This research focuses on enhancing water quality for concrete construction by utilizing treated wastewater from wetlands. The study employs a dual-stage treatment process involving charcoal and ...aggregate layers for primary treatment, followed by water hyacinths for secondary treatment. Investigating water hyacinths’ ability to absorb nutrients and contaminants from wastewater is a unique aspect of the study, offering a potential solution for soil and water remediation. Water hyacinths, especially stems and leaves, act as natural filters, effectively indicating heavy-metal pollution in tropical regions. The primary goal is heavy-metal removal from wastewater, allowing treated-water use in concrete production at varying proportions (20 %, 40 %, 60 %, 80 %, and 100 %). Silica fume at 15 % concentration is incorporated to enhance the concrete’s durability. Concrete specimens undergo thorough preparation and mechanical property evaluations, compared to conventional M20-grade concrete. The results reveal improvements in mechanical properties, particularly with 80 % treated wastewater in the mix. The dual-stage treatment process removes heavy metals, and the inclusion of silica fume enhances the concrete’s durability and resistance.
Determination of trace element concentrations in atmospheric aerosols is important because of their toxic effects on human health. Additionally, they are now widely used in source apportionment ...studies. There is a number of methods for sample preparation of ambient particulate matter. One of the most widely used is microwave-assisted digestion of filter-based samples. Since the water-soluble fraction is bioavaliable, the aim of our study was to determine the concentration of selected trace elements (V, Cr, Mn, Ni, Cu, Zn, As, Cd, Sb, Tl, and Pb) in this fraction and compare it to the amounts obtained by two different microwave digestion procedures - one using a mixture of H2O2 and HNO3 and the other using a mixture of HF, HCl, and HNO3. The recoveries of the digestion procedures used were tested on certified reference material (NIST SRM 1648 Urban Particulate Matter). The procedures were applied to filters containing PM10 particles collected at an urban background location in Ljubljana, Slovenia. Among the elements analysed, V, Zn, As, and Cd displayed the highest concentration within the water-soluble fraction, with Cr, Ni, Tl and Pb displaying the lowest concentrations. The comparison between the two applied digestion procedures showed that Cr, Ni, Sb and Tl were strongly bound to the sample matrix.
Določevanje elementov v sledovih v atmosferskih delcih je pomembno zaradi njihovega toksičnega vpliva na človekovo zdravje. V zadnjem času se koncentracije teh elementov tudi zelo pogosto uporabljajo v študijah povezanih s porazdelitvijo po virih. Za določevanje elementov v sledovih se uporabljajo različne priprave vzorcev. Najpogostejši je razklop filtrov s pomočjo mikrovalovne peči. Ker je vodotopen delež tudi biološko dostopen, je bil namen naše študije določitev te frakcije posameznih elementov (V, Cr, Mn, Ni, Cu, Zn, As, Cd, Sb, Tl and Pb) in primerjava s koncentracijami po dveh različnih razklopih - prvi z mešanico H2O2 in HNO3 ter drugi z mešanico HF, HCl in HNO3. Izkoristke uporabljenih razklopov smo preverili s standardnim referenčnim materialom (NIST SRM 1648 Urban Particulate Matter). Preverjena postopka smo uporabili na filtrih, ki so vsebovali delce PM10, vzorčevane v Ljubljani, Slovenija. Med analiziranimi elementi so bili izrazito dobro topni v vodi V, Zn, As in Cd, najmanj pa Cr, Ni, Tl, in Pb. Primerjava med obema uporabljenima razklopoma je pokazala, da so Cr, Ni, Sb in Tl v delce izredno stabilno vezani.
