Removal Of By-products Research Articles

Removal of nitrate from water by conducting polyaniline via electrically switching ion exchange method in a dual cell reactor: Optimizing and modeling

Abstract The paper investigates the performance and modeling of the PANI-Cl−, PANI-ClO4− and PANI-SO42− on removal of nitrate in a dual cell reactor and the electrically switching ion exchange (ESIX) approach has been employed as a safety measure. In this experiment, the conducting polyaniline is synthesized via an electrochemical method on the platinum electrode in three various acidic mediums and the Ion exchange technique is processed by controlling the potentiostat condition. The independent variables in the response surface methodology (RSM) using central composite design (CCD) include pH and concentration (mg/L) of the solution. A better result in removal of nitrate was obtained for PANI-SO42−, followed by removal of 87% nitrate ions. It has been observed that after three times of regeneration and reusing of synthesized polymer, the removal of nitrate is still higher than 60%. Furthermore, the Nitrate ions have been removed without any toxic by-product and optimal removal of nitrate ions (87%) has been predicted at a controlled potential of 1.5 V, pH: 6 and concentration: 88 mg/L for PANI-SO42−.

In situ FT-IR study and evaluation of toluene abatement in different plasma catalytic systems over metal oxides loaded γ-Al2O3

Silver and nickel based catalysts with γ-Al2O3 support were synthesized via impregnation method for the removal of toluene in the presence of continuous discharge or adsorption- discharge plasma. An elaborate FT-IR analysis confirmed the formation of transient species during the plasma-catalytic oxidation of toluene. TOF-MS analysis indicated benzoic acid was not an important pathway of aromatic rings opening. NiO/Al2O3 catalyst displayed a higher enhancement of CO2 selectivity and ozone decomposition ability. Moreover, the active component (O and OH) areas would increase during the discharge process in adsorption-discharge plasma system that were conducive to the removal of the organic byproducts.

Impacts of ferrate oxidation on natural organic matter and disinfection byproduct precursors

This study investigated the effectiveness of ferrate (Fe(VI)) oxidation in combination with ferric chloride coagulation on the removal of natural organic matter (NOM) and disinfection byproduct (DBP) precursors. Twelve natural waters were collected and four treatment scenarios were tested at bench-scale. Results showed that intermediate-ferrate treatment (i.e., coagulation and particle removal followed by ferrate oxidation) was most effective followed by pre-ferrate treatment (i.e., ferrate oxidation followed by coagulation and particle removal (conventional treatment)) or conventional treatment alone (i.e., no oxidation), and the least effective was ferrate oxidation alone (i.e., no coagulation). At typical doses, direct ferrate oxidation of raw water decreased DBP formation potentials (DBPFPs) by about 30% for trihalomethanes (THMs), 40% for trihaloacetic acids (THAAs), 10% for dihaloacetic acids (DHAAs), 30% for dihaloacetonitriles (DHANs), and 5% for haloketones (HKs). The formation potential of chloropicrin (CP) consistently increased after direct ferrate oxidation. Pre-ferrate followed by conventional treatment was similar to conventional treatment alone for NOM and DBP precursor removal. Ferrate pre-oxidation had positive effects on subsequent coagulation/particle removal for THM and THAA precursor removal and may allow the use of lower coagulant doses due to the Fe(III) introduced by ferrate decomposition. On the other hand, intermediate-ferrate resulted in substantially improved removal of NOM and DBP precursors, which can be attributed to initial removal by coagulation and particle removal, leaving precursors that are particularly susceptible to oxidation by ferrate. The Fe(III) resulting from ferrate decay during intermediate-ferrate process was primarily present as particulate iron and could be effectively removed by filtration.

Antioxidative Responses and Morpho-anatomical Alterations for Coping with Flood-Induced Hypoxic Stress in Grass Pea (Lathyrus sativus L.) in Comparison with Pea (Pisum sativum)

