Process Water Recovery via Forward Osmosis

Forward osmosis (FO) is an emerging membrane technology promising low cost water recovery from high salinity effluents that involves two steps to recover water. Initially, a concentrated draw solution (CDS) recovers water from the effluent, and subsequently, the diluted draw solution (DDS) must be treated for water recovery and draw solution regeneration. Water recovery into the CDS requires almost no energy; however, energy is required to recover water from the DDS and regenerate the CDS. Aqueous carbonated trimethylamine (TMA-CO2-H2O) is an effective draw solution as it consists of highly soluble compounds, namely TMA and CO2, and results into CDSs of high osmotic pressure, capable to achieve a high water recovery yield. Further, TMA and CO2 undergo a phase transformation, from aqueous to vapor, upon mild heating of the DDS, thus facilitating water recovery from it. A fundamental theoretical and experimental investigation of the ternary system TMA-CO2-H2O as draw solution in Forward Osmosis (FO) was conducted. A new database for the Mixed Solvent Electrolyte (MSE) model of the OLI Systems (www.olisystems.com) software was developed to determine the interaction parameters, using new experimental data and regression analysis. The experimental data included VLE, speciation, pH, density, and conductivity. The database developed was shown to accurately predict the chemical properties of aqueous trimethylamine solutions (TMA-CO2-H2O) within 15% within the temperature range 20 to 60 °C. Further, the TMA-CO2 separation efficiency and decomposition kinetics were systematically studied and a decomposition mechanism for the draw solution was proposed. The rate determining step was found to be TMA desorption from the DDS and the draw solute separation process stoichiometric. The temperature and pressure effects on the draw solute separation efficiency were also quantified. A new methodology to obtain speciation data at high temperatures was developed and was validated experimentally. This methodology is applicable to chemical systems that share similar properties to the ternary TMA-CO2-H2O and can be used in kinetics studies. Finally, an energy efficient draw solution separation and regeneration process was designed and operated at both laboratory and pilot-scale. The experimental results were compared to simulations carried out in the OLI Flowsheet process modeling software within 15% error. The specific equivalent work was found to range from 6.8-16.7 kWh/m3 of fresh water produced. Therefore, the niche of the TMA-CO2-H2O based FO process in the water recovery industry was identified in the treatment of high salinity effluents, as this process is more energy efficient that the conventional water recovery processes.Ph.D

Απεικόνιση και έλεγχος κβαντικών διαδρομών ηλεκτρονίων μέσα σε ισχυρά πεδία αλληλεπίδρασης ακτινοβολίας laser και ατόμων

