TITLE:
A Review of the Distribution Coefficient (Kd) of Some Selected Heavy Metals over the Last Decade (2012-2021)
AUTHORS:
Chabi Dari Seidou, Tiejun Wang, Mikouendanandi Mouendo Rahmat Brice Espoire, Yibin Dai, Yutao Zuo
KEYWORDS:
Kd Values, Heavy Metals, PRISMA, Sorption, Desorption
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.10 No.8,
August
30,
2022
ABSTRACT: This review synthesizes the methods for estimating
the distribution coefficient (Kd)
and provides a compilation of Kd values for five heavy metals (As, Pb, Cd, Cu, and Zn) based on research
published in the last decade (2012-2021). We used the PRISMA method
to ensure the transparency of the collected data. For mono-metal systems (MS),
the Kd values ranged from
10-2 to 107 L/kg for Pb,
from 10-2 to 106 L/kg for Cd,
As, and Zn, and from 10-2 to 105 L/kg for Cu.
In competitive systems (CS), the Kd values ranged from 10-2 to 105 L/kg for Cu,
and 10-2 to 104 L/kg for Pb,
Cd, and Zn, while no Kd value for As was reported under CS. It was found that the Kd values of heavy metals are
affected not only by soil chemical and physical properties but also by the
nature and characteristics of the metal involved along with experimental
conditions. The totals references number of Kd data observation per element metal are represented as follows: Cd 35 (50%), Zn 35
(50%), Pb 33 (47.14%), Cu 33 (47.14%), and As 19 (27.14%). Overall, most
research was done 1) on MS rather than CS, 2) on sorption rather than desorption, 3) on soil rather than sediments , and 4) most literature have reported the Kd values, derived from batch
method than on column method. Despite significant progress over the past decade
towards a better understanding of the variation in Kd values and the effect of factors influencing them to
provide important parameters for predicting and controlling toxic metals in
soils, additional research is still warranted to the complexity of underlying
processes.