Electrochemical Removal of Microorganisms in Drinking Water

It is known that silver, even in small concentrations (hundred parts of milligrams per liter), has the ability to destroy microorganisms, i.e. it has strong bactericidal abilities. Cleansing vast amount of water using bactericidal ability of silver is usually performed in electrochemical way. The advantages of electrochemical disinfection process like: (a) environmental compatibility, (b) versatility to kill a wide variety of microorganisms under mild conditions, (c) no need for adding chemical medicines and (d) the benefits of in-situ generation greatly lower problems and dangers of usage gas chlorine in water disinfection, which is greatest during transport and storing of this disinfectant. Appliances for electrochemical disinfection of drinking water eliminate these faults of conventional disinfection methods. Medical researches show that excess of chlorine in water reacts with organic matter, leading to mutations and cancer formation in digestion organs and bladder. This paper represents research of succesful microbiological disinfection of natural water that contains Acinetobacter, Pseudomonas aeruginisa, Sulfate-reducing clostridium, Streptococcus (F), Aeromonas, Citrobacter (F), Esherichia coli, Enterobacter (F) and Bacillus by water-disinfection appliance. This appliance can be used in water systems like water sorces, traps, reservoires, pools etc. (certificate of Clinical Center of Serbia)

Electrical Conductivity of Lignocellulose Composites Loaded with Electrodeposited Copper Powders

Composites based on polymers with conductive fillers have been gaining more and more significant roles in a variety of technological domains and are in the research focus of numerous studies as a part of growing research trend. Natural polymers based on renewable materials with addition of chosen materials can be directly used as contemporary materials by electrochemical methods. This article is concerned with the preparation characterization of the basic components: electrodeposited copper powder and lignocellulose as well as composite materials prepared by the compression molding of lignocellulose and galvanostatically obtained copper powder mixtures. Analysis of the most significant properties of individual components and prepared composites included quantitative structural analysis, morphological analysis, determination of density and porosity and measurements of electrical conductivity. Different investigation techniques including SEM, TGA, DSC, X-ray, FTIR, particle size distribution and conductivity measurements were used. The electrical conductivity of the composites is LT 10(-15) MS/m, unless the metal content reaches the percolation threshold of 14.4% (v/v), beyond which the conductivity increases markedly by as much as 14 orders of magnitude. It was found that this transition occurs at lower volume fractions than stated in the literature which can be due to the filler with high specific area

Synthesis and characterization of electroconducting composite materials based on biodegradable polymers and metal powders

