Electrocatalytic evolution of hydrogen on a novel SrPdO3 perovskite electrode

SrPdO₃ was prepared for the first time by the citrate method. XRD, SEM and TGA characterizations were carried out. The catalytic activity toward hydrogen evolution reaction (HER) was investigated, the activation energy, and reaction order and reaction mechanism have been determined using Tafel polarization and impedance techniques. The modified surface showed up to 100 times more efficiency towards electrocatalytic production of hydrogen. Adsorption of hydrogen on the catalyst was the rate-determining step and the reaction order at the surface of the catalyst is 0.86. The molar magnetic susceptibility was measured using Faraday's method and anti-ferromagnetic character was observed.     

Novel dispersed magnetite core–shell nanogel polymers as corrosion inhibitors for carbon steel in acidic medium

Novel core–shell preparing poly(2-acrylamido-2-methylpropane sulfonic acid) (PAMPS) and copolymers with acrylic acid (AA) or acrylamide (AM) magnetic nanogels with controllable particle size produced via free aqueous polymerization at room temperature have been developed for the first time. The crosslinking polymerization was carried out in the presence of N,N′-methylenebisacrylamide (MBA) as a crosslinker, N,N,N′,N′-tetramethylethylenediamine (TEMED) and potassium peroxydisulfate (KPS) as redox initiator system. The structure and morphology of the magnetic nanogels were characterized by Fourier transform infrared spectroscopy (FTIR), transmission and scanning electron microscopy (TEM and SEM). The effectiveness of the synthesized compounds as corrosion inhibitors for carbon steel in 1 M HCl was investigated by various electrochemical techniques such as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed enhancement in inhibition efficiencies with increasing the inhibitor concentrations and temperatures. The results showed the nanogel particles act as mixed inhibitors. Adsorption of nanogel particles was found to fit the Langmuir isotherm and was chemisorption.     

Mechanical characterization and chemical resistances of cured unsaturated polyester resins modified with vinyl ester resins based on recycled poly(ethylene terephthalate)

Unsaturated polyester resin (UP) was prepared from glycolyzed oligomer of poly(ethylene terephthalate) (PET) waste based on diethylene glycol (DEG). New diacrylate and dimethacrylate vinyl ester resins prepared from glycolysis of PET with tetraethylene glycol were blended with UP to study the mechanical characteristics of the cured UP. The vinyl ester resins were used as crosslinking agents for unsaturated polyester resin diluted with styrene, using free‐radical initiator and accelerator. The mechanical properties of the cured UP resins were evaluated. The compressive properties of the cured UP/styrene resins in the presence of different vinyl ester concentrations were evaluated. Increasing the vinyl ester content led to a pronounced improvement in the compression strength. The chemical resistances of the cured resins were evaluated through hot water, solvents, acid, and alkali resistance measurements. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3175–3182, 2007     

Erratum to: Conductivity Sensors Based System Development and Application to Investigate the Interfacial Behaviour between Supersonic Steam Jet and Water

Instruments and Experimental Techniques - An Erratum to this paper has been published: https://doi.org/10.1134/S0020441221050249     

Assessment of greywater reuse as a potential mitigation measure for water shortages and sanitation problems in senior high schools

The study assessed water shortages and its effects on sanitation in Senior High Schools using structured questionnaires involving water availability, water use pattern and perception of greywater reuse. Additionally, an observation of the sanitation situation was done to validate the responses. The study found that water availability was an issue as this caused students to use more than an hour round trip to access water resulting in poor sanitation and hygiene practices. Meanwhile, an average greywater generation rate of 14.5 L per person per day, is always disposed of despite its potential reuse. Greywater reuse was accepted by respondents as 59% proposed reusing it if available for non‐potable applications (94%) such as toilet cleaning and flushing. This is because, there is a significant association between cleanliness of the toilet facilities and usage (P < 0.05). Respondents who declined greywater reuse cited health risks (58%), uncomfortable feeling (37%) and cultural issue (5%).     

