Erratum to: Upgrading fuel potentials of waste biomass via hydrothermal carbonization (Hem. Ind. 75 (5) 297–305 (2021))

This article has been published under the category Technical paper instead of Original scientific paper by mistake made by the Editorial Office of the journal Hemijska industrija during the proofreading process. Apologies are offered to authors and readers of the journal Hemijska industrija.Related to published version: [https://vinar.vin.bg.ac.rs/handle/123456789/10170

Optimization of material quality obtained by hydrothermal carbonization and its application in the adsorption of heavy metals from aqueous solutions

Predmet istraživanja ove doktorske disertacije je optimizacija kvaliteta materijala dobijenog hidrotermalnom karbonizacijom (HTC) iskorišćenog supstrata gljiva Agaricus bisporus (eng. Spent Mushroom Supstrate - SMS) i ispitivanje primene dobijenih hidročađi supstrata (HC) kao adsorbenta jona Pb2+ i Cd2+ iz vodenih rastvora. Ispitivan je uticaj procesne temperature na fizičko-hemijske, strukturne i gorivne karakteristike SMS-a i HC dobijenih na 180, 200, 220, 240 i 260 °C (HC-180, HC-200, HC-220, HC-240 i HC- 260). Zaključeno je da je hidrotermalni proces pozitivno uticao na gorivne karakteristike HC, što je vidljivo kroz povećanje vezanog ugljenika, gornje toplotne moći i energetske gustine, kao i kroz smanjenje sadržaja isparljivih materija u odnosu na sirovu biomasu. Strukturne i morfološke karakteristike ispitivanih materijala su određene korišćenjem skenirajućeg elektronskog mikroskopa (SEM) i tehnikom infracrvene spektroskopije sa Furijeovom transformacijom (FTIR). SEM analiza je pokazala formiranje mikrosfera i pukotina na površini HC, dok je FTIR spektroskopijom utvrđeno dominantno prisustvo aromatičnih i kiseoničnih funkcionalnih grupa (KFG). Termičko ponašanje ispitivanih materijala je procenjeno na osnovu termogravimetrijske i diferencijalne termičke (TGA/DTA) analize. Određeni su kinetički i termodinamički parametri korišćenjem model-free metoda: Flynn-Wall-Ozawa (FWO) i Kissinger-Akahira-Sunose (KAS). Metodama termičke analize je potvrđeno da je HTC perspektivan tretman konverzije SMS-a u visoko-energetski ugljenični materijal. Ispitana je mogućnost primene HC kao sorbenta jona Pb2+ i Cd2+ iz vodenih rastvora. Kako bi se izvršio odabir optimalne HC koja će se koristi kao sorbent ispitivanih teških metala, izvršen je preliminarni adsorpcioni test, radi utvrđivanja adsorpcionih kapaciteta korišćenih ugljeničnih materijala. HC-200 je pokazao najbolje performanse za uklanjanje ovih metala, čiji je sorpcioni kapacitet za jone Pb2+ i Cd2+ iznosio 98 mg g–1, odnosno 41 mg g–1. Kako bi se dodatno poboljšao kapacitet adsorpcije HC-200, izvršena je njegova fizičko-hemijska aktivacija. Prvo je uzorak tretiran 20% rastvorom CaCl2·5H2O, a zatim je fizički aktiviran procesom pirolize na 500 °C, pri čemu je sintetisan nov ugljenični materijal nazvan Kalcijum-piro-hidročađ (Ca-PHC). Detaljna karakterizacija odabrane hidročađi pre i posle modifikacije izvršena je SEM analizom, Brunauer-Emmett-Teller (BET) analizom specifične površine i poroznosti, i FTIR spektroskopijom, a zatim su ispitane njihove adsorpcione performanse. Ca-PHC je pokazao znatno bolju sposobnost da uklanja jone Pb2+ i Cd2+ iz vodenog rastvora u poređenju sa HC, pa je stoga dalje korišćen za detaljnije ispitivanje adsorpcionih procesa. Adsorpcioni eksperimenti uklanjanja jona Pb2+ i Cd2+ su urađeni u šaržnom sistemu, kako bi se izvršila optimizacija radnih parametara: pH, mase adsorbenta, početne koncentracije jona metala, vreme kontakta i temperature. Maksimalni sorpcioni kapaciteti Ca-PHC za jone Pb2+ i Cd2+ iznosili su 297 mg g–1, odnosno 131 mg g–1. Pokazano je da se proces sorpcije može opisati Frojndlihovom izotermom i da prati kinetički model pseudo-drugog reda. Termodinamički parametri pokazali su da je vezivanje jona metala za sorbent spontan i endoterman proces. Na osnovu dobijenih rezultata utvrđeno je da se joni metala vezuju za površinu sorbenta mehanizmom jonske izmene, površinskom kompleksacijom i katjon-π interakcijom. Prikazani rezultati sugerišu da HTC kao ekološki prihvatljiva tehnologija može biti dobro rešenje za konverziju vlažne otpadne biomase u visoko-energetske materijale. Pored toga, dobijene HC su pokazale dobre adsorpcione performanse, a kapacitet adsorpcije im je dodatno poboljšan fizičko-hemijskom aktivacijom. Na osnovu