Kompozitni materijali dobijaju sve veću industrijsku primenu u svetu. Kompoziti bazirani na polimerima sa provodnim puniocima su u novije vreme u širem istraživačkom fokusu pre svega zbog njihovog rastućeg značaja sa gledišta primene. Prirodni polimeri na bazi obnovljivih materijala sa dodatkom odabranih punioca mogu se direktno koristiti kao savremeni materijali u: elektronici, medicini, industriji, kao kontaktni provodni materijali, elektromagnetni i radiotalasni štitovi, fototermalni optički snimači, elektronski nosevi osetljivi na određene hemikalije, ali i kao ekonomski prihvatljiviji katalizatori. U tezi su prikazani eksperimentalni rezultati istraživanja svojstava kompozitnih materijala na bazi lignocelulozne matrice (LC) punjenih elektrolitičkim bakarnim prahom i hemijski dobijenim srebrnim prahom. Udeо metalnih punilaca u kompozitnim materijalima u ispitnim uzorcima variran je u opsegu od 1.6- 30% (v/v), a uzorci su pripremljeni kompaktiranjem-presovanjem. U eksperimentalnom delu za analizu i karakterizaciju polaznih konstituenata i istraživanih kompozita korišćene su različite eksperimentalne metode i tehnike. Mikrostrukturna i morfološka analiza vršena je primenom skening elektronske mikroskopije (SEM) i optičke mikroskopije. Određena je veličina i distribucija čestica konstituenata, kao i gustina, poroznost i električna provodnost kompozita u zavisnosti od udela punilaca. Тeza se bavi sintezom i karakterizacijom elektroprovodnih kompozitnih materijala pripremljenih hladnim presovanjem mešavina lignoceluloze i elektrohemijski dobijenog bakarnog praha i hemijski dobijenog srebrnog praha pri različitim pritiscima, kao i ispitivanjem uticaja veličine i morfologije čestica na provodnost i perkolacioni prag dobijenih kompozita. Karakterizacija je uključivala različite tehnike ispitivanja: SEM, TGA, DSC, X-ray, FTIR, raspodelu veličina čestica i merenja provodnosti metodama DC U/I i impedansnom spektroskopijom. Rezultati su pokazali da oblik i morfologija čestica punioca igra značajnu ulogu na pojavu i ponašanje električne provodnosti pripremljenih uzoraka i pojavu...Composite materials are gaining increasing industrial applications worldwide. Composites based on polymers with conductive fillers have been recently in the wider research focus primarily because of their growing importance from the point of application. Natural polymers based on renewable materials with selected fillers can be used directly as contemporary materials in: electronics, medicine, industry, as contact conductive materials, electromagnetic and radio wave shields, photothermal optical recorders, electronic noses sensitive to certain chemicals, as well as economically acceptable catalysts. In this thesis the results of experimental studies of the properties of composite materials based on lignocellulosic matrix (LC) filled with electrolytic copper powder and chemically obtained silver powder are presented. Volume fractions of metal fillers in the composite materials in tested samples were varied in the range of 1.6-30% (v/v), and the samples were prepared by compression – cold pressing. In the experimental part of the analysis and characterization of the starting constituents and studied composites different experimental methods and techniques were used. Microstructural and morphological analysis were performed using scanning electron microscopy (SEM) and optical microscopy. Particle size and distribution of the constituents, as well as density, porosity and electrical conductivity of composites depending on the volume fraction of the fillers were determined. This thesis deals with the synthesis and characterization of conductive composite materials prepared by cold pressing of mixtures of lignocellulose and electrodeposited copper powder and chemically deposited silver powder obtained at different pressures, as well as examination of the influence of particle size and morphology on the conductivity and percolation threshold of the composites. Characterization included a variety of testing techniques: SEM, TGA, DSC, X-ray, FTIR, particle size distribution and conductivity measurement by DC U/I method and impedance spectroscopy..

Optimizacija zapremine radioaktivnog obeleživača pri merenju zapreminskog protoka u zatvorenim cevovodima

In chemical processes it is essential that the flow in the process is accurately defined. Fluid velocity measurements are important for fluid flow quality performance in flow systems. This study focuses on determination of the volumetric flow rate and its standard (relative) deviation for calibration of conventional flow meters by using a radiotracer approach. The measurements for flow meter calibration were performed at a pilot-scale flow rig using Technetium-99 m (99mTc) as a radiotracer in the form of pertechnetate ion (99mTcO4-). The measured data were analyzed, and precision of the experimental setup was investigated under two different approaches – IAEA’s RTD software and sum approximation of raw data. For the first time, the variation of standard deviation of calculated flow rate with the injection volume and activity of the radiotracer was determined. Plug flow with axial dispersion was used to simulate the measured RTD curves and investigate the flow dynamics of the flowing water. The results of the study have shown the possibility of in situ calibration of flow meters with a relative error lower than 1 %. They also revealed a slight dependency of the precision of output results on the injection volume as well as similar results for manual and specialized RTD software data processing.U hemijskim procesima od suštinskog značaja je tačno definisan i precizan protok. Merenja brzine fluida su važna za karakterizaciju kvaliteta protoka tečnosti u sistemima. Ova studija se fokusira na određivanje zapreminskog protoka i standardnog (relativnog) odstupanja izmerenih vrednosti u cilju kalibracije konvencionalnih merača protoka korišćenjem metode radioaktivnog obeleživača. Merenja potrebna za kalibraciju merača protoka izvedena su na pilot postrojenju korišćenjem Tehnecijuma-99m (99mTc) kao radiotrejsera u obliku pertehnetatnog jona (99mTcO4-). Izmereni podaci su analizirani, a preciznost eksperimentalne postavke je ispitivana pomoću dva različita pristupa: upotrebom softvera za određivanje raspodele vremena zadržavanja (eng. residence time distribution, RTD) koga je razvila Međunarodna agencija za atomsku energiju i zbirne aproksimacije neobrađenih podataka. Po prvi put je utvrđena varijacija standardne devijacije izračunatog protoka u odnosu na zapreminu i u odnosu na aktivnost ubrizganog radioaktivnog obeleživača. Model protoka sa aksijalnom disperzijom je korišćen za simulaciju izmerenih RTD krivih i istraživanje dinamike protoka vode. Rezultati studije su pokazali mogućnost in situ kalibracije merača protoka sa relativnom greškom manjom od 1%. Takođe su pokazali malu zavisnost preciznosti izlaznih rezultata od količine ubrizganog obeleživača, kao i slične rezultate za manuelnu obradu i specijalizovanu obradu podataka upotrebom RTD softvera

