1
|
Liu S, Miao C, Yao S, Ding H, Zhang K. Soil stabilization/solidification (S/S) agent---water-soluble thiourea formaldehyde (WTF) resin: Mechanism and performance with cadmium (Ⅱ). Environ Pollut 2021; 272:116025. [PMID: 33277061 DOI: 10.1016/j.envpol.2020.116025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 09/13/2020] [Accepted: 10/06/2020] [Indexed: 06/12/2023]
Abstract
It is vital for the development and application of heavy metal stabilization/solidification (S/S) agents to reveal the mechanism of the reaction between water-soluble thiourea formaldehyde (WTF) resin and heavy metal and evaluate its repairing effect. Based on the density functional theory analysis of the WTF resin structure, the mechanism analysis and scanning electron microscope (SEM) showed that the three-dimensional network structure with thiocarbonyl and hydroxyl groups is very conducive to the capture of Cd2+. The reduction rate of Cd2+ in soil added WTF resin could reach 70.6%-86.0%. The result of BCR's sequential extraction also proved that the 86.4%-94.1% of Cd in the soil repaired by WTF resin changed from acid-soluble state to residue state. Enzyme activity analysis and 16sRNA sequencing experiments showed that such a structure does not harm soil health. The urease and phosphatase tests showed the nitrogen and phosphorus cycle of the soil added WTF resin was repaired. Even compared with the remediation agents Na2S and hydroxyapatite, WTF resin still performed better in repairing soil health. These findings provide valuable insights into the efficient causes of WTF resin and its harmless effects on soil. The results obtained provide a critical reference for the future application of practical and gentle heavy metal S/S agents.
Collapse
Affiliation(s)
- Shejiang Liu
- School of Environmental Science & Engineering, Tianjin University, No.135, Yaguan Rd., Jinnan District, Tianjin, 300350, China
| | - Chen Miao
- School of Environmental Science & Engineering, Tianjin University, No.135, Yaguan Rd., Jinnan District, Tianjin, 300350, China
| | - Shanshan Yao
- School of Environmental Science & Engineering, Tianjin University, No.135, Yaguan Rd., Jinnan District, Tianjin, 300350, China
| | - Hui Ding
- School of Environmental Science & Engineering, Tianjin University, No.135, Yaguan Rd., Jinnan District, Tianjin, 300350, China.
| | - Kai Zhang
- Tianjin TEDA Greening Group Co., Ltd., China
| |
Collapse
|
2
|
Liu SJ, Jiang JY, Wang S, Guo YP, Ding H. Assessment of water-soluble thiourea-formaldehyde (WTF) resin for stabilization/solidification (S/S) of heavy metal contaminated soils. J Hazard Mater 2018; 346:167-173. [PMID: 29274510 DOI: 10.1016/j.jhazmat.2017.12.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Revised: 12/04/2017] [Accepted: 12/07/2017] [Indexed: 05/22/2023]
Abstract
Stabilization/Solidification (S/S) can be regarded as necessary for remediation of heavy metal contaminated soil. There is, however, solid agent is not very convenient to use. Water-soluble thiourea-formaldehyde (WTF) is a novel chelating agent, which has more practical applications. The process of WTF resin for S/S process of heavy metal contaminated soils was studied. Laboratory-prepared slurries, made of field soils spiked with Cd2+ and Cr6+ were treated with WTF resin. The toxicity characteristic leaching procedure (TCLP) showed that with 2 wt% WTF, in the neutral condition of soil after treatment for 7 d, the leaching concentrations of Cd2+ and Cr6+ in contaminated soil were decreased by 80.3% and 92.6% respectively. Moreover, Tessier sequence extraction procedure showed WTF resin reduced the leaching concentration by transforming heavy metal from exchange form to organic form. The structure of WTF is obtained according to elemental analysis result and reaction mechanism. Through analysis of the infrared spectrogram of WTF and WTF heavy mental chelating precipitation, WTF can form stable chelate with heavy mental through coordination. The significant groups are hydroxyl, nitrogen and sulphur function groups in WTF mainly. Toxicology test revealed that the WTF resin is nontoxic to microorganism in the soils.
