The copper complexation ability of a synthetic humic-like acid formed by an abiotic humification process and the effect of experimental factors on its copper complexation ability

TY - JOUR

T1 - The copper complexation ability of a synthetic humic-like acid formed by an abiotic humification process and the effect of experimental factors on its copper complexation ability

AU - Yang, Ting

AU - Hodson, Mark Edward

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PY - 2018/3/26

Y1 - 2018/3/26

N2 - Humic acids have an important impact on the distribution, toxicity and bioavailability of hazardous metals in the environment. In this study, a synthetic humic-like acid (SHLA) was prepared by an abiotic humification process using catechol and glycine as humic precursors and a MnO2 catalyst. The effect of physico-chemical conditions (ionic strength from 0.01M to 0.5M NaNO3, pH from 4 to 8, temperature from 25 °C to 45 °C and humic acid concentration from 5 to 100mg/L) on the complexation ability of SHLA for Cu2+ were investigated. A commercial humic acid (CHA, CAS: 1415-93-6) from Sigma-Aldrich was also studied for comparison. The results showed that for pH 4 to 8, the conditional stability constants (log K) of SHLA and CHA were in the range 5.63-8.62 and 4.87-6.23, respectively and complexation capacities (CC) were 1.34-2.61 mmol/g and 1.42-2.31 mmol/g, respectively. The Cu complexation ability of SHLA was higher than that of the CHA due to its higher number of acidic functional groups (SHLA: 19.19 mmol/g; CHA: 3.87 mmol/g), extent of humification and aromaticity (AL/AR: 0.333 (SHLA); 1.554 (CHA)), and O-alkyl functional groups (SHLA:15.56%; CHA:3.45%). The log K and complexation efficiency (fraction of metal bound to SHLA) of SHLA were higher at higher pH, lower ionic strength, higher temperature and higher SHLA concentration. Overall, SHLA was a good and promising complexation agent for copper in both soil washing of copper contaminated soil and the treatment of copper-containing wastewater

AB - Humic acids have an important impact on the distribution, toxicity and bioavailability of hazardous metals in the environment. In this study, a synthetic humic-like acid (SHLA) was prepared by an abiotic humification process using catechol and glycine as humic precursors and a MnO2 catalyst. The effect of physico-chemical conditions (ionic strength from 0.01M to 0.5M NaNO3, pH from 4 to 8, temperature from 25 °C to 45 °C and humic acid concentration from 5 to 100mg/L) on the complexation ability of SHLA for Cu2+ were investigated. A commercial humic acid (CHA, CAS: 1415-93-6) from Sigma-Aldrich was also studied for comparison. The results showed that for pH 4 to 8, the conditional stability constants (log K) of SHLA and CHA were in the range 5.63-8.62 and 4.87-6.23, respectively and complexation capacities (CC) were 1.34-2.61 mmol/g and 1.42-2.31 mmol/g, respectively. The Cu complexation ability of SHLA was higher than that of the CHA due to its higher number of acidic functional groups (SHLA: 19.19 mmol/g; CHA: 3.87 mmol/g), extent of humification and aromaticity (AL/AR: 0.333 (SHLA); 1.554 (CHA)), and O-alkyl functional groups (SHLA:15.56%; CHA:3.45%). The log K and complexation efficiency (fraction of metal bound to SHLA) of SHLA were higher at higher pH, lower ionic strength, higher temperature and higher SHLA concentration. Overall, SHLA was a good and promising complexation agent for copper in both soil washing of copper contaminated soil and the treatment of copper-containing wastewater

KW - METAL

KW - remediation

KW - soil

KW - humic acids

KW - copper

KW - contaminated soil

U2 - 10.1007/s11356-018-1836-2

DO - 10.1007/s11356-018-1836-2

M3 - Article

SN - 0944-1344

VL - 25

SP - 15873

EP - 15884

JO - Environmental Science and Pollution Research (ESPR)

JF - Environmental Science and Pollution Research (ESPR)

ER -