Removal of lead by rice husk biochars produced at different temperatures and implications for their environmental utilizations.
Chemosphere
; 235: 825-831, 2019 Nov.
Article
in En
| MEDLINE
| ID: mdl-31284130
ABSTRACT
Rice husk is a common agricultural waste. The utilization of rice husk biochar depends on the characteristics of biochar and its interaction mechanisms with heavy metals. In the present study, rice husk biochars at three different temperatures 300, 500, and 700⯰C were produced (RH300, RH500, and RH700). The characteristics of these rice husk biochars and their interaction mechanisms with lead (Pb) were investigated, in order to reveal the potential environmental applications of the biochars. It was observed that the surface area (from 0.632 to 193.149â¯m2/g) and pH (from 7.13 to 9.80) of the rice husk biochars significantly increased as production temperature rose from 300 to 700⯰C, while the number of functional groups (e.g., carboxyl) decreased. The Langmuir maximum removal capacity (Qmax) values for Pb are in the order of RH300â¯<â¯RH500â¯<â¯RH700 (14.1, 21.7, and 26.7â¯mg/g respectively). Although RH300 has the smallest Qmax value, its exchangeable Pb amount is the largest (2.61 versus 0.223-0.377â¯mg/g), suggesting RH300 may be suitable for water treatment due to the easy separation of immobilized Pb and better recycling usage. The Pb immobilized on RH500 and RH700 was mainly acidic soluble and generally stable. Hydrocerussite is one important form within the acidic soluble fraction. Within the generally stable formation, pyromorphite is a form for the immobilized Pb on the rice husk biochars, particularly for RH500 and RH700. These findings suggest RH500 and RH700 are of promising potential to be applied in soil remediation to immobilize Pb and reduce its environmental risks.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Water Pollutants, Chemical
/
Water Purification
/
Lead
Language:
En
Journal:
Chemosphere
Year:
2019
Document type:
Article
Affiliation country:
China