Electrical Conductivity of Lignocellulose Composites Loaded with Electrodeposited Copper Powders. Part III. Influence of Particle Morphology on Appearance of Electrical Conductive Layers

The electrical conductivity of the system based on lignocellulose (LC) biopolymer matrix filled with electrodeposited copper powder has been studied. Galvanostatically produced copper powder, having highly porous, highly dendritic particles with high values of specific area was used as filler. Volume fraction of the electrodeposited copper powder was varied from 2.0-29.8 vol%. Analysis of the most significant properties of prepared composites and its components included measurements of electrical conductivity, impedance spectroscopy (IS) behavior, structural and morphological analysis. The composite preparation conditions allowed the formation of a random distribution of metallic particles in the polymer matrix volume. It was shown that percolation threshold depends on both particle shape and type of spatial distribution. IS measurements have shown that particle morphology having pronounced grain boundaries has great effect on appearance of electric conductive layers, i.e.. movement. of percolation threshold towards lower filler volume fractions. IS response of the composites showed existence of electrical conductive layers, each having different resistivity which increases towards interior of the composite

Electrochemical Removal of Microorganisms in Drinking Water

It is known that silver, even in small concentrations (hundred parts of milligrams per liter), has the ability to destroy microorganisms, i.e. it has strong bactericidal abilities. Cleansing vast amount of water using bactericidal ability of silver is usually performed in electrochemical way. The advantages of electrochemical disinfection process like: (a) environmental compatibility, (b) versatility to kill a wide variety of microorganisms under mild conditions, (c) no need for adding chemical medicines and (d) the benefits of in-situ generation greatly lower problems and dangers of usage gas chlorine in water disinfection, which is greatest during transport and storing of this disinfectant. Appliances for electrochemical disinfection of drinking water eliminate these faults of conventional disinfection methods. Medical researches show that excess of chlorine in water reacts with organic matter, leading to mutations and cancer formation in digestion organs and bladder. This paper represents research of succesful microbiological disinfection of natural water that contains Acinetobacter, Pseudomonas aeruginisa, Sulfate-reducing clostridium, Streptococcus (F), Aeromonas, Citrobacter (F), Esherichia coli, Enterobacter (F) and Bacillus by water-disinfection appliance. This appliance can be used in water systems like water sorces, traps, reservoires, pools etc. (certificate of Clinical Center of Serbia)

Electrodeposition of Fe Powder from Citrate Containing Electrolytes

Polarization characteristics of the electrodeposition processes of Fe powders from different citrate electrolytes and the morphology of the obtained powders were investigated. The effect of complexing agents on the cathodic polarization, the current efficiency and morphology of electrodeposited Fe powders were investigated. The morphology of obtained powders depends on the kind of supporting electrolyte, but not on the current density in investigated range. A characteristic feature of powders deposited from citrate-chloride supporting electrolyte is cauliflower-like compressed structure. On the other side, Fe powders electrodeposited from citrate-sulfate supporting electrolyte appeared in the form of spongy-like agglomerates. Possibility of Fe powders protection from corrosion in the process of production and during long-term storing has been shown

Electrical Conductivity of Lignocellulose Composites Loaded with Electrodeposited Copper Powders. Part II. Influence of Particle Size on Percolation Threshold

