Ionogels for flexible conductive substrates and their application in biosensing.

Ionogels are highly conductive gels made from ionic liquids dispersed in a matrix made of organic or inorganic materials. Ionogels are known for high ionic conductivity, flexibility, high thermal and electrochemical stability. These characteristics make them suitable for sensing and biosensing applications. This review discusses about the two main constituents, ionic liquids and matrix, used to make ionogels and effect of these materials on the characteristics of ionogels. Here, the material properties like mechanical, electrochemical and stability are discussed for both polymer matrix and ionic liquid. We have briefly described about the fabrication methods like 3D printing, sol-gel, blade coating, spin coating, aerosol jet printing etc., used to make films or coating of these ionogels. The advantages and disadvantages of each method are also briefly summarized. Finally, the last section provides a few examples of application of flexible ionogels in areas like wearables, human-machine interface, electronic skin and detection of biological molecules.

Dual modifications of chitosan with PLK for amputation of cyanide ions: Equilibrium studies and optimization using RSM.

The aim of the study is to characterize and hierarchically modify chitosan using partially lateritized khondalite (PLK) rock. PLK is a metamorphic rock rich in mineral oxides and is not commercialized thus, treated as a mining reject. Chitosan was sequentially altered to Chitosan-PLK (Ch-PLK) and Chitosan-PLK-Epichlorohydrin (Ch-PLK-ECH) and both the materials were characterized by FT-IR, SEM, EDX, XRD, XRF and BET surface area analysis. The adsorbents were used for removal of cyanide ions from aqueous solution using batch adsorption experiments. The experiments were performed varying operational parameters and were optimized using RSM. The conditions optimized by RSM were carried out, more than 90 % of CN- adsorption was observed. The isotherm and kinetics studies have shown that the adsorption process fitted well with Langmuir isotherm model and pseudo second order kinetics. Using Langmuir isotherm, the maximum adsorption capacities of Ch-PLK and Ch-PLK-ECH towards cyanide ions at 30 °C were found to be 23.98 mg g-1 and 65.27 mg g-1 respectively. Thermodynamic studies described that adsorption process was spontaneous, enthalpy-driven over entire temperature range. Column studies established that the adsorbents may be applicable to large volume of samples. The adsorbents were tested for regeneration for 5 adsorption-desorption cycles suggesting reusability of the materials.

Recent advancements in the mitigation of obnoxious nitrogenous gases.

Nitrogenous gaseous emissions commonly have an obnoxious odor associated with it, which when discharged into the environment results in serious environmental problems and health hazards. Several strategies for mitigation of nitrogenous odorants have been reported which include physical, chemical and biological methods. Biological treatments are widely employed because of their efficiency even at low concentration, where physical and chemical methods are not effective. Most commonly used biological treatment methods are biofiltration, biotrickling filters and membrane bioreactors with innovative reactor design, mixing pattern, and air sparging, for example FEBR, ALR, etc. These treatment methods require a critical assessment for the mitigation of obnoxious nitrogen emissions, especially in the context of environmental protection. This review offers a critical evaluation of treatment methods for the mitigation of nitrogenous odorous compound with a key emphasis on biological treatment systems. Also, various mathematical modelling techniques required for optimized operation of biotreatment systems has been discussed.

Application of electronic nose for industrial odors and gaseous emissions measurement and monitoring--An overview.

The present review evaluates the key modules of the electronic nose, a biomimetic system, with specific examples of applications to industrial emissions monitoring and measurement. Regulations concerning the odor control are becoming very strict, due to ever mounting environmental pollution and its subsequent consequences and it is advantageous to employ real time measurement system. In this perspective, systems like the electronic nose are an improved substitute for assessing the complex industrial emissions over other analytical techniques (odorant concentration measurement) and olfactometry (odor concentration measurement). Compared to tools like gas chromatography, electronic nose systems are easy to develop, are non-destructive and useful for both laboratory and on field purposes. Although there has been immense development of more sensitive and selective sensor arrays and advanced data mining techniques, there have been limited reports on the application of electronic nose for the measurement of industrial emissions. The current study sheds light on the practical applicability of electronic nose for the effective industrial odor and gaseous emissions measurement. The applications categorization is based on gaseous pollutants released from the industries. Calibration and calibration transfer methodologies have been discussed to enhance the applicability of electronic nose system. Further, industrial gas grab sampling technique is reviewed. Lastly, the electronic mucosa system, which has the ability to overcome the flaws of electronic nose system, has been examined. The review ends with the concluding remarks describing the pros and cons of artificial olfaction technique for the industrial applications.

Calibration transfer between electronic nose systems for rapid in situ measurement of pulp and paper industry emissions.

Electronic nose systems when deployed in network mesh can effectively provide a low budget and onsite solution for the industrial obnoxious gaseous measurement. For accurate and identical prediction capability by all the electronic nose systems, a reliable calibration transfer model needs to be implemented in order to overcome the inherent sensor array variability. In this work, robust regression (RR) is used for calibration transfer between two electronic nose systems using a Box-Behnken (BB) design. Out of the two electronic nose systems, one was trained using industrial gas samples by four artificial neural network models, for the measurement of obnoxious odours emitted from pulp and paper industries. The emissions constitute mainly of hydrogen sulphide (H2S), methyl mercaptan (MM), dimethyl sulphide (DMS) and dimethyl disulphide (DMDS) in different proportions. A Box-Behnken design consisting of 27 experiment sets based on synthetic gas combinations of H2S, MM, DMS and DMDS, were conducted for calibration transfer between two identical electronic nose systems. Identical sensors on both the systems were mapped and the prediction models developed using ANN were then transferred to the second system using BB-RR methodology. The results showed successful transmission of prediction models developed for one system to other system, with the mean absolute error between the actual and predicted concentration of analytes in mg L(-1) after calibration transfer (on second system) being 0.076, 0.1801, 0.0329, 0.427 for DMS, DMDS, MM, H2S respectively.

Air-lift reactor system for the treatment of waste-gas-containing monochlorobenzene.

An air-lift bioreactor (ALR) system, applied for the treatment of waste-gas-containing monochlorobenzene (MCB) was seeded with pure culture of Acinetobacter calcoaceticus, isolated from soil as a starter seed. It was found that MCB was biologically converted to chloride as chloride was mineralized in the ALR. After the built up of the biomass in the ALR, the reactor parameters which have major influence on the removal efficiency and elimination capacity were studied using response surface methodology. The data generated by running the reactor for 150 days at varying conditions were fed to the model with a target to obtain the removal efficiency above 95% and the elimination capacity greater than 60%. The data analysis indicated that inlet loading was the major parameter affecting the elimination capacity and removal efficiency of >95%. The reactor when operated at optimized conditions resulted in enhanced performance of the reactor.