西南科技大学地质工程硕士专业学位论文 第 II 页
Abstract
Arsenic in the acid mine drainage comes from the weathering of
arsenic-containing pyrite and arsenopyrite, which leads to the high concentration arsenic
of surface and groundwater. It threatens the environment and local people satefy.
Permeable reactive barrier (PRB) is a effective treatment technology for acid mine
drainage, which remove most of heavy metals and arsenic by adsorption and
precipitation. In this study, we took bone char and arsenic (V) respectively as alkali
media and contaminant. With building the different loads of manganese coating on
media, we experimentally investigated the effects of coating layer on adsorption
behaviors, including maximal adsorption, kinetic and desorption. The transport behavior
of arsenic (V) in bone char also was investigated using column experiment, the
corresponding relation of coating layer and retention ability of arsenic (V) was
quantitatively described. At the same time, the Five factors and three levels 27 groups
factorial experiment to investigate Fe, Al, Mn three common cation effect on the
migration behavior of arsenic. As transport was modeled based on Matlab. The main
results of study can summrized as follow:
(1) Manganese-coated layer can efficiently improve the adsorption capacity of
arsenic (V) on bone char as high as 78 times than fresh bone char. The maximum
adsorption capacity is 9.46 mg/g at pH=4 for As (V).
(2) Manganese-coated layer immobilize more arsenic (V) than fresh bone char
under the same desorption condition. The desorbed arsenic proportion from various
manganese-coated bone char is 0.02-0.6% of adsorbed arsenic amount, which is
superior to fresh bone char (30%). Two desorption processes were found in those high
manganese-coated bone char (B
5
, B
6
and B
7
).
(3) The retention intensity of arsenic (V) in bone char linearly increases with the
manganese-coated amount, which the retardation factor (Y) = 15.1 X (manganese
amount, mg/g) + 19.8.
(4) The neutralization ability of various manganese-coated bone char decreases
with the degree of coating of bone char. The resistances of manganese-coated bone char
to acid and alkali environment are strong. The phosphate release from bone char is