This article is concerned with synthesis and characterization of electroconductive composite materials prepared by the compression molding of mixtures of lignocellulose and electrochemically deposited copper powder under different pressures, and investigation of the influence of particle size on conductivity and percolation threshold of obtained composites. Electrodeposited copper powder content was varied from 2.0-29.8 vol%. Analysis of the most significant properties of individual components and prepared composites included structural and morphological analysis and measurements of hardness and electrical conductivity. Hardness of the investigated composites, as expected, increased with the increase of the processing pressure, as well as lowering the particle size compared to previous work. The significant increase of the electrical conductivity can be observed as the copper powder content reaches the percolation threshold. The packaging effect and more pronounced interpartical contact with smaller, highly porous, highly dendritic particles with high values of specific area lead to "movement" of percolation threshold towards lower filler content, which for the particles LT 45 mu m and highest processing pressure of 27 MPa was 7.2% (v/v). In the investigated range of electrodeposited copper powder concentrations and applied pressures the increase of the electrical conductivity of composites is as much as fourteen orders of magnitude. It was found that this transition occurs at lower volume fractions than stated in the literature which can be due to the filler with high specific area

Influence of process parameters of simultaneous anodization/anaphoretic electrodeposition synthesis of hydroxyapatite/titanium oxide composite coatings on adhesion

In-situ synthesis of hydroxyapatite/titanium oxide (HAp/TiO2) coating on titanium was performed via anaphoretic deposition of hydroxyapatite (HAp) and simultaneous anodization of Ti to produce highly adherent and strengthened composite coating. The influence of electric potential, time, electrolyte concentration and pH value of the anodization process on titanium surface roughness and anodization of titanium was examined, as well as influence of same process parameters on adhesion strength and compactness of composite HAp/TiO2 coatings was investigated. Prior to novel in situ method of synthesis of hydroxyapatite/titanium oxide composite coatings by simultaneous anodization/anaphoretic electrodeposition described in this manuscript, optimization of anodization process of titanium was performed. Anodization was executed under different electric potentials and different distances of counter electrodes from working electrodes, but all anodization processes had constant quantity of electric charge. Characterization of titanium samples, prepared from grade 6 Ti, and having rectangular contact surfaces of 10×10×0.89 mm included SEM/EDS analyses, X-ray diffraction analyses, AFM surface topography, morphology and roughness analyses and linear measurements of roughness.A chemical precipitation method was used to prepare hydroxyapatite powder by the reaction of calcium oxide (obtained by calcination of CaCO3 for 5 h at 1000 °C in air) and phosphoric acid. A stoichiometric amount of the calcium oxide was stirred in distilled water and phosphoric acid was added drop wise to the suspension in order to obtain hydroxyapatite powder, Ca10(PO4)6(OH)2.Two types of HAp coatings were prepared, in order to compare the adhesion, morphology and consistency of the HAp and composite HAp/TiO2 on Ti, namely cathaphoretic and anaphoretic coatings, respectively [1,2]. The prepared coatings were characterized by field emission scanning electron microscopy, X-ray diffraction and electron dispersive spectroscopy. Adhesion was investigated by ASTM D 3359 – 97 Test method B. Uniform and adherent HAp/TiO2 composite coating on Ti was obtained. Since smaller size of HAp crystals within highly porous coating structures is of improved binding ability to various biomolecules, our coating is expected to be of excellent coverage and compactness. The obtained coating can be good candidate for bone implants due to improved adhesion

Influence of Electrolytic Copper Powder Particle Morphology on Electrical Conductivity of Lignocellulose Composites and Formation of Conductive Pathways

Composites based on polymers with conductive fillers have been gaining more significant roles in a variety of technological domains and they are getting in the research focus of numerous studies as a part of growing research trend. Galvanostatically produced copper powder with high values of specific area was used as filler for synthesis of electroconductive composite materials prepared by the compression molding of mixtures of lignocellulose and electrochemically deposited copper powder. This article is concerned with characterization of these composites. Analysis of the most significant properties of prepared composites and its components included measurements of electrical conductivity, impedance spectroscopy (IS) behavior and structural and morphological analysis. Volume fraction of the copper powder was varied from 2.0-29.8% (v/v). The significant increase of the electrical conductivity can be observed as the copper powder content reaches the percolation threshold (PT). It was shown that PT depends on both particle shape and type of spatial distribution. IS measurements have shown that particle morphology having pronounced grain boundaries has great effect on appearance of electric conductive layers. The packaging effect and more pronounced interpartical contact with copper powder particles lead to "movement" of PT, which for the particles LT 45 mu m and highest processing pressure of 27 MPa was 7.2% (v/v). IS response of the composites showed existence of electrical conductive layers, each having different resistivity which increases towards interior of the composite