Adsorption Features of Loess Calcareous Nodules to Heavy-Metal Ions in Aqueous Solution

This paper explores the use of calcareous tuberculosis as an adsorbent and heavy-metal ions (Cu2+, Zn2+, Cd2+, and Pb2+) as adsorbates, and the influence of varying levels of particle size, adsorption time, p...

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Autores principales:	Qi Li, Yanan Li
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	loess calcareous nodules heavy-metal ions single adsorption adsorption rate Engineering (General). Civil engineering (General) TA1-2040
Acceso en línea:	https://doaj.org/article/0175833b94b5474c86cd899c01a5e1cf
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spelling	oai:doaj.org-article:0175833b94b5474c86cd899c01a5e1cf2021-11-25T17:15:54ZAdsorption Features of Loess Calcareous Nodules to Heavy-Metal Ions in Aqueous Solution10.3390/coatings111113142079-6412https://doaj.org/article/0175833b94b5474c86cd899c01a5e1cf2021-10-01T00:00:00Zhttps://www.mdpi.com/2079-6412/11/11/1314https://doaj.org/toc/2079-6412This paper explores the use of calcareous tuberculosis as an adsorbent and heavy-metal ions (Cu<sup>2+</sup>, Zn<sup>2+</sup>, Cd<sup>2+</sup>, and Pb<sup>2+</sup>) as adsorbates, and the influence of varying levels of particle size, adsorption time, pH, adsorbent dosage, and initial concentration of heavy metals is studied through an experiment of single heavy-metal adsorption. In addition, the impact of the temperature and other factors on the adsorption of heavy-metal ions by calcareous nodules is analyzed to identify the optimal conditions for the adsorption of heavy-metal ions by calcareous nodules. As shown by the research findings, the adsorption rates of Cu<sup>2+</sup>, Zn<sup>2+</sup>, and Pb<sup>2+</sup> gradually declined with the increase in particle size, with no evident effect on Cd<sup>2+</sup>. In the meantime, with further increases in factors such as the adsorption time, adsorbent dosage, and temperature, the adsorption rates of Cu<sup>2+</sup>, Zn<sup>2+</sup>, Cd<sup>2+</sup>, and Pb<sup>2+</sup> experienced gradual increases. The adsorption rates of Cu<sup>2+</sup>, Zn<sup>2+</sup>, and Cd<sup>2+</sup> gradually declined with the increase in initial concentration of heavy-metal ions, whereas the adsorption rate of Pb<sup>2+</sup> experience increased first and then declined. As the pH increased, the adsorption rate of Cd<sup>2+</sup> experience increased first and then declined at a slow pace. The adsorption rates of Cu<sup>2+</sup>, Zn<sup>2+</sup>, and Pb<sup>2+</sup> increased first and then decreased. The adsorption capacity of calcareous nodules toward the four heavy-metal ions was in the order of Pb<sup>2+</sup> > Zn<sup>2+</sup> > Cu<sup>2+</sup> > Cd<sup>2+</sup>. When the particle size was set to 0.25 mm, the adsorption time was set to 120 min, and the dosage was set to 0.6 g, the calcareous nodules included Pb<sup>2+</sup>, Zn<sup>2+</sup>, and Cu<sup>2+</sup>. Moreover, Cd<sup>2+</sup> was able to achieve stronger adsorption capacity, with the adsorption rate able to reach 83.33%, 77.78%, 73.81%, and 81.93% of its maximum level. Therefore, as the particle size of the heavy-metal ions decreased, the adsorption capacity generally became stronger. As the adsorption time increased, the temperature and the amount of adsorbent also increased. The optimal pH value for the adsorption of calcareous nodules toward Pb<sup>2+</sup>, Zn<sup>2+</sup>, Cu<sup>2+</sup>, and Cd<sup>2+</sup> was found to be 7, 6, 5, and 8, respectively, and the optimal temperature was 50 °C. In summary, calcareous nodules are a natural, low-cost, and effective adsorbent.Qi LiYanan LiMDPI AGarticleloess calcareous nodulesheavy-metal ionssingle adsorptionadsorption rateEngineering (General). Civil engineering (General)TA1-2040ENCoatings, Vol 11, Iss 1314, p 1314 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	loess calcareous nodules heavy-metal ions single adsorption adsorption rate Engineering (General). Civil engineering (General) TA1-2040
