Arsenic removal by coagulation and filtration: comparison of groundwaters from the United States and Bangladesh

Arsenic contamination of drinking water is a concern in many parts of the world. In the United States, the Environmental Protection Agency recently reduced the maximum contaminant level of arsenic in drinking water from 50 to 10 μ/L (ppb). In Bangladesh the arsenic concentration in drinking water can be as high as hundreds of parts per billion while the maximum contaminant level is 50 ppb. Consequently, there is a great need for new cost-effective methods to remove arsenic from drinking water. Here arsenic removal by coagulation and filtration was investigated using groundwater from a city in southern Colorado in the United States and from Sonargaon in Bangladesh. The results of the bench-scale experiments conducted indicate that coagulation with ferric ions followed by filtration is effective in reducing arsenic concentration in the water tested. However, the actual efficiency of removal is highly dependent on the raw water quality. Further, addition of a polyelectrolyte coagulant aid may lead to improved permeate fluxes during tangential flow microfiltration but has little effect on the residual arsenic concentration.     

A new method of processing the time-concentration data of reaction kinetics

Experimental data of reaction kinetics are usually in the form of concentration versus time. For kinetics investigation it is more convenient to have the data in the form of reaction rate versus concentration. Converting time-concentration data into concentration-reaction rate data is an ill-posed problem in the sense that if inappropriate methods are used the noise in the original data will be amplified leading to unreliable results. This paper describes a conversion procedure, independent of reaction rate model or mechanism, that manages to keep noise amplification under control. The performance of this procedure is demonstrated by applying it to several sets of published kinetic data. Since these data are accompanied by their rate equations, the computed rates are used to obtain the unknown parameters in these equations. Comparison of these parameters with published figures and the ease with which they are obtained highlights the advantages of the new procedure.     

Polyelectrolyte multilayer modified nanofiltration membranes for the recovery of ionic liquid from dilute aqueous solutions

The feasibility of nanofiltration membranes fabricated by static polyelectrolyte layer‐by‐layer deposition of poly(styrene sulfonate) and poly(allylamine hydrochloride) on poly(ether sulfone) ultrafiltration and alumina microfiltration membranes for the recovery of ionic liquid from low molecular weight sugar was investigated. The surface properties of these modified membranes were correlated with their performances. The selectivity for 1‐butyl‐3‐methylimidazolium chloride over cellobiose and glucose was found to be as high as 50.5/2.3 for modified alumina and 32.3/3.5 for modified poly(ether sulfone) membranes with optimized number of bilayers. The values for membrane permeance were 4.8 and 2.5 L m^?1 h² bar^?1, respectively. For low depositions, the separation mechanism was predominantly governed by size‐exclusion. For higher depositions, the enhanced negative zeta potential of the modified membranes suggested preferred dominating electrostatic interactions, resulting in high selectivity of ionic liquids over low molecular weight sugars. At very high depositions, the molecular weight cut‐off of the membrane becomes constricting for size‐exclusion effect. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45349.     

Simultaneous scanning optical and acoustic microscopy

We have demonstrated a combined scanning acoustic and optical microscope capable of simultaneously recording acoustic and optical images of the same field of view. The estimated resolution of the optical (6328 ?) and acoustic (550 MHz) images is 2 ?m, in good agreement with theory. The system is ideally suited to photoacoustic microscopy.     

EXTRACTION OF HNO 3 AND SOME IONS WITH TRIBUTYL PHOSPHATE (TBP)-MIXED TRIALKYL PHOSPHINE OXIDES (TRPO)/KEROSENE

Tributyl phosphate (TBP) and trialkyl phosphine oxides (TRPO) are important extractants. They are widely used in industrial extraction processes, especially in the nuclear power industry. However, both TBP and TRPO suffer from several disadvantages. TBP has a low extractability for trivalent transuranium elements such as Am 3+ and Pu 3+ while TRPO has low loading capacity for HNO 3 and UO 2 2+ . The extraction of HNO 3 and 20 other ions of importance in the nuclear power industry was studied using TBP-TRPO/kerosene. The loading capacity of UO 2 2+ and HNO 3 in TBP-TRPO/kerosene was determined. The synergistic extraction characteristics of the mixture for Am 3+ and TcO 4 - were studied. the influence of high-concentration UO 2 2+ on the extraction of Am 3+ , Eu 3+ , Pu 4+ , and TcO 4 - was investigated. The experimental results show that TBP-TRPO/kerosene mixtures display both a high extractability for a number of ions and a high loading capacity for UO 2 2+ and HNO 3 .     

A Hybrid Intelligent Multiagent System for E-Business

The paper describes a new multiagent system with enhanced capabilities obtained through a hybrid of intelligent techniques. The processing in the model is handled by two types of agents: distributed agents and a central administrator agent. Localized processing at the individual agents is carried out using mathematical techniques and genetic algorithms. The central administrator agent dynamically obtains information about the problem domain from the Internet and maintains a knowledge pool using a clustering technique called the growing self-organizing map (GSOM). Distributed agents communicate with the central administrator agent if they need further knowledge about the problem domain to provide solutions to user-defined tasks. The approach integrates traditional mathematical, data mining, and evolutionary techniques with a multiagent system. The proposed system is implemented as a travel optimizer application for the e-tourism domain. Finally, the possibilities of integrating the proposed technique with currently available e-tourism applications to provide the customer with enhanced solutions are identified.     

Fast algorithm to determine optical properties of a turbid medium from time-resolved measurements

After analytical expressions for the time-resolved reflectance are introduced from the diffusion approximation under the three most commonly used boundary conditions, a novel algorithm is demonstrated for determining the reduced scattering and the absorption coefficients from time-resolved reflectance (or backscatter) measurements at two positions on the surface of biotissue. The algorithm is straightforward and fast and involves only some simple mathematical operations, avoiding complicated iterative nonlinear fitting to the time-resolved curve. The derived reduced scattering coefficient is not affected by whatever boundary condition is applied. The algorithm was verified with time-resolved data from the Monte Carlo model. Both a semi-infinite medium and a turbid slab medium were tested. In contrast to the nonlinear fitting method, this algorithm allows both the scattering and the absorption coefficients to be determined to a high accuracy.