.

The high chemical and structural stabilities of zirconium (Zr)-based metal-organic frameworks (MOFs) in aquatic media make them ideal candidates for wastewater treatment. Rational decoration or Zr-MOFs with functional groups can significantly extend their application in this area. In this work, two well-known Zr-MOFs, UiO-66 and MIL-140-A, were functionalized with dihydrotetrazine function to increase their capability in water treatment. Investigations reveal that these two dihydrotetrazine (DHTZ)-functionalized MOFs, namely UiO-66(Zr)-DHTZ and MIL-140(Zr)-DHTZ, can be applied as a two-component array for highly selective and sensitive discrimination of arsenate (AsO43-) and phosphate (PO43-) ions in water in the presence of other anions. Photoluminescence (PL) tests using UiO-66(Zr)-DHTZ show that this MOF can detect these two anions via a ratiometric response, 1.74 for arsenate and 1.84 for phosphate at 2 μM, with superior detection limits (7.2 × 10-8 M for AsO43- and 4.3 × 10-8 M for PO43-). The ratiometric PL response of UiO-66(Zr)-DHTZ toward arsenate and phosphate anions arises possibly from the arsenate-dihydrotetrazine hydrogen bonding. In the next step, colorimetric tests using MIL-140(Zr)-DHTZ were conducted to discriminate the arsenate from phosphate with a very low detection limit at nanomolar level. This MOF undergoes a yellow-to-pink color change in the presence of arsenate ions, while no color change is observed in the presence of phosphate. This color change is observed through conversion of dihydrotetrazine sites inside the pores of MIL-140(Zr)-DHTZ into tetrazine. Altogether, the PL response of UiO-66(Zr)-DHTZ is originated from the hydrogen bond-donating/accepting character of DHTZ function, while the colorimetric response of MIL-140(Zr)-DHTZ is based on the chemical conversion of DHTZ function. This work clearly shows that the decoration of Zr-based MOFs with multicharacter functional groups can develop their application in wastewater treatment as multipurpose platforms.

Phosphate ions detection by using an electrochemical sensor based on laser-scribed graphene oxide on paper

In this work, electrodes based on laser-scribed reduced graphene oxide were fabricated using filter paper as the substrate. To fabricate the electrodes, a water suspension of graphene oxide was filtered to produce a continuous and uniform film of graphene oxide on the filter paper surface. Subsequently, a CO2 laser was used to “write” the working, counter and reference eelctroes by reducing graphene oxide in specific areas to define complete sensors. Referecnce electrodes were then coated with a commercial Ag/AgCl conductive paste to produce a quasi Ag/AgCl reference. As fabricated devices were employed as electrochemical sensors for detection of phosphate ions in water by employing the molybdenum blue method. This method exploits the reaction between molybdate and phosphate ions in acidic media leading to a Keggin-type complex (PMo12O403−) which, being electrochemically active, enables the indiret detection of phosphate ions. Sensors exhibited high selectivity and sensitive detection of phosphate ions in a wide linear range, from 1 to 20 µM; with a limit of detection of 0.4 µM. To demonstrate that sensors could be utilized for in-situ phosphate ion detection, paper substrate was first pre-loaded with sulphuric acid and molybdate ions. During analysis, these chemicals were then desorbed directly into the test sample eliminating the need for any kind of external manipulation or reagent addition. Thus, this paper presents the fabrication of a portable, easy-to-use, biodegradable and fast phosphate ions sensor for in situ and real-time monitoring of water quality.

Preparation and self-assembly of ionic (PNIPAM-co-VIM) microgels and their adsorption property for phosphate ions.

