Search

The occurrence and distribution of yttrium and rare earth elements (REYs), along with major elements and heavy metal(loid)s (HMs) in coal fly ash (CFA) from five coal-fired power plants (CFPPs), were analyzed, and the REY-associated ecological and health risks were assessed. The individual REYs in CFA were abundant in the following order: Ce > La > Nd > Y > Pr > Gd > Sm > Dy > Er > Yb > Eu > Ho > Tb > Tm > Lu. The total REY content ranged from 135 to 362 mg/kg, averaging 302 mg/kg. The mean light-to-heavy REY ratio was 4.1, indicating prevalent light REY enrichment in CFA. Significantly positive correlations between the REYs suggested that they coexist and share similar origins in CFA. REYs were estimated to pose low to moderate ecological risks, with risk index (RI) values ranging from 66 to 245. The hazard index (HI) and target cancer risk (TCR) of REYs from CFA, estimated to be higher for children (HIc = 0.15, TCRc = 8.4 × 10−16) than for adults (HIa = 0.017, TCRa = 3.6 × 10−16), were well below the safety limits (HI = 1, TCR = 1.0 × 10−6). However, the danger to human health posed by HMs in the same CFA samples (HIc = 5.74, TCRc = 2.6 × 10−4, TCRa = 1.1 × 10−4) exceeded the safe thresholds (excl. HIa = 0.63). The mean RI and HI attributed to REYs in CFA were 14% and 2.6%, respectively, of the total risks that include HMs.

Nowadays, exopolysaccharides (EPS) produced from bacterial cells are manufactured for their use in different industries in the world, mainly in the food, pharmaceutical, and wastewater industries. The characteristics of EPS, such as being biodegradable, safe, high adsorption capacity, and reusable, make them significant and potential applications in the purification of contaminated water of heavy metals. In this study, the possible application in biosorption Ni2+ ions from contaminated water was assessed using this exopolysaccharide as a biosorbent. The new exopolysaccharide from the bacterial strain K. oxytoca J7 was extracted, isolated, and characterized using SEM, FTIR, XRD, TGA/DTG, and MALDI-TOF MS analysis. Likewise, the cytotoxic activity was performed for EPS from K. oxytoca J7 strain. The aim of this study was to investigate the possible application of non-toxic exopolysaccharide in the purification of contaminated water by removing Ni2+ ions. The results obtained from the biosorption study showed that the Langmuir model is well suited to describe the adsorption process of Ni2+ ions by EPS from K. oxytoca J7, with a maximum adsorption capacity of 269.97 mg g–1. The importance of this study is the possible use of natural nontoxic exopolysaccharide extracted from the pathogen microorganism, K. oxytoca J7, for the removal of Ni2+ ions from the contaminated water.

The occurrence and distribution of yttrium and rare earth elements (REYs), along with major elements and heavy metal(loid)s (HMs) in coal fly ash (CFA) from five coal-fired power plants (CFPPs), were analyzed, and the REY-associated ecological and health risks were assessed. The individual REYs in CFA were abundant in the following order: Ce > La > Nd > Y > Pr > Gd > Sm > Dy > Er > Yb > Eu > Ho > Tb > Tm > Lu. The total REY content ranged from 135 to 362 mg/kg, averaging 302 mg/kg. The mean light-to-heavy REY ratio was 4.1, indicating prevalent light REY enrichment in CFA. Significantly positive correlations between the REYs suggested that they coexist and share similar origins in CFA. REYs were estimated to pose low to moderate ecological risks, with risk index (RI) values ranging from 66 to 245. The hazard index (HI) and target cancer risk (TCR) of REYs from CFA, estimated to be higher for children (HIc = 0.15, TCRc = 8.4 × 10−16) than for adults (HIa = 0.017, TCRa = 3.6 × 10−16), were well below the safety limits (HI = 1, TCR = 1.0 × 10−6). However, the danger to human health posed by HMs in the same CFA samples (HIc = 5.74, TCRc = 2.6 × 10−4, TCRa = 1.1 × 10−4) exceeded the safe thresholds (excl. HIa = 0.63). The mean RI and HI attributed to REYs in CFA were 14% and 2.6%, respectively, of the total risks that include HMs.

