Enhancing phosphate adsorption by Mg/Al layered double hydroxide functionalized biochar with different Mg/Al ratios

Ronghua Li; Jim J Wang; Baoyue Zhou; Mukesh Kumar Awasthi; Amjad Ali; Zengqiang Zhang; Lewis A Gaston; Altaf Hussain Lahori; Amanullah Mahar

doi:10.1016/j.scitotenv.2016.03.151

Enhancing phosphate adsorption by Mg/Al layered double hydroxide functionalized biochar with different Mg/Al ratios

Sci Total Environ. 2016 Jul 15:559:121-129. doi: 10.1016/j.scitotenv.2016.03.151. Epub 2016 Apr 5.

Authors

Ronghua Li¹, Jim J Wang², Baoyue Zhou³, Mukesh Kumar Awasthi⁴, Amjad Ali⁵, Zengqiang Zhang⁵, Lewis A Gaston³, Altaf Hussain Lahori⁵, Amanullah Mahar⁶

Affiliations

¹ College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, China; School of Plant, Environmental and Soil Sciences, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA.
² School of Plant, Environmental and Soil Sciences, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA. Electronic address: JJWang@agcenter.lsu.edu.
³ School of Plant, Environmental and Soil Sciences, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA.
⁴ College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, China; Department of Biotechnology, Amicable Knowledge Solution University, Satna, India.
⁵ College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, China.
⁶ College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, China; Centre for Environmental Sciences, University of Sindh, Jamshoro, 76080, Pakistan.

PMID: 27058131
DOI: 10.1016/j.scitotenv.2016.03.151

Abstract

Mg/Al ratio plays a significant role for anion adsorption by Mg/Al-layered double hydroxides (Mg/Al-LDHs) modified biochar. In this study, Mg/Al-LDHs biochar with different Mg/Al ratios (2, 3, 4) were prepared by co-precipitation for phosphate removal from aqueous solution. Factors on phosphate adsorption including Mg/Al ratio, pH, and the presence of other inorganic anions were investigated through batch experiments. Increasing Mg/Al ratio in the Mg/Al-LDHs biochar composites generally enhanced phosphate adsorption with Langmuir adsorption maximum calculated at 81.83mg phosphorous (P) per gram of 4:1Mg/Al-LDHs biochar at pH3.0. The adsorption process was best described by the pseudo-second-order kinetic model. Solution pH had greater effects on the phosphate adsorption by Mg/Al LDHs biochar composites with lower Mg/Al ratios. The presence of other inorganic anions decreased the phosphate adsorption efficiency in the order of F(-) > SO4(2-) > NO2(-) >Cl(-). Phosphate adsorption mechanism involves ion exchange, electrostatic attraction and surface inner-sphere complex formation. Overall, Mg/Al-LDHs biochar composites offer a potential alternative of carbon-based adsorbent for phosphate removal from aqueous solution.

Keywords: Mg/Al ratio; Phosphate; adsorption; biochar; layered double hydroxides.

Publication types

Research Support, Non-U.S. Gov't