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Abstract : Evaluation of Kinetics of Leaching of Lignins and Tannins in Batch Adsorption of Cr (VI) by Emblica officinalis Leaf Powder (EOLP)
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Abstract: The present paper is aimed to assess the contents of lignin and tannin leached in the batch adsorption test filtrate and to evaluate the kinetics of leaching of lignin and tannins. For the purpose, raw Emblica officinalis leaf powder (EOLP) has been used as adsorbent for removal of Cr (VI) from aqueous solution in batch mode of operation. Test results indicate that EOLP imparts lignin and tannin in batch test filtrate. Both lignin and tannin contents are related to pH, chemical oxygen demand (COD), initial Cr(VI) concentration (C0) residual Cr(VI) concentration in batch test filtrate (C),amount of adsorbent (Wad) and the time of contact (t). Dimensionless parameters are developed and the lignin and tannin contents are well correlated with dimensionless parameters. From the studies conducted on rate of leaching of both soluble lignin and tannins, the kinetics of leaching of soluble lignin and tannin follow a pseudo second order type rate kinetics. Linear regression models are developed based on pseudo second order kinetics for determination of lignin and tannin contents in batch test filtrate. However, these findings need further verification in future investigations. Keywords: Emblica officinalis leaf powder (EOLP), batch test filtrate, chromium (VI), leaching, kinetics.a.Download Full Article |
Abstract : Emerging Tools for Recognition and/or Removal of Dyes from Polluted Sites: Molecularly Imprinted Membranes
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Abstract: Dyes are used in different industries as textile, paper, food processing, cosmetic, leather tanning, rubber, printing and so on. These chemical substances have negative effect on the quality of the water and food, causing human diseases and environmental problems. In view of these aspects, colorant have attracted the interest of the scientists in developing efficient routes for their detection and/or removal from the polluted sites. Although traditional technologies used for removal of dyes are efficient, there is the necessity of developing innovative systems both more cheaply and of easy performance. In this scenario, the integration of the membrane science with the molecular imprinting technology is an alternative way that present many advantages such us the removal or detection of a specific dye or a class of dyes and cost reduction processes. In fact, exploiting the benefits of these two technologies it is possible to develop molecularly imprinted membranes able to recognize a dye of interest in specific mode. This potential is promising for combatting the illegal use of dyes in food, drinks and aquaculture as well as for their removal. The main positive aspects of the imprinted membranes are their chemical stability, reusability, as well as the resistance to the pH and temperature. In addition, their preparation requires short operation time and it is not expensive. All these properties have an encouraging impact in dealing with the problem of dyes contamination. This short review offers a description of the concept of molecular imprinting, starting from the approach of the synthesis of imprinted polymers until the description of the preparation of imprinted membranes. The application of imprinted polymers and membranes for the detection and/or removal of dyes from polluted sites will be also discussed. Keywords: Specific recognition, molecular imprinting, molecularly imprinted membranes, dyes removal.Download Full Article |
Abstract : Investigation of Best Operating Conditions for Treatment of Oily Wastewters with Hollow Fiber Ultrafiltartion Membranes
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Abstract: This paper investigates the optimum operating conditions for treatment of oily wastewaters by application of UF process using the Taguchi method. The following operating conditions have been considered in this investigation: Back Wash time; Trans-membrane pressure (TMP); Flow rate and temperature. The optimum operating conditions of UF were found as follows: Backwash time of 5 s; TMP of 2 bar; Flow rate of 12 L min-1 and temperature of 30 °C. Experimental results presents that the importance level of the percentage contributions of each item is: (1) TMP (98.80 %), (2) back wash time (7.85 %), (3) flow rate (1.11 %), and (4) the feed temperature (0.819 %). Keywords: Taguchi method, ultrafiltration, Oily wastewater treatment.Download Full Article |
Abstract : RO Membrane to Remove Sulfate: an Inland Brackish Water Desalination Pilot Study
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Abstract: The City of Fargo completed a Facility Plan of their Water Treatment Plant (WTP) in 2011 to address two main issues: increasing water demands and high sulfate concentrations within a raw water source (Sheyenne River) primarily due to Devils Lake flooding. Reverse Osmosis (RO) was recognized as the most appropriate technology for sulfate reduction, and recommended for use in the WTP expansion. An RO pilot study was performed to evaluate its feasibility for two operational scenarios. RO membranes experienced rapid fouling in the Polishing Scenario, which used RO to further treat filtered water from the existing WTP (pretreatment, lime softening, ozone, and granular filtration). RO membranes exhibited superior performance in the Parallel Scenario, which was a separate treatment process (coagulation/flocculation/sedimentation + microfiltration/ultrafiltration +RO) parallel to the existing WTP. RO membrane autopsies indicated that membrane fouling was organic and biological for the Polishing Scenario while organic and scaling for the Parallel Scenario. Optimization studies were performed in the Parallel Scenario to determine optimal coagulation conditions for pretreatment as well as flux, recovery, and membrane cleaning regimes for both the MF/UF and the RO. Uniquely, an RO membrane selection pilot was conducted for both scenarios to evaluate RO membranes from four different manufacturers. The slight difference surface chemistry among various RO membrane can cause substantial different performance. It was found that one RO membrane could not be cleaned adequately, although it has many successful applications elsewhere. This one year pilot study proved that RO technology is feasible to reduce sulfate concentrations to acceptable levels in the City’s finished water. Keywords: RO membrane, sulfate, fouling, surface water, microfiltration, ultrafiltration.Download Full Article |
Abstract : Molecularly Imprinted Nanofiber Membranes: Localization of Molecular Recognition Sites on the Surface of Nanofiber
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Abstract: Two types of molecularly imprinted nanofiber membrane were fabricated from chitosan, adopting D-phenylalanine (D-Phe) or L-phenylalanine (L-Phe) as a print molecule. Molecularly imprinted nanofiber membranes were fabricated by applying a co-axial, two capillary spinneret so that molecular recognition sites could be localized on the surface of formed nanofiber. Though the effect was not so prominent, the amount of molecular recognition site for nanofibers with localized molecular recognition site (core-shell molecularly imprinted nanofiber membranes) was higher than that with delocalized one (usual molecularly imprinted nanofiber membranes). Those membranes showed permselectivity. The enantiomer preferentially incorporated into membrane was selectively transported. Keywords: Chiral separation, core-shell, membrane, electrospray deposition, molecular imprinting, nanofiber membrane, optical resolution, permselectivity.Download Full Article |