Unraveling sorption of lead in aqueous solutions by chemically modified biochar derived from coconut fiber: A microscopic and spectroscopic investigation.
In this study, we examined the efficacy of nine different types of coconut-fiber derived biochars (CFBs), prepared at different temperatures and chemically modified with ammonia, hydrogen peroxide and nitric acid, to remove lead (Pb2+) from aqueous solutions. Langmuir-qmvalues of the biochars pyrolyzed at 300°C and modified with ammonia and nitric acid increased from 49.5 to 105.5 and 85.2mgg-1, respectively, compared to control (unmodified), whereas hydrogen peroxide treatment had no effect. The maximum amount of Pb adsorbed on biochars was in the order of CFB-700>MCFB-300-NH3·H2O>CFB-500>MCFB-300-HNO3>CFB-300. X-ray absorption fine structure (XAFS) spectroscopy results revealed that Pb-montmorillonite, Pb(C2H3O2)2, PbSO4, Pb-Al2O3and Pb3(PO4)2were the five most important Pb species observed in Pb-loaded biochars, and as such, favoring Pb immobilization in aqueous solutions. Overall, the sorption capacity of CFBs pyrolyzed at 300°C substantially increased for Pb2+with ammonia and nitric acid modification. However, these chemical modifications did not improve the sorption of Pb on CFBs pyrolyzed at temperatures ≥500°C, thereby highlighting a temperature dependent response of chemically modified biochars to Pb sorption in this study.
School of Environmental and Chemical Engineering, Foshan University, Foshan, Guangdong 528000, China; Ministry of Education Key Laboratory of Protection and Development Utilization of Tropical Crop Germplasm Resources, Hainan University, Haikou, Hainan 570228, China.
Weidong
W
Wu
Ministry of Education Key Laboratory of Protection and Development Utilization of Tropical Crop Germplasm Resources, Hainan University, Haikou, Hainan 570228, China.
Jianhong
J
Li
Ministry of Education Key Laboratory of Protection and Development Utilization of Tropical Crop Germplasm Resources, Hainan University, Haikou, Hainan 570228, China.
Tian
T
Lan
The New Zealand Institute for Plant and Food Research Limited, Ruakura Research Centre, Private Bag 3123, Hamilton, New Zealand.
Karin
K
Müller
Institute of Soil and Environmental Sciences, University of Agriculture Faisalabad, Faisalabad 38040, Pakistan; MARUM, University of Bremen, Bremen D-28359, Germany; Department of Geosciences, University of Bremen, Bremen D-28359, Germany.
Nabeel Khan
NK
Niazi
School of Environmental and Chemical Engineering, Foshan University, Foshan, Guangdong 528000, China.
Xin
X
Chen
School of Environmental and Chemical Engineering, Foshan University, Foshan, Guangdong 528000, China.
Song
S
Xu
Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039, China.
Lirong
L
Zheng
Ministry of Education Key Laboratory of Protection and Development Utilization of Tropical Crop Germplasm Resources, Hainan University, Haikou, Hainan 570228, China.
Yingchao
Y
Chu
Key Laboratory of Soil Contamination Bioremediation of Zhejiang Province, School of Environmental and Resource Sciences, Zhejiang A & F University, Lin'an, Hangzhou, Zhejiang 311300, China.
Jianwu
J
Li
Guangdong Dazhong Agriculture Science Co. Ltd., Hongmei Town, Dongguan, Guangdong 523169, China.
Guodong
G
Yuan
School of Environmental and Chemical Engineering, Foshan University, Foshan, Guangdong 528000, China; Key Laboratory of Soil Contamination Bioremediation of Zhejiang Province, School of Environmental and Resource Sciences, Zhejiang A & F University, Lin'an, Hangzhou, Zhejiang 311300, China; Guangdong Dazhong Agriculture Science Co. Ltd., Hongmei Town, Dongguan, Guangdong 523169, China. Electronic address: nzhailongwang@163.com.
Hailong
H
Wang
Biochar; Chemical modification; Heavy metal; SEM-EDX; XAFS