Diagnostic analysis of RO desalting treated waste water

Diagnostic analysis of reverse osmosis membranes that were fed with Western treatment plant (WTP) recycled water was investigated by both thermodynamic calculations and laboratory experiments in order to predict the feasibility of RO desalting for WTP. The thermodynamic calculations suggested that RO recoveries of 80–85% were feasible with careful control of feed water pH and the use of chemical additives such as antiscalants and chelating agents, it also predicted the major minerals of concern to be silica, calcium fluoride, calcium carbonate, and calcium phosphate. Following the thermodynamic simulations, diagnostic laboratory experiments were undertaken. The experiments showed that the major contributor to scale formation was indeed calcium phosphate and possibly another calcium based compound, which was strongly suspected to be calcium carbonate. Based on previously published literature that indicated anti-scalants did not substantially decrease the scaling effect of calcium phosphate and laboratory tests that indicated controlling the pH to 6.4 in the feed water dramatically reduced scaling formation, it was suggested that the feed water could be controlled by pH adjustments only. Inter-stage pH correction was suggested as an optional technique to enhance the overall water recovery to above 95%

Low-cost inorganic cation exchange membrane for electrodialysis: optimum processing temperature for the cation exchanger

The optimum temperature for fixing zirconium phosphate, obtained by precipitation, on a low-cost ceramic support was determined in order to obtain an inorganic cation exchange membrane for electrodialysis. Zirconium phosphate ion exchange capacity maximised between 450 and 550°C, thus it was considered the optimum processing temperature. The origin of this maximum was investigated by means of X-ray diffraction and termogravimetry and evolved gas analysis. Zirconium phosphate formation by precipitation in the porous network of the support was verified by scanning electron microscopy and energy dispersive X-ray analysis and mercury intrusion porosimetry. The membrane obtained after thermal treatment at 450°C displayed selectivity to the cations present in the spent rinse water of the chromium plating process. This property allows the recovery of chromium by removing the cations through the cation exchange ceramic membrane.The authors wish to express their gratitude to the Spanish Ministry of Science and Innovation for the support given to the research study (National Basic Research Programme, Ref. CTQ2008-06750-C02-02), as well as for the FPU student grant awarded to one of the authors (Ref.: AP2009-4409).Mestre, S.; Sales, S.; Palacios, M.; Lorente, M.; Mallol, G.; Pérez-Herranz, V. (2013). Low-cost inorganic cation exchange membrane for electrodialysis: optimum processing temperature for the cation exchanger. Desalination and Water Treatment. 51(16-18):3317-3324. https://doi.org/10.1080/19443994.2012.749177S331733245116-18Strathmann, H. (2010). Electromembrane Processes: Basic Aspects and Applications. Comprehensive Membrane Science and Engineering, 391-429. doi:10.1016/b978-0-08-093250-7.00048-7Drioli, E., & Fontananova, E. (s. f.). Integrated Membrane Processes. Membrane Operations, 265-283. doi:10.1002/9783527626779.ch12Strathmann, H. (s. f.). Fundamentals in Electromembrane Separation Processes. Membrane Operations, 83-119. doi:10.1002/9783527626779.ch5Alberti, G., Casciola, M., Costantino, U., & Levi, G. (1978). Inorganic ion exchange membranes consisting of microcrystals of zirconium phosphate supported by Kynar®. Journal of Membrane Science, 3(2), 179-190. doi:10.1016/s0376-7388(00)83021-5Semiat, R., & Hasson, D. (s. f.). Seawater and Brackish-Water Desalination with Membrane Operations. Membrane Operations, 221-243. doi:10.1002/9783527626779.ch10Bregman, J. ., & Braman, R. . (1965). Inorganic ion exchange membranes. Journal of Colloid Science, 20(9), 913-922. doi:10.1016/0095-8522(65)90064-4Bishop, H. K., Bittles, J. A., & Guter, G. A. (1969). Investigation of inorganic ion exchange membranes for electrodialysis. Desalination, 6(3), 369-380. doi:10.1016/s0011-9164(00)80226-xRajan, K. S., Boies, D. B., Casolo, A. J., & Bregman, J. . (1966). Inorganic ion-exchange membranes and their application to electrodialysis. Desalination, 1(3), 231-246. doi:10.1016/s0011-9164(00)80255-6INAMUDDIN, KHAN, S., SIDDIQUI, W., & KHAN, A. (2007). Synthesis, characterization and ion-exchange properties of a new and novel ‘organic–inorganic’ hybrid cation-exchanger: Nylon-6,6, Zr(IV) phosphate. Talanta, 71(2), 841-847. doi:10.1016/j.talanta.2006.05.042HELEN, M., VISWANATHAN, B., & MURTHY, S. (2007). Synthesis and characterization