The fundamental mechanism underlying harmonic emission in the strong-field regime is governed by tunnel ionization of the atom, followed by the motion of the electron wave-packet in the continuum, and finally by its recollision with the atomic core. Due to the quantum nature of this process, the properties of the electron wave-packet strongly correlate with those of the emitted radiation. In this Thesis, overlapping the harmonic radiation emitted by different interfering electron quantum paths and imaging the correspondent interference pattern, has been succeeded to investigate the intricacies associated with the recollision process. The spatial extreme-ultraviolet (EUV)-intensity distribution has been mapped onto a spatial ion distribution, produced in the EUV focal area through linear and nonlinear ionization processes of rare gases atoms. Due to the high degree of accuracy that the present approach provides, has been possible to be demonstrated the quantum nature of the recollision process. Additionally, based again on the ion-imaging technique, a novel single-shot second-order autocorrelation scheme for extreme-ultraviolet (EUV) radiation has been proposed. Using simple analytical and detailed numerical modeling, an evaluation toward selecting an optimum configuration has been performed. The implementation of the concept to characterize attosecond pulses is discussed, and the proposed setups are assessed. Finally, is demonstrated the generation of a broadband coherent continuum EUV radiation by the interaction of rare gases with a many-cycle infrared (IR) laser field ellipticity-modulated by utilizing a compact collinear many cycle-polarization gating (CMC-PG) device. The CMC-PG device formulates the many-cycle driving pulse in such a way that the EUV emission is canceled anywhere else but in a small energetic interval of the proper small duration; the so-called “gate”. The “gate”-width has been measured and is in agreement with the theoretical calculations. The spectral width of the generated EUV radiation can support isolated pulses of 200 asec duration. The simplicity, the compactness, the long term stability, and the high IR energy output within the “gate”, make the CMC-PG device an ideal tool for generating energetic isolated attosecond pulses.Ο βασικός μηχανισμός που οδηγεί στην εκπομπή ανώτερης τάξης αρμονικών σε συνθήκες ισχυρού- πεδίου, δύναται να αναλυθεί σε τρία στάδια: αρχικά το άτομο ιονίζεται μέσω φαινομένου σήραγγος, ακολουθεί η κίνηση του ηλεκτρονικού κυματοπακέτου μακρυά από τον πυρήνα και τελικά λαμβάνει χώρα η επανασύνδεση του ηλεκρονίου με τον ατομικό πυρήνα και η παράλληλη εκπομπή ηλεκτρομαγνητικής ακτινοβολίας. Λόγω της κβαντικής φύσης της διαδικασίας, οι ιδιότητες του ηλεκτρονικού κυματοπακέτου συσχετίζονται στενά με τις ιδιότητες της εκπεμπόμενης ακτινοβολίας. Στην παρούσα Διατριβή εξετάζονται ενδογενείς ιδιότητες της διαδικασίας επανασύνδεσης. Αυτό καθίσταται δυνατό μέσω της ανάλυσης της εκ συμβολής χωρικής κατανομής της έντασης της εκπεμπόμενης ακτινοβολίας. Η χωρική αυτή κατανομή δημιουργείται από την υπέρθεση μερών της εκπεμπόμενης ακτινοβολίας προερχόμενα από δύο διακριτές τάξεις ηλεκτρονικών κβαντικών διαδρομών (των “μακρών” και των “βραχέων”). Τα δύο αυτά μέρη εστιάζονται μαζί και η χωρική κατανομή της έντασης του μακρού υπεριώδους (ΕUV), στην εστιακή περιοχή, απεικονίζεται μέσω της καταγραφής της χωρικής κατανομής ιόντων που προκύπτουν από μονοφωτονικές ή διφωτονικές διαδικασίες ιονισμού ατόμων ευγενών αερίων. Χάρις στον υψηλό βαθμό ακριβείας που προσφέρεται από τη συγκεκριμένη μέθοδο, γίνεται δυνατό να καταδειχθεί η κβαντική φύση της διαδικασίας επανασύνδεσης. Eπιπλέον, βασισμένη στην ίδια απεικονιστική τεχνική με τη χρήση ιόντων, στην παρούσα Διατριβή προτείνεται μια καινοτόμος μέθοδος αυτοσυσχέτισης δεύτερης τάξης και μονής-βολής (single-shot) για τον χαρακτηρισμό υπερβραχέων παλμών με φάσμα συχνοτήτων εντοπισμένο στην περιοχή του μακρού υπεριώδους. Χρησιμοποιώντας απλά αναλυτικά πρότυπα (μοντέλα), καθώς και λεπτομερή υπολογιστικά, πραγματοποιείται μια αποτίμηση όσον αφορά στην επιλογή της βέλτιστης διάταξης και εξετάζονται διάφοροι τρόποι υλοποίησης της μεθόδου. Τέλος, στην Διατριβή αυτή, γίνεται η περιγραφή της γένεσης σύμφωνης ακτινοβολίας μακρού υπεριώδους (ΕUV) ευρέος συνεχούς φάσματος που έχει προκύψει από την αλληλεπίδραση ευγενών αερίων με πολλών-κύκλων υπέρυθρου (IR) παλμού. Ο παλμός αυτός έχει χρονικά διαμορφωμένη ελλειπτικότητα στην πόλωση μέσω της χρήσης μιας συμπαγούς και μονού κλάδου συσκευής “gating” (CMC-PG). Η συσκευή “gating” (CMC-PG) παρέχει τη δυνατότητα διαμόρφωσης ενός πολλών-κύκλων υπέρυθρου (IR) παλμού λέηζερ κατά τρόπον ώστε η γένεση του μακρού υπεριώδους να αναστέλλεται κατά το μεγαλύτερο μέρος της χρονικής διάρκειας του παλμού και να λαμβάνει χώρα μόνο μέσα σε ένα βραχύ χρονικό διάστημα υψηλού ενεργειακού περιεχομένου• την λεγόμενη “πύλη” (gate). Έτσι η γένεση της ακτινοβολίας μακρού υπεριώδους περιορίζεται μέσα σε αυτή την “πύλη” (gate), το εύρος της οποίας εκτιμάται και βρίσκεται πως είναι σε συμφωνία με τους θεωρητικούς υπολογισμούς. Το φασματικό εύρος της παραγόμενης ακτινοβολίας μακρού υπεριώδους είναι ικανό να υποστηρίξει τη δημιουργία μονήρων υπερβραχέων παλμών διάρκειας 200 asec (asec = 10⁻¹⁸ δευτερόλεπτα). Η απλότητα, η σύμπηξη των λειτουργικών μερών της σε μικρό χώρο, η μακράς διάρκειας σταθερότητά της, καθώς και το μεγάλο ενεργειακό περιεχόμενο εντός της “πύλης”, καθιστούν την εν λόγω συσκευή “gating” (CMC-PG) ένα ιδανικό εργαλείο για την παραγωγή μονήρων παλμών με διάρκεια μικρότερη του fsec (fsec = 10⁻¹⁵ δευτερόλεπτα)

