Economical treatment of reverse osmosis reject of textile industry effluent by electrodialysis–evaporation integrated process

Membrane separation methods such as electrodialysis (ED) can reduce the volume load on evaporators by facilitating further concentration of rejects from reverse osmosis (RO) plants. ED studies were carried out on a bench-scale system using five membrane cell pairs to obtain a textile effluent concentrate containing approximately 6 times the quantity of salts present in the RO reject. The limiting current densities were determined to be in the range 2.15–3.35 amp/m² for feed flow rates varying from 18 to 108 L/h. Apart from feed rate, the influence of volume of concentrate and current on membrane performance was evaluated to optimize current utilization. An estimation of energy requirement of an integrated process constituting ED and evaporation for concentration of inorganics present in textile effluent from 4.35% to 24% was made and found to be approximately one eighth of the operating cost incurred by evaporation alone. Detailed design of a commercial ED system revealed that a membrane area of 13.1 m² was required to treat a feed rate of 1500 L/h. The payback period to recover capital investment was found to be 110 days.     

Thin film composite sodium alginate membranes for dehydration of acetic acid and isobutanol

Dehydration of widely used organic solvents such as acetic acid (AA) and isobutanol (IB) is challenging tasks, which form close boiling mixtures with water. Sodium alginate (SA) thin film composite membranes were prepared and crosslinked with 2,4‐toluene diisocyanate (TDI) and glutaraldehyde for dehydration of IB and AA/water mixtures through pervaporation (PV). The crosslinked and uncrosslinked SA composite membranes were characterized by Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy, and universal testing machine for intermolecular interactions, crystalline nature, thermal stability, surface morphology, and tensile strength, respectively. At a feed composition of 98 wt % IB and 95 wt % AA aqueous solutions, the TDI crosslinked SA composite membrane exhibited separation factors of 3229 and 708 with reasonable fluxes of 0.021 and 0.012 kg m^?2 h^?1, respectively. The results obtained in the study for IB and AA systems were compared with other SA membranes reported in the literature. The membranes appeared to have potential for commercial PV ability to dehydrate the solvents up to desirable purity levels (>99%) and feasibility of preparing them in a composite form which would enable scale‐up into modular configurations. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40018.     

Nafion and modified-Nafion membranes for polymer electrolyte fuel cells: An overview

Polymer electrolyte fuel cells (PEFCs) employ membrane electrolytes for proton transport during the cell reaction. The membrane forms a key component of the PEFC and its performance is controlled by several physical parameters, viz. water up-take, ion-exchange capacity, proton conductivity and humidity. The article presents an overview on Nafion membranes highlighting their merits and demerits with efforts on modified-Nafion membranes. Energy security refers to various security measures that a given nation, or the global community as a whole, must carryout to maintain an adequate energy supply     

Separation of nickel from copper in ammoniacal/ammonium carbonate solution using ACORGA M5640 by selective stripping

Separation of nickel from copper in ammoniacal/ammonium carbonate solution using ACORGA M5640 by selective stripping was carried out. The influence of equilibration time, equilibrium pH and extractant concentration on the extraction of both the metals was studied. It was found that the copper extraction equilibrium was reached in a shorter time than the nickel extraction equilibrium. Nickel extraction decreases above an equilibrium pH of 9.0, while the extraction of copper remains unaffected by the changes in the equilibrium pH range of 7–10. Co-extraction, ammonia scrubbing and the selective stripping of copper and nickel were performed for a solution containing 3 g/l each of copper and nickel and 60 g/l ammonium carbonate. The extraction and the percentage stripping of copper and nickel were almost quantitative.     

Relationship between normal load and dynamic co-efficient of friction on rock-rubber wear mechanism

In this study, rubber compounds were produced in varying proportions of carboxylated acrylonitrile butadiene rubber (XNBR) and natural rubber (NR) and the parameters such as cure characteristics, wear behavior against various surfaces at different normal loads, and frictional works were tested. The tensile strength and dynamic co-efficient of friction of sample containing 80 wt.% of XNBR was high compared to other samples by 2% and 10% respectively. The results of XNBR and NR vulcanizates under normal pressure ranging from 43 to 118 kPa were reported. Based on these results the relationship between normal load and dynamic co-efficient of friction has been proposed. It was also observed that sample containing 80 wt.% of XNBR exhibits lesser volume loss than compared to other samples.     

Strombus gigas inspired biomimetic ceramic composites via SHELL—Sequential Hierarchical Engineered Layer Lamination

Nature has produced remarkable structural designs based on many millennia of evolutionary optimization. Biological materials, such as the sea-shell, possess unique microstructures and properties that provide inspiration for the next generation of structural ceramics. Strombus gigas (Queen conch) shells contain a hierarchical, multilayered, crossed-lamellar architecture built with two natural materials (calcium carbonate and protein) with at least three identifiable scales (or orders) of structure. Drawing on Strombus gigas for inspiration, we have developed a new process to realize such complex micro-architectures in macroscopic form. SHELL (Sequential Hierarchical Engineered Layer Lamination) is a thermoplastic forming process that is capable of producing the third order structural complexity over the micron-millimeter length scales. We have fabricated silicon nitride—boron nitride ceramics via SHELL that are endowed with excellent damage tolerance, exhibit graceful failure, and exhibit toughening mechanisms similar to those observed in Strombus gigas.     

Mapping the total phosphorus concentration of biosolid amended surface soils using LANDSAT TM data

Conventional methods for soil sampling and analysis for soil variability in chemical characteristics are too time-consuming and expensive for multi-seasonal monitoring over large-scale areas. Hence, the objectives of this study are: 1) to determine changes in chemical concentrations of soils that are amended with treated sewage sludge; and 2) to determine if LANDSAT TM data can be used to map surface chemical characteristics of such amended soils. For this study, we selected two fields in NW Ohio, designated as F34 and F11, that had been applied with 34 and 11 ton acre^− 1 of biosolids, respectively. Soil samples from a total of 70 sampling locations across the two fields were collected one day prior to LANDSAT 5 overpass and were analyzed for several elemental concentrations. The accumulation of Ba, Cd, Cu, S and P were found to be significantly higher in the surface soils of field F34, compared to field F11. Regression equations were established to search for algorithms that could map these five elemental concentrations in the surface soils using six, dark-object-subtracted (DOS) LANDSAT TM bands and the 15 non-reciprocal spectral ratios derived from these six bands for the May 20, 2005, LANDSAT 5 TM image. Phosphorus (P) had the highest R² adjusted value (67.9%) among all five elements considered, and the resulting algorithm employed only spectral ratios. This model was successfully tested for robustness by applying it to another LANDSAT TM image obtained on June 5, 2005. Our results enabled us to conclude that LANDSAT TM imagery of bare-soil fields can be used to quantify and map the spatial variation of total phosphorous concentration in surface soils. This research has significant implications for identification and mapping of areas with high P, which is important for implementing and monitoring the best phosphorous management practices across the region.