predstavljenog, može se zaključiti da je novosintetisani ugljenični materijal, Ca-PHC, iz iskorišćenog supstrata gljiva visoko efikasan biosorbent Pb2+ i Cd2+ jona iz vodenih rastvora, čijom se upotrebom na taj način može doprineti cirkularnoj ekonomiji i minimiziranju otpada u rastućoj industriji pečuraka.The subject of research of this doctoral dissertation is the optimization of the material quality obtained by hydrothermal carbonization (HTC) of the spent mushroom substrate (SMS) of Agaricus bisporus and the examination of application of the obtained hydrochar (HC) as an adsorbent of Pb2+ and Cd2+ ions from aqueous solutions. The influence of process temperature on the physicochemical, structural and fuel characteristics of the SMS and HC obtained at 180, 200, 220, 240 and 260 °C (HC-180, HC- 200, HC-220, HC-240 and HC-260) was investigated. The hydrothermal process had a positive effect on the fuel characteristics of the HC, which was visible through the increase of the fixed carbon, higher heating value and energy densification, as well as the reduction of volatile matter in relation to the raw biomass. Structural and morphological characteristics of SMS and HC were determined using SEM and FTIR analysis. SEM analysis showed the formation of microspheres and cracks on the surface of the chars, while FTIR spectra confirmed the dominant presence of the aromatics and oxygen-rich functional groups. The thermal behavior of the tested material was assessed using the thermogravimetric and differential thermal (TGA/DTA) analysis. The kinetic and thermodynamic parameters were determined using the model-ree methods: Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS). The methods of thermal analysis have confirmed that HTC is a promising treatment for the conversion of SMS to high-energy carbon material. The possibility of using HC as a sorbent of Pb2+ and Cd2+ ions from aqueous solutions was investigated. In order to select the optimal HC to be used as a sorbent of the invastigated heavy metals, a preliminary adsorption test was performed to determine the adsorption capacities of the carbon materials used. The HC-200 showed the best performance for the removal of these metals, whose sorption capacities for Pb2+ and Cd2+ ions were 98 mg g–1 and 41 mg g–1, respectively. In order to improve the adsorption capacity of the selected chars, the physicochemical activation was performed. The HC-200 was first treated with a 20% solution of CaCl2·5H2O, and then physically activated by pyrolysis at 500 °C. The obtained material was labeled as Calcium-pyro-hydrochar (Ca-PHC). The characterization of selected hydrochar before and after modification by SEM, BET and FTIR analysis was performed, and then their adsorption performance was examined. The Ca-PHC showed a significantly better ability to remove Pb2+ and Cd2+ ions from aqueous solutions, and therefore it was further used to investigate the adsorption process. Adsorption experiments of Pb2+ and Cd2+ ions were performed in the batch system, to optimize the following operating parameters: pH, adsorbent mass, initial metal ion concentration, contact time and temperature. The maximum sorption capacities of Ca-PHC for Pb2+ and Cd2+ ions were 297 mg g–1 and 131 mg g–1, respectively. Based on the obtained results, it was shown that the sorption process can be described by the Freundlich isotherm and followed a pseudo- other kinetic model. Thermodynamic parameters showed that the binding of metal ions to the sorbent was a spontaneous and endothermic process. The results obtained by examining the kinetics of the process and the mechanism of ion exchange, and the characterization of Ca-PHC found that metal ions bind to the sorbent surface by ion-exchange mechanism, surface complexation, mineral deposition and cation-π interaction. The presented results suggest that HTC as an environmentally friendly technology may be the good solution for the conversion of wet biomass into high-energy material. In addition, the obtained HCs showed satisfying adsorption performance and and its adsorption capacity was further improved by physicochemical activation. Based on the above, it can be concluced that the newly synthesized carbon material, Ca-PHC, from the SMS is a highly efficient biosorbent of Pb2+ and Cd2+ ions from aqueous solutions, whose use may contribute the circular economy and waste minimization in the growing mushroom industry

