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Tetraphenyldithiodiphosphonate is synthesized by polymerization precipitation. The P = S bond of the material has strong polarity, which is conducive to improving the electron mobility of the complex and inhibiting the accumulation between molecules. The synthesized tetraphenyldithiodiphosphonate is characterized by FT-IR, SEM, XPS and XRD. In addition, the pseudo-second-order kinetic model is used to simulate the experimental data well, and the adsorption process conforms to the Langmuir isotherm model. Thermodynamic studies of adsorption have shown that the adsorption process is essentially a spontaneous endothermic process. At room temperature, tetraphenyldithiodiphosphonate demonstrates a maximum adsorption capacity for uranium(VI) reaching 398.8 mg g−1. [ABSTRACT FROM AUTHOR]

In this study, amino modified mesoporous silica (HMS-TEEPA-TEA) was used for the first time to remove uranium (VI) from aqueous solution. The synthesized HMS-TEEPA-TEA was characterized by SEM, EDS, FTIR, BET and XPS techniques. The present work attempted to optimize and compare the adsorption process parameters like pH, adsorbate concentration, and adsorbent dose using Box-Behnken designs of response surface methodology. The adsorption amount and removal rate reached 337.26 mg/g and 99.57%, respectively. Model P> F < 0.0001 in this experiment (generally P > F < 0.05 is considered significant), indicating that the model is extremely significant and can be considered as highly referable for its predicted response values. The fit of the data to the Langmuir isotherm and the proposed secondary kinetics indicates that the adsorption process is monolayer and chemical in nature. The effect of copper on HMS-TEEPA-TEA adsorption is more complex than other background ions. The removal of uranium (VI) by HMS-TEEPA-TEA remained above 80% for four consecutive experiments with repeated adsorbent use. The results indicate that HMS-TEEPA-TEA is an effective adsorbent for the removal of uranium (VI) from aqueous solutions with the advantages of low cost, high availability and easy production. [ABSTRACT FROM AUTHOR]

In this study, Polyethyleneimine modified magnetic chitosan (MCS-PEI) was synthesized by grafting polyethyleneimine onto chitosan and adding magnetic Fe3O4 with sodium polyphosphate as crosslinking agent. The structure of the prepared material was characterized by FT-IR, SEM, EDS, XRD and XPS, which showed MCS-PEI was successfully synthesized. After a series of single factor experiments, the adsorption data fitted well with the Langmuir model (R2 = 0.99), being the maximum adsorption capacity equal 181.8 mg g−1. The pseudo-second-order model (R2 = 0.997) and Dubinin-Radushkevich model (R2 = 0.9598) indicated that the adsorption process was chemical adsorption. And thermodynamic studies showed that the adsorption was spontaneous and exothermic. The adsorption rate decreased by no more than 4% after the four adsorption–desorption experiments. This work illustrates that MCS-PEI is an environmental friendly, efficient and low-cost adsorbent. [ABSTRACT FROM AUTHOR]

In this work, a new material containing chitosan(CS)-hexachlorocyclotriphosphazene (HP) composite was synthesized with polyphosphoric acid as the cross-linking agent for the effective removal of uranium(VI) from aqueous solution. The prepared material was characterized by FTIR, EDS, SEM, BET and XPS. According to batch experiments, its adsorption equilibrium (Qe = 398.8 mg g−1) was reached within 50 min at pH 6.0. The adsorption process could be well fitted to the pseudo-second-order model and the Langmuir model. The thermodynamic analysis indicated that the adsorption was an exothermic and spontaneous process. Furthermore, the CS-HP has superior absorption reusability. This study proved that CS-HP could be considered as the highly efficient and sustainable material for removal of uranium(VI) from aqueous solution. [ABSTRACT FROM AUTHOR]

Bis(diphenyl phosphate) imine(Htpop) was synthesized as an adsorbent for the effective removal of U(VI) from aqueous solutions using triphenyl phosphate(TPP) as the starting material. Htpop possesses notable polarity, characterized by the presence of -P O(phosphoryl) and -N-H(imino) functional groups, along with other bulky substituents. It has the capability to form chelates with metal ions, thus enabling the removal of radionuclide U(VI) from aqueous solution. The overall adsorption experiment shows that both phosphoryl and imino groups interact with uranyl ions, and the removal rate reaches 99.53 % at pH 6.0. The adsorption process conforms to the Pseudo-second-order kinetic model and Langmuir isotherm model. [ABSTRACT FROM AUTHOR]