spellingShingle	loess calcareous nodules heavy-metal ions single adsorption adsorption rate Engineering (General). Civil engineering (General) TA1-2040 Qi Li Yanan Li Adsorption Features of Loess Calcareous Nodules to Heavy-Metal Ions in Aqueous Solution
description	This paper explores the use of calcareous tuberculosis as an adsorbent and heavy-metal ions (Cu<sup>2+</sup>, Zn<sup>2+</sup>, Cd<sup>2+</sup>, and Pb<sup>2+</sup>) as adsorbates, and the influence of varying levels of particle size, adsorption time, pH, adsorbent dosage, and initial concentration of heavy metals is studied through an experiment of single heavy-metal adsorption. In addition, the impact of the temperature and other factors on the adsorption of heavy-metal ions by calcareous nodules is analyzed to identify the optimal conditions for the adsorption of heavy-metal ions by calcareous nodules. As shown by the research findings, the adsorption rates of Cu<sup>2+</sup>, Zn<sup>2+</sup>, and Pb<sup>2+</sup> gradually declined with the increase in particle size, with no evident effect on Cd<sup>2+</sup>. In the meantime, with further increases in factors such as the adsorption time, adsorbent dosage, and temperature, the adsorption rates of Cu<sup>2+</sup>, Zn<sup>2+</sup>, Cd<sup>2+</sup>, and Pb<sup>2+</sup> experienced gradual increases. The adsorption rates of Cu<sup>2+</sup>, Zn<sup>2+</sup>, and Cd<sup>2+</sup> gradually declined with the increase in initial concentration of heavy-metal ions, whereas the adsorption rate of Pb<sup>2+</sup> experience increased first and then declined. As the pH increased, the adsorption rate of Cd<sup>2+</sup> experience increased first and then declined at a slow pace. The adsorption rates of Cu<sup>2+</sup>, Zn<sup>2+</sup>, and Pb<sup>2+</sup> increased first and then decreased. The adsorption capacity of calcareous nodules toward the four heavy-metal ions was in the order of Pb<sup>2+</sup> > Zn<sup>2+</sup> > Cu<sup>2+</sup> > Cd<sup>2+</sup>. When the particle size was set to 0.25 mm, the adsorption time was set to 120 min, and the dosage was set to 0.6 g, the calcareous nodules included Pb<sup>2+</sup>, Zn<sup>2+</sup>, and Cu<sup>2+</sup>. Moreover, Cd<sup>2+</sup> was able to achieve stronger adsorption capacity, with the adsorption rate able to reach 83.33%, 77.78%, 73.81%, and 81.93% of its maximum level. Therefore, as the particle size of the heavy-metal ions decreased, the adsorption capacity generally became stronger. As the adsorption time increased, the temperature and the amount of adsorbent also increased. The optimal pH value for the adsorption of calcareous nodules toward Pb<sup>2+</sup>, Zn<sup>2+</sup>, Cu<sup>2+</sup>, and Cd<sup>2+</sup> was found to be 7, 6, 5, and 8, respectively, and the optimal temperature was 50 °C. In summary, calcareous nodules are a natural, low-cost, and effective adsorbent.
format	article
author	Qi Li Yanan Li
author_facet	Qi Li Yanan Li
author_sort	Qi Li
title	Adsorption Features of Loess Calcareous Nodules to Heavy-Metal Ions in Aqueous Solution
title_short	Adsorption Features of Loess Calcareous Nodules to Heavy-Metal Ions in Aqueous Solution
title_full	Adsorption Features of Loess Calcareous Nodules to Heavy-Metal Ions in Aqueous Solution
title_fullStr	Adsorption Features of Loess Calcareous Nodules to Heavy-Metal Ions in Aqueous Solution
title_full_unstemmed	Adsorption Features of Loess Calcareous Nodules to Heavy-Metal Ions in Aqueous Solution
title_sort	adsorption features of loess calcareous