In an attempt to reuse fibrous textile waste and, at the same time, to address dye pollution in textile wastewater, waste cotton-based yarn was utilized as a cheap and sustainable adsorbent, as well as a row material for carbon adsorbent production. Unmodified yarn and cotton-based carbon adsorbents were used as adsorbents for dye removal from water. Cotton and cotton/polyester yarn samples underwent thermal modification through carbonization followed by chemical activation with KOH. Various techniques, including scanning electron microscopy, Fourier transform infrared spectroscopy, nitrogen adsorption–desorption isotherms, and surface charge determination, were employed to analyze the morphological and surface characteristics of the cotton-based adsorbents. Adsorption properties were evaluated by testing the removal of selected cationic and anionic dyes from water. The impact of temperature, initial pH and concentration of the dye solution, and contact time on adsorption were investigated, and experimentally obtained data were analyzed using theoretical models. While carbonization alone did not significantly enhance adsorption properties, activated samples exhibited high efficacy in removing both cationic and anionic dyes from water. Despite the negative influence of the polyester component in the carbon precursor on the efficiency of activated samples in removing methyl orange, the results indicated that activated cotton and cotton/polyester yarn could be used to prepare highly efficient adsorbents for the rapid removal of methylene blue from real wastewater samples.

Organic and inorganic pollutants, accumulated in the environment, could pose a potential danger to living organisms. Some of these pollutants negatively affect the physiological activities of living organisms, and in certain concentrations, they can be lethal to biotic communities. In addition to the natural sources of emission of these substances in the environment, a large number of anthropogenic activities contribute to a sudden increase in their concentration. The development of new and improving existing ecologically sustainable techniques to prevent or reduce their outflow and retention in the environment is more necessary than ever. Therefore, the focus of this work will be examining the efficiency of environmentally friendly adsorbent based on modified starch and diatomaceous earth for the removal of selected organic and inorganic pollutants from aqueous solutions. The influence of the chemical modification of starch, followed by the addition of diatomaceous earth, on its structural, morphological, and adsorption properties, will be examined. The possibility of using starch-diatomaceous earth adsorbent for the removal of brilliant green dye, pharmaceutical compounds, and lead ions from aqueous solutions will be evaluated through the adsorption efficiency under the given conditions.

Fly ash (FA) is an industrial waste material generated during coal combustion in thermal power plants. In order to reuse this kind of industrial waste, and at the same time to reduce its quantity, fly ash was used as a cheap material for the preparation of efficient adsorbents for the removal of selected dyes from water. For that purpose, different modification methods were used to obtain alkali-activated fly ash samples. The success of the modification process and characterization of the unmodified and modified materials was monitored by Fourier transform infrared spectroscopy, and scanning electron microscopy/energy dispersive spectroscopy. The adsorption properties of examined samples were studied through the adsorption of methylene blue, crystal violet, alizarin red, and methyl orange. All samples showed the highest adsorption efficiency for crystal violet removal, while the sample modified with a combination of NaOH, Na2SiO3, and diatomaceous earth (FA/geopolymer) was the most efficient adsorbent for all selected dyes. Therefore, the influence of initial pH value and contact time on adsorption was examined for the adsorption of crystal violet onto FA/geopolymer. It was found that alkaline modification improves the adsorption characteristics of fly ash making it a promising candidate to solve the problem of colored wastewater.