Flooding stress constrains crop growth and yield because most agricultural species are flood-sensitive. However, many of the plant species that live in permanently or temporarily flooded habitats have evolved specific traits to cope with these harsh conditions. Grass pea (Lathyrus sativus L.) is a legume that tolerates stresses such as drought, diseases, and pests; however, it is unclear whether grass pea has a tolerance mechanism for flooding stress. To understand if grass pea tolerates hypoxia and how it deals with hypoxic stress, the effects of hypoxia on root tip death, physiological, and morpho-anatomical alterations in grass pea and pea (Pisum sativum), which is sensitive to hypoxia, were compared. The results showed that activities of antioxidant enzymes, namely superoxide dismutase, catalase, ascorbate peroxidase, and glutathione content in grass pea were greater than in pea during hypoxia, which protected the root tip from oxidative damage and reduced ion leakage, which helped maintain membrane integrity. Furthermore, aerenchyma and lateral root development accompanied by ethylene production, moderate ROS accumulation-mediated cell death, and Ca2+ spatial-temporal heterogeneity developed well in grass pea compared to pea, which may not only facilitate internal gas diffusion but also promote removal of toxic by-products under hypoxic conditions. These results demonstrate that grass pea is more tolerant to hypoxic stress induced by flooding than garden pea seedlings. This discovery not only provides significant information for understanding the hypoxia-tolerant mechanisms in plants, but also promotes the usability of grass pea in flood-prone areas.

Influence of the shielding gas flow on the removal of process by-products in the selective laser melting process

Selective laser melting is a promising additive manufacturing technology for the production of complex metal components. The technique uses metallic powder as a starting material and a laser for melting and building-up parts layer by layer. One crucial factor influencing the process stability and therefore the part quality is the shielding gas flow. In addition to the shielding properties of the inert atmosphere the gas flow is responsible for the removal of process by-products like spatter and welding fumes originating from the process zone. Insufficient removal or inhomogeneous gas flow distribution may lead to increased interaction between laser and process by-products. Consequences are attenuation of the laser spot as well as redeposition of this by-products on surfaces which are exposed to the laser afterwards. Firstly, a conclusion on all known process by-products is drawn. Secondly, based on these considerations the uniformity of the gas flow is investigated by the width of single welds. Furthermore process deviations are provoked by unfavorable gas flow conditions. Thirdly, the impact of this deviations on building surface and part quality is investigated by 3D confocal microscopy, microsections and ultrasonic testing. Finally, theoretical approach for the formation of these process deviations and arising material defects is presented.

Techno-economic evaluation of the direct conversion of CO2 to dimethyl carbonate using catalytic membrane reactors

The production of dimethyl carbonate (DMC) caught more interest in the past decades due to its versatile use (e.g. as fuel additive), low toxicity and fast biodegradability. Different ‘green’ production routes are being developed to replace the conventional and rather toxic production of DMC via phosgene. The direct conversion of CO2 and methanol toward DMC is an environmental and economically interesting production route for the chemical industry.This work describes the process design of the direct conversion of CO2 to dimethyl carbonate, providing a valuable insight and a better understanding of the process limitations. In this design, membrane reactors are used for continuous removal of water by-product, in order to overcome the equilibrium limitations. The rigorous Aspen Plus simulations show that even when using an excess of methanol, the attainable conversion is low and the DMC concentration in the reactor effluent is less than 1.5mol%. Purifying this diluted stream to the desired concentrations demands large size equipment and a substantial amount of energy (13.61kWh/kg DMC) resulting in high investment and utility costs, thus making the process not profitable. The focus for new membrane reactors could be on the selective removal of DMC (instead of water) from the reaction area to allow for a more concentrated DMC stream.

The removal of estrogenic activity with UV/chlorine technology and identification of novel estrogenic disinfection by-products

As a recently developed disinfection technology, ultraviolet (UV)/chlorine treatment has received much attention. Many studies have evaluated its effects on pathogen inactivation, contaminant removal, and formation of disinfection by-products (DBPs), but its potential for environmental estrogen removal and estrogenic DBP generation, which can also be a risk to both ecosystem and human health, have not been evaluated. In this study, UV/chlorine treatment resulted in a greater removal of estrogenic activity in synthetic effluent samples containing 17β-estradiol (E2) than did UV or chlorine treatment alone regardless of the water quality. For both the UV/chlorine and chlorine treatments, there was significant interference from NH3–N, although the UV/chlorine treatment was less affected. Estrogen receptor based affinity chromatography was used to isolate the specific estrogenic DBPs, and a novel product, with high estrogenic activity compared to E2, Δ9(11)-dehydro-estradiol, was identified. It was generated by all three treatments, and might be previously mistakenly recognized as estrone (E1). This study demonstrated that UV/chlorine is a better treatment for the removal of 17β-estradiol than chlorine and UV alone. The new identified estrogenic DBP, Δ9(11)-dehydro-estradiol, which can be isolated by affinity chromatography, could be an emerging concern in the future.

