Stabilization and solidification of Pb in cement matrices

Gollmann, Maria Angélica Cardoso; Silva, Márcia M. da; Masuero, Ângela Borges; Santos, João Henrique Zimnoch dos

doi:10.1016/j.jhazmat.2010.03.032

Cited by 66 publications

(35 citation statements)

References 39 publications

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“…15 (heat flow curves) by the isothermal calorimetric measurements, in which the main peak of heat evolution appeared at 10.70 hours, while in the control sample was identified at 7.65 hours. This retarding effect of Pb(NO 3 ) 2 is in good agreement with previous results in OPC as well as in CAC, where the presence of Pb 2+ was always detrimental to the setting and compressive strengths of the samples [2,48,49]. Thermogravimetric results also confirmed this fact, yielding a low hydration degree (5.24% of weight loss vs. 5.32% for control sample).…”

Section: Lead Saltssupporting

confidence: 91%

Study of the early hydration of calcium aluminates in the presence of different metallic salts

Durán

Sirera

Perez-Nicolas

et al. 2016

Cement and Concrete Research

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The effect of chlorides and nitrates of Li(I), Cr(III), Zn(II), Cu(II), Pb(II) nitrate and Cr(VI) (chromate) on the early hydration of ternary system of calcium aluminates (CA, CA 2 , C 12 A 7 ) was reported. Li(I) and Cr(III) caused a strong acceleration of the hydration, while Zn(II) as well as chromate gave rise to a slight acceleration. On the contrary, Pb(II) and Cu(II) retarded the hydration. A clear formation of AFm phases during the first hydration stages was found and related to the acceleration ability.Anions (nitrate or chloride as counterions or even chromate) were able to be incorporated into the interlayer space of AFm, yielding insoluble and stable compounds.A balance between the insolubility of the metal hydroxides (dependant on the low amphoteric character of the compound) and the ability of the formation of AFm hydrates seems to be very important to lean the equilibrium towards the retarding of the hydration or towards the acceleration, respectively.2

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Section: Lead Saltssupporting

confidence: 91%

Study of the early hydration of calcium aluminates in the presence of different metallic salts

Durán

Sirera

Perez-Nicolas

et al. 2016

Cement and Concrete Research

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“…These results are in agreement with previous data reporting great immobilization in hydrated cementitious matrices for Pb and Zn, ranging from 99.82 to 99.99%. Cr is an exception and it has been reported to be immobilized in lower degree (from 85.97 to 93.33%) [31]. Owing to the large retention ability of cement matrices, the released amounts of both Pb and Zn were well below the upper limit of the regulatory norm (400 and 800 mg m -2 , respectively) [32], as it has been also 12 reported in a previous work [33].…”

Section: Leaching Tests Of Heavy Metals In Cmch-modified Cement Mortarsmentioning

confidence: 50%

Interaction of carboxymethylchitosan and heavy metals in cement media

Lasheras-Zubiate

Navarro-Blasco

Álvarez

et al. 2011

Journal of Hazardous Materials

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The performance of an etherified chitosan, carboxymethyl chitosan (CMCH), when added to cement mortars doped with heavy metals, was assessed. In the presence of heavy metals (Cr, Pb, Zn) strong modifications of the fresh-state properties were evaluated. The addition of the polymer was seen to be useful in minimising some of these modifications, as those related to the setting time. A competitive mechanism for adsorption between the oxoanionic form of the metals and the carboxylate groups of the chitosan derivative was established. Studies on the metal chelating ability of the polymer and leaching from the hardened specimens showed scarce complexation under alkaline conditions, pointing to physical entrapment based on metal adsorption. However, significant chelation of metals was proved at near-neutral pH, suggesting the potential usefulness of the polymer as a agent for removing heavy metals from polluted waters and subsequently immobilizing them in cement mortars. Leaching tests carried out on polymer-metal complex-bearing samples showed a significant reduction in the amount of released Pb and Zn.

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“…Cement is the most adaptable binder currently available for this immobilization. A growing number of papers have dealt with this subject, mainly using ordinary Portland cement (OPC), some of its phases or OPC modified by calcium aluminate, calcium sulphate, and/or admixtures [1][2][3][4][5][6][7], occasionally forming new phases with the metallic cations. In addition, G. Qian and co-workers have extensively studied the S/S processes of toxic metals in fly ashcalcium sulfoaluminate cement, Friedel's salt or fly ashes [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Solidification/stabilization of toxic metals in calcium aluminate cement matrices

Navarro-Blasco

Durán

Sirera

et al. 2013

Journal of Hazardous Materials

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The ability of calcium aluminate cement (CAC) to encapsulate toxic metals (Pb, Zn and Cu) was assessed under two curing conditions. Changes in the consistency and in the setting time were found upon the addition of the nitrates of the target metals. Both Pb and Cu caused a delay in CAC hydration, while Zn accelerated the stiffening of the mortar. Compressive strengths of the metal-doped mortars, when initially cured at 60ºC/100% RH, were comparable with that of the free-metal mortar. Three different pore size distribution patterns were identified and related to the compounds identified by XRD and SEM. Sorbent capacities of CAC for the toxic metals were excellent: a total uptake was achieved for up to 3 wt.% loading of the three metals. In this way, CAC mortars were perfectly able to encapsulate the toxic metals, allowing the use of CAC for waste management as proved by the leaching tests.

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Stabilization and solidification of Pb in cement matrices

Cited by 66 publications

References 39 publications

Study of the early hydration of calcium aluminates in the presence of different metallic salts

Study of the early hydration of calcium aluminates in the presence of different metallic salts

Interaction of carboxymethylchitosan and heavy metals in cement media

Solidification/stabilization of toxic metals in calcium aluminate cement matrices

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