Using N-isopropyl acrylamide (NIPAM) as the main monomer, 1-vinyl imidazole (VIM) containing tertiary amine groups as the functional comonomer, and 1,5-dibromo pentane as the crosslinking agent, ionic P(NIPAM-co-VIM) microgels were prepared by a two-step method. The crosslinking agent was reacted with tertiary amino groups by the quaternary amination. The results of zeta potential and particle size analysis showed that P(NIPAM-co-VIM) microgels were positively charged and had a particle size of about 400 nm, and the microgels with 11 wt% VIM still showed temperature sensitivity with a volume phase transition temperature of approximately 37.5 °C. The effects of VIM content, ambient temperature, and pH on the adsorption properties of the microgels for phosphate anions were explored. The self-assembly of the positively charged P(NIPAM-co-VIM) microgels with polyelectrolytes and the adsorption behavior of the layers for phosphate anions were studied using a quartz crystal microbalance (QCM). It was found that at a phosphate concentration of 0.3 mg mL-1, VIM mass fraction of 11%, pH of 5, and temperature of 20 °C, the largest adsorption capacity of P(NIPAM-co-VIM) microgel on phosphate ions could reach 346.3 mg g-1. The frequency responses of the microgel-modified QCM sensor could reach 3.0, 18.8, and 25.9 Hz when exposed to 10-8, 10-7, and 10-6 M phosphate solutions. Therefore, the ionic (PNIPAM-co-VIM) microgels could be promising for fabricating anion-binding materials for separation and sensing applications.

Defect-rich covalently-crosslinked UiO-66(Zr)-NH2/PVC adsorption ultrafiltration membrane for effective phosphate ions removal from water

BackgroundPhosphorus in wastewater is a major environmental concern. Very small phosphorus inputs in the environment can cause algal blooms that can deplete the dissolved oxygen and decrease the water quality, leading to eutrophication. Furthermore, some algal blooms produce toxins and bacterial growth that can cause human illness through exposure to contaminated water. Therefore, It is necessary to remove phosphorus before it is discharged to the environment. Methodsadsorbent enhanced adsorptive ultrafiltration (UF) has recently emerged as an advanced ion recovery technology with membrane filtration function and adsorption function, and is very effective in removing cationic bisphosphate and anionic phosphate. Significant findingsHerein, a novel defect-rich and covalently-crosslinked octanoic acid (OA)-UiO-66(Zr)-NH2/PVC adsorption ultrafiltration membrane are designed for removal of phosphate ions in water. The OA-UiO-66-NH2/PVC-33 membrane achieved the adsorption capacity (∼30 mgg−1) and higher removal efficiency (∼90%). The OA-UiO-66(Zr)-NH2/PVC ultrafiltration membrane exhibited a higher water flux of 266.9 L/(m2·h·bar) compared to those of pristine PVC and UiO-66-NH2/PVC. Filtration and cyclic stability experiments reveal that OA-UiO-66(Zr)-NH2/PVC membrane can maintain a high retention capacity and exhibit excellent regeneration performance after 5 cycles.

Portuino-A Novel Portable Low-Cost Arduino-Based Photo- and Fluorimeter.

A novel portable low-cost Arduino-controlled photo- and fluorimeter for on-site measurements has been developed. The device uses LEDs as a light source and a phototransistor as a light sensor. The circuit is based on the discharge of a capacitor with the photocurrent from the phototransistor. Validation experiments for absorbance measurements were performed by measuring protein concentration using the Bradford method and measuring phosphate ions in water using a commercial test kit. The emission light of the excited fluorescent dyes rhodamine 6G and calcofluor white was measured to validate the usability of the device as a fluorescence photometer. In all validation experiments, similar correlation coefficients and limit of detection could be achieved with the portable photo- and fluorimeter and a laboratory spectrometer and fluorimeter. Real sample analysis was performed, measuring phosphate concentration in freshwater and concentration of green fluorescent protein, extracted from Escherichia coli.

