Ammonium-functionalized mesoporous silica MCM-41 for phosphate removal from aqueous solutions. Issue 23 (14th May 2016)

• Record Type: Journal Article
• Authors: Kang, Jin-Kyu; Kim, Jae-Hyun; Kim, Song-Bae; Lee, Sang-Hyup; Choi, Jae-Woo; Lee, Chang-Gu
• Is Part Of: Desalination and water treatment. Volume 57:Issue 23(2016)
• Page Start: 10839
• Page End: 10849
• Publication Date: 2016-05-14
• Subjects: Mesoporous silica -- MCM-41 -- Phosphate -- Sorption -- Surface functionalization; Saline water conversion -- Periodicals; Saline water conversion; Water -- Purification; Periodicals; 628.167
• DOI: 10.1080/19443994.2015.1038590
• Languages: English
• ISSNs: 1944-3994

Abstract

Abstract: The aim of this study was to investigate the removal of phosphate (P) using ammonium-functionalized MCM-41 (A-MCM-41). Batch experiments were performed with A-MCM-41 under various conditions including the adsorbent dose, reaction time, initial P concentration, and solution pH. The results showed that the phosphate removal in the MCM-41 (initial P conc. = 2 mgP L − 1 ) was negligible with the percent removal of ≤1.0% at the adsorbent dosages between 0.5 and 2.0 g L − 1 . In the case of A-MCM-41, the percent removal increased from 73.6 to 100% as the adsorbent dose increased from 0.5 to 2.0 g L − 1 . This indicated an enhancement of the phosphate removal due to the surface modification of the MCM-41 through the functionalization of the ammonium group (NH3 + ). The results also demonstrated that the phosphate removal by the MCM-41 was minimal throughout the acidic and alkaline pH conditions (3.1% at pH 3.5; ≤1.0% at pH 5.4–10.7), whereas the phosphate removal by the A-MCM-41 was effective throughout the acidic and neutral pH values (94.7–97.6% at pH 3.5–7.4). In highly alkaline conditions, however, the phosphate removal by the A-MCM-41 was greatly reduced (3.4% at pH 10.7) due to the competition of the hydroxyl groups (OH − ) with phosphate ions for sorption sites. The results indicated that the pseudo-second-order model was most suitable for describing the kinetic data with the parameter values of q e = 1.86 mgP g − 1 and k 2 = 183.98 g mgP − 1 h − 1 . The Redlich–Peterson isotherm fits well with the equilibrium data, with the parameter values of K R /a R = 7.90 mgP g − 1 and g = 0.83.