of composite membranes based on α-zirconium phosphate and silicotungstic acid. Journal of Membrane Science, 292(1-2), 98-105. doi:10.1016/j.memsci.2007.01.018Yu.S. Dzyaz’ko, V.N. Belyakov, N.V. Stefanyak, S.L. Vasilyuk, Anion-exchange properties of composite ceramic membranes containing hydrated zirconium dioxide, Russ. J. Appl. Chem. 79 (2006) 769–773.Linkov, V. ., & Belyakov, V. . (2001). Novel ceramic membranes for electrodialysis. Separation and Purification Technology, 25(1-3), 57-63. doi:10.1016/s1383-5866(01)00090-9Linkov, V. M., Dzyaz’ko, Y. S., Belyakov, V. N., & Atamanyuk, V. Y. (2007). Inorganic composite membranes for electrodialytic desaltination. Russian Journal of Applied Chemistry, 80(4), 576-581. doi:10.1134/s1070427207040118El-Sourougy, M. R., Zaki, E. E., & Aly, H. F. (1997). Transport characteristics of ceramic supported zirconium phosphate membrane. Journal of Membrane Science, 126(1), 107-113. doi:10.1016/s0376-7388(96)00273-6Sánchez, E., Mestre, S., Pérez-Herranz, V., & García-Gabaldón, M. (2005). Síntesis de membranas cerámicas para la regeneración de baños de cromado agotados. Boletín de la Sociedad Española de Cerámica y Vidrio, 44(6), 409-414. doi:10.3989/cyv.2005.v44.i6.340Sánchez, E., Mestre, S., Pérez-Herranz, V., Reyes, H., & Añó, E. (2006). Membrane electrochemical reactor for continuous regeneration of spent chromium plating baths. Desalination, 200(1-3), 668-670. doi:10.1016/j.desal.2006.03.475Alberti, G., Casciola, M., Costantino, U., & Vivani, R. (1996). Layered and pillared metal(IV) phosphates and phosphonates. Advanced Materials, 8(4), 291-303. doi:10.1002/adma.19960080405Alberti, G., & Torracca, E. (1968). Crystalline insoluble salts of polybasic metals - II. Synthesis of crystalline zirconium or titanium phosphate by direct precipitation. Journal of Inorganic and Nuclear Chemistry, 30(1), 317-318. doi:10.1016/0022-1902(68)80096-xTrobajo, C., Khainakov, S. A., Espina, A., & García, J. R. (2000). On the Synthesis of α-Zirconium Phosphate. Chemistry of Materials, 12(6), 1787-1790. doi:10.1021/cm0010093Alberti, G. (1978). Syntheses, crystalline structure, and ion-exchange properties of insoluble acid salts of tetravalent metals and their salt forms. Accounts of Chemical Research, 11(4), 163-170. doi:10.1021/ar50124a007Rajeh, A. O., & szirtes, L. (1995). Investigations of crystalline structure of gamma-zirconium phosphate. Journal of Radioanalytical and Nuclear Chemistry Articles, 196(2), 319-322. doi:10.1007/bf02038050Krogh Andersen, A. M., Norby, P., Hanson, J. C., & Vogt, T. (1998). Preparation and Characterization of a New 3-Dimensional Zirconium Hydrogen Phosphate, τ-Zr(HPO4)2. Determination of the Complete Crystal Structure Combining Synchrotron X-ray Single-Crystal Diffraction and Neutron Powder Diffraction. Inorganic Chemistry, 37(5), 876-881. doi:10.1021/ic971060hFeng, Y., He, W., Zhang, X., Jia, X., & Zhao, H. (2007). The preparation of nanoparticle zirconium phosphate. Materials Letters, 61(14-15), 3258-3261. doi:10.1016/j.matlet.2006.11.132Clearfield, A. (2000). INORGANIC ION EXCHANGERS, PAST, PRESENT, AND FUTURE. Solvent Extraction and Ion Exchange, 18(4), 655-678. doi:10.1080/07366290008934702Szirtes, L., Shakshooki, S. K., Szeleczky, A. M., & Rajeh, A. O. (1998). Thermoanalyncal Investigation of Some Layered Zirconium Salts and Their Various Derivatives I. Journal of Thermal Analysis and Calorimetry, 51(2), 503-515. doi:10.1007/bf03340188Al-Othman, A., Tremblay, A. Y., Pell, W., Letaief, S., Burchell, T. J., Peppley, B. A., & Ternan, M. (2010). Zirconium phosphate as the proton conducting material in direct hydrocarbon polymer electrolyte membrane fuel cells operating above the boiling point of water. Journal of Power Sources, 195(9), 2520-2525. doi:10.1016/j.jpowsour.2009.11.052Thakkar, R., Patel, H., & Chudasama, U. (2007). A comparative study of proton transport properties of zirconium phosphate and its metal exchanged phases. Bulletin of Materials Science, 30(3), 205-209. doi:10.1007/s12034-007-0036-3Jiang, P., Pan, B., Pan, B., Zhang, W., & Zhang, Q. (2008). A comparative study on lead sorption by amorphous and crystalline zirconium phosphates. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 322(1-3), 108-112. doi:10.1016/j.colsurfa.2008.02.035García-Gabaldón, M., Pérez-Herranz, V., García-Antón, J., & Guiñón, J. L. (2009). Use of ion-exchange membranes for the removal of tin from spent activating solutions. Desalination and Water Treatment, 3(1-3), 150-156. doi:10.5004/dwt.2009.453García-Gabaldón, M., Pérez-Herranz, V., García-Antón, J., & Guiñón, J. L. (2009). Effect of hydrochloric acid on the transport properties of tin through ion-exchange membranes. Desalination and Water Treatment, 10(1-3), 73-79. doi:10.5004/dwt.2009.69

