“Green” adsorbents in the wastewater treatment service

In this study, the adsorption of acetic acid on the so-called "green" adsorbents was studied. Waste materials, i.e. eggshells and coffee grounds were used as adsorbents. In addition, activated carbon was used to compare the adsorption efficiency with "green" adsorbents. The obtained results showed that the equilibrium time of all studied adsorbents is achieved in 30 minutes. By comparing the adsorption efficiency of acetic acid on the tested adsorbents, it was shown that their use as cheap adsorbents under the tested conditions is possible. The coffee grounds showed a relatively high adsorption efficiency, very similar to the adsorption efficiency obtained when using the commercial and most commonly used adsorbent, i.e. activated carbon

Procjena broja nodula i nodularnosti u odljevcima od nodularnog lijeva korištenjem toplinske analize

The effect of parameters which are identified and measured by thermal analysis on the nodule count and nodularity in ductile iron castings was analyzed in this paper. The obtained results show that the nodule count and nodularity increases with increasing the temperature of eutectic undercooling (TEP) and graphite factor 1 (GRF 1) and decreasing recalescence (TR), graphite factor 2 (GRF2) and value of the first derivative of the cooling curve at TS (d/dt TS). The processing of obtained results was performed by multiple regression analysis. Based on the measured thermal parameters, models for estimation of the nodule count and nodularity were established. The high correlation coefficients between the measured and the estimated values of the nodule count (nodularity) confirm that there is a tight correlation between the thermal parameters of ductile iron melt and microstructural features of ductile iron castings.U ovom radu je analiziran utjecaj parametara koji su registrirani i mjereni toplinskom analizom na broj nodula/mm2 i nodularnost u odljevcima od nodularnog lijeva. Dobiveni rezultati pokazuju da broj nodula/mm2 i nodularnost rastu s povećanjem temperature eutektičnog pothlađenja (TEP) i grafitnog faktora 1 (GRF 1), te smanjenjem rekalescencije (TR), grafitnog faktora 2 (GRF 2) i vrijednost prve derivacije krivulje hlađenja na solidus temperaturi (d/dt TS). Obrada dobivenih rezultata je provedena višestrukom regresijskom analizom. Na osnovi mjerenih toplinskih parametara, formirani su modeli za procjenu broja nodula/mm2 i nodularnosti. Visoke vrijednosti koeficijenata korelacije između mjerenih i procijenjenih vrijednosti broja nodula/mmm2 (nodularnosti) potvrđuju da postoji čvrsta korelacija između toplinskih parametara taline nodularnog lijeva i mikrostrukturnih značajki odljevaka od nodularnog lijeva

Environmentally friendly waste for wastewater treatment

In this paper, the adsorption properties of two wastes from the metallurgical industry were studied: waste after shot blasting of the castings and waste moulding mixture, and waste from the wood industry, i.e. oak sawdust. A solution of Cu(II) ions was used as the adsorbate. Experimental data have shown that the waste from the metallurgical industry can be used as an adsorbent for removal of Cu(II) ions from wastewater. For oak sawdust, it could not be confirmed with certainty whether it had adequate adsorption properties due to the release of substances that lead to the coloration of the adsorbates. Lagergren\u27s and Ho\u27s model was used to describe the adsorption kinetics of the system waste moulding mixture/Cu(II) ions and waste after shot blasting of the castings/Cu(II) ions. It was concluded that both systems are better described by Ho\u27s model, i.e. that the adsorption kinetics in both systems take place according to pseudo-second order reactions

Environmentally friendly waste for wastewater treatment

In this paper, the adsorption properties of two wastes from the metallurgical industry were studied: waste after shot blasting of the castings and waste moulding mixture, and waste from the wood industry, i.e. oak sawdust. A solution of Cu(II) ions was used as the adsorbate. Experimental data have shown that the waste from the metallurgical industry can be used as an adsorbent for removal of Cu(II) ions from wastewater. For oak sawdust, it could not be confirmed with certainty whether it had adequate adsorption properties due to the release of substances that lead to the coloration of the adsorbates. Lagergren\u27s and Ho\u27s model was used to describe the adsorption kinetics of the system waste moulding mixture/Cu(II) ions and waste after shot blasting of the castings/Cu(II) ions. It was concluded that both systems are better described by Ho\u27s model, i.e. that the adsorption kinetics in both systems take place according to pseudo-second order reactions

“Green” adsorbents in the wastewater treatment service

In this study, the adsorption of acetic acid on the so-called "green" adsorbents was studied. Waste materials, i.e. eggshells and coffee grounds were used as adsorbents. In addition, activated carbon was used to compare the adsorption efficiency with "green" adsorbents. The obtained results showed that the equilibrium time of all studied adsorbents is achieved in 30 minutes. By comparing the adsorption efficiency of acetic acid on the tested adsorbents, it was shown that their use as cheap adsorbents under the tested conditions is possible. The coffee grounds showed a relatively high adsorption efficiency, very similar to the adsorption efficiency obtained when using the commercial and most commonly used adsorbent, i.e. activated carbon