Upgrading fuel potentials of waste biomass via hydrothermal carbonization

In recent decades, massive exploitation of fossil fuels caused a growing demand for the production of energies from renewable sources. Hydrochar obtained from waste biomass via hydrothermal carbonization (HTC) possesses good potentials as a biofuel. Therefore, we performed HTC of corn cob, paulownia leaves, and olive pomace at different temperatures (180, 220, and 260oC). The main goal of this study was to comparatively evaluate the influence of HTC conditions on the structure and fuel characteristics of the obtained solids. The results showed that the yields of hydrochar decrease significantly with increasing temperature in all samples. The carbon content and higher heating value increased and reached the highest values in hydrochars obtained at 260°C, while the content of volatile matter decreased. Furthermore, the Van Krevelen diagram reveals that the transformation of feedstock to lignite-like products upon HTC was achieved. In this study, the results showed that processes of dehydration and decarboxylation during HTC provoke intensive biomass transformation and that hydrochars obtained at higher temperatures have significantly enhanced fuel properties and fewer volatiles compared to the feedstock.Link to erratum: [https://vinar.vin.bg.ac.rs/handle/123456789/10171

AggLb Is the Largest Cell-Aggregation Factor from Lactobacillus paracasei Subsp paracasei BGNJ1-64, Functions in Collagen Adhesion, and Pathogen Exclusion In Vitro

Eleven Lactobacillus strains with strong aggregation abilities were selected from a laboratory collection. In two of the strains, genes associated with aggregation capability were plasmid located and found to strongly correlate with collagen binding. The gene encoding the auto-aggregation-promoting protein (AggLb) of Lactobacillus paracasei subsp. paracasei BGNJ1-64 was cloned using a novel, wide-range-host shuttle cloning vector, pAZILSJ. The clone pALb35, containing a 11377-bp DNA fragment, was selected from the SacI plasmid library for its ability to provide carriers with the aggregation phenotype. The complete fragment was sequenced and four potential ORFs were detected, including the aggLb gene and three surrounding transposase genes. AggLb is the largest known cell-surface protein in lactobacilli, consisting of 2998 aa (318,611 Da). AggLb belongs to the collagen-binding superfamily and its C-terminal region contains 20 successive repeats that are identical even at the nucleotide level. Deletion of aggLb causes a loss of the capacity to form cell aggregates, whereas overexpression increases cellular aggregation, hydrophobicity and collagen-binding potential. PCR screening performed with three sets of primers based on the aggLb gene of BGNJ1-64 enabled detection of the same type of aggLb gene in five of eleven selected aggregation-positive Lactobacillus strains. Heterologous expression of aggLb confirmed the crucial role of the AggLb protein in cell aggregation and specific collagen binding, indicating that AggLb has a useful probiotic function in effective colonization of host tissue and prevention of pathogen colonization