Green Zero-Waste Metal Extraction and Recycling from Printed Circuit Boards

The development of a truly circular economy necessitates the recovery and recycling of resources from secondary streams. In this work, we studied the extraction of metals from printed circuit boards (PCBs) using choline chloride: ethylene glycol deep eutectic solvents: Cu, Ni, Zn, and Sn were selectively extracted from the PCBs, with >75% extraction after 72 h for Cu, Ni, and Sn, and circa. 45% extraction for Zn. This solvometallurgical approach promises to minimize the use of water and acid/base reagents in processing. The results show a considerable ability to compete with current methods of metal extraction and therefore generate a strong potential to attain the goal of a sustainable circular economy via zero-waste green urban mining

Green Zero-Waste Metal Extraction and Recycling from Printed Circuit Boards

The development of a truly circular economy necessitates the recovery and recycling of resources from secondary streams. In this work, we studied the extraction of metals from printed circuit boards (PCBs) using choline chloride: ethylene glycol deep eutectic solvents: Cu, Ni, Zn, and Sn were selectively extracted from the PCBs, with >75% extraction after 72 h for Cu, Ni, and Sn, and circa. 45% extraction for Zn. This solvometallurgical approach promises to minimize the use of water and acid/base reagents in processing. The results show a considerable ability to compete with current methods of metal extraction and therefore generate a strong potential to attain the goal of a sustainable circular economy via zero-waste green urban mining

