Adsorptive removal of nitrilotris(methylenephosphonic acid) antiscalant from membrane concentrates by iron-coated waste filtration sand

Removal and Recovery of Phosphonate Antiscalants

Adsorption of antimony(III) on goethite in the presence of competitive anions

The aim of this research is to study the feasibility of removing nitrates from water by means of anion exchange. In the purposed work an attempt was made to utilize strong basic anion resin to remove nitrate in the presence of competitive anion. Amberjet Cl- 4200 ion exchange resin was used in a batch scale. The fixation rate of nitrate without the presences of any competitive anion was almost constant (94.60-96.43) when the nitrate concentrations are in the range of 100-150 mg L(-1). The fixation rate of nitrate in the presences of two competitive anions (sulphate and chloride) was reduced to 82% when the concentration of nitrate was 100 mg L(-1).

Antimony (Sb) emissions to the environment are increasing, and there is a dearth of knowledge regarding Sb fate and behavior in natural systems. In natural systems, the presence of competitive anions may compete with Sb for adsorption sites on mineral surfaces, hence increasing its potential bioavailability. Accordingly, the adsorption of Sb(III) on kaolinite was investigated in the presence of competitive anions. Kinetic studies suggest that adsorption reaction of Sb(III) on kaolinite is rapid initially and becoming slow after 12 h both in binary Sb(III)–kaolinite system and in ternary Sb(III)-competitive anion–kaolinite system. The presence of PO43− has a much stronger and more obvious promotive effect on the adsorption of Sb(III) on kaolinite compared with the other two anions. The adsorption data of Sb(III) on kaolinite in the absence and presence of competitive anions at three temperatures were successfully modeled using Langmuir (r2 > 0.95) and Freundlich (r2 > 0.95) isotherms. Accompanied the adsorption of Sb(III) on kaolinite, significant oxidation of Sb(III) to Sb(V) had occurred under the experimental conditions used in this study. The presence of kaolinite which has a larger specific surface area could increase the contact area between the adsorbed Sb(III) and oxygen in the bulk solution, which promoted the oxidation rate of Sb(III) to Sb(V).

Sand and sand-GAC filtration technologies in removing PPCPs: A review

Sand filters are a physical treatment unit in water treatment plants that have considerable potential for removing large suspended matter. However, these filters are somewhat inefficient in removing micro-pollutants. In this study, using waste leachate, carbon nanoparticles were coated on the silica particles to increase the surface adsorption capacity on silica substrates of rapid sand filters. The surface properties of nano-adsorbents produced by scanning electron microscopy, Raman spectroscopy and EDS test were investigated. Furthermore, the adsorption capacity of 4-Nonylphenol was examined using a new nanocomposite under different operational conditions (contact time, temperature and initial concentration) and after obtaining pHzpc, the effect of pH, total dissolved solids (TDS) and total organic carbon (TOC) on the efficacy of 4-Nonylphenol removal was tested. The adsorption isotherms in three temperature amounts of 15, 25, and 50 °C were also studied and Langmuir isotherm well fit the experimental data. To evaluate the thermal effect on the adsorption process, the thermodynamic study was also conducted. The results demonstrated that this reaction is spontaneous, endothermic and thermodynamically desirable. The experimental data also showed that the new engineered material is a good reusable adsorbent in water treatment.

Levulinic acid (LA) is a versatile compound used in biofuels, resins, etc., and its efficient recovery is required for its high value-added use. This study investigates the use of four anion exchange resins -Lewatit M-500 (a strong basic anion exchanger) and three weak basic anion exchangers (WBAEs), namely Amberlite IRA-67, Lewatit MP-62, and Lewatit MP-64- for LA recovery. The effects of pH, agitation time, LA concentration, resin dosage, and temperature on the adsorption efficiency were studied via batch experiments. Solution pH significantly influenced the yield. The highest efficiency was obtained at pH 2.1 for the WBAEs and pH 5 for Lewatit M-500. The kinetic data followed the pseudo-second-order model with R2 >0.99. Increasing temperature slightly decreased the efficiency, with negative values for enthalpy (ΔH°) and Gibbs free energy (ΔG°), suggesting that the process was spontaneous and exothermic. The yield increased with resin dosage but decreased with higher initial LA concentrations. The highest adsorption capacity obtained from the four resins followed the order: Lewatit MP-62 (487.7 mg/g) > Amberlite IRA-67 (418.0 mg/g) > Lewatit MP-64 (371.6 mg/g) > Lewatit M-500 (278.7 mg/g). The successive adsorption-desorption trials using Lewatit MP-62 showed a slight decline (90% to 85%) in recovery efficiency over five cycles.