Simple ultrasound-heating process for preparation of magnetite-sulphur adsorbent for rapid uptake of phosphate ion in solution

ABSTRACT The current paper describes the results of adsorptive performance of magnetite-sulphur nanocomposite (MSNP) for the removal of phosphate which causes eutrophication; providing algae nutrients to grow at alarming rate and therefore starve other aquatic organisms of much needed oxygen. The nanocomposite was prepared by ultrasonic-heating method using sulphur and magnetite nanoparticles as starting materials in the presence of citric acid as stabilising agent. Formation of nanocomposite was verified by FTIR, SEM, EDX, TEM, UV-Vis, XRD, TGA and pH of point of zero charge measurements. Adsorptive removal of phosphate by the nanocomposite was investigated in aqueous solution by determining the effects of catalyst dosages, contact time, phosphate initial concentrations and pH of the solution on phosphate adsorption. The results indicated that phosphate uptake reached maximum adsorption capacity at 38.58 mg/g, corresponding to pH 4.5, suggesting that acidic conditions favour removal of phosphate ions in water. Adsorption process was consistent with both Langmuir isotherm model and pseudo-second order. The calculated parameters from Langmuir model and pseudo-second order showed that the phosphate adsorption on MSNP is a feasible process. Adsorption mechanism was attributed to bimolecular interactions involving anionic species of phosphate and cationic sites of MSNP. The spent MSNP was easily regenerated with NaOH and reused for more than four adsorption-desorption cycles. The adsorbent showed good reusability and therefore suitable for phosphate removal and other water contaminants.

Adsorption of nitrate and phosphate in an aqueous solution on composites of PVA and chitosan prepared from a Somanniathelphusa sinensis shell

Abstract In this study, chitosan was prepared from the shell of Somanniathelphusa sinensis, which is a crab ubiquitous in Vietnam. The 3-level, 3-factor Box–Behnken design was applied to the preparation of chitosan to investigate effects of factors such as the HCl solution concentration, protein removal time and deacetylation time on the degree of deacetylation (%DD). Scanning electron microscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy and gel permeation chromatography were employed to examine the chitosan structure, as well as pH titration and antibacterial testing of the chitosan solution. Results revealed that as-p chitosan comprises specific functional groups, with almost no impurities. Its average molecular weight was ∼225,000 g/mol, and %DD was ∼89.7%. The chitosan/PVA composite was prepared and investigated for the adsorption of nitrate and phosphate ions in water. Experimental results revealed that the adsorption capacity of a chitosan/PVA (1:2) composite is better than that of chitosan. Accordingly, the theoretical maximum adsorption capacities of nitrate and phosphate ions on chitosan were 122.0 mg/g and 344.8 mg/g, respectively. The corresponding values on the chitosan/PVA (1:2) composite were 135.1 mg/g and 384.6 mg/g. Adsorption kinetics data at 25 °C were well fitted to the pseudo-second-order model (R2 > 0.998). These results revealed that crab shell chitosan and the chitosan/PVA (1:2) composite can be used for the adsorption of nitrates and phosphates in aqueous solutions.

A novel platform based on gold nanoparticles chemically impregnated polyurethane foam sorbent coupled ion chromatography for selective separation and trace determination of phosphate ions in water

The sorption characteristics of phosphate ions from aqueous molybdate solution of pH ≤ 2 onto malachite green (MG) impregnated thiophenol (TP) functionalized Au nanoparticles based polyurethane foam (PUF) solid platform (MG-AuNPs-treated PUF) was studied. Phosphate uptakes followed Langmuir and Freundlich models. Based on the retention profile, a dual mechanism involving a “weak base anion exchanger i.e. solvent extraction” and a “surface adsorption” of phosphate retention as complex ion associate {[MG]+.[H2PMo12O40]−}PUF is anticipated. Complete retention of phosphate at various concentrations (0.01–100.0 μg mL−1) onto the sorbent packed column at 3–5 mL min−1 flow rate was achieved. A highly sensitive strategy for enriching, quantitative recovery and trace determination of phosphate in water using the sorbent packed column was developed. Under the optimized parameters, a linear concentration range of 0.07–25 μg L−1 and limits of detection (LOD) and quantification (LOQ) of 0.02 and 0.07 μg L−1 phosphate were achieved, respectively. The proposed and reference methods for analysis of phosphate in water samples were subjected to statistical treatment (student's t and F tests) at 95% confidence with no significant difference indicating the precision and accuracy of the proposed assay. The settled sorbent in flow mode was robust sufficient to be reused for five times without significant decrease in its performance. The intraday repeatability and interday stability of the established sorbent packed column towards phosphate (10.0 μg L−1) determination was studied. An estimated coefficient of variation less than ±5% was achieved revealing the suitably of the modified PUFs in column mode. The established column enabled multiple enrichment of phosphate from water and expanded the range of phosphate level which can be determined in water.

