Valorisation of Waste Wood Biomass as Biosorbent for Congo Red Removal

Abstract

Obojene otpadne vode koje sadrže sintetska bojila predstavljaju veliki ekološki problem, zbog kemijske stabilnosti bojila i otpornosti na biorazgradnju. Adsorpcija je jedna od najčešće korištenih i najučinkovitijih metoda za uklanjanje bojila iz otpadnih voda. Cilj ovoga rada bio je ispitati šest biosorbensa za uklanjanje kongo crvenila (CR) iz vodenih otopina adsorpcijom. Kao biosorbensi korišteni su lignocelulozni otpadni materijali drvne industrije (piljevine jele, ariša, smreke, euroameričke topole, bukve, hrasta lužnjaka, graba i duglazije). Pri tome se koristila nepromjenjiva koncentracija biosorbensa od 10 g/L, koncentracija adsorbata bila je 50 mg/L bez podešavanja pH, temperatura 25 °C i vrijeme adsorpcije od 3 do 360 minuta. Najveći postotak uklanjanja bojila nakon 360 minuta postignut je upotrebom jele i euroameričke topole koje su se pokazale najpogodnije za daljnja istraživanja. Serije šaržnih adsorpcijskih eksperimenata su provedene s ciljem ispitivanja utjecaja početne koncentracije bojila (10, 30, 50 i 100 mg/L), pH vrijednosti (4-9) te koncentracije biosorbensa (1-10 g/L) na uklanjanje bojila pri 25 °C. Najveći postotak uklanjanja od 74 % i 42 % postignute su za piljevine euroameričke topole i jele, pri čemu su adsorpcijski kapaciteti iznosili 8,48 i 5,04 mg/g. Rezultati pokazuju kako se piljevine jele i euroameričke topole mogu koristiti kao potencijalni biosorbensi za uklanjanje kongo crvenila iz vodenih otopina.Coloured wastewater that contain synthetic dyes present a huge ecological problem, because of the chemical stability of a dye and their resistance to biodegradation. Adsorption is one of the most frequently used and most effective method for dye removal from wastewater. The main goal of this work was evaluate six bioadsorbents for the removal of Congo red (CR) from aqueous solutions by adsorption. As bioadsorbents lignocellulose waste materials from the wood industry were used (sawdust of fir, larch, spruce, poplar, beech, lucerne oak, hornbeam and douglas fir). In batch experiments 10 g/L of adsorbent was used, while the concentration of CR was 50 mg/L without pH adjustment at temperature 25 °C and contact time from 30 to 360 minutes. The highest dye removal percentage was achieved after 360 minutes by using fir and poplar sawdusts, which proved to be the most suitable adsorbents for further research. Batch adsorption experiments were conducted to investigate the effect of initial CR concentration (10, 30, 50, and 100 mg/L), pH (4-9) and bioadsorbent concentration (1-10 g/L) on dye removal at 25 °C. Maximum removal efficiencies of 74% and 42% and experimentally obtained adsorption capacities of 8.48 and 5.04 mg/g were achieved for poplar fir, respectively. The results show that sawdust of fir and poplar can be used as potential bioadsorbents for Congo red removal from aqueous solutions