摘要
通过两类矿物前体对A s(Ⅲ)阴离子的吸附反应的实验研究发现:这两类矿物前体在吸附反应过程中pH值均发生了明显变化,它们对A s(Ⅲ)的吸附均属于化学吸附。M g-A l-LDO从环境中获取阴离子以恢复重建LDH的结晶结构,并释放OH-使溶液pH升高;F e(OH)3凝胶改变了A s(Ⅲ)的络合配位数,同时产生H+离子,使溶液pH降低;M g-F e-LDO兼有二者的特点。在室温条件下,M g-A l-LDO和M g-F e-LDO对A s(Ⅲ)的吸附容量分别为83.2×1-0 3和87.45×1-0 3,而F e(OH)3凝胶为204.9×1-0 3。矿物前体对溶液中阴离子污染物的吸附能力大大高于对应的矿物,主要原因是它们的吸附机理不同,前者为化学吸附,而后者以物理吸附为主。
Absorption reaction of two types of mineral precursor was experimentally researched. Mg-Al-LDO and Mg-Fe-LDO （Layered Double Oxide） were obtained by calcining relevant hydrotalcite （Layered Double Hydroxide, LDH）. Fe （OH）3 gel was produced by co-precipitation method. It is found that pH value changed obviously during absorption,so that it is believed that As （ Ⅲ ）＇s absorbed by the two types of mineral precursor is chemical one in principle. Mg-Al- LDO obtains As anion from the ambient to recover its crystal structure of LDH and releases OH into the solution,increasing its pH value as a result. After being absorbed by Fe（OH）3 gel,coordination number of As （ Ⅲ ） increased from 2 to 3,and the chemical bond between As and O shifted from electrovalent type to covalent one,H^＋ ion was set free simultaneously,which descended pH value of the solution. Mg-Fe-LDO＇s reation with As （ Ⅲ ） is accompanied with complicated pH changes of ascending and then descending. This means that it has double effect on As （ Ⅲ ）,i. e. , LDO＇s sorbing and Fe-O-OH＇s sucking. At room temperature, Absorption capability of Mg-Al- LDO and Mg-Fe-LDO is 83.2× 10^-3 and 87.45 × 10^-3 respectively. It is 204.9× 10^- 3 for Fe（OH）3 gel. Compared with previous work of ours and the others ,absorption capability of mineral precursors on anion pollutants is much higher than that of relevant minerals. The main reason is that they are different in absorption mechanism,i, e. ,the precursors are characterized by chemical absorbing and the minerals are dominated by physical adsorbing. By means of heating the medium, absorption of the precursors can be increased obviously, because the absorbing reaction is enhanced and disturbing factors,especially dissolved CO2,is restrained.
出处
《矿物岩石》
CAS
CSCD
北大核心
2005年第3期109-113,共5页
Mineralogy and Petrology
基金
IFS(InternationalFoundationforScience)
项目编号:W/3787-1