Development and validation of anin situand real-time quantification method for bicarbonate, carbonate and orthophosphate ions by ATR FT-IR spectroscopy in aqueous solutions

Bicarbonate salts are used in various industrial processes and could even serve as an alternative source of carbon in bioprocesses involving photosynthetic organisms. Industrial productions require efficient monitoring and control to ensure that their output will meet target specifications. To this end, a simple and rapid in situ quantification method was developed for bicarbonate, carbonate and phosphate ions using Attenuated Total Reflectance-Fourier Transform Infrared (ATR FT-IR) spectroscopy combined with partial least squares (PLS). The resulting multivariate approach allows the simultaneous determination of inorganic carbon and orthophosphate ions concentrations in aqueous solutions (R2 > 0.98, root-mean-square-errors of the cross validation RMSECV < 3.3%). Validation of the method was achieved through replicability and repeatability tests. Univariate calibration graphs are linear over a concentration range of 150 mM (R2 > 0.9990). Quantification limits for those ions were in the 6.9-17.2 mM range, as determined from univariate models. The multivariate model was successfully applied to a microalgal culture of Scenedesmus obliquus using bicarbonate as the carbon source and a phosphate buffer to maintain the pH. This analytical technique did not require extraction or chemical treatment and no sample preparation is needed. The results demonstrate the potential of ATR FT-IR method to study inorganic carbon and phosphate species during a bioprocess.

Ab Initio Molecular Dynamics Simulation of the Phosphate Ion in Water: Insights into Solvation Shell Structure, Dynamics, and Kosmotropic Activity.

The structure and dynamics of solvation shells of the phosphate ion in deuterated water are studied by means of Born-Oppenheimer molecular dynamics simulation. The total number of molecules in the first and second solvation shells is found to be close to the effective hydration number reported experimentally. The OD bonds that are hydrogen bonded to the phosphate ion are found to be red shifted as compared to bulk water, which is consistent with experimental results. However, the two OD bonds of the same water molecule in the first hydration shell are found to be vibrationally distinct, which can be attributed to different strengths of the ion-water and water-water hydrogen bonds near the ion. Also, the hydrogen bonds formed by the second solvation shell OD bonds are somewhat stronger than the bulk. This finding shows a long ranged effect of the phosphate ion on water and also gives insights into the water structure making property of this anion. The dynamics of water in the first solvation shell is found to be significantly slower than that of the bulk. We have investigated the origin of the orientational slowing down of the first solvation shell water molecules and made connections to similar results observed experimentally.

Detection of Posner's clusters during calcium phosphate nucleation: a molecular dynamics study.