Poly (cyclotriphosphazene-co-4,4′-diaminodiphenyl sulfone) (PZD) microspheres were prepared by precipitation polymerization with simple scheme and convenient operation, and used as a special effect adsorbent for adsorbing cationic dye, which is methylene blue (MB) in water. The synthesized PZD microspheres were characterized by SEM, TEM and XPS techniques. The influences of temperature, adsorption time, pH initial MB solution concentration and adsorbent dosage on MB adsorption were studied. The experimental results show that the adsorption of MB dye by PZD microspheres is more in line with the pseudo-second-order kinetics model than the pseudo-first-order kinetic model. In addition, the adsorption process was further resolved using Weber's intraparticle diffusion model. Thermodynamic experiments show that the adsorption process is spontaneously carried out by endotherm. The mechanism of adsorption of MB dye by PZD microspheres may be related to the existence of a lot of electron-rich atoms N, P, S in the adsorbent, the electrostatic attraction and π–π stacking effect between PZD microspheres and MB dye. [ABSTRACT FROM AUTHOR]

Highly crosslinked organic–inorganic hybrid polymer poly(cyclotriphosphazene-co-melamine) microspheres (PZM) were synthesized by a simple method. The microspheres was characterized by FTIR, SEM and EDX. It was applied to eliminate thorium(IV) from aqueous solution under various conditions, i.e., pH, initial concentration, dosage and contact time. The experimental data were well-imitated via the pseudo-second-order kinetic model and its adsorption processes comply with the Langmuir isotherm model. Adsorption thermodynamic studies demonstrated that the adsorption process, in essence, was spontaneous and endothermic. Furthermore, the maximum experimental adsorption capacity was 98.6 mg g−1 for initial thorium(IV) concentration 50 mg L−1. When pH = 0.0, the thorium(IV) removal efficiency reached at 76.9%, which indicates that the adsorbent can also was used in a peracid environment. Adsorption behavior of thorium(IV) onto the microspheres were weakly affected via temperature, implying that adsorption would be done at room temperature. [ABSTRACT FROM AUTHOR]

Poly(cyclotriphosphazene-co-4,4′-diaminodiphenyl ether) microspheres (PZA) was based on hexachlorocyclotriphosphazene (HCCP) and 4,4′-diaminodiphenyl ether (ODA). It was synthesized via one-step precipitation method. The PZA microspheres were characterized by FT-IR, XPS, zeta potential and SEM/EDS. Through experimental research, PZA microspheres had the optimal adsorption performance with pH value 3.5, contact time of 60 min, thorium(IV) ions concentration of 30 mg L−1, and PZA microspheres of 10 mg. The maximum adsorption capacity of PZA microspheres for thorium(IV) was 29.04 mg g−1. The adsorption process could be described by the quasi-second order kinetic model and simulated by the Langmuir isotherm equation. [ABSTRACT FROM AUTHOR]

In order to reveal the action mechanism of porous structure of aerated concrete waste residues as aggregate on its working performance and phosphorus removal performance, the porous aggregate is prepared by adjusting the of hydrogen peroxide (H 2 O 2) content to simulate the pore structure of aerated concrete. The results show that with the increase of H 2 O 2 content, the porosity and pore diameter of porous aggregate increases, which causes that the loose bulk density, cylinder compressive strength and softening coefficient decrease and the water absorption through time increases. The correlation coefficients between the four performances and total porosity exceeds 0.95. With the increase of H 2 O 2 content, the pH value decreases and TP removal rate increases. The better fitting of the pseudo-second-order model and Elovich model confirms the key existence of chemical adsorption. In the fitting curve of Intraparticle diffusion model the second stage of rapid absorption becomes the main control step due to calcium and aluminum ions from capillary pores and gel pores and the hydration of unreacted particles. The Ca/Si and Al/Si decreases by 57.7% and 46.6% in EDS maps after phosphorus removal, and CaO/SiO 2 and Al 2 O 3 /SiO 2 in XRF results decrease. The hydration of unreacted C 4 A 3 Š and dissolution of Ca2+ and Al3+ during phosphorus removal promote the chemical absorption of porous aggregate. P/Si increases by 631.9% and P 2 O 5 /SiO 2 increases from 0.01 to 0.11. The fluffy substances appears on the smooth inner wall of the porous aggregate in SEM morphology is phosphate mineral. • " 3 wt% H 2 O 2 increases porosity and average pore diameter of porous aggregate to 71.2% and 0.35 mm. • H 2 O 2 decreases loose bulk density, cylinder compressive strength and softening coefficient. • The 60-day removal rates of TP reached 53.98%. • TP removal of aerated concrete waste residue is mainly dominated by Ca2+ and Al3+ from the hydration of C 2 S and C 4 A 3 Š." [ABSTRACT FROM AUTHOR]

