The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform

Phillip Pendleton - One of the best experts on this subject based on the ideXlab platform.

  • Kinetics of dodecanoic acid adsorption from Caustic Solution by activated carbon.
    Journal of colloid and interface science, 2003
    Co-Authors: Phillip Pendleton
    Abstract:

    This study examines the influences of adsorbent porosity and surface chemistry and of carbon dosage on dodecanoic acid adsorption kinetics from aqueous and 2 M NaOH Solutions as batch adsorption processes. Both adsorbents are steam-activated carbons prepared from either coconut or coal precursors. Prior to use the adsorbents were washed in deionized water or 2 M NaOH. Mass transfer coefficients and effective overall diffusion coefficients indicate a minor contribution from adsorbent porosity. In contrast, high surface oxygen content impedes transport to and into the adsorbent structure. Carbon dosage shows a proportional increase in transport coefficients with increasing mass; these coefficients are constant when normalized per unit mass. Neither water nor NaOH treatment of the adsorbents has a significant influence on dodecanoic acid adsorption kinetics. Molecular and Knudsen diffusion coefficients are defined to demonstrate that the overall effective diffusion coefficient values and the diffusion process are controlled by surface diffusion.

  • adsorption of anionic surfactant by activated carbon effect of surface chemistry ionic strength and hydrophobicity
    Journal of Colloid and Interface Science, 2001
    Co-Authors: Phillip Pendleton
    Abstract:

    Abstract This work investigates the interrelationship between the adsorbent surface chemistry and relative hydrophobic nature and the Solution ionic strength and Solution hydrophobicity during dilute anionic surfactant Solution adsorption. The adsorbents were coconut- and coal-based, steam-activated carbons and wood-based, acid-activated carbons. The adsorptives were dodecanoic acid and octanoic acid dissolved in water or strong Caustic Solution. The activated carbons (ACs) were immersed in the strong Caustic Solution at different temperatures for various lengths of time prior to adsorption measurements. The oxygen content and surface functional group chemistry of each AC sample was analyzed using elemental analysis and X-ray photoelectron spectroscopy. The equilibrium Solution concentration of each surfactant was determined using gas chromatography–flame ionization detection techniques. The amount of surfactant adsorbed by each AC indicates that an inverse linear relationship exists between the amount of surfactant adsorbed and the adsorbent oxygen content. Although the steam-activated carbons offer lower pore volumes than the acid-activated carbons, they exhibit the higher adsorption capacity. The high Solution chemistry pH promotes adsorbent surface oxidation and anionic surfactant dissociation, leading to an interfacial repulsion force and decreased C 12 - and C 8 -acid adsorption. Overall, this study demonstrates that both the surface chemistry and the Solution properties should be considered for an adsorption analysis since each has a significant influence on the adsorption process.

Xiao Dong Chen - One of the best experts on this subject based on the ideXlab platform.

  • Fouling and cleaning of whey protein concentrate fouled ultrafiltration membranes
    Desalination, 2008
    Co-Authors: Mayank Omprakash Nigam, Bipan Bansal, Xiao Dong Chen
    Abstract:

    Ultrafiltration membranes are used extensively in dairy industry. The formation of fouling deposits during processing of dairy fluids has a significant impact on the performance of these membranes. In the current study, performance of a 30 kDa membrane has been investigated which is used to process reconstituted whey protein concentrate. The increase in Solution concentration is observed to have a varying impact on the permeate flux. 0.2 wt% Caustic Solution gives the best performance for cleaning the fouled membranes.

Xueyi Guo - One of the best experts on this subject based on the ideXlab platform.

  • Removal of selenium from Caustic Solution by adsorption with CaAl layered double hydroxides
    Hydrometallurgy, 2020
    Co-Authors: Wen Yan, Xueyi Guo, Qinghua Tian, Xu Zhipeng, Liu Zhu
    Abstract:

    Abstract Removal of selenium from Caustic Solution by adsorption with Ca Al Layered Double Hydroxides (Ca Al LDHs) was proposed. Ca Al LDHs with a hexagonal platelet structure were successfully synthetized by co-precipitation. 94% of Se(VI) was removed at 30 °C for 30 min with NaOH concentration of 1 mol·L−1 and adsorbent dosage of 40 g·L−1. Temperature played an important role in Se(VI) removal. At low temperature (30 °C–70 °C), Ca Al LDHs underwent an anion exchange with Se(VI) to form Ca4Al2O6SeO4(H2O)10, with the d-spacing expanding from 7.95 A to 10.15 A. When increasing temperature above 80 °C, Ca4Al2O6SeO4(H2O)10 began to decomposed to Ca3Al2O6(H2O)6 and Ca(OH)2, resulting in SeO42− into the liquor. Kinetic data were well fitted to pseudo-second-order model, indicating Se(VI) removal process was controlled by the chemisorption. The adsorption isotherms were in good agreement with Langmuir isotherm model, suggesting Se(VI) removal was a monolayer adsorption. The maximum adsorption capacity was calculated to be 138.76 mg·g−1 at 30 °C. Desorption and regeneration results indicated that Ca Al LDHs can be reused at least three times without significantly reducing its absorption capacity for Se(VI).