Clay minerals in sediments have strong adsorption capacities for pollutants, but their role in the distribution of antibiotics in estuaries and nearby coastal areas is unclear. We evaluated the clay mineral montmorillonite (SWy-2) adsorption capacity for tetracycline (TC). We assessed the adsorption capacity of SWy-2 for TC by measuring the removal percentage of 30 mg/L TC over time. The effects of pH and ionic strength on the TC adsorption onto SWy-2 were investigated. We analyzed the kinetics of TC adsorption using a pseudo-second-order model and determined the adsorption isotherm using the Langmuir equation. SWy-2 particles were characterized using zeta potential, Fourier transform infrared (FTIR), and X-ray diffraction (XRD) analyses before and after TC adsorption. The removal percentage of 30 mg/L TC by SWy-2 reached 70.76% within 0.25 h and gradually increased to 78.64% at 6 h. TC adsorption was influenced by pH and ionic strength, where low pH enhanced and high ionic strength reduced the adsorption. The kinetics of TC adsorption followed a pseudo-second-order model, and the adsorption isotherm adhered to the Langmuir equation. The saturated adsorption capacity (qmax) of SWy-2 for TC was 227.27 mg/g. Zeta potential, FTIR, and XRD analyses confirmed that electrostatic interactions and chemical bonds played a significant role in the TC adsorption by SWy-2. SWy-2 clay mineral exhibits a substantial adsorption capacity for TC, indicating its potential as an effective sorbent to mitigate antibiotic contamination in estuaries and nearby coastal areas. The observed effects of pH and ionic strength on TC adsorption have implications for the environmental fate and transport of antibiotics. The pseudo-second-order kinetic model and Langmuir isotherm equation provide valuable insights into the adsorption behavior and capacity of TC on SWy-2. Characterization analyses support the involvement of electrostatic interactions and chemical bonds in the SWy-2-TC adsorption mechanism.

This study was to understand the sorption behavior of Sb(III) on kaolinite as a function of various solution properties such as pH, initial Sb concentration, temperature and humic acid (HA). Kinetic studies suggested that the adsorption equilibrium was achieved within 24 h and the order of reaction with regard to the Sb(III) concentration is two. The adsorption of Sb(III) is strongly dependent on pH and decreases with increasing pH. The Langmuir and Freundlich models were used to fit the adsorption data obtained at three different temperatures. The thermodynamic parameters (ΔG, ΔH and ΔS) were calculated from the dependence of the adsorption process on the reaction temperature, and the calculated parameters suggested that the adsorption of Sb(III) on kaolinite is spontaneously exothermic. The presence of competitive anions have no obvious effect on the adsorption of Sb(III) on kaolinite.

Sorption of heavy metals by Lithuanian glauconite

Th(IV) adsorption on alumina: Effects of contact time, pH, ionic strength and phosphate

The physicochemical properties (capacity, kinetics and selectivity) of the ion exchange resins Amberlite IRA900, IRA400, IRA96 and IRA67 were determined to evaluate their comparative suitability for lactic acid recovery. Both the kinetics of lactic acid sorption from aqueous solutions and the equilibrium were assessed using mathematical models, which provided a close interpretation of the experimental results. The best resins (Amberlite IRA96 and IRA67) were employed in further fixed-bed operation using aqueous lactic acid solutions as feed. In this set of experiments, parameters such as capacity, regenerant consumption, percentage of lactic acid recovery and product concentration were measured. Amberlite IRA67, a weak base resin, was selected for lactic acid recovery from SSF (simultaneous saccharification and fermentation) broths. Owing to the presence of nutrients and ions other than lactate, a slightly decreased capacity was determined when using SSF media instead aqueous lactic acid solutions, but quantitative lactic acid recoveries at constant capacities were obtained in four sequential load/regeneration cycles.

Enhanced removal of nitrate from water using amine-grafted agricultural wastes

Comparison of strongly basic anion exchange resins applicability for the removal of palladium(II) ions from acidic solutions

The goal was to remove arsenate species in the presence of competitive anions by coupling of liquid-phase polymer-based retention, LPR, a procedure based on the selective As(V) adsorption properties of cationic water-soluble polymers, with an electro-catalytic oxidation process (EO) of As(III) into its more easily removable As(V). The electro-catalytic oxidation of As(III) to As(V) was performed with an organic supporting electrolyte, poly[3-(methacryloylamine)propyl)]trimethyl ammonium chloride, P(ClMPTA), which is recognized as an efficient reagent in removing divalent arsenate species. The bulk electro-catalytic conversion of As(III) to As(V) was carried out with a Pt-gauze electrode, and the resulting mixtures were introduced into a LPR cell to remove the As(V)-polymer adducts. Using P(ClMPTA) and ammonium salts at a 20:1 polymer:As(III) molar ratio at pH 8, complete (100%) Arsenic retention was achieved. For binary mixtures of Arsenic with competitive anions (e.g., SO42−, HPO42−, NO3−, and NO2−), the retention profile varied in the range 100–70%. In addition, the As(V) retention efficiency was found to be directly related to the consumed charge in the mol ratio As(III) in solution with competitive anionic species.