A new synthetic method was designed to prepare poly (trimesoyl chloride-co-polyethyleneimine) (PEI-TMC). Characterization of PEI-TMC was investigated by FTIR, SEM, EDS, XPS, TGA, and BET. TGA test revealed that the PEI-TMC had excellent thermal stability. The BET specific surface area (4.74 ​m2 ​g−1) and pore diameter of about 9.44 ​nm indicated that PEI-TMC possessed a mesoporous structure. The adsorption behavior of U(VI) on the PEI-TMC was investigated. The thermodynamic analysis showed that the process of PEI-TMC adsorption of U(VI) was endothermic and spontaneous, and the adsorption efficiency was better at higher temperatures. The U(VI) sorption on PEI-TMC was conformed to the Langmuir adsorption isotherm and pseudo-second-order kinetic models. The adsorption mechanism of U(VI) with PEI-TMC was systematically elucidated by XPS and FTIR. Under the best condition, the maximum adsorption capacity of PEI-TMC could reach 212.8 ​mg ​g−1 ​by calculating the Langmuir isothermal model. It indicated that PEI-TMC was a potential adsorbent for the treatment of U(VI)-containing wastewater. Diagram of PEI synthesis and its adsorption mechanism for U(VI). Image 1 • A new and facile method is used to prepare PEI-TMC. • The application field of PEI-TMC was expanded for the separation of U(VI). • Excellent adsorption performance was demonstrated. [ABSTRACT FROM AUTHOR]

The preparation of easily synthesized and cheap composite materials for the efficient removal of toxic oxoanions still remains challenging in sewage treatment. Herein, a new carbonized manganese-crosslinked sodium alginate (Mn/SA-C) was fabricated for the removal of arsenite (As(III)), arsenate (As(V)) and hexavalent chromium (Cr(VI)) in water. The results indicated that the Mn/SA-C pretreated with MnSO 4 solution (Mn/SA-C-S) exhibited a rapid adsorption toward As(III) and As(V) with the removal efficiency of >98% within 10 min, and had a high adsorption capacity toward As(III), As(V), and Cr(VI) with the maximum value of 189.29, 193.29, and 104.50 mg/g based on the Langmuir model, respectively. The removal efficiency of As(III), As(V), and Cr(VI) could be further significantly enhanced by coupling a photocatalytic process. For example, the time in which >98% of Cr(VI) (10 mg/L) was removed dramatically shortened from 360 min (adsorption) to 45 min (adsorption-photocatalysis), and the removal efficiency of As(III) increased by ∼10% within initial 5 min. This was primarily attributed to the Mn-catalyzed production of the photocatalytic excitons for Cr(VI) reduction, and the superoxide (•O 2 −) and hydroxyl (•OH) radicals for As(III) oxidation. The adsorption removal of arsenic (As) was primarily ascribed to surface complexation with MnO and precipitation by MnS 2 , and oxidative adsorption because of Mn valence cycle. The removal mechanisms of Cr(VI) mainly contained reduction by MnO and MnS 2 , complexation with MnO and carboxyl/hydroxyl groups as well as Cr(OH) 3 precipitation. Our research provides a promising Mn/SA-C-S material for rapid and efficient removal of As(III), As(V), and Cr(VI) in contaminated water through an adsorption-photocatalysis synergistic strategy. [Display omitted] • A novel carbonized manganese-crosslinked sodium alginate (Mn/SA-C) was prepared. • >98% of As(III) and As(V) was rapidly adsorbed within 10 min under dark condition. • As(III), As(V) and Cr(VI) adsorption fitted well to pseudo-second-order models. • The removal of As(III), As(V) and Cr(VI) was enhanced by coupling a photocatalysis. • Adsorption-photocatalysis mechanisms of As(III), As(V) and Cr(VI) were proposed. [ABSTRACT FROM AUTHOR]