TY - JOUR
T1 - Heavy metal dissolution mechanisms from electrical industrial sludge
AU - Gunarathne, Viraj
AU - Rajapaksha, Anushka Upamali
AU - Vithanage, Meththika
AU - Adassooriya, Nadeesh
AU - Cooray, Asitha
AU - Liyanage, Sudantha
AU - Athapattu, Bandunee
AU - Rajakaruna, Nishanta
AU - Igalavithana, Avanthi Deshani
AU - Hou, Deyi
AU - Alessi, Daniel S.
AU - Ok, Yong Sik
N1 - Publisher Copyright:
© 2019
PY - 2019/12/15
Y1 - 2019/12/15
N2 - In this paper, we investigate the release of heavy metals from sludge produced from an electrical industry using both organic and inorganic acids. Single and sequential extractions were conducted to assess heavy metals in different phases of the sludge. Metal release from sludge was investigated in the presence of three inorganic acids (nitric, sulfuric, and phosphoric) and three organic acids (acetic, malic, and citric) at concentrations ranging from 0.1 to 2.0 mol L−1. Sequential extraction indicated the presence of Cu primarily in the carbonate fraction, Pb in the residual fraction, and Ni in the Fe[sbnd]Mn oxide fraction. The cumulative release rates of heavy metals (i.e., Pb, Cu, and Ni) by 1.0 mol L−1 of acid increased with the use of the following acids in the order of: malic < sulfuric < acetic < phosphoric < citric < nitric. Acetic acid exhibited the highest release of Cu, at a rate of 72.62 × 10−11 mol m−2 s−1 at pH 1, and malic acid drove the release of Pb at a maximum rate of 3.90 × 10−11 mol m−2 s−1. Meanwhile, nitric acid provided the maximum rate of Ni release (0.23 × 10−11 mol m−2 s−1) at pH 1. The high rate of metal release by organic acids is explained through ligand-promoted mechanisms that enhance the release of metal ions from the sludge. The results from our study emphasize that an understanding of the metal release mechanism is key to selecting the optimal acid for the maximum recovery of heavy metals.
AB - In this paper, we investigate the release of heavy metals from sludge produced from an electrical industry using both organic and inorganic acids. Single and sequential extractions were conducted to assess heavy metals in different phases of the sludge. Metal release from sludge was investigated in the presence of three inorganic acids (nitric, sulfuric, and phosphoric) and three organic acids (acetic, malic, and citric) at concentrations ranging from 0.1 to 2.0 mol L−1. Sequential extraction indicated the presence of Cu primarily in the carbonate fraction, Pb in the residual fraction, and Ni in the Fe[sbnd]Mn oxide fraction. The cumulative release rates of heavy metals (i.e., Pb, Cu, and Ni) by 1.0 mol L−1 of acid increased with the use of the following acids in the order of: malic < sulfuric < acetic < phosphoric < citric < nitric. Acetic acid exhibited the highest release of Cu, at a rate of 72.62 × 10−11 mol m−2 s−1 at pH 1, and malic acid drove the release of Pb at a maximum rate of 3.90 × 10−11 mol m−2 s−1. Meanwhile, nitric acid provided the maximum rate of Ni release (0.23 × 10−11 mol m−2 s−1) at pH 1. The high rate of metal release by organic acids is explained through ligand-promoted mechanisms that enhance the release of metal ions from the sludge. The results from our study emphasize that an understanding of the metal release mechanism is key to selecting the optimal acid for the maximum recovery of heavy metals.
KW - Industrial waste
KW - Pollution mitigation
KW - Resource recovery
KW - Sludge treatment
KW - Trace metals
UR - http://www.scopus.com/inward/record.url?scp=85070919975&partnerID=8YFLogxK
U2 - 10.1016/j.scitotenv.2019.133922
DO - 10.1016/j.scitotenv.2019.133922
M3 - Article
C2 - 31446288
AN - SCOPUS:85070919975
SN - 0048-9697
VL - 696
JO - Science of the Total Environment
JF - Science of the Total Environment
M1 - 133922
ER -