Graphene membranes for water desalination

Extensive environmental pollution caused by worldwide industrialization and population growth has led to a water shortage. This problem lowers the quality of human life and wastes a large amount of money worldwide each year due to the related consequences. One main solution for this challenge is water purification. State-of-the-art water purification necessitates the implementation of novel materials and technologies that are cost and energy efficient. In this regard, graphene nanomaterials, with their unique physicochemical properties, are an optimum choice. These materials offer extraordinarily high surface area, mechanical durability, atomic thickness, nanosized pores and reactivity toward polar and non-polar water pollutants. These characteristics impart high selectivity and water permeability, and thus provide excellent water purification efficiency. This review introduces the potential of graphene membranes for water desalination. Although literature reviews have mostly concerned graphene's capability for the adsorption and photocatalysis of water pollutants, updated knowledge related to its sieving properties is quite limited.Peer reviewe

Limits of RO recovery imposed by calcium phosphate precipitation. Desalination 183

Abstract The presence of phosphate ions causes a difficulty confronting RO purification of secondary treated wastewater and limits the water recovery. These ions can readily lead to membrane blockage by precipitation of sparingly soluble calcium phosphate salts. Currently, it is far from clear if calcium phosphate scale deposition can be reliably inhibited by dosage of antiscalants. Major efforts were devoted to a systematic evaluation of the effectiveness of currently available calcium phosphate antiscalants. The inhibitory capability of the tested antiscalants was assessed using a continuous-flow laboratory system, equipped with a tubular RO membrane. Feed solution of controlled composition, dosed with an antiscalant, was continuously passed through the membrane. Both concentrate and permeate recycled to the feed vessel. Antiscalant effectiveness was evaluated from the rate of membrane permeability decay. Five antiscalants were tested under various solution supersaturation conditions and antiscalant concentrations. All antiscalants proved to be ineffective over most solution compositions tested. Results of this study delineate the restricted range of conditions under which currently available antiscalant are likely to provide an acceptable calcium phosphate scale inhibition

Modification of a polypropylene feed spacer with metal oxide-thin film by chemical bath deposition for biofouling control in membrane filtration

© 2018 Elsevier B.V. Surface modification of polypropylene feed spacers typical of spiral wound membrane modules was studied by generation of crystalline ZnO nanorods. A seeding layer made by deposition of ZnO nanoparticles (20–40–60 nm diameter) from aqueous dispersions served as nucleation centers for crystallization. A uniform layer of ZnO nanorods was grown on the seeding layer by chemical bath deposition from a zinc acetate solution. Biocidal activity was estimated by antibacterial tests in static liquid culture against Escherichia coli and antibiofouling tests in flow-through/cross-flow mode against a mixture of Pseudomonas fluorescens and Bacillus subtilis. Best biocidal activity was displayed by 20 nm ZnO particles, suggesting a tradeoff between surface coverage, roughness and particle size. Although the seed layer itself displayed acceptable antibacterial activity, a marked improvement was achieved by the nanorods, proving that the morphology of the deposition layer was involved in the antibacterial mechanism. Antibiofouling activity was further improved by superhydrophobic over-coating of the nanorods with octadecyl-phosphonic acid. Modified spacers reduced permeate flux decay by at least 40% compared to controls. The enhanced antibiofouling activity of crystalline ZnO nanorods, compared with amorphous ZnO nanoparticles, can be explained by a combination of the abrasive surface of the crystalline nanorods, hydrophobic repulsion and cumulative oxidation