In an attempt to reuse fibrous textile waste, and at the same time to reduce its quantity, waste hemp and flax fibers, and cotton yarn were used as cheap and sustainable adsorbents for the removal of pharmaceuticals from water. In order to improve their adsorption properties, waste fibers, and yarn samples were modified using 18% NaOH solution. Morphology, surface chemistry, and structural characteristics were examined through scanning electron microscopy, Fourier transform infrared spectroscopy, degree of surface crystallinity, and crystallinity index. Adsorption properties were analyzed through the determination of iodine sorption and water retention, as well as, the adsorption of selected sedatives. Modification with 18% NaOH increased the content of amorphous areas in examined fibers and yarn samples, improving their adsorption characteristics. Utilization of both unmodified and modified samples enables fast and highly efficient removal (adsorption efficiency ranging from 75 to 100%) of sedatives from water, making waste hemp and flax fibers and cotton yarn samples promising adsorbents for water treatment., U cilju smanjenja količine vlaknastog tekstilnog otpada, kao i njegove ponovne upotrebe, u ovom radu je ispitana mogućnost primene otpadnih vlakana konoplje i lana i pamučnog prediva, kao jeftinih i održivih adsorbenata za uklanjanje lekova iz vode. Izvršena je hemijska modifikacija otpadnih vlakana i prediva 18% rastvorom NaOH, da bi se poboljšala adsorpciona svojstva materijala. Morfologija, hemija površine i strukturne karakteristike korišćenih materijala ispitane su skenirajućom elektronskom mikroskopijom, infracrvenom spektroskopijom sa Furijeovom transformacijom, kao i određivanjem stepena površinske kristaliničnosti i indeksa kristalnosti. Adsorpciona svojstva su analizirana kroz vrednosti sorpcije joda i sposobnosti zadržavanja vode, kao i određivanjem adsorpcionih kapaciteta ispitivanih materijala za uklanjanje odabranih sedativa. Primenjeni alkalni tretman dovodi do povećanja sadržaja amorfnih oblasti u ispitivanim uzorcima vlakana i prediva, poboljšavajući njihove adsorpcione karakteristike. Dobijeni rezultati su pokazali da primena nemodifikovanih i modifikovanih otpadnih vlakana konoplje i lana i pamučnog prediva omogućava brzo i visoko efikasno uklanjanje (efikasnost adsorpcije u opsegu 75 - 100%) sedativa iz vode.

Nowadays, exopolysaccharides (EPS) produced from bacterial cells are manufactured for their use in different industries in the world, mainly in the food, pharmaceutical, and wastewater industries. The characteristics of EPS, such as being biodegradable, safe, high adsorption capacity, and reusable, make them significant and potential applications in the purification of contaminated water of heavy metals. In this study, the possible application in biosorption Ni2+ ions from contaminated water was assessed using this exopolysaccharide as a biosorbent. The new exopolysaccharide from the bacterial strain K. oxytoca J7 was extracted, isolated, and characterized using SEM, FTIR, XRD, TGA/DTG, and MALDI-TOF MS analysis. Likewise, the cytotoxic activity was performed for EPS from K. oxytoca J7 strain. The aim of this study was to investigate the possible application of non-toxic exopolysaccharide in the purification of contaminated water by removing Ni2+ ions. The results obtained from the biosorption study showed that the Langmuir model is well suited to describe the adsorption process of Ni2+ ions by EPS from K. oxytoca J7, with a maximum adsorption capacity of 269.97 mg g–1. The importance of this study is the possible use of natural nontoxic exopolysaccharide extracted from the pathogen microorganism, K. oxytoca J7, for the removal of Ni2+ ions from the contaminated water.

Fly ash is a by-product of coal combustion in thermal power plants. Heavy metal(loid)s (HMs) are the most recognized among the many dangerous compounds in fly ash. These substances may contaminate the environment and can pose a threat to human health. Various analytical techniques are used to analyze HMs in leachate. To investigate the possibility of contamination of the environment, heavy metals and metalloids (Pb, Zn, Mn, Fe, As, Ba, Be, Cu, Cr, Co, Cd, Sb, Se, and V) were leached from fly ash using a toxicity characteristic leaching procedure (TCLP). The fly ash samples used in this work were obtained from four thermal power plants (Kostolac, Kolubara, Tent B, and Morava). Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) technique was used to determine the concentration of these elements in the leachate. Accurate elemental analysis was achieved with this technique. Among all analyzed metal(loid)s, Fe, Mn, Zn, and As were the most abundant.