Hydroxyapatite (HA), the main mineral phase of mammalian tooth enamel and bone, originates in body fluids from amorphous calcium phosphate (ACP). ACP presents short-range order in the form of small domains with size of 0.9 nm and chemical formula Ca9(PO4)6, known as Posner's clusters. In this study, the aggregation and clustering of calcium and phosphate ions in water has been investigated by means of shell-model molecular dynamics simulations. Calcium phosphate aggregates form in solution with compositions and Ca coordination that are similar to those found in Posner's cluster, but the stoichiometry of these species is dependent on the ionic composition of the solution: calcium-deficient clusters in solutions with low Ca : P ratio; cluster containing protonated phosphate groups in neutral solutions; sodium ions partially substituting calcium in solutions containing a mixture of sodium and calcium ions. These Posner-like clusters can be connected by phosphate groups, which act as a bridge between their central calcium ions. The simulations of the aggregation in solution of calcium phosphate clusters are an unbiased and unequivocal validation of Posner's model, and reveal for the first time the structure and composition of the species that form during the early stages of ACP nucleation at a scale still inaccessible to experiment.

The retention profile of phosphate ions in aqueous media onto ion pairing immobilized polyurethane foam: Kinetics, sorption and chromatographic separation

A strategy for enriching, separating and determining the inorganic phosphate ions in water based on the use of polyurethane foam (PUFs) physically immobilized with some ion pairing or basic dyes has been reported. The retention of inorganic phosphate from the test aqueous solution containing molybdate ions onto untreated- and ion pairing reagent e.g. crystal violet (CV) or tetrabutylammoniumtetrafluoroborate (Bu4N+·BF4−) impregnated PUFs solid phase extractor was followed the order: unloaded<CV<Bu4N+·BF4− treated PUFs sorbent at pH3.5–4.5. The kinetics of analyte sorption onto Bu4N+·BF4− treated PUFs at optimized pH (pH3.4–4.5) was fast and followed first order rate equation with an overall rate constant of 0.062min−1. Film and intraparticle transport are the main factors controlling the rate of phosphate sorption onto the sorbent from solutions at pH=3.5–4.5. Phosphate uptake followed Langmuir and Freundlich isotherm models. Thus, a dual-mode sorption involving absorption related to “weak base anion exchanger” and an added component for “surface adsorption” is the most probable retention mechanism for phosphate uptake by Bu4N+·BF4− loaded PUFs sorbent. Chromatographic separation of phosphate by Bu4N+·BF4− treated PUFs packed column was carried out. The number (N) and the height equivalent to the theoretical plates (HETP), critical and breakthrough capacities were found equal 81±4, 0.13±0.02mm, 2.5±0.2 and 27.25±2.06mgg−1, respectively. These results suggested the use of the proposed Bu4N+·BF4− treated PUFs in packed column for separation of trace levels of phosphate in water. The retained phosphate were recovered quantitatively (102.6±2.4–106.2±3.2%) with NaOH (0.5molL−1) and analyzed. The proposed column was applied for separation and recovery of phosphate ions in waste- and seawater samples. The results were in good agreement with the spiked and expected phosphate concentrations at 95% confidence.

Adsorption of Phosphate Ion in Water with Lithium-Intercalated Gibbsite

In order to enhance adsorption capacity of gibbsite (Al(OH) 3 as an adsorbent for the adsorption of phosphate in water, gibbsite was modified through lithium-intercalation. The purification method of Tributh and Lagaly was applied prior to intercalation. The Li-Intercalation was prepared by the dispersion of gibbsite into LiCl solution for 24 hours. This intercalation formed an cationic clay with the structure of [LiAl 2 (OH) 6 ] + and exchangeable Cl - anions in the gibbsite interlayer. A phosphate adsorption test using Lithium-intercalated gibbsite (LIG) resulted in optimum adsorption occurring at pH 4.5 with an adsorption capacity of 11.198 mg phosphate/g LIG which is equivalent with 1.04 wt% LIG. The adsorption capacity decreased with decreasing amounts of H 2 PO 4 - /HPO 4 - species in the solution. This study showed that LIG has potential as an adsorbent for phosphate in an aqueous solution with pH 4.5–9.5.

Anharmonicities and coherent vibrational dynamics of phosphate ions in bulk H2O.