Photochemical and Thermal Transformations of Thiophene o-Distyrylbenzene Analogues in Acidic Media

Intramolecular photochemical reactions of thiophene analogues of o-distyrylbenzene, 2,2'-(o-phenylenedivinylene)dithiophenes (1a,b), 3,3'-(o-phenylenedivinylene)dithiophene (2a) and 3,3'-(o-phenylenedivinylene)dibenzothiophene (2b), were studied in acidic media at low concentrations. A 1,6- and 1,5-ring closure of hexatriene system leading to dihydronaphthalene or indene derivatives, respectively, was observed

Expression of bacteriocin LsbB is dependent on a transcription terminator

The production of LsbB, leaderless class II bacteriocin, is encoded by genes (lsbB and lmrB) located on plasmid pMN5 in Lactococcus lactis BGMN1-5. Heterologous expression of the lsbB gene using the pAZIL vector (pAZIL-lsbB) in L. lactis subsp. cremoris MG7284 resulted in a significant reduction (more than 30 times) of bacteriocin LsbB expression. Subcloning and deletion experiments with plasmid pMN5 revealed that full expression of LsbB requires the presence of a complete transcription terminator located downstream of the lsbB gene. RNA stability analysis revealed that the presence of a transcription terminator increased the RNA stability by three times and the expression of LsbB by 30 times. The study of the influence of transcription terminator on the expression of other bacteriocin genes (lcnB, for lactococcin B production) indicated that this translational terminator likely functions in a lsbB-specific manner rather than in a general manner

Expression of bacteriocin LsbB is dependent on a transcription terminator

The production of LsbB, leaderless class II bacteriocin, is encoded by genes (lsbB and lmrB) located on plasmid pMN5 in Lactococcus lactis BGMN1-5. Heterologous expression of the lsbB gene using the pAZIL vector (pAZIL-lsbB) in L. lactis subsp. cremoris MG7284 resulted in a significant reduction (more than 30 times) of bacteriocin LsbB expression. Subcloning and deletion experiments with plasmid pMN5 revealed that full expression of LsbB requires the presence of a complete transcription terminator located downstream of the lsbB gene. RNA stability analysis revealed that the presence of a transcription terminator increased the RNA stability by three times and the expression of LsbB by 30 times. The study of the influence of transcription terminator on the expression of other bacteriocin genes (lcnB, for lactococcin B production) indicated that this translational terminator likely functions in a lsbB-specific manner rather than in a general manner

Prednosti i nedostatci sadašnjeg ustroja školske medicine (Advantages and Shortcomings of The New School Medicine Structure)

Početkom siječnja 1998. godine školska medicina u Hrvatskoj postala je isključivo preventivna djelatnost. Provode je specijalisti školske medicine u zavodima za javno zdravstvo.Š kolska medicina i u nas i u svijetu ima dugu tradiciju.  Od svojih početaka sredinom 19. stoljeća razvijala se kao preventivna djelatnost usmjerena pretežno problemima organske etiologije dominirajućim u pobolu školske djece (tuberkuloza, zarazne bolesti, slaba uhranjenost). Prvi školski liječnici su imenovani u Š vedskoj 1840. godine, a kao zasebna djelatnost školska medicina se zatim razvijala u mnogim europskim zemljama (1).  Nastali su znanstveni temelji školske higijene, istražuju se čimbenici koji u školi utječu na zdravlje učenika i razrađuju metode za uklanjanje čimbenika koji nepovoljno utječu na njihov rast i razvoj. Prosvjetne i upravne vlasti preuzimaju zadaće uređenja školskih prostora i učila prema higijenskim   postavkama, prilagođavanjem programa i opterećenja prema fiziološkim mogućnostima učenika te uvođenjem tjelesnog odgoja. Ističe se potreba redovitog liječničkog nadzora nad zdravstvenim stanjem učenika i uvjetima rada u školi. Ovi zahtjevi šire dotadašnju koncepciju zaštite zdravlja učenika, koja je bila ograničena na sanitarno-higijenski nadzor i provođenje protuepidemijskih mjera, kako bi se djecu sačuvalo od zaraznih bolesti i spriječilo širenje epidemija putem škola. Pojedini gradovi razvijaju sedamdesetih godina sistematski nadzor nad zdravljem učenika (Paris, Bruxelles, Wisbaden…) osnivanjem posebnih službi školskih liječnika s programima praćenja zdravstvenog stanja učenika koji uključuju: redovite preglede, rano otkrivanje bolesti i praćenje odvijanja nastave, posebice tjelesnog odgoja. Za siromašnu i zdravstveno ugroženu djecu osnivaju se školske kuhinje i oporavilišta, a za djecu s posebnim potrebama specijalne ustanove. Početkom dvadesetog stoljeća organiziraju se (Š vicarska, Engleska, Francuska,) školske poliklinike sa zubnim i specijalističkim ambulantama

