University of Alberta, 442 Earth Sciences Building, Edmonton, Alberta, T6G 2E3, Canada.
Korea Biochar Research Center, O-Jeong Eco-Resilience Institute (OJERI) & Division of Environmental Science and Ecological Engineering, Korea University, Seoul, Republic of Korea.
Environ Sci Pollut Res Int. 2018 Sep;25(26):25799-25812. doi: 10.1007/s11356-018-1368-9. Epub 2018 Feb 10.
Biochar is recognized as an effective material for recovering excess nutrients, including phosphorus (P), from aqueous solutions. Practically, that benefits the environment through reducing P losses from biochar-amended soils; however, how salinity influences P sorption by biochar is poorly understood and there has been no direct comparison on P sorption capacity between biochars derived from different feedstock types under non-saline and saline conditions. In this study, biochars derived from wheat straw, hardwood, and willow wood were used to compare P sorption at three levels of electrical conductivity (EC) (0, 4, and 8 dS m) to represent a wide range of salinity conditions. Phosphorus sorption by wheat straw and hardwood biochars increased as aqueous solution P concentration increased, with willow wood biochar exhibiting an opposite trend for P sorption. However, the pattern for P sorption became the same as the other biochars after the willow wood biochar was de-ashed with 1 M HCl and 0.05 M HF. Willow wood biochar had the highest P sorption (1.93 mg g) followed by hardwood (1.20 mg g) and wheat straw biochars (1.06 mg g) in a 25 mg L P solution. Although the pH in the equilibrium solution was higher with willow wood biochar (~ 9.5) than with the other two biochars (~ 6.5), solution pH had no or minor effects on P sorption by willow wood biochar. The high sorption rate of P by willow wood biochar could be attributed to the higher concentrations of salt and other elements (i.e., Ca and Mg) in the biochar in comparison to that in wheat straw and hardwood biochars; the EC values were 2.27, 0.53, and 0.27 dS m for willow wood, wheat straw, and hardwood biochars, respectively. A portion of P desorbed from the willow wood biochar; and that desorption increased with the decreasing P concentration in the aqueous solution. Salinity in the aqueous solution influenced P sorption by hardwood and willow wood but not by wheat straw biochar. We conclude that the P sorption capacity of the studied biochars is dependent on the concentration of the soluble element in the biochar, which is dependent on the biochar type, as well as the salinity level in the aqueous solution.
生物炭被认为是一种从水溶液中回收过量养分（包括磷）的有效材料。实际上，这通过减少生物炭改良土壤中磷的损失而有益于环境；然而，盐度如何影响生物炭对磷的吸附作用还知之甚少，并且在非盐和盐条件下，从未对不同原料类型衍生的生物炭的磷吸附能力进行过直接比较。在这项研究中，使用小麦秸秆、硬木和柳树木衍生的生物炭来比较在三个电导率（EC）水平（0、4 和 8 dS m）下的磷吸附作用，以代表广泛的盐度条件。随着水溶液中磷浓度的增加，小麦秸秆和硬木生物炭对磷的吸附作用增加，而柳树木生物炭对磷的吸附作用则呈现相反的趋势。然而，在柳树木生物炭用 1 M HCl 和 0.05 M HF 脱灰后，其磷吸附作用模式与其他生物炭相同。在 25 mg L P 溶液中，柳树木生物炭的磷吸附量最高（1.93 mg g），其次是硬木（1.20 mg g）和小麦秸秆生物炭（1.06 mg g）。尽管柳树木生物炭平衡溶液的 pH 值较高（约 9.5），但与其他两种生物炭（约 6.5）相比，溶液 pH 值对柳树木生物炭的磷吸附作用没有影响或影响较小。柳树木生物炭对磷的高吸附速率可能归因于生物炭中盐和其他元素（即 Ca 和 Mg）的浓度高于小麦秸秆和硬木生物炭；柳树木、小麦秸秆和硬木生物炭的 EC 值分别为 2.27、0.53 和 0.27 dS m。一部分磷从柳树木生物炭中解吸出来，而解吸量随着水溶液中磷浓度的降低而增加。水溶液中的盐度影响硬木和柳树木生物炭对磷的吸附作用，但不影响小麦秸秆生物炭。我们得出结论，所研究的生物炭的磷吸附能力取决于生物炭中可溶性元素的浓度，而这取决于生物炭的类型以及水溶液中的盐度水平。