PGM recovery from spent automotive catalysts via pyrometallurgical treatment

95 σ.Στην παρούσα διπλωματική εργασία παρουσιάζεται η δομή και λειτουργία των καταλυτικών μετατροπέων, με τους οποίους είναι εφοδιασμένα όλα τα σύγχρονα οχήματα, οι μηχανισμοί που οδηγούν στην απενεργοποίηση αυτών καθώς και οι τρόποι επεξεργασίας τους μετά το τέλος του κύκλου ζωής τους (αναγέννηση για επανάχρηση ή ανακύκλωση για την ανάκτηση των πολύτιμων μετάλλων της ομάδας της πλατίνας που περιέχονται σε αυτούς). Το πειραματικό μέρος της διπλωματικής αυτής αφιερώνεται στη μελέτη του μηχανισμού ανάκτησης των πολύτιμων μετάλλων της ομάδας της πλατίνας που περιέχονται στους καταλυτικούς μετατροπείς των οχημάτων, με πυρομεταλλουργικές μεθόδους. Στην εργασία διερευνήθηκαν παράγοντες που επηρεάζουν το μηχανισμό ανάκτησης των μετάλλων αυτών. Πιο συγκεκριμένα μελετήθηκε η επίδραση της θερμοκρασίας, του χρόνου παραμονής του φορτίου στη θερμοκρασία που επιλέχθηκε και τέλος η επίδραση της ποσότητας του μετάλλου συλλέκτη (χαλκός) στην ανάκτηση των πολύτιμων μετάλλων σε αυτό. Το θερμοκρασιακό εύρος που μελετήθηκε στην παρούσα εργασία είναι από 1450οC έως 1600οC με βήμα 50οC. Αντίστοιχα, η επίδραση του χρόνου παραμονής του φορτίου στην υψηλή θερμοκρασία εξετάστηκε για χρόνους παραμονής 30, 60 και 120min, ενώ η επίδραση της ποσότητας του μετάλλου συλλέκτη (χαλκός) μελετήθηκε για ποσότητα χαλκού ίση με 10, 15 και 20g, για σταθερή ποσότητα σκόνης καταλύτη 50g. Επιτεύχθηκαν ανακτήσεις των πολύτιμων μετάλλων της ομάδας της πλατίνας στο χαλκό, οι οποίες για την πλατίνα κυμαίνονται από 63,16 έως 89,50%, για το παλλάδιο από 46,80 έως 82,61% και για το ρόδιο από 44,32 έως 82,22%. Αναλυτικότερα, μπορούν να δοθούν τα σημαντικότερα συμπεράσματα που προέκυψαν από την παρούσα ερευνητική εργασία. Αναφορικά με την επίδραση της θερμοκρασίας, παρουσιάζεται μια γραμμική αύξηση των ποσοστών ανάκτησης και για τα τρία μέταλλα συναρτήσει της θερμοκρασίας, με σχεδόν ίδιο ρυθμό. Επίσης, ο χρόνος παραμονής επηρεάζει σε μεγάλο βαθμό το ποσοστό ανάκτησης των πολύτιμων μετάλλων της ομάδας της πλατίνας στο μέταλλο συλλέκτη και μάλιστα φαίνεται να υπάρχει μια σχεδόν γραμμική αύξουσα σχέση μεταξύ των ανακτήσεων των μετάλλων και του χρόνου παραμονής στην θερμοκρασία τήξης, με το ρυθμό αυτής να είναι μικρότερος στην περίπτωση της πλατίνας και σαφώς μεγαλύτερος για τα άλλα δύο πολύτιμα μέταλλα. Τέλος, η αύξηση της ποσότητας του μετάλλου συλλέκτη ευνοεί την ανάκτηση των πολύτιμων μετάλλων της ομάδας της πλατίνας, μέχρι η ποσότητα αυτού να φτάσει στο 16,7% (15g στα 90g του φορτίου), ενώ στη συνέχεια περαιτέρω αύξηση αυτής δεν οδηγεί σε αύξηση των ποσοστών ανάκτησης των πολύτιμων μετάλλων στο χαλκό.This diploma thesis presents the structure and function of modern automotive catalytic converters, the main reasons that lead to their deactivation and the regeneration techniques via both pyrometallurgical and hydrometallurgical treatments. In the present thesis, the research concentrates on the recovery mechanism of the PGMs (Platinum Group Metals) from the catalytic dust via pyrometallurgical treatment. The main three factors examined, which affect the recovery rates are the temperature, the residence time and the amount of mass of the collector metal, which in this case study is copper (Cu). A temperature range from 1450 to 1600οC, along with residence time from 30 to 120min and copper mass from 10 to 20g have been tested in order to get the best possible PGM recovery rates into the copper bullion. The maximum recovery rates achieved in this research for all three PGMs that exist in the automotive catalysts are for platinum (Pt) 89.50%, for palladium (Pd) 82.61% and for rhodium (Rh) 82.22%. Finally the most significant conclusions can be summarised as follows. In first, regarding the effect of the temperature, its increase causes a linear increase in the recovery rates for all three platinum group metals, with nearly the same rate. Also, the residence time greatly affects the recovery rates of the precious metals and eventually there seems to be an almost linear increasing dependence between the recovery rates of the PGMs and the residence time itself. Finally, concerning the amount of mass of the collector metal, it is clear that increasing the amount of mass of the copper up to a maximum of 16,7% (15g to 90g total) favors the recovery of the PGMs, but then further increase of the copper mass does not result in any increase in the recovery rates of the PGMs.Γεώργιος Ι. Κολλιόπουλο

Effect of chemical species and temperature on the stability of air nanobubbles

Abstract The colloidal stability of air nanobubbles (NBs) was studied at different temperatures (0–30 °C) and in the presence of sulfates, typically found in mining effluents, in a wide range of Na2SO4 concentrations (0.001 to 1 M), along with the effect of surfactants (sodium dodecyl sulfate), chloride salts (NaCl), and acid/base reagents at a pH range from 4 to 9. Using a nanobubble generator based on hydrodynamic cavitation, 1.2 × 108 bubbles/mL with a typical radius of 84.66 ± 7.88 nm were generated in deionized water. Multiple evidence is provided to prove their presence in suspension, including the Tyndall effect, dynamic light scattering, and nanoparticle size analysis. Zeta potential measurements revealed that NBs are negatively charged even after two months (from − 19.48 ± 1.89 to − 10.13 ± 1.71 mV), suggesting that their stability is due to the negative charge on their surface. NBs were found to be more stable in alkaline solutions compared to acidic ones. Further, low amounts of both chloride and sulfate dissolved salts led to a reduction of the size of NBs. However, when high amounts of dissolved salts are present, NBs are more likely to coalesce, and their size to be increased. Finally, the investigation of the stability of air NBs at low temperatures revealed a non-monotonic relationship between temperature and NBs upon considering water self-ionization and ion mobility. This research aims to open a new frontier towards the application of the highly innovative NBs technology on the treatment of mining, mineral, and metal processing effluents, which are challenging aqueous solutions containing chloride and sulfate species

Fe–Mn Alloys Electroforming Process Using Choline Chloride Based Deep Eutectic Solvents