The Role of Zinc, Manganse and Copper in Rumen Metabolism and Immune Function: A Review Article

Trace minerals are dietary elements required by the body in minute amounts, ranging from 0.10 to 50.0 mg/kg dry matter in beef cattle diets [1]. These trace minerals are all necessary for the biochemical processes of the body that support proper growth and maintenance. For example, Cu is necessary for the function of superoxide dismutase and its removal of toxic byproducts from metabolic pathways [2]. The removal of these toxic byproducts allows for metabolism to proceed efficiently, uninhibited by damaging oxygen free radicals. Zinc, an important trace mineral for enzyme function, aides in the regulation of nucleic acid production, carbohydrate metabolism, and protein synthesis, thus providing a stable framework for development [3]. The immune system is part of the host’s defense against destructive forces from outside the body, such as bacteria, viruses, and parasites, or from within, such as malignant cells or those that produce autoantibodies [4]. This system is composed of two branches: the innate or non-specific immune system, and the adaptive or specific immune system [5]. In this review paper, an attempt has been made to review effects of mineral supplements in Rumen Metabolism, effects on Immune Function in different species of animals.

Removal of Ethylene and By-products Using Dielectric Barrier Discharge with Ag Nanoparticle-Loaded Zeolite for Keeping Freshness of Fruits and Vegetables

Removal of Ethylene and By-products Using Dielectric Barrier Discharge with Ag Nanoparticle-Loaded Zeolite for Keeping Freshness of Fruits and Vegetables

Performance of Agroindustrial Wastes for Removal of Disinfection By-products From Water

The aim of the present work was to use agroindustrial wastes as alternative adsorbents for the removal of trihalomethanes (THMs). SEM micrographs of sugar cane bagasse and coconut mesocarp samples showed a high degree of particle agglomeration, with particle sizes of 114.4 ± 74.0 μm, while the sugar cane bagasse particles were larger (557.3 ± 169.5 μm). The pyrogram obtained for sugar cane bagasse revealed the presence of many compounds with different functional groups containing oxygen atoms. In the case of the coconut mesocarp, the range of oxygenated functional groups was smaller. The adsorption processes showed fast kinetics, with equilibrium reached after around 240 min of contact. Adsorption tests revealed different selectivities of the biomass adsorption sites for the THMs. Adsorption percentages obtained with coconut mesocarp ranged from 49.2 ± 2.57 to 71.9 ± 1.88 %, while the values obtained for sugar cane bagasse were between 31.8 ± 1.08 and 67.4 ± 1.27 %. The orders of removal (significant at p CHBrCl2>CHBr2Cl>CHBr3 (using sugar cane bagasse) and CHBr2Cl>CHBrCl2>CHCl3>CHBr3 (using coconut mesocarp). Use of the sugar cane bagasse resulted in high removal percentages of chloroform (51.1 %) and dichlorobromoform (42.3 %) in the first 5 min of contact, showing that this biomass had greater affinity for trihalomethane compounds with more chlorine atoms in their structures. This finding has considerable environmental importance, given that these are the two commonest compounds found in water distribution networks.

Comparing a silver-impregnated activated carbon with an unmodified activated carbon for disinfection by-product minimisation and precursor removal

During disinfection, bromide, iodide and natural organic matter (NOM) in source waters can lead to the formation of brominated and/or iodinated disinfection by-products (DBPs), which are often more toxic than their chlorinated analogues. The objective of this study was to compare the efficiency of a silver-impregnated activated carbon (SIAC) with the equivalent unimpregnated granular activated carbon (GAC) for the removal of bromide, iodide and NOM from a matrix of synthetic waters with variable NOM, halide, and alkalinity concentrations, and to investigate the impact on DBP formation. An enhanced coagulation (EC) pre-treatment was employed prior to sample exposure to either carbon adsorbent. Excellent halide removals were observed by the SIAC treatment across the sample matrix, with iodide concentrations consistently reduced to below the method reporting limit (<2μg/L) from as high as 25μg/L, and 95±4% removal of bromide achieved. Bromide removal by unimpregnated GAC was poor, however iodide removal was comparable to that achieved by SIAC. The combination of EC with SIAC treatment removed 77±8% of the dissolved organic carbon (DOC) present, across the sample matrix, which was similar to removals by EC/GAC (67±14%). Combined EC/SIAC treatment reduced both total trihalomethanes (tTHMs) and total dihaloacetonitriles (tDHANs) formation by 97±3%, while also achieving a greater than 74% removal of two chloropropanones and a 92±8% decrease in chloral hydrate (CH), compared to untreated samples, regardless of the sample's starting water quality (bromide, alkalinity and NOM concentration). Combined EC/GAC treatment led to similar DBP removals to EC/SIAC for the fully chlorinated DBPs, however, brominated DBPs were less efficiently removed, or experienced concentration increases.