Collapse
Affiliation(s)
- She-Jiang Liu
- School of Environmental Science & Engineering, Tianjin University, No.135, Yaguan Rd., Jinnan District, Tianjin, 300350, China
| | - Jia-Yu Jiang
- School of Environmental Science & Engineering, Tianjin University, No.135, Yaguan Rd., Jinnan District, Tianjin, 300350, China
| | - Shen Wang
- School of Environmental Science & Engineering, Tianjin University, No.135, Yaguan Rd., Jinnan District, Tianjin, 300350, China
| | - Yu-Peng Guo
- School of Environmental Science & Engineering, Tianjin University, No.135, Yaguan Rd., Jinnan District, Tianjin, 300350, China
| | - Hui Ding
- School of Environmental Science & Engineering, Tianjin University, No.135, Yaguan Rd., Jinnan District, Tianjin, 300350, China.
| |
Collapse
|
3
|
Liu SJ, Guo YP, Yang HY, Wang S, Ding H, Qi Y. Synthesis of a water-soluble thiourea-formaldehyde (WTF) resin and its application to immobilize the heavy metal in MSWI fly ash. J Environ Manage 2016; 182:328-334. [PMID: 27497309 DOI: 10.1016/j.jenvman.2016.07.086] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 07/26/2016] [Accepted: 07/27/2016] [Indexed: 06/06/2023]
Abstract
Because of the high concentrations of heavy metals, municipal solid waste incineration (MSWI) fly ash is classified as a hazardous waste, which need to be treated to avoid damaging the environment. A novel water-soluble thiourea-formaldehyde (WTF) resin was synthesized by two step reactions (hydroxymethylation reaction and condensation reaction) in the laboratory. Synthetic conditions, removal of free formaldehyde in the resin and the ability of immobilization heavy metals in the MSWI fly ash were studied. The possible molecular structure of the resin was also discussed by elemental analysis and FTIR spectra. Experimental results showed that the synthesis conditions of WTF resin were the formaldehyde/thiourea (T/F) mole ratio of 2.5:1, hydroxymethylation at pH 7.0-8.0 and 60 °C for 30min, and condensation of at pH 4.5-5.0 and 80 °C. In addition, the end point of condensation reaction was measured by turbidity point method. The result of elemental analysis and FTIR spectra indicated that thiourea functional group in the WTF resin chelated the heavy metal ions. Melamine can efficiently reduce the free formaldehyde content in the resin from 8.5% to 2%. The leaching test showed that the immobilization rates of Cr, Pb and Cd were 96.5%, 92.0% and 85.8%, respectively. Leaching concentrations of Cr, Pb and Cd in the treated fly ash were decreased to 0.08 mg/L, 2.44 mg/L and 0.23 mg/L, respectively. The MSWI fly ash treated by WTF resin has no harm to the environment.
Collapse
Affiliation(s)
- She-Jiang Liu
- School of Environmental Science & Engineering, Tianjin University, No. 92, Weijin Rd., Nankai District, Tianjin, 300072, China
| | - Yu-Peng Guo
- School of Environmental Science & Engineering, Tianjin University, No. 92, Weijin Rd., Nankai District, Tianjin, 300072, China
| | - Hong-Yang Yang
- School of Environmental Science & Engineering, Tianjin University, No. 92, Weijin Rd., Nankai District, Tianjin, 300072, China
| | - Shen Wang
- School of Environmental Science & Engineering, Tianjin University, No. 92, Weijin Rd., Nankai District, Tianjin, 300072, China
| | - Hui Ding
- School of Environmental Science & Engineering, Tianjin University, No. 92, Weijin Rd., Nankai District, Tianjin, 300072, China.
| | - Yun Qi
- School of Environmental Science & Engineering, Tianjin University, No. 92, Weijin Rd., Nankai District, Tianjin, 300072, China
| |
Collapse
|