U cilju iskorišćenja industrijskog otpada, leteći pepeo je modifikovan radi dobijanjaefikasnih adsorbenata za uklanjanje metilensko plavog iz vode. Leteći pepeo je aktiviran uprisustvu NaOH na 550oC, i modifikovan različitim količinama polietilenimina.Karakterizacija polaznog i modifikovanih uzoraka izvršena je skenirajućom elektronskommikroskopijom i infracrvenom spektroskopijom sa Furijeovom transformacijom. Ispitan jeuticaj vremena kontakta i početne koncentracije adsorbata na adsorpcione kapacitetenemodifikovanog i modifikovanog letećeg pepela. Pokazano je da adsorpcionekarakteristike zavise od količine dodatog polietilenimina, kao i da adsorpcija prati brzinupseudo-drugog reda, a ravnotežni adsorpcioni podaci pokazuju bolje slaganje sa Frojndlihovom izotermom., In attempt to reuse industrial waste, fly ash was modified and converted into efficientadsorbent for the removal of methylene blue from water. Fly ash was activated in thepresence of NaOH at 550oC, and modified with different amounts of polyethyleneimine.The raw and modified samples were characterized by scanning electron microscopy andFourier transform infrared spectroscopy. The influence of contact time and initialadsorbate concentration on the adsorption capacity of unmodified and modified fly ash wasalso examined. It has been shown that the adsorption characteristics depend on the amountof polyethyleneimine added, that the adsorption follows a pseudo-second-order rate, andthe equilibrium adsorption data show better agreement with the Freundlich isotherm.

Accumulation of waste represents one of the biggest problems of modern civilization, from the energy, construction, urban, ecological and technological point of view. In this work, fly ash, as waste material from the power plant Nikola Tesla, was activated with sodium hydroxide at elevated temperature and then chemically modified with different amounts of polyethylenimine (PEI). The successfulness of modification was confirmed by scanning electron microscopy and Fourier transform infrared spectroscopy. Prepared materials were then used to remove cadmium from wastewater and an increase in adsorption efficiency was observed for the fly ash sample modified with a smaller amount of PEI, with respect to the unmodified sample. The results of the adsorption experiments were processed using Langmuir and Freundlich adsorption isotherms and pseudo-first and pseudo-second order kinetic models. Also, the possibility of reusing the material in several cycles was examined. It was found that fly ash, modified with an optimal amount of polyethyleneimine, could be an effective adsorbent.

The aim of this paper is to show the possibility of using waste materials, blends of (wood ash, fly ash, from thermal power plant, and metakaolin) for the production of alkali activated materials that can be used to purify wastewater from different kinds of pollutants such as heavy metals. Heavy metals are toxic, especially cadmium, so they must be removed from wastewater to prevent or minimize contact with the environment and humans. The synthesis of the alkali activated materials was performed by mixing solid precursors with a liquid alkali activator. Two- and three-component systems of wood ash, fly ash and metakaolin (wood ash/fly ash, wood ash/metakaolin, fly ash/metakaolin and wood ash/fly ash/metakaolin) were used as precursor materials. The alkali activator solution was a mixture of sodium silicate solution and sodium hydroxide solution of concentrations (6M and 12M). The characterization of alkali activated materials was studied by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM/EDS). XRD measurements of investigated samples showed a characteristic halo between 18 and 35º 2 with a dominant crystal phase of quartz. FTIR spectroscopy showed that the main vibration band of all investigated samples appeared between 1037-996 cm-1, and corresponds to Si-O-Si/Si-O-Al bands. SEM/EDS analysis was used to determine the microstructure of the samples. The adsorption efficiency of the investigated alkali activated materials for removing cadmium ions from aqueous solution was tested under different conditions: initial concentration of cadmium ions in the range of 20-100 mg/l, pH values from 3 to 7 and mass of adsorbents from 0.02-0.05 g.

