Use of granulated modified zeolite Y for the removal of inorganic arsenic and selenium species

Column studies were performed to evaluate the performance of modified zeolite-Y with ion Fe (zeolite-FeY) in removing As(III), As(V), Se(IV) and Se(VI) from groundwater. The removal capacities for zeolite-FeY was carried out on arsenic and selenium species in aqueous solution by co-precipitation technique with DBDTC-Pp complex in the pH range of 1.5–2.5 followed by the neutron activation analysis (NAA) using a TRIGA-MkII reactor with an average flux of 2.1 × 10¹² neutrons cm⁻² s⁻¹ and inductively coupled plasma-mass spectrometry (ICP-MS) technique as comparison. The accuracy between the results obtained from both techniques were compared and evaluated.     

Nickel–cobalt oxide/activated carbon composite electrodes for electrochemical capacitors

Nanostructured synthesis of nickel–cobalt oxide/activated carbon composite by adapting a co-precipitation protocol was revealed by transmission electron microscopy. X-ray diffraction analysis confirmed that nickel–cobalt oxide spinel phase was maintained in the pure and composite phases. Cyclic voltammetry, galvanostatic charge–discharge tests and ac impedance spectroscopy were employed to elucidate the electrochemical properties of the composite electrodes in 1.0 M KCl. The specific capacitance which was the sum of double-layer capacitance of the activated carbon and pseudocapacitance of the metal oxide increased with the composition of nickel–cobalt oxide before showing a decrement for heavily-loaded electrodes. Utilisation of nickel–cobalt oxide component in the composite with 50 wt. % loading displayed a capacitance value of ～59 F g^?1. The prepared composite electrodes exhibited good electrochemical stability.     

A flow cell optosensor for lead based on immobilized gallocynin in chitosan membrane

Gallocynin immobilized in chitosan membrane has been studied as a sensor element of an optical sensor for lead using a flowing system. By using this set up, lead in solution has been determined in the concentration range from 1.0x10(-1) to 1.0x10(3) ppm with a detection limit of 0.075 ppm. The standard deviation of the method for the repeatability of lead detection at a concentration of 100 ppm was found to be 2.10%. The response of the sensor was reproducible and can be regenerated by using acidified saturated KNO(3) solution. Interference from foreign ions was also studied at 1:1 mole ratio of Pb(II):foreign ions.     

Flexible broadcasting and multicasting in 4λ × 10 Gb/s AOPR TWDM PON system

In this letter, we propose a new architecture of Time Wavelength Division Multiplexing Passive Optical Network (TWDM PON) system to support dynamic multi wavelength allocation (DMWA) in both upstream and downstream directions using an integrated semiconductor optical amplifier (SOA) and arrayed waveguide grating (AWG) with multi wavelength select continuous wave (CW) pump probe signal module. The significance of this architecture is the flexible routing function with the capability of multicasting and broadcasting between multiple optical line terminal (OLT) PON port with multiple optical distribution network (ODN) link using a new wavelength tuning free (WTF) OLT transmitter module to eliminate wavelength tuning delay in downstream signal utilizing multicasting Cross Gain Modulation (XGM) wavelength conversion. The experimental results show that 4λ × 10-Gb/s TWDM PON system can be used to connect 4096 users with the conventional fixed wavelength OLT transceivers with 36 dB link loss.     

Sugar recovery of enzymatic hydrolysed oil palm empty fruit bunch fiber by chemical pretreatment

An investigation was conducted to study the effect of solvent composition and temperature on the efficiency of pretreatment prior to enzymatic hydrolysis. The aim was to improve the sugar recovery of oil palm empty fruit bunch fiber (EFBF) through enzymatic hydrolysis. Two types of pretreatments, namely, acidified-glycerol (AC-g) pretreatment and alkaline-glycerol (AL-g) pretreatment were conducted. The study proved that AL-g pretreatment promoted higher delignification and enzymatic hydrolyzed sugar yield compared to AC-g pretreatment. Total sugar recovery of 81.44 and 96.55 % was achieved from AL-g pretreatment at 80 and 120 °C respectively, following the enzymatic hydrolysis. However, downstream industrial processes, involving enzyme treatment along the processing line have the preference of acidic condition. Thus, AC-g pretreatment was favorable. Approximately 51.74 % total sugar had been recovered successfully from enzymatic hydrolysis of EFBF after 3 h of pretreatment by using solvent comprising of 50 % acetic acid and 80 % aqueous glycerol at a ratio of 97:3 at 120 °C.     

Electrochemical DNA biosensor for the detection of Trichoderma harzianum based on a gold electrode modified with a composite membrane made from an ionic liquid, ZnO nanoparticles and chitosan, and by using acridine orange as a redox indicator

An electrochemical DNA biosensor was developed that is based on a gold electrode modified with a nanocomposite membrane made from an ionic liquid, ZnO nanoparticles and chitosan. A single-stranded DNA probe was immobilized on this electrode. Acridine orange was used as the hybridization probe for monitoring the hybridization of the target DNA. The biosensor was capable of detecting target DNA in the concentration range from 1.0?×?10?C14 to 1.8?×?10?C4?mol?L-1, with a detection limit of 1.0?×?10?C15?mol?L-1. The approach towards constructing a DNA biosensor allows studies on the hybridization even with crude DNA fragments and also to analyze sample obtained from real samples. The results show that the DNA biosensor has the potential for sensitive detection of a specific sequence of the Trichoderma harzianum gene and provides a quick, sensitive and convenient method for the study of microorganisms.

Development of a single-run liquid chromatography-mass spectrometry analysis for the detection of 11 multiclass contaminants of emerging concern using a direct filtration method

In toxicological analysis, the analytical validation method is important to assess the exact risk of contaminants of emerging concern in the environment. Syringe filters are mainly used to remove impurities from sample solutions. However, the loss of analyte to the syringe filter could be considerable, causing an underestimate of the analyte concentrations. The current study develops and validates simultaneous liquid chromatography-mass spectrometry analysis using a direct filtration method to detect four groups of contaminants of emerging concern. The adsorption of the analyte onto three different matrices and six types of syringe filters is reported. The lowest adsorption of analytes was observed in methanol (16.72%), followed by deionized water (48.19%) and filtered surface lake water (48.94%). Irrespective of the type of the matrices, the lowest average adsorption by the syringe filter was observed in the 0.45 μm polypropylene membrane (15.15%), followed by the 0.20 μm polypropylene membrane (16.10%), the 0.20 μm regenerated cellulose (16.15%), the 0.20 μm polytetrafluoroethylene membrane (47.38%), the 0.45 μm nylon membrane (64.87%) and the 0.20 μm nylon membrane (71.30%). In conclusion, the recommended syringe filter membranes for contaminants of emerging concern analysis are polypropylene membranes and regenerated cellulose, regardless of the matrix used.