KINETIC STUDY OF ADSORPTION OF HEAVY METALS ON BLAST FURNACE SLAG

In this paper, blast furnace slag was investigated as a potential adsorbent for the removal of zinc and copper ions from the aqueous solution. The adsorption was performed by a static, so-called "batch" process. Adsorption properties were studied by monitoring the influence of contact time adsorbent with adsorbate. Performed studies have shown that the equilibrium in the tested system is achieved in 30 minutes. Intraparticle diffusion model, heterogeneous diffusion model and film diffusion model were used to test the zinc and copper ion diffusion in a competitive adsorption. The obtained results showed that intraparticle diffusion controlled the adsorption process

COMPARISON OF ACETIC ACID ADSORPTION KINETICS ON DIFFERENT WASTE MATERIALS

In this paper, the adsorption properties of two metallurgical wastes (slag and anode dust) and two municipal wastes (eggshells and coffee grounds) were described. Acetic acid was used as the adsorbate Adsorption kinetic was monitored during the adsorption process. The obtained results showed that all tested waste materials can be used as potential cheap adsorbents. Adsorption took place relatively quickly. Equilibrium was reached in 15 minutes, and the adsorption kinetics followed the pseudo-first-order reactions, i.e., can be described by the Lagergren model. All qe values calculated using Ho's model have a negative sign. That indicates that the Ho model is not suitable for describing the kinetics of the tested adsorption systems.&nbsp

Technical aspects of lithotripters and application of shock wave therapy /ESWL/ in the treatment of urinary tract stones

Danas tretman litotripsije udarnim valovima (ESWL) predstavlja prvi izbor za liječenje kamenaca u bubregu, u mokraćovodima i bubrežnim nakapnicama. U usporedbi s otvorenim i endoskopskim metodama, ESWL je neinvazivna metoda, metoda za koju nije potrebna anestezija, a postiže visoke postotke uspješnosti tretmana u bolesnika s urolitijazom. Učinkovitost ESWL leži u njegovoj osobitosti fragmentiranja konkremenata „in vivo“ koji se nakon tretmana spontano eliminiraju kroz mokraćni sustav. Današnji uređaju za litotripsiju sastoje se od četiri osnovne komponente: (1) generatora udarnih valova, (2)sustava fokusiranja, (3) mehanizma povezivanja, i (4) jedinice za sliku/lokalizaciju konkrementa. Generatori udarnih valova mogu biti: elektrohidraulični, piezoelektrični ili elektromagnetski. Mehanizam djelovanja omogućava da konkrement bude fragmentiran, onog trenutka kada snaga udarnih valova nadilazi vlačnu čvrstoću kamena. Iako nedovoljno razjašnjena, fragmentacija konkrementa nastaje kombinacijom mehanizama, pri čemu se snaga udarnih valova, uz učinak kavitacije smatra najvažnijim. U Kliničkoj bolnici Dubrava danas koristimo LITHOSKOP® multifunkcijski litotriptor tvrtke Siemens koji posjeduje prilagodljivu udarnu glavu za izvođenje litotripsije u pozicijama iznad i ispod stola te nema potrebe za repozicioniranjem pacijenta tijekom procedure. Frekvencija udarnih valova glave je 60-120 pulseva/min sa dubinom penetracije maksimalno 16 cm, a energija je podesiva u 38 razina. Rentgenski C-luk, služi za lokalizaciju i sinkrono slijedi automatsko pomicanje terapijske glave. Osim lokalizacije rentgenskim zrakama sustav je opremljen i naprednim računalnim programom za automatsko pomicanje pacijenata u terapijski fokus nakon označavanja kamena te s Color Doppler ultrazvučnim aparatom koji omogućuje "inline" ultrazvučnu lokalizaciju.Nowadays, the treatment using shock wave lithotripsy (ESWL) is becoming the first choice for the treatment of stones in kidneys, ureter, and renal pelvis. Compared with open and endoscopic methods, ESWL is a minimally invasive method which does not require anaesthesia, and achieves high success rates in patients with urolithiasis. The effectiveness of ESWL lies in its specifics of fragmenting calculi "in vivo" which are upon treatment spontaneously eliminated through the urinary tract. All lithotripsy devices consist of four basic components: (1) shock wave generator, (2) focusing system, (3) linking mechanism, and (4) units for image/localization of stones. Shock wave generators can be electrohydraulic, electromagnetic or piezoelectric. The mechanism of activity that allows stones be fragmented the moment when the power of shock waves exceeds the tensile strength of the stone. Although incompletely explained, fragmentation of stones is performed by the combination of mechanisms, while the strength of shock waves and cavitation are considered to be the most important. In Clinical Hospital Dubrava nowadays LITHOSKOP ®, a multifunctional lithotripter made by Siemens, is used. It has a flexible impact head to perform lithotripsy in positions above and below the table, and there is no need for repositioning the patient during the procedure. Frequency of the head shock waves is 60-120 pulses/min with a penetration depth up to 16 cm and the energy is adjustable to 38 levels. The X-ray C-arm is used for localization and it synchronously follows the automatic movement of the therapeutic head. In addition to the localization of X-ray system it is also equipped with advanced software to automatically move patients in therapeutic focus after selecting the stone and with Color Doppler ultrasound device that enables "inline" ultrasound localization