Adsorption of nitrilotriacetate (NTA), Co and CoNTA by gibbsite

被引:33
作者
Girvin, DC [1 ]
Gassman, PL [1 ]
Bolton, H [1 ]
机构
[1] PACIFIC NW LAB, ENVIRONM MICROBIOL GRP, RICHLAND, WA 99352 USA
关键词
delta-Al2O3; adsorption; chelate; cobalt; desorption; gibbsite (alpha-Al(OH)(3)); nitrilotriacetic acid (NTA);
D O I
10.1346/CCMN.1996.0440606
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Adsorption of Co2+, nitrilotriacetic acid (NTA) and equal-molar Co2+ and NTA by a low surface area (LSA) commercial gibbsite (3.5 m(2) g(-1)) was investigated in batch as a function of pH (4.5 to 10.5), adsorbate (0.5 to 10 mu M) and adsorbent (0.5 to 75 g L-1) concentrations and ionic strength (0.01 to 1 M NaClO4). The adsorption of Co2+ (Co-only) and the acid form of NTA (NTA-only) by gibbsite in 0.01 M NaClO4 exhibit cation-like and anion-like adsorption edges, respectively. For the equal-molar CoNTA chelate, Co and NTA adsorption edges were similar but not identical to the Co-only and NTA-only edges. Differences suggest the existence of a ternary CoNTA surface complex with the Co in the intact chelate coordinated to surface hydroxyls. NTA-only adsorption was insensitive to ionic strength variation, indicating weak electrostatic contributions to surface coordination reactions. This is consistent with the formation of inner-sphere surface NTA complexes and ligand exchange reactions in which monodentate, bidentate and binuclear NTA surface complexes form. Cobalt adsorption increases (edge shifts to lower pH by 1 pH unit) on LSA gibbsite as ionic strength increases from 0.01 to 1 M NaClO4. For the same ionic strength change, a similar shift in the Co-only edge was observed for another commercial gibbsite (16.8 m(2) g(-1)); however, no change was observed for delta-Al2O3. Ionic strength shifts in Co2+ adsorption by gibbsite were described as an outer-sphere CoOH+ surface complex using the triple-layer model. Results suggest that, at waste disposal sites where Co-60 and NTA have been co-disposed, NTA will not promote ligand-like adsorption of Co for acid conditions, but will reduce cation-like adsorption for basic conditions. Thus, where gibbsite is the dominant mineral sorbent, NTA will not alter Co-60 mobility in acidic pore waters and groundwaters; however, NTA could enhance Co-60 mobility where alkaline conditions prevail, unless microbial degradation of the NTA occurs.
引用
收藏
页码:757 / 768
页数:12
相关论文
共 55 条
[1]  
[Anonymous], ENV CHEM ALUMINUM
[2]  
[Anonymous], 1974, Critical Stability Constants
[3]  
AYERS JA, 1970, DECONTAMINATION NUCL
[4]  
BALL JW, 1980, 78116 US GEOL SURV
[5]   ANALYSES OF ADSORPTION-KINETICS USING A STIRRED-FLOW CHAMBER .1. THEORY AND CRITICAL TESTS [J].
BAR-TAL, A ;
SPARKS, DL ;
PESEK, JD ;
FEIGENBAUM, S .
SOIL SCIENCE SOCIETY OF AMERICA JOURNAL, 1990, 54 (05) :1273-1278
[6]   Degradation of metal-nitrilotriacetate complexes by Chelatobacter heintzii [J].
Bolton, H ;
Girvin, DC ;
Plymale, AE ;
Harvey, SD ;
Workman, DJ .
ENVIRONMENTAL SCIENCE & TECHNOLOGY, 1996, 30 (03) :931-938
[7]   EFFECT OF ETHYLENEDIAMINETETRAACETIC ACID ON THE ADSORPTION OF COPPER(II) AT AMORPHOUS SILICA [J].
BOURG, ACM ;
SCHINDLER, PW .
INORGANIC & NUCLEAR CHEMISTRY LETTERS, 1979, 15 (5-6) :225-229
[8]   ADSORPTION CHARACTERISTICS OF METAL-EDTA COMPLEXES ONTO HYDROUS OXIDES [J].
BOWERS, AR ;
HUANG, CP .
JOURNAL OF COLLOID AND INTERFACE SCIENCE, 1986, 110 (02) :575-590
[9]  
BOWERS AR, 1982, THESIS U DELAWARE NE
[10]  
Bragg WL, 1965, CRYSTALLINE STATE, VIV