Design and fabrication of miniaturized PEM fuel cell combined microreactor with self-regulated hydrogen mechanism

In this work we present the design and fabrication of the miniaturized PEM fuel cell combined microreactor system with hydrogen regulation mechanism and testing of prototype microreactor. The system consists of two components (i) fuel cell component and (ii) microreactor component. The fuel cell component represents the miniaturized PEM fuel cell system (combination of screen printed fuel cell assembly and an on-board hydrogen storage medium). Hydrogen production based on catalytic hydrolysis of chemical hydride takes place in the microreactor component. The self-regulated hydrogen mechanism based on the gaseous hydrogen produced from the catalytic hydrolysis of sodium borohydride (NaBH4) gets accumulated as bubbles at the vicinity of the hydrophobic coated hydrogen exhaust holes. When the built up hydrogen bubbles pressure exceeds the burst pressure at the hydrogen exhaust holes the bubble collapses. This collapse causes a surge of fresh NaBH4 solution onto the catalyst surface leading to the removal of the reaction by-products formed at the active sites of the catalyst. The catalyst used in the system is platinum deposited on a base substrate. Nickel foam, carbon porous medium (CPM) and ceramic plate were selected as candidates for base substrate for developing a robust catalyst surface. For the first time the platinum layer fabricated by pulsed electrodeposition and dealloying (EPDD) technique is used for hydrolysis of NaBH4. The major advantages of such platinum catalyst layers are its high surface area and their mechanical stability. Prototype microreactor system with self-regulated hydrogen mechanism is demonstrated.

Novel electrostatic precipitator using unipolar soft X-ray charger for removing fine particles: Application to a dry de-NOX process

The novel electrostatic precipitator (ESP), consisting of a soft X-ray charger and a collection part, was demonstrated and applied to a dry de-NOX process to evaluate its performance in by-product particle removal. NOX gas was oxidized by ozone (O3) and neutralized by ammonia (NH3) sequentially, and finally converted to an ammonium nitrate (NH4NO3) aerosol with ∼100-nm peak particle diameter. The unipolar soft X-ray charger was introduced for charging the by-product particles in this dry de-NOX process. For the highest particle collection efficiency, the optimal operating conditions of the soft X-ray charger and collection part were investigated by adjusting the applied voltage of each device. The results showed that ∼99% of NOX was removed when the O3/NOX ratio was increased to 2 (i.e., the maximum production conditions of the NH4NO3 by-product particles by the gas-to-particle conversion process). The highest removal efficiency of particle (∼90%) was observed with operating conditions of positive polarity and an applied voltage of ∼2–3kV in the charger chamber. The unipolar soft X-ray charger has potential for particle removal systems in industrial settings because of its compact size, ease of operation, and non-interruptive charging mechanism.

A pattern-like micro-fine lines of circuits construction for the multi-touch screens

The newest study plans to adopt electrochemical engineering as the technological premise for Multi-Touch Screen ITO (indium tin oxide) thin membrane etching by utilizing the electrochemical process to remove the conductive material ITO deposited on the D.C. positive charge. By coordinating the masked patterns as the template for etching on the Multi-Touch Screens ITO thin membrane layer with pattern-like micro-fine lines, it simplifies the previous metal etching's multilevel processes (the photoresist coating, exposure, imaging, etching of the photoresist and so forth) into a simple one-step process (mask-based electrochemical etching). The study findings show that: using the appropriate process parameters (including the electrical conditions; electrochemical liquid control; electrochemical byproduct removal and such) is able to derive a preferred etching quality on the line's side flange. Using a higher temperature or higher concentration of the processing liquid is able to derive a higher ITO line etching speed. As the masked micro-electrochemical etching method the study proposes is able to rapidly map out a micro-fine line pattern on the surface's Multi-Touch Screens ITO thin member layer within a relative short time. The Multi-Touch Screen ITO is easily constructed throughout the processes of semiconductor production.

Using HPSEC to identify NOM fraction removal and the correlation with disinfection by-product precursors

In this study high performance size exclusion chromatography (HPSEC) was used to compare an ultrafiltration (UF) membrane and alum coagulation for their capacity to remove different fractions of natural organic matter (NOM) from water. At the same time, the removal of disinfection by-product (DBP) precursors, as measured by trihalomethane formation potential (THMFP) and haloacetic acid formation potential (HAAFP), was also detected. The results show that the UF membrane mainly removed the aliphatic biopolymer fraction, while alum coagulation mainly removed the humic substances fraction. The results of DBP precursor analysis show that more THMFP was removed by the UF membrane than HAAFP, while the reverse was true for alum coagulation. It is conjectured that the aliphatic biopolymer fraction is the major precursor for trihalomethanes (THMs), while the humic substances fraction is the major precursor for haloacetic acids (HAAs).

