Removal of heavy metals from aqueous phases using chemically modified waste Lyocell fiber

Adsorptive separation of Pb(II) and Cu(II) from aqueous solutions using as-prepared carboxymethylated waste Lyocell fiber

“…Although Cu(II) adsorption was supposedly favored, Pb(II) exhibited greater inhibitory effects, especially at higher concentrations, such that it was able to push significant portion of the initially adsorbed Cu(II) back into the solution when the adsorption became very competitive. This phenomenon is consistent with that observed by Sheng et al (2007) in the biosorption of Pb(II), Cu(II), and Cd(II) onto a marine algae, but is not in agreement with the adsorption of same metals using cellulose waste xanthate (CWX) (Bediako et al 2015b), iminodiacetic acid (IDA)-chelating resin , and diethylenetriamine (DETA)-functionalized adsorbent (Liu et al 2008). In the previous study using cellulose waste xanthate (Bediako et al 2015b) and in the studies by Li et al (2011) and Liu et al (2008) using IDA-and DETA-related adsorbents, respectively, Cu(II) selectivity was observed.…”

“…The adsorption isotherm experiments in this study were conducted in single solutions of Cu(II) and Pb(II) at the respective pH values of 4 and 5 and in binary metal solutions at pH 4. These pH conditions were found suitable for effective adsorption of the two metals without precipitations, based on previous studies (Bediako et al 2015b;Ge et al 2014;Li et al 2015;Liu et al 2008). From the present data, the maximum uptakes, affinities, and intensities of adsorption were estimated by fitting the data to the Langmuir, Freundlich, and Redlich-Peterson isotherm models (Table 1).…”

“…This suggests that at the initial lower concentrations there were sufficient binding sites to accommodate greater portions of the metal ions, but these sites got saturated with increase in metal concentrations so that no more metal ions could be attached at the higher concentrations. Adsorption studies in the binary metal systems were conducted at pH 4 in order to prevent precipitation, specifically copper (Bediako et al 2015b). Adsorption at lower concentrations appeared very competitive compared with those at higher concentrations where Pb(II) selectivity was observed.…”

Potencial da casca da laranja como biossorvente alternativo para remoção de metais pesados em águas residuais

“…A adsorção é um processo que ocorre quando uma substância (adsorvato), presente em um líquido ou gás, permanece retida sobre a superfície de um sólido (adsorvente), em virtude de interações intermoleculares, eletrostáticas, dipolares, de Van der Waals, ou de um conjunto destas (LAKHERWAL, 2014;BEDIAKO et al, 2015;GHORBEL-ABID;TRABELSI-AYADI, 2015). Essas interações dependem da natureza das espécies envolvidas, podem ocorrer de forma isolada ou simultânea, de modo que quanto mais fortes forem as interações mais efetivo será o processo de adsorção (GHORBEL-ABID; TRABELSI-AYADI, 2015; ANASTOPOULOS; KYZAS, 2015;BEDIAKO et al, 2015).…”

“…Essas interações dependem da natureza das espécies envolvidas, podem ocorrer de forma isolada ou simultânea, de modo que quanto mais fortes forem as interações mais efetivo será o processo de adsorção (GHORBEL-ABID; TRABELSI-AYADI, 2015; ANASTOPOULOS; KYZAS, 2015;BEDIAKO et al, 2015). O avanço nas pesquisas com materiais adsortivos permite que a adsorção de metais possa se dá por diferentes vias, a exemplo da troca iônica, interação ácido-base, polarização de eletrônica, forças de dispersão, etc.…”