  • selenium vi removal from Caustic Solution by synthetic ca al cl layered double hydroxides
    Transactions of Nonferrous Metals Society of China, 2019
    Co-Authors: X U Shaodong, Xueyi Guo, Wen Yan, Liuyang Dong, Jie Gao
    Abstract:

    Abstract To extract selenium(VI) from the highly Caustic leachate of copper anode slime, the Ca–Al–Cl layered double hydroxides (Ca–Al–Cl–LDHs) with a formula of Ca2Al(OH)6Cl·2H2O by three co-precipitation methods were synthesized. A plate-like morphology and hexagonal crystal structure with typical mineral phases and functional groups were identified by the FESEM, XRD, FTIR, BET and XPS analysis. The forward feeding sample exhibits the best adsorption capacity of Se(VI). The factor experiments then reveal a favorable adsorption process with low temperature, low NaOH concentration and high adsorbent dosage. Furthermore, the adsorption kinetics and isotherm parameters can be well described by the Langmuir isotherm and the pseudo-second-order models, respectively. Accordingly, the maximum adsorption amount of Se(VI) onto Ca–Al–Cl–LDHs reaches 188.6 mg/g at 50 °C.

  • synthesis and application of friedel s salt in arsenic removal from Caustic Solution
    Chemical Engineering Journal, 2017
    Co-Authors: Xueyi Guo, Qinghua Tian, Lei Zhang
    Abstract:

    Abstract Conventional way to remove arsenic from Caustic Solution is neutralization-precipitation process, which costs a large amount of acidic reagents while huge wastes are generated. This study proposed a method for arsenic removal from Caustic Solution using Friedel’s salt as an adsorbent. Friedel’s salt was synthesized by coprecipitation in different feeding ways and characterized by XRD, FESEM, DSC-TGA and FT-IR techniques. The Friedel’s salt synthesized in forward feeding way showed smallest crystallite size and exhibited the highest adsorption capacity of As(V). The As(V) adsorption properties of Friedel’s salt was evaluated in detail under the effects of contact time, temperature, OH− concentration and adsorbent dosage. Kinetic experiments were done and the data was well predicted by pseudo-second-order model, indicating the adsorption process is controlled by the chemisorption. Temperature shows positive effect on As(V) adsorption, which indicated an endothermic interaction between As(V) and Friedel’s salt. The adsorption process could be well described by Langmuir isotherm model, with a maximum adsorption capacity of 172.41 mg·g−1 at 70 °C. Moreover, the adsorption mechanism was elucidated with the characterizations of the Friedel’s salt after adsorption.

  • Synthesis and application of Friedel’s salt in arsenic removal from Caustic Solution
    Chemical Engineering Journal, 2017
    Co-Authors: Xueyi Guo, Qinghua Tian, Xu Zhipeng, Xu Runze, Zhang Lei
    Abstract:

    Abstract Conventional way to remove arsenic from Caustic Solution is neutralization-precipitation process, which costs a large amount of acidic reagents while huge wastes are generated. This study proposed a method for arsenic removal from Caustic Solution using Friedel’s salt as an adsorbent. Friedel’s salt was synthesized by coprecipitation in different feeding ways and characterized by XRD, FESEM, DSC-TGA and FT-IR techniques. The Friedel’s salt synthesized in forward feeding way showed smallest crystallite size and exhibited the highest adsorption capacity of As(V). The As(V) adsorption properties of Friedel’s salt was evaluated in detail under the effects of contact time, temperature, OH− concentration and adsorbent dosage. Kinetic experiments were done and the data was well predicted by pseudo-second-order model, indicating the adsorption process is controlled by the chemisorption. Temperature shows positive effect on As(V) adsorption, which indicated an endothermic interaction between As(V) and Friedel’s salt. The adsorption process could be well described by Langmuir isotherm model, with a maximum adsorption capacity of 172.41 mg·g−1 at 70 °C. Moreover, the adsorption mechanism was elucidated with the characterizations of the Friedel’s salt after adsorption.