Phosphates feature prominently in the energetics of metabolism and are important solvation sites of DNA and phospholipids. Here we investigate the ion H2PO4(-) in aqueous solution combining 2D IR spectroscopy of phosphate stretching vibrations in the range from 900-1300 cm(-1) with ab initio calculations and hybrid quantum-classical molecular dynamics based simulations of the non-linear signal. While the line shapes of diagonal peaks reveal ultrafast frequency fluctuations on a sub-100 fs timescale caused by the fluctuating hydration shell, an analysis of the diagonal and cross-peak frequency positions allows for extracting inter-mode couplings and anharmonicities of 5-10 cm(-1). The excitation with spectrally broad pulses generates a coherent superposition of symmetric and asymmetric PO2(-) stretching modes resulting in the observation of a quantum beat in aqueous solution. We follow its time evolution through the time-dependent amplitude and the shape of the cross peaks. The results provide a complete characterization of the H2PO4(-) vibrational Hamiltonian including fluctuations induced by the native water environment.

Blister-colorimetric determination of phosphate ions in water, agricultural samples, and biological samples

A procedure was proposed for the determination of phosphate ions in a blister cell (pellet cartridge) with a dry reagent mixture. The procedure is suitable for the quantitative determination of phosphate in different samples using a dry reagent mixture in an ampule or a blister without dissolving the reagents. After an ampule or a blister cell was opened and several drops of a test liquid were added, a color developed, whose intensity was proportional to the concentration of phosphate ions in the solution. The solution was then diluted to 2 mL with water and analyzed by photometry. The composition of the mixture was determined, and the procedure for the quantitative determination of phosphate ions was proposed; the procedure involves the formation and reduction of phosphomolybdic acid and the use of auxiliary reagents. The error of the colorimetric determination of phosphate ions in aqueous solutions, soil extracts, and urine was estimated with the participation of inexperienced operators.

Removal of Phosphate in Water to Layered Double Hydroxide

Layered double hydroxide (LDH) has been used to remove phosphate ion in water as an effective adsorbent of this anion at low concentration. LDH which contains Mg2+ and Al3+ as divalent and trivalent metals respectively was prepared as has been published by many authors. A fixed portion of this LDH was suspended in the weakly basic solution containing phosphate. The suspension was stirred moderately followed by filtration. The concentration of phosphate ion in the filtrate was determined by the molybdenum blue method. The result indicates that the LDH used in this experiment was effective in removing phosphate from water. Furthermore, it was also certified that the phosphate anions removed from water were quantitatively transferred onto the solid of LDH.

Naked-eye detection of phosphate ions in water at physiological pH: a remarkably selective and easy-to-assemble colorimetric phosphate-sensing probe.

Wereporthereinacolorimetricsensor that can detect phosphate anions in an aqueoussolutionofneutralpHvalues.Thesensoriseasytoassembleand shows a high sensitivity and excellent selectivity forphosphateionsoverotheranions.In assembling the sensor, we tookadvantage of metal±ligandinteractions.Suchinteractionsaresohighlyfavorablethattheyoccureveninpolarmedia.Furthermore,themetalioncanpresentsomegeometricalpreferences,thusimpartingselective binding tendencies towards anions of a givenshape.

Naked-Eye Detection of Phosphate Ions in Water at Physiological pH: A Remarkably Selective and Easy-To-Assemble Colorimetric Phosphate-Sensing Probe

Mit bloßem Auge sichtbar ist der Farbumschlag, den Phosphationen bei Zugabe zu einer wässrigen Lösung von Hbpmp (2,6-Bis(bis(2-pyridylmethyl)aminomethyl)-4-methylphenol), Zinkperchlorat und Brenzcatechinviolett (Molverhältnis 1:2:1) auslösen. Auf dem Photo sind neben einer Kontrolle ohne Anionen (links) Lösungen zu sehen, die Phosphationen (gelbe Lösung) oder verschiedene andere anorganische Anionen enthalten.