Synthesis and process development of polyether polyol with high primary hydroxyl content using a new propoxylation catalyst

The establishment of a Lewis acid-mediated selective propoxylation reaction using a specific borane catalyst enabled the synthesis of a novel class of PPG with an increased primary hydroxyl content of up to 70%. In addition, we developed a high yielding continuous process for producing the new PPG with a low amount of by-products by using tube reactors combined with film evaporators for by-product removal. Our new PPG achieves an excellent balance between reactivity and humidity resistance. As a result, it has important advantages for a broad area of polyurethane applications.

Effect of substrate temperature on copper antimony sulphide thin films from thermal evaporation

Copper antimony Sulfide (CAS) thin films were deposited on glass substrate using thermal evaporation technique at different substrate temperatures. Using CuCl2.2H2O, SbCl3 and thiourea as parental materials, the evaporant source material was synthesized by solvothermal method. Moreover, phase identification using X-Ray diffraction was made after the removal of by-products. The CuSbS2 bulk material was pelletized using hydraulic press and used as a target material for developing CAS films on glass substrate with different substrate temperatures such as, Room Temperature (without substrate temperature), 100 °C, 200 °C, 300 °C and 400 °C. The source material and the deposited CAS films were subjected to X-ray diffraction analysis, Raman spectroscopy, Transmission Electron Microscopy, Scanning Electron Microscopy, Atomic Force Microscopy, X-Ray Photo Electron Spectroscopy, Energy Dispersive X-ray Spectral analysis and UV–Vis Spectroscopy. Hall Effect measurement was carried out to investigate, whether the CAS films exhibits p-type conductivity. The deposited films were found to have the band gap in the range of 2.18 eV and 1.62 eV.

Photocatalytic degradation of the antibiotic chloramphenicol and effluent toxicity effects

Chloramphenicol sodium succinate (CAP, C15H15Cl2N2 Na2O8) is a broad-spectrum antibiotic exhibiting activity against both Gram-positive and Gram-negative bacteria as well as other groups of microorganisms only partially removed by conventional activated sludge wastewater treatment plants. Thus, CAP and its metabolites can be found in effluents. The present work deals with the photocatalytic degradation of CAP using TiO2 as photocatalyst. We investigated the optimization of reaction contact time and concentration of TiO2 considering CAP and its by-products removal as well as effluent ecotoxicity elimination. Considering a CAP real concentration of 25mgL−1, kinetic degradation curves were determined at 0.1, 0.2, 0.4, 0.8, 1.6 and 3.2gL−1 TiO2 after 5, 10, 30, 60 and 120min reaction time. Treated samples were checked for the presence of by-products and residual toxicity (V. fischeri, P. subcapitata, L. sativum and D. magna). Results evidenced that the best combination for CAP and its by-products removal could be set at 1.6gL−1 of TiO2 for 120min with an average residual toxicity of approximately 10%, that is the threshold set for negative controls in most toxicity tests for blank and general toxicity test acceptability.

Pressure-Dependent Etching Mechanism and Induced Dielectric Properties Variation of BZN Thin Films in SF6/Ar Plasma

Reactive ion etching was used to study bismuth zinc niobate (BZN) thin films etching in SF6/Ar plasma as a function of pressure. The etch rate increases as the pressure increases from 1 to 20 mTorr and decreases when the pressure exceeds 20 mTorr. The film surfaces were analyzed to determine the etching mechanism using X-ray photoelectron spectroscopy. Pressure is found to have an effect on etch reaction and non-volatile etch by-products removal through different ion density and energy, thus resulting in varying compositions, element chemical binding states on the film surface. Dielectric properties of the film, modified by SF6/Ar plasma, show an obvious variation with pressure. The permittivity shows a slight decrease in the range of 1–20 mTorr but a sharp decrease at 30 mTorr. Instead, the dielectric loss variation exhibits an opposite trend.

ChemInform Abstract: 3‐(Dimethylamino)‐1‐propylamine: A Cheap and Versatile Reagent for Removal of Byproducts in Carbohydrate Chemistry.

Abstract3‐(dimethylamino)‐1‐propylamine is used as reagent for selective anomeric deacylation in carbohydrate chemistry to give 1‐O deprotected sugars in high yields without chromatographic purification.