  • Dearsenization of Caustic Solution by synthetic hydrocalumite
    Hydrometallurgy, 2016
    Co-Authors: Xueyi Guo, Qinghua Tian, Xu Zhipeng, Xu Runze, Jing Zhang
    Abstract:

    Abstract Arsenic is enriched in liquor during the processing of copper anode slime by alkali fusion-leaching. The conventional method of removing arsenic from Caustic liquors requires the neutralization followed by the introduction of calcium oxide or calcium hydroxide. In this work, the hydrocalumite, Ca 2 Al(OH) 6 Cl·2H 2 O, are proved for the first time to remove up to 91% arsenic from Caustic Solution. Hydrocalumite is a mineral anion exchanger belonging to the layered double hydroxides (LDHs) which was synthesized by co-precipitation of calcium chloride and aluminum chloride in sodium hydroxide Solution. It was characterized by XRD, FESEM and TG-DSC. Experimental parameters affecting the dearsenization process, such as temperature, NaOH concentration, initial arsenic concentration and hydrocalumite dosage were investigated in detail. The main phases of dearsenization products formed from hydrocalumite at different temperature were identified as Ca 6 Al 3 (OH) 18 (H 2 O) 6 –AsO 4 (flat hexagonal), Ca 3 Al 2 (OH) 6 –(AsO 4 ) 2 (cubic) and Ca(OH) 2 (Octahedron-single). The apparent activation energy in dearsenization by hydrocalumite was estimated to be 12.43 kJ/mol over the range of 30–80 °C.

Miodrag N. Tekić - One of the best experts on this subject based on the ideXlab platform.

  • Flux recovery of tubular ceramic membranes fouled with whey proteins
    Desalination, 2009
    Co-Authors: Svetlana S. Popović, Spasenija D. Milanović, Mirela D. Iličić, Mirjana Djurić, Miodrag N. Tekić
    Abstract:

    Membrane process efficiency is governed by the formation of fouling deposits during processing of dairy fluids. Because of fouling with whey proteins, permeate flux can drastically decline during filtration process. This paper describes the flux recovery procedure for ceramic tubular membranes (50 and 200 nm pore sizes) fouled with whey proteins. The results comprehend the effect of rinsing and cleaning agent choice and concentration, on the cleaning efficiency. As chemical cleaning agents, the Caustic Solution and the commercial detergents P3-ultrasil 67 and P3-ultrasil 69 were selected. The observations are that rinsing with deionised water contributes to a flux recovery to a certain degree. For the 50 nm membrane, the choice of the 1.0% (w/w) Caustic Solution, as cleaning agent, gives the best flux recovery. For the 200 nm, total flux recovery was not observed regardless of the cleaning agent choice and concentration. Cleaning with chosen commercial detergent appeared to be less efficient than cleaning with Caustic Solution for the chosen ceramic membranes. Also, a mathematical model, proposed in this study, has shown high agreement with experimentally obtained data.

G J Witkamp - One of the best experts on this subject based on the ideXlab platform.

  • magnetic separation and characterization of vivianite from digested sewage sludge
    Separation and Purification Technology, 2019
    Co-Authors: T Prot, Philipp Wilfert, A I Dugulan, K Goubitz, Leon Korving, Van Hoa Nguyen, Dick De Ridder, Peter Carlo Rem, A Bouderbala, G J Witkamp
    Abstract:

    To prevent eutrophication of surface water, phosphate needs to be removed from sewage. Iron (Fe) dosing is commonly used to achieve this goal either as the main strategy or in support of biological removal. Vivianite (Fe(II) 3 (PO 4 ) 2 * 8H 2 O) plays a crucial role in capturing the phosphate, and if enough iron is present in the sludge after anaerobic digestion, 70–90% of total phosphorus (P) can be bound in vivianite. Based on its paramagnetism and inspired by technologies used in the mining industry, a magnetic separation procedure has been developed. Two digested sludges from sewage treatment plants using Chemical Phosphorus Removal were processed with a lab-scale Jones magnetic separator with an emphasis on the characterization of the recovered vivianite and the P-rich Caustic Solution. The recovered fractions were analyzed with various analytical techniques (e.g., ICP-OES, TG-DSC-MS, XRD and Mossbauer spectroscopy). The magnetic separation showed a concentration factor for phosphorus and iron of 2–3. The separated fractions consist of 52–62% of vivianite, 20% of organic matter, less than 10% of quartz and a small quantity of siderite. More than 80% of the P in the recovered vivianite mixture can be released and thus recovered via an alkaline treatment while the resulting iron oxide has the potential to be reused. Moreover, the trace elements in the P-rich Caustic Solution meet the future legislation for recovered phosphorus salts and are comparable to the usual content in Phosphate rock. The efficiency of the magnetic separation and the advantages of its implementation in WWTP are also discussed in this paper.