The possibility of utilizing waste lignocellulosic fibers for the removal of selected sedative residues from polluted water was investigated as an attempt to reuse textile waste and reduce its disposal costs. To increase the adsorption efficiency, waste hemp (H) and flax (F) fibers were modified with a benzoyl peroxide solution. Unmodified and modified fibers (HBP and FBP) were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy, and it was found that applied modification caused the differences in morphology and surface chemistry, as the consequence of changes in the distribution of hemicelluloses in the structure of examined fibers. Adsorption properties were examined in the means of adsorption kinetics, isotherms, and the influence of the initial pH of the adsorption solution. The applied modification increases the adsorption capacities of examined fibers, especially for bromazepam removal. Also, modification increases the adsorption rate and changes its order, while adsorption equilibrium data fits better the Langmuir isotherm model. Obtained results showed that waste hemp and flax fibers can be applied as low-cost adsorbents to efficiently remove sedative residues from water.

Frequent changes in clothing fashion trends and the furniture industry have led to the excessive consumption of textiles to meet human needs. This leads to an increase in the production and finishing of textile materials, and the generation of large amounts of waste, making the textile industry one of the main polluters of the environment nowadays. Therefore, there are concerns about the reckless disposal of chemical and solid textile waste (natural or synthetic yarns, fibers, pieces of clothing, etc.) which can cause serious soil, water, and air pollution. To reduce the amount of waste generated in the industry, and preserve the environment and human health, it is necessary to apply modern trends of sustainable development. These trends imply the simultaneous satisfaction of the principles of ecological efficiency, social responsibility, and economic profitability. In this way, waste from the textile industry becomes a resource of the circular economy system with the aim of realizing sustainable development. In this work, waste materials of lignocellulosic, cellulosic, and synthetic origin were used as biosorbents for the purification of water polluted by organic and inorganic pollutants. This kind of waste utilization represents a special way of recycling, which is one of the most important links in the chain of sustainable development., Česte promene modnih trendova u odevnoj industriji, kao i industriji nameštaja, dovode do prekomerne potrošnje tekstila. Ovo direktno utiče na povećanje proizvodnje i dorade tekstilnih materijala, kao i stvaranja velike količine otpada, što tekstilnu industriju čini jednim od najvećih zagađivača životne sredine. Poseban problem predstavlja odlaganje hemijskog i čvrstog tekstilnog otpada (prirodna i sintetička prediva, vlakna, komadi odeće itd.) koji mogu izazvati ozbiljno zagađenje zemljišta, vode i vazduha. U cilju smanjenja količine otpada koji se generiše u industriji, a samim tim i očuvanja životne sredine i zdravlja ljudi, primenjuju se moderni trendovi održivog razvoja, koji podrazumeva istovremeno zadovoljenje principa ekološke efikasnosti, društvene odgovornosti i ekonomske isplativosti. Na taj način otpad iz tekstilne industrije postaje resurs sistema cirkularne ekonomije sa ciljem realizacije održivog razvoja. U ovom radu, otpadni materijali lignoceluloznog, celuloznog i sintetičkog porekla korišćeni su kao biosorbenti za prečišćavanje vode zagađene organskim i neorganskim polutantima. Ovakvo korišćenje otpada predstavlja specijalni vid reciklaže koja je jedna od najvažnijih karika u lancu održivog razvoja.

The immense quantity of industrial waste is a global problem that requires new solutions in accordance with the principles of circular economy and sustainable development. Therefore, in this work, fly ash obtained as waste from thermal power plants was used as an adsorbent for the removal of pharmaceutical residues from water. To improve the adsorption efficiency of fly ash, different modification methods were applied. Obtained adsorbents were characterized by SEM and FTIR. In order to improve the adsorption characteristics, the adsorption parameters were optimized (volume, initial concentration, and pH value of adsorbate solution, adsorbent mass, and contact time between adsorbent and adsorbate). Artificial neural networks were applied to establish the correlation between the examined adsorption parameters and to define the parameters having the greatest influence on the adsorption efficiency. The chemometric approach enabled the reduction of variables, i.e., the number of experiments necessary for the optimization of pharmaceutical residue adsorption onto modified fly ash, giving a good basis for the commercial application of fly ash in the field of wastewater treatment.