The paper considers the perception of metals such as gold, silver, bronze and iron in Hesiod’s Theogony and Works and Days, composed around late 8th or early 7th century BC. An analysis reveals that ...gold appears exclusively as an attribute of the gods. Only gods wear objects of gold and their works are golden, too; indeed, they are described as golden themselves. Arguably this metal not only serves as a metaphor for the quality of the immortal and unreachable gods, i.e. Aphrodite, Dionysus, Hera, Zeus and Apollo, but also appears in the ‘distant territories of the divine cosmos’ – golden is Triton’s palace, golden are the apples guarded by a horrible snake on the edge of the earth. Hesiod’s golden race, the first mortal race, excellent in all aspects, free of troubles and hard work, is, significantly, also closest to the gods. The silver race, created after the golden one, is inferior to the first just as silver is less precious than gold. Hardly ever mentioned in Hesiod’s poems, this metal is omitted from descriptions of jewellery or weapons. What is described as silver are river whirlpools, the colossal pillars of the underworld, and the feet of the nymph Thetis. A possible interpretation is that all these objects are untamed and unreachable, similar to gold but not divine anymore. After the silver race, the gods create the bronze race. This is a race of violent giants, fierce and strong, who are born from the ash tree. Bronze is therefore even farther from the divine: it is human. Moreover, it is the first alloy, and the manufacture of bronze objects demands much more knowledge and skill in comparison with gold and silver. Hesiod uses bronze as a synonym for all that is hard and strong in both poems – bronze is the material of the anvil, of the high walls, door, and doorstep which hold back the Titans in Tartarus, and of the arms carried by Memnon and Heracles. The only race not associated with metals is the race of heroes, exempted in this respect from the progressive devaluation. The fifth and last race is the iron race, to which the poet himself belongs. It is described as beset by the sorrow, hard work and cares sent by the gods. Made of iron are mostly tools and weapons; iron is the soul of Death, hard and heartless. With iron, the worst of all metals, the cycle of devaluation is complete. However, archaeological investigations present a somewhat different picture. In the early Iron Age, i.e. contemporary with the two Hesiodic poems, iron ultimately prevails in the territory of today’s Europe. Yet it is not used only to produce weapons and tools – this period reveals a rapid increase in iron jewellery as well. The abundance of the latter shows that iron was not only new but even fashionable, despite being unsuitable for the making of jewellery. In fact, it may have been prized more than gold itself in this period. Why, then, does the poet characterise the iron race as the worst, despite all the advantages brought by this metal? Simply because iron is the material supplying tools and weapons, which are used in labour and warfare respectively. In the golden age, by contrast, men lived in peace, leisure, and opulence like the immortal gods. Innovation and technological progress, such as the knowledge of iron and its techniques, are not perceived to contribute to tranquillity and prosperity; rather, they are associated with harrowing work and war.
V dvanajstih vzorcih tal iz okolice vrtcev, šol, zelenjavnih vrtov in dvorišč v Mežiški dolini, s koncentracijami Pb od 469 do 4333 mg kg-1 in Zn od 313 do 8670 mg kg-1, smo določili mobilnost in ...biodostopnost Pb in Zn. Koncentracija Pb je v enajstih vzorcih presegla kritično vrednost, koncentracija Zn pa v devetih (glede na uredbo v Ur.l.RS št. 68, 1996). Mobilnost Pb in Zn določena s TCLP metodo (Toxicity Characteristic Leaching Procedure) je pokazala, da nobeden od vzorcev ni presegal vrednosti, ki bi tla po metodologiji EPA (US Environmental Protection Agency) uvrščala med nevarne odpadke. Koncentacije Pb in Zn v testni rastlini solati (Lactuca sativa L.) so bile pod mejo detekcije instrumenta (atomski absorpcijski spektrofotometer). S fiziološko osnovanim PBET ekstrakcijskim testom (Physiologically Based Extraction Test) smo vzorcem in talnim prašnim delcem določili delež Pb, ki je biodostopen v človeškem prebavnem sistemu. Iz simulirane želodčne faze je bilo dostopnega 2,8 - 22,8 %, iz črevesne pa 1,2 - 9,0 % celokupnega Pb v tleh. Koncentracije biodostopnega Pb so bile v prašnih delcih manjše kot v vzorcih tal.
The domain of catalytic hydrogenation continues to grow fast, reflecting the wide range of chemical applications that can be enhanced by the easy use of molecular hydrogen. The advances in ...characterization techniques and their application have improved our understanding of the catalytic processes and mechanisms occurring in both homogeneous and heterogeneous catalysis. The aim of this volume, although not exhaustive, is to provide a general overview of new progress of the hydrogenation reactions. This volume comprises a series of various contributions, as reviews or original articles, treating heterogeneously and homogeneously catalyzed hydrogenation reactions. It is composed of three parts: hydrogenation reactions in fine organic chemistry, hydrogenation reactions in environmental chemistry and renewable energy, and special topics in hydrogenation.
Pet reprezentančnih vzorcev močno onesnažene zemljine z območja stare cinkarne v Celju (Slovenija), ki so vsebovali od 7300 do 17200 mg kg-1 celokupnega Pb, od 6000 do 63600 mg kg-1 celokupnega Zn in ...od 24 do 250 mg kg-1 celokupnega Cd, smo remedirali z metodo stabilizacije s 15 ut.% portland cementa. Po 4 mesecih stabilizacije se je mobilnost Pb, Zn in Cd določena s TCLP metodo ("Toxicity Characteristic Leaching Procedure") 5,8 - 17,4, 8,1 - 35,8 oz. 4,3 - 7,3-krat zmanjšala. Potencialna dostopnost Pb, Zn in Cd za rastline, določena z ekstrakcijo z dietilentriaminpentaocetno kislino (DTPA), se je po stabilizaciji 1,6 - 9,8, 1,1 - 2,1 oz. 1,3 - 4,1-krat zmanjšala. Biodostopni delež Pb določen s fiziološko osnovanim ekstrakcijskim testom ("Physiologically Based Extraction Test"; PBET) se je v črevesni frakciji po stabilizaciji 5,9 - 11,3-krat zmanjšal.
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