Aqueous solvents, despite being effective in the electrodeposition of metals with positive reduction potential, fail to deposit metals with negative reduction potential due to their narrow electrochemical potential window. Deep eutectic solvents (DESs), a class of ionic liquids, are a promising alternative of inexpensive, biodegradable, non-toxic anhydrous solvents that present wide electrochemical potential windows. The present work reports on the potential of choline chloride/ethylene glycol DES in the electrodeposition of Fe–Mn alloys. Cyclic voltammetry tests showed that increasing the quantity of Mn in the bath composition decreases the deposition current of the alloy

Non-aqueous electrodeposition of Fe-Mn alloys using choline chloride based deep eutectic solvents

Deep eutectic solvents (DESs) are green anhydrous solvents that have recently been proposed in sustainable non-aqueous metal electrodeposition processes. The use of DESs over aqueous solutions allows metal electrodeposition without significant side reactions, such as the evolution of hydrogen gas, which is responsible for embrittlement phenomena. In the current work, the electrolytic deposition of Fe-Mn alloys, which present good application in temporary biomedical devices, using DESs was assessed. Three DESs were studied: (a) choline chloride and ethylene glycol (ChCl/EG), (b) choline chloride and glycerol (ChCl/Gly), and (c) choline chloride and urea (ChCl/Urea). The physicochemical properties (viscosity and conductivity) of the three DESs of interest, with and without the presence of dissolved Fe and Mn salts, were thoroughly studied. Cyclic voltammetry analyses showed that the reduction potential of both metals was within the potential window for the three DESs studied, which allowed the successful electrodeposition of Fe-Mn alloys. The deposit obtained from the ChCl/Urea DES presented the highest amount of Mn (49.71 at%). The latter, as well as the fact that the ChCl/Urea based electrolyte showed good stability at T = 80 °C after four electrodeposition cycles, are promising indicators of the potential success of the use of non-aqueous electrodeposition of Fe-Mn alloys using DESs

Self referencing attosecond interferometer with zeptosecond precision

In this work we demonstrate the generation of two intense, ultrafast laser pulses that allow a controlled interferometric measurement of higher harmonic generation pulses with 12.8 attoseconds in resolution (half the atomic unit of time) and a precision as low as 680 zeptoseconds (10−21 seconds). We create two replicas of a driving femtosecond pulse which share the same optical path except at the focus where they converge to two foci. An attosecond pulse train emerges from each focus through the process of high harmonic generation. The two attosecond pulse trains from each focus interfere in the far field producing a clear interference pattern in the extreme ultraviolet region. By controlling the relative optical phase (carrier envelope phase for pulsed fields) between the two driving laser pulses we are able to actively influence the delay between the pulses and are able to perform very stable and precise pump-probe experiments. Because of the phase shaping operation occurs homogeneously across the entire spatial profile, we effectively create two indistinguishable intense laser pulses or a common path interferometer for attosecond pulses. Commonality across the two beams means that they are extremely stable to environmental and mechanical fluctuations up to a Rayleigh range from the focus. In our opinion this represents an ideal source for homodyne and heterodyne spectroscopic measurements with sub-attosecond precision

Synthesis of a Novel Adsorbing Agent by Coupling Chitosan, β-Cyclodextrin, and Cerium Dioxide: Evaluation of Hexavalent Chromium Removal Efficacy from Aqueous Solutions

The present study aimed at synthesizing a novel adsorbing agent by coupling chitosan, β-cyclodextrin, and cerium dioxide (Chit/β-CyD/Ce). Its efficiency towards the removal of hexavalent chromium from aqueous solutions was studied and compared to an adsorbent comprising of only chitosan and cerium dioxide. Batch water purification experiments in varying experimental conditions (initial adsorbent concentration 5–100 mg/L, adsorbate concentration 0.1–2 g/L, pH 2–11, and temperature 15–50 °C) were carried out to evaluate the effectiveness of both adsorbents. In all the experimental cases, the Chit/β-CyD/Ce adsorbent exhibited the higher efficacy. The optimum operating conditions were found to be at an initial adsorbent concentration of 2 g/L, pH = 3, and temperature of 50 °C, with the Chit/β-CyD/Ce adsorbent being able to fully remove Cr(VI) from solutions with up to 50 mg/L Cr(VI) at these conditions. The adsorption of hexavalent chromium onto both adsorbents occurs in a multilayer pattern of a heterogeneous surface following the Freundlich isotherm model. Furthermore, the adsorption process was exothermic and obeyed the pseudo-second-order kinetic model, thus indicating the occurrence of chemisorption. Finally, FTIR, XRD, and SEM analyses were performed to characterize the synthesized adsorbents and verify the adsorption process