Retki elementi zemljine kore (engl. Rare Earth Elements, REE) koriste se u proizvodnji uređaja visoke tehnologije, optičkih vlakana, superprovodnika, itd. Osim ruda koje su glavni izvor REE, u novije vreme oni se dobijaju iz nusproizvoda ili otpadnih materijala. Sve češće se ispituje mogućnost primene letećeg pepela kao sirovine za dobijanje REE. Uzorci letećeg pepela korišćeni u ovom radu potiču iz četiri termoelektrane sa teritorije Republike Srbije (Tent B, Morava, Kostolac i Kolubara). Ekstrakcija REE je vršena pomoću TCLP ekstrakcionog fluida. Metodom masene spektrometrije sa indukovano spregnutom plazmom analizirano je 17 elemenata (Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th). Najviše koncentracije REE izmerene su u uzorku pepela iz termoelektrane Tent B., Rare earth elements (REEs) are used as components in high-technology devices, fiber optics, superconductors, etc. In addition to ores, by-products or waste materials are being considered as alternative sources for obtaining REEs. The potential for extracting REE from fly ash is being intensively studied. The fly ash samples used in this work were obtained from four thermal power plants from the Republic of Serbia (Tent B, Morava, Kostolac and Kolubara). The REE were extracted by TCLP extraction fluid. The ICP MS method was used for the analysis of 17 elements (Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th). The highest concentrations of REE were measured in the sample of fly ash from the Tent B power plant.

Waste hemp and flax fibers, and cotton and cotton/polyester yarns, available in large quantities from the textile industry, were used as cheap and effective sorbents for the removal of methylene blue from wastewater. Waste fibers and yarns were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, iodine sorption, water retention, and point of zero charge, as well as through the determination of crystallinity index and degree of surface crystallinity. Adsorption of methylene blue was optimized by examining the influence of contact time, initial concentration, temperature, and pH value. It was found that the more ordered structure of cotton and cotton/polyester yarns leads to lower adsorption capacities and better agreement with pseudo-second order kinetic and Langmuir isotherm model, while the more heterogeneous structure of flax and hemp fibers show higher capacities for methylene blue adsorption, better described by the pseudo-first order kinetic and Freundlich isotherm model. Based on the obtained results, waste lignocellulosic fibers and yarns can be utilized for the discoloration of wastewater, thereby solving the problem of waste generated in the textile industry.

This study aims to investigate the effect of alkalization and chemical coupling methods on the surface and adsorption properties of waste cotton and cotton/polyester yarns. The simple and cheap alkali treatment was performed using 10% and 18% NaOH solution, while the chemical coupling method involved combining cotton and cotton/polyester yarns and fly ash, using sodium carboxymethyl cellulose and sodium alginate as binders. Morphological and surface characteristics of unmodified and modified cotton and cotton/polyester yarns were analyzed by scanning electron microscopy and Fourier transform infrared spectroscopy, while adsorption properties were assessed by the removal of lead and cadmium ions from aqueous solution. It was found that chemical modification with 18% NaOH solution positively affected the adsorption properties of only cotton yarns, increasing the removal efficiency of lead ions up to 75%. On the other hand, modification with fly ash improves the adsorption properties of both, cotton and cotton/polyester yarns, increasing the efficiency in removing lead ions by using sodium carboxymethyl cellulose, and cadmium ions by using alginate as a binder. Using the chemical coupling method, effective adsorbents are obtained starting from waste yarn, which gives it added value, the amount of non-degradable waste material can be reduced and the criteria of a cleaner environment and circular economy can be met.

