Uklanjanje metala iz vode primenom stabilisanog i „zelenom“ sintezom produkovanog nano gvožđa (0)

Abstract

Predmet izučavanja ove disertacije je ispitivanje mogućnosti primene stabilisanog nano Fe(0) i „zelenom“ sintezom produkovanog nano Fe(0) u uklanjanju Cr(VI), Cd(II), Cu(II), Ni(II), Pb(II) i As(III) iz vode. Sinteza nano Fe(0) za stabilizaciju izvršena je konvencionalnom metodom redukcije gvožđa sa natrijum borhidridom u prisustvu materijala za stabilizaciju: kaolinita, bentonita i karboksimetil celuloze. Za „zelenu” sintezu nano Fe(0) korišćeno je lišće drveća: hrasta, duda i višnje. Karakterizacija dobijenih nanomaterijala izvršena je transmisionom i skenirajućom elektronskom mikroskopijom. Rezultati karakterizacije su pokazali da se tokom sinteze nano Fe(0) natrijum borhidridom i stabilizacije kaolinitom, bentonitom i karboksimetil celulozom, formiraju nano čestice Fe(0) veličine 20 do 90 nm, dok su veličine čestica nano Fe(0) sintetisanih „zelenom“ metodom iznosile 10-30 nm i okarakterisane su kao nano čestice sfernog oblika, različitih veličina bez značajane aglomeracije. Primena nano Fe(0) na efikasnost uklanjanja metala iz vode ispitivana je pri različitim uslovima: uticaju doze nanomaterijala, početne koncentracije metala, pH vrednosti rastvora i kontaktnog vremena. Dobijeni rezultati prilikom ispitivanja uticaja doze nanomaterijala na efikasnosti uklanjanja odabranih metala iz vode primenom stabilisanih i „zelenih“ nanomaterijala pokazali su da se povećanjem doze nanomaterijala povećava efikasnost uklanjanja. Prilikom primene stabilisanih nanomaterijala, koncentracije 14.00 gFe(0)/l, postignute su visoke efikasnosti uklanjanja, već pri dozama od 2 ml, dok je efikasnost uklanjanja primenom „zelenih“ nanomaterijala koncentracije 1,395 gFe(0)/l bila niža. Prilikom ispitivanja uticaja pH vrednosti na uklanjanje metala iz vode primenom ispitivanih nanomaterijala, određeni su optimalni opsezi pH vrednosti pri kojima se postiže najveća adsorpcija metala na ispitivanim nanomaterijalima. Veza između metala i ispitivanih nanomaterijala objašnjena je modelovanjem Langmuir-ove i Freunlich-ove adsorpcione izoterme. Veće adsorpcione kapacitete prilikom adsorpcije svih ispitivanih metala pokazali su nanomaterijali produkovani „zelenom“ sintezom u odnosu na stabilisane nanomaterijale, što je povezano sa veličinom čestica, tj. manje nanočestice nanomaterijala produkovanih „zelenom” sintezom imaju veću specifičnu površinu i samim tim mogu ponuditi više reaktivnih mesta, veću reaktivnost i bolju disperziju. Ispitivanje kinetike adsorcije Cr(VI), Cd(II), Cu(II), Ni(II), Pb(II) i As(III) na ispitivanim stabilisanim i „zelenom“ sintezom produkovanim nanomaterijalima pokazalo je veoma brzu reakciju adsorpcije metala na ispitivanim nanomaterijalima i bolje slaganje eksperimentalno dobijenih podataka sa pseudo-drugim kinetičkim modelom. Rezultati dobijeni u ovom istraživanju omogućiće procenu primene nano Fe(0) za uklanjanje metala iz vode, posebno adsorpciju metala iz vode kao i odabir najefikasnijeg i najekonomičnijeg adsorbensa za uklanjanje različitih metala iz vode.

This work is concerned with exploring the possibility of application of stabilized nano Fe(0) and nano Fe (0) produced by “green” synthesis in the removal of Cr(VI), Cd(II), Cu(II), Ni(II), Pb(II) and As(III) from the water. Synthesis of nano Fe(0) for the stabilization is carried out according to conventional method of iron reduction with sodium borohydride in the presence of a material for stabilization: kaolinite, bentonite and carboxymethyl cellulose. Leaves of oak, mulberry and cherry trees used for “green” synthesis of nano Fe(0). Characterization of nanomaterials was performed by transmission and scanning electron microscopy. The characterization results have shown that during the synthesis and stabilization of nano Fe (0) process formed nanoparticles with size from 20 to 90 nm, while the nano Fe (0) particles synthesized by "green" method were within the size of 10-30 nm and characterized as spherical nanoparticles with various sizes without significant agglomeration. Application of nano Fe (0) on the removal efficiency of metals from water was studied under different conditions: the influence of nanomaterials dose, the initial metal concentrations, pH value of the solution and the contact time. The results obtained during the examination of the impact of nanomaterial dose on the removal efficiency of selected metals from water have shown that increasing of nanomaterial dose increases removal efficiency. High removal efficiency is achieved when used 2 ml of stabilized nanomaterials, concentration of 14.00 gFe(0)/L, while when "green" nanomaterials, concentration of 1,395 gFe(0)/L, were used the removal efficiency was lower. The optimal ranges of pH values at which the tested nanomaterials reach the maximum adsorption of metals were obtained, during the examination of the influence of pH value on removal of metals from water by using the tested nanomaterials The relation between the metals and tested nanomaterials is explained by modeling of Langmuir's and Freunlich's adsorption isotherm. Nanomaterials produced by "green" synthesis showed higher adsorption capacity than stabilized nanomaterials, which is related with particle size, i.e. the nanoparticles produced by "green" synthesis have less particles, higher specific surface area and therefore can offer more reactive sites, greater reactivity and better dispersion. Kinetics tests showed a very fast adsorption of metal on the tested nanomaterials and better agreement with the experimental data to second pseudo-kinetic model. The results obtained in this study will enable the assessment of the application of nano Fe (0) for the removal of metals from water, especially for the adsorption of metals from water as well as the selection of the most efficient and most economical of the adsorbent for the removal of various metals from water.