A sustainable approach to the recycling of rice straw through pelletization and controlled burning

A technique for controlled burning of rice straw is presented. It relies on well-designed rice straw pellets to be burned in fluidized bed. The developed pellets have high burning rate, no fly ashes emissions and minimum bed fouling. The pellets are manufactured from ground rice straw in a disc pelletizer with the aid of bonding and suitable additive materials. The pellets are tested under controlled conditions in a test rig, which represents a single pellet fluidized bed. It is equipped with a nitrogen gun to eject the pellet and freeze the reaction at any predetermined time during combustion. The ejected pellets are weighed as well as elementary analyzed for both carbon and hydrogen, to calculate the burning rate as well as the combustion efficiency, respectively. The effect of several parameters has been evaluated including straw particle size, pellet size, type and concentration of bonding material as well as anti-sintering additives. Also, the pellets’ mechanical characteristics have been evaluated. It has been found that char combustion phase represents the controlling phase of the pellet combustion. The burning rate is higher as the void fraction of the pellet is higher. Starch showed better combustion and mechanical characteristics out of the five tested bonding materials. Adding kaolin to the pellets results in improving the sintering characteristics of the pellets. The experimental results were compared with two combustion models: the oxygen diffusion controlled and the kinetic-diffusion models. It has been found that oxygen diffusion controlled model more accurately simulates the combustion of the pellet during its char combustion phase. The model has been used to evaluate the effect of some operational parameters on the pellet combustion characteristics such as bed temperature, gas flow and oxygen concentration.     

Application of anionic acrylamide‐based hydrogels in the removal of heavy metals from waste water

Crosslinked acrylamide (AM) and 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) homopolymers and copolymers were prepared by free radical solution polymerization using N,N′‐methylenebisacrylamide as the crosslinker. The chemical structures of hydrogels were characterized by FTIR analysis and the results were consistent with the expected structures. These hydrogels were used for the separation of Cd(II), Cu(II), and Fe(III) ions from their aqueous solutions. The influence of the uptake conditions such as pH, time and initial feed concentration on the metal ion binding capacity of hydrogel was also tested. The selectivity of the hydrogel towards the different metal ions tested was Cd(II) > Cu(II) > Fe(III). It was observed that the specific interaction between metal ions and ionic comonomers in the hydrogel affected the metal binding capacity of the hydrogel. The recovery of metal ions was also investigated in acid media. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and characterization of novel core‐shell magnetic nanogels based on 2‐acrylamido‐2‐methylpropane sulfonic acid in aqueous media

Ultrafine well‐dispersed Fe₃O₄ magnetic nanoparticles were directly prepared in aqueous solution using controlled coprecipitation method. The synthesis of Fe₃O₄/poly (2‐acrylamido‐2‐methylpropane sulfonic acid) (PAMPS), Fe₃O₄/poly (acrylamide‐co‐2‐acrylamido‐2‐methylpropane sulfonic acid) poly(AM‐co‐AMPS) and Fe₃O₄/poly (acrylic acid‐co‐2‐acrylamido‐2‐methylpropane sulfonic acid) poly(AA‐co‐AMPS) ‐core/shell nanogels are reported. The nanogels were prepared via crosslinking copolymerization of 2‐acrylamido‐2‐methylpropane sulfonic acid, acrylamide and acrylic acid monomers in the presence of Fe₃O₄ nanoparticles, N,N′‐methylenebisacrylamide (MBA) as a crosslinker, N,N,N′,N′‐tetramethylethylenediamine (TEMED) and potassium peroxydisulfate (KPS) as redox initiator system. The results of FTIR and ¹H‐NMR spectra indicated that the compositions of the prepared nanogels are consistent with the designed structure. X‐ray powder diffraction (XRD) and transmission electron microscope (TEM) measurements were used to determine the size of both magnetite and stabilized polymer coated magnetite nanoparticles. The data showed that the mean particle size of synthesized magnetite (Fe₃O₄) nanoparticles was about 10 nm. The diameter of the stabilized polymer coated Fe₃O₄ nanogels ranged from 50 to 250 nm based on polymer type. TEM micrographs proved that nanogels possess the spherical morphology before and after swelling. These nanogels exhibited pH‐induced phase transition due to protonation of AMPS copolymer chains. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012