The possibility of using waste cotton and cotton/polyester yarns to remove lead and chromium ions from polluted water was investigated in this work. Structural, morphological, and adsorption properties of yarns were determined by iodine sorption, water retention scanning electron microscopy, Fourier transform infrared spectroscopy, and streaming potential method for determination of an isoelectric point. It was found that the presence of polyester component negatively affects adsorption capacity, through the reduced porosity of cotton/polyester yarn surface, increased surface, and structural crystallinity. Relatively fast adsorption of lead and chromium ions from binary mixture onto cotton and cotton/polyester yarns follows the pseudo-second order kinetic, while equilibrium data fitted better with the Langmuir isotherm model, with maximal adsorption capacity from 259.0 to 824.7 mu g/g. Although, cotton yarn shows slightly higher maximal adsorption capacities, both cotton and cotton/polyester yarns can be utilized as cheap and highly efficient adsorbents for removal of lead and chromium ions from water.

Using two types of industrial waste materials (yarns and fly ash), adsorbents for removing heavy metal ions from water were obtained. To improve the adsorption efficiency of cotton and cottonpolyester yarns, modification using fly ash and sodium alginate as a binder, was applied. Characterization of materials was performed by Scanning electron microscopy and Fourier transform infrared spectroscopy, while the concentration of lead and cadmium ions was determined using atomic absorption spectroscopy. The modification of the material has contributed to an increase in the adsorption efficiency of lead and cadmium by up to twice in comparis onto the unmodified materials. It was found that the kinetics of the metal adsorption process can be better described by a second-order pseudo model. The results showed that by combining two types of industrial waste, cotton and cotton/polyester yarns and fly ash, highly efficient adsorbents for removing lead and cadmium from aqueous solutions are obtained.

Different natural fibers and yarns (hemp, flax, and cotton), obtained as a waste from textile industry, were used for the removal of methylene blue from aqueous solution. In attempt to increase the adsorption efficiency, examined fibers and yarn were modified by sodium hydroxide solution. Characterization of examined samples was performed by scanning electron microscopy and Fourier transform infrared spectroscopy. It was shown that applied modification caused the differences in the distribution of hemicelluloses in the structure of examined fibers and fibers in yarn, inducing the changes in morphology and surface chemistry. These changes slightly improved the adsorption properties of hemp fibers, while in the case of cotton yarn modification had a negative effect on methylene blue adsorption. Nevertheless, adsorption efficiency of these waste fibers and yarns highly increase with the pH of the solution, enabling their utilization for methylene blue removal from wastewaters.

As coal combustion in thermal power plants generates huge amounts of waste such as bottom ash and fly ash, there is a need to find new applications for these materials. One of the ways of its reuse is chemical or thermal modification of the ash in order to obtain new materials, which can be further used as adsorbents of various pollutants from water. The subject of this research was the alkali modification and alkali activation of fly ash in purpose to increase the adsorption capacity towards heavy metal ions. The success of modification process and characterization of the obtained materials was monitored by Fourier transform infrared spectroscopy, X-ray fluorescence spectroscopy and scanning electron microscopy. The concentration of zinc and cadmium ions after adsorption was determinated by atomic absorption spectroscopy. The kinetics of the adsorption process on the most efficient adsorbent were examined and the experimental data were compared with pseudo-first and pseudo-second order models. The achieved results show a positive effect of alkaline modification of fly ash on adsorption efficiency of both metals, while alkaline activation gives an exceptionally effective adsorbent in the case of zinc.

Researches in the field of nanotechnology indicate the possibility of the development and application of bionanocomposites based on clay minerals and biopolymers as promising materials for the removal of pollutants from contaminated water. Therefore, this study is based on an examination of the effect of intercalation of starch or cationic starch with kaolin clay or diatomaceous earth on the adsorption properties of the obtained materials for the removal of anionic and cationic dyes from aqueous solutions. Structural characterization of the obtained materials was performed by Fourier transform infrared spectroscopy while the morphology of the samples was determined by Scanning electron microscopy. The removal efficiency of methyl orange and crystal violet dyes was tested in a batch system, while the dye concentration after the adsorption process was determined by UV-Vis spectrophotometry. It was found that modification of cationic starch with clay and diatomaceous earth improved the efficiency for removing crystal violet dye from an aqueous solution.

