Résumé

<p>Adsorption &nbsp; of &nbsp; Methylene &nbsp; Blue &nbsp;(MB), &nbsp; Bromocresol &nbsp; Green &nbsp;(BG) &nbsp; and &nbsp; Methyl &nbsp; Red &nbsp;(MR) &nbsp;were &nbsp; carried &nbsp;out &nbsp;in &nbsp;batch &nbsp;on &nbsp;a &nbsp;low &nbsp;cost &nbsp;treated &nbsp;adsorbent, &nbsp;Bryophyllum &nbsp;pinnatum &nbsp;(Lam.) &nbsp;Kurz stem &nbsp; powder &nbsp;(BPP) &nbsp;and &nbsp;its &nbsp;activated &nbsp;carbon &nbsp;(ACBP). &nbsp;Adsorption &nbsp;capacities &nbsp;of &nbsp;the &nbsp;two &nbsp;adsorbents &nbsp; were &nbsp; compared &nbsp; to &nbsp; that &nbsp; of &nbsp; commercial &nbsp; activated &nbsp; carbon &nbsp;(CAC) &nbsp; and &nbsp;were &nbsp; also &nbsp; evaluated &nbsp; as &nbsp; function &nbsp;of &nbsp;pH &nbsp;and &nbsp;dose &nbsp;of &nbsp;adsorbent. &nbsp;Freundlich &nbsp;and &nbsp;Langmuir &nbsp;isotherms &nbsp;models &nbsp;were &nbsp;used &nbsp; to &nbsp; test &nbsp; the &nbsp; equilibrium &nbsp; data &nbsp; which &nbsp; were &nbsp; best &nbsp; represented &nbsp; with &nbsp; maximum &nbsp; monolayer &nbsp; adsorptions &nbsp;capacities &nbsp;of &nbsp;255.754 &nbsp;(pH &nbsp;11.15), &nbsp;253.807 &nbsp;(pH &nbsp;3.35) &nbsp;and &nbsp;195.313 &nbsp;mg.g-­‐1 (pH &nbsp;3.25) &nbsp;for &nbsp; MB, &nbsp;MR &nbsp;and &nbsp;BG &nbsp;respectively &nbsp;on &nbsp;ACBP. &nbsp;On &nbsp;CAC &nbsp;their &nbsp;capacities &nbsp;were &nbsp;respectively &nbsp;176.367 &nbsp;(pH &nbsp; 11.15), &nbsp;342.466 &nbsp;(pH &nbsp;3.35) &nbsp;and &nbsp;108.342 &nbsp;mg.g-­‐1 &nbsp;(pH &nbsp;3.25) &nbsp;for &nbsp;MB, &nbsp;MR &nbsp;and &nbsp;BG; &nbsp;whereas, &nbsp;on &nbsp;BPP &nbsp;the &nbsp; adsorption &nbsp;capacities &nbsp;were &nbsp;respectively &nbsp;61.013 &nbsp;(pH &nbsp;11.15), &nbsp;165.289 &nbsp;(pH &nbsp;3.35) &nbsp;and &nbsp;51.733 &nbsp;mg.g-­‐1 &nbsp; (pH &nbsp;3.25) &nbsp;for &nbsp;MB, &nbsp;MR &nbsp;and &nbsp;BG. &nbsp;The &nbsp;linear &nbsp;correlation &nbsp;coefficient &nbsp;R2 was &nbsp;used &nbsp;to &nbsp;elucidate &nbsp;the &nbsp; best &nbsp; fitting &nbsp; isotherm &nbsp;model &nbsp;(R2 ≈ 0.98). &nbsp; The &nbsp; separation &nbsp; factor &nbsp;RL values &nbsp;between &nbsp;0.03 &nbsp; and &nbsp; 0.95 &nbsp;indicate &nbsp;a &nbsp;favorable &nbsp;adsorption. &nbsp;The &nbsp;adsorption &nbsp;kinetics &nbsp;showed &nbsp;that &nbsp;this &nbsp;process &nbsp;could &nbsp; be &nbsp;well &nbsp;described &nbsp;with &nbsp;the &nbsp;pseudo-­‐second &nbsp;order &nbsp;model. &nbsp;The &nbsp;results &nbsp;have &nbsp;shown &nbsp;that, &nbsp;ACBP &nbsp; has &nbsp; excellent &nbsp; adsorption &nbsp; capacity &nbsp; compared &nbsp; to &nbsp; the &nbsp; values &nbsp; of &nbsp; BPP &nbsp; or &nbsp; with &nbsp; CAC. &nbsp; The &nbsp; equilibrium &nbsp; data &nbsp; were &nbsp; best &nbsp; represented &nbsp; by &nbsp; the &nbsp; used &nbsp; isotherms &nbsp; models &nbsp; of &nbsp; Langmuir &nbsp; and &nbsp; Freundlich.&nbsp;<br>&nbsp;</p>