Adsorption of phosphate from seawater on calcined MgMn-layered double hydroxides
Adsorption of phosphate from seawater on calcined MgMn-layered double hydroxides
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DOI：
10.1016/j.jcis.2005.04.025
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发表时间：
2005-10-01
影响因子：
9.9
通讯作者：
Hirotsu, T
中科院分区：
文献类型：
--
作者：
Chitrakar, R;Tezuka, S;Hirotsu, T
研究了MgMn-3-300（Mg/Mn摩尔比为3的MgMn型层状双氢氧化物，300 ℃焙烧）在浓度为0.30 mg-P/dm（3）的富磷海水中对磷酸盐的吸附性能。它显示了最高的磷酸盐吸收从海水中的无机吸附剂研究（水滑石，煅烧水滑石，活性氧化镁，水合氧化铝，氧化锰（δ-MnO 2））。MgMn-3-300在吸附剂/溶液比为0.05 g/2 dm（3）时的磷酸盐吸收达到7.3 mg-P/g。对海水中Na+、K+、Ca ~（2+）、Cl ~-和SO_（4 ~（2-））的吸附分析表明，该吸附剂对磷酸根离子具有明显的选择性。采用间歇法研究了初始磷酸盐浓度、温度、pH和盐度对磷吸收的影响。随着吸附温度的升高，吸附磷的量略有增加。吸附等温线符合Freundlich方程，常数logK-F = 1.25，1/n = 0.65，表明该吸附剂即使在磷酸盐浓度很低且有大量共存离子的溶液中也能有效地去除磷酸盐。pH依赖性显示在pH 8.5左右的最大磷酸盐吸收。pH依赖性曲线表明，磷酸盐的选择性吸附主要是通过HPO 42-的离子交换进行的。盐度影响的研究表明，吸附剂中存在两种吸附位：一种是弱相互作用的非特异性吸附位，另一种是强相互作用的特异性吸附位。用5 M NaCl + 0. 5 M NaCl的混合溶液解吸磷酸盐效果较好。1 M NaOH（1 M = 1 mol/dm（3）），吸附剂的溶解可以忽略不计。该吸附剂对吸附/解吸循环具有高的化学稳定性;即使在重复第七次循环后，它仍保持良好的磷酸盐吸收。(c)2005年爱思唯尔公司All rights reserved.
Adsorptive properties of MgMn-3-300 (MgMn-type layered double hydroxide with Mg/Mn mole ratio of 3, calcined at 300 degrees C) for phosphate were investigated in phosphate-enriched seawater with a concentration of 0.30 mg-P/dm(3). It showed the highest phosphate uptake from the seawater among the inorganic adsorbents studied (hydrotalcite, calcined hydrotalcite, activated magnesia, hydrous aluminum oxide, manganese oxide (delta-MnO2)). The phosphate uptake by MgMn-3-300 reached 7.3 mg-P/g at an adsorbent/solution ratio of 0.05 g/2 dm(3). The analyses of the uptakes of other constituents (Na+, K+, Ca2+, Cl-, and SO42-) of seawater showed that the adsorbent had a markedly high selectivity for the adsorption of phosphate ions. Effects of initial phosphate concentration, temperature, pH, and salinity on phosphate uptake were investigated in detail by a batch method. The phosphate uptake increased slightly with an increase in the adsorption temperature. The adsorption isotherm followed Freundlich's equation with constants of log K-F = 1.25 and 1/n = 0.65, indicating that it could effectively remove phosphate even from a solution of markedly low phosphate concentration as well as with large numbers of coexisting ions. The pH dependence showed a maximum phosphate uptake around pH 8.5. The pH dependence curve suggested that selective phosphate adsorption progresses mainly by the ion exchange of HPO42-. The study on the effect of salinity suggested the presence of two kinds of adsorption sites in the adsorbent: one nonspecific site with weak interaction and one specific site with strong interaction. The effective desorption of phosphate could be achieved using a mixed solution of 5 M NaCl + 0. 1 M NaOH (1 M = 1 mol/dm(3)), with negligible dissolution of adsorbent. The adsorbent had high chemical stability against the adsorption/desorption cycle; it kept a good phosphate uptake even after the repetition of the seventh cycle. (c) 2005 Elsevier Inc. All rights reserved.