The objective of this study was to evaluate the adsorption efficiency of a cationic functionalized wheat starch, obtained with betaine hydrochloride and glycidyl trimethylammonium chloride by an environmentally friendly process without the use of organic solvents. Surface functional groups of samples were characterized by Fourier transform infrared spectroscopy, the morphology of the materials was examined using scanning electron microscopy, the nitrogen content was determined by elemental analysis, while UV-VIS spectroscopy and liquid chromatography-tandem mass spectrometry were used for adsorption investigation. The efficiency of obtained cationic starches to adsorb the anionic and cationic dyes, as well as selected pharmaceuticals and pesticides was investigated. Adsorption experiments were performed in a batch system to determine the effect of contact time, initial concentration, and pH of the solution on the removal efficiency of crystal violet dye, which was chosen as the model for the detailed study of adsorption. Pseudo-first and pseudosecond order models were used to examine the adsorption kinetic, while Langmuir and Freundlich isotherm models were applied to equilibrium adsorption data. The results showed that environmentally and economically acceptable adsorbents prepared in this study could be effective in removing the examined organic pollutants.

U cilju dobijanja adsorbenata za uklanjanje organskih boja iz otpadnih voda, u okviru ovog rada su primenjene dve vrste industrijskih otpadnih materijala. Otpadna prediva pamuka i mešavine pamuk/poliestar modifikovana su korišćenjem smeše natrijum karboksimetil celuloze i letećeg pepela. Karakterizacija polaznih i modifikovanih prediva izvršena je skenirajućom elektronskom mikroskopijom i infracrvenom spektroskopijom sa Furijeovom transformacijom, dok je adsorpcija metilensko plavog i metil oranža primenjena za ispitivanje efikasnosti uklanjanja. Svi ispitivani uzorci pokazuju bolju efikasnost u uklanjanju metilensko plavog, a primenjena modifikacija povećava adsorpcionu efikasnost skoro dva puta. Pokazano je da se kombinovanjem dve vrste otpada, pamučnog prediva i letećeg pepela, dobijaju visoko efikasni adsorbenti za uklanjanje metilensko plavog iz vode., In order to obtain adsorbents for the removal of organic dyes from wastewater, two types of industrial waste materials were used in this study. Waste cotton and cotton/polyester yarns were modified using a mixture of sodium carboxymethyl cellulose and fly ash. Characterization of the unmodified and modified yarns was performed by scanning electron microscopy and infrared spectroscopy with Fourier transform, while the adsorption of methylene blue and methyl orange was used to examine the removal efficiency. All tested samples show better efficiency in removing methylene blue, and applied modification increase the adsorption efficiency almost twice. It has been shown that by combining waste cotton yarn and fly ash, highly efficient adsorbents for removal of methylene blue from water can be obtained.

The aim of the presented research was to investigate the application possibility of wood ash and metakaolin to obtain alkali-activated materials as relatively new materials in the building industry. Thus, in order to assess the adequate use of these waste materials, structural and radiological characteristics should be considered. Until now, the focus has been on ash from thermal power plants produced by burning coal, but a large part of households in our country have individual fireplaces in which wood is used as the basic raw material; thus, it is very interesting to measure the activity concentration of radionuclide in wood ash as well as the possibility of reusing that ash for other purposes. All materials were studied, in terms of physical and chemical characteristics, by methods such as X-ray diffraction (XRD), Fourier transform infra-red (FTIR) spectroscopy, and scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM/EDS). XRD measurements of wood ash samples showed that it consists of calcite and larnite. FTIR spectroscopy revealed a polymeric Si–O–Al framework in alkali-activated materials and Si–O bonding bands corresponding to silicon dioxide. Determination of radionuclide content was performed by means of gamma-ray spectrometry. Results showed that the alkaline activation process led to the decrease in the activity concentration of radionuclides detected in the measured samples. External radiation hazard index (Hex) for wood ash was reduced by more than 50% after alkali activation. The results of activity concentration measurements in alkali-activated materials indicate potential for their safe application in building construction.