Prednosti i nedostatci sadašnjeg ustroja školske medicine (Advantages and Shortcomings of The New School Medicine Structure)

Početkom siječnja 1998. godine školska medicina u Hrvatskoj postala je isključivo preventivna djelatnost. Provode je specijalisti školske medicine u zavodima za javno zdravstvo.Š kolska medicina i u nas i u svijetu ima dugu tradiciju.  Od svojih početaka sredinom 19. stoljeća razvijala se kao preventivna djelatnost usmjerena pretežno problemima organske etiologije dominirajućim u pobolu školske djece (tuberkuloza, zarazne bolesti, slaba uhranjenost). Prvi školski liječnici su imenovani u Š vedskoj 1840. godine, a kao zasebna djelatnost školska medicina se zatim razvijala u mnogim europskim zemljama (1).  Nastali su znanstveni temelji školske higijene, istražuju se čimbenici koji u školi utječu na zdravlje učenika i razrađuju metode za uklanjanje čimbenika koji nepovoljno utječu na njihov rast i razvoj. Prosvjetne i upravne vlasti preuzimaju zadaće uređenja školskih prostora i učila prema higijenskim   postavkama, prilagođavanjem programa i opterećenja prema fiziološkim mogućnostima učenika te uvođenjem tjelesnog odgoja. Ističe se potreba redovitog liječničkog nadzora nad zdravstvenim stanjem učenika i uvjetima rada u školi. Ovi zahtjevi šire dotadašnju koncepciju zaštite zdravlja učenika, koja je bila ograničena na sanitarno-higijenski nadzor i provođenje protuepidemijskih mjera, kako bi se djecu sačuvalo od zaraznih bolesti i spriječilo širenje epidemija putem škola. Pojedini gradovi razvijaju sedamdesetih godina sistematski nadzor nad zdravljem učenika (Paris, Bruxelles, Wisbaden…) osnivanjem posebnih službi školskih liječnika s programima praćenja zdravstvenog stanja učenika koji uključuju: redovite preglede, rano otkrivanje bolesti i praćenje odvijanja nastave, posebice tjelesnog odgoja. Za siromašnu i zdravstveno ugroženu djecu osnivaju se školske kuhinje i oporavilišta, a za djecu s posebnim potrebama specijalne ustanove. Početkom dvadesetog stoljeća organiziraju se (Š vicarska, Engleska, Francuska,) školske poliklinike sa zubnim i specijalističkim ambulantama

Efficient synthesis and detailed thermal studies of zinc phthalocyanine

A facile and efficient, one step synthesis of macrocyclic molecule zinc phthalocyanine (ZnPc), was proposed. Dark violet crystals of ZnPc dye were obtained in high boiling point solvent of dimethylformamide (DMF) in the presence of 2,2,6,6-tetramethylpiperidine (TMP) as a catalyst. Detailed thermogravimetric and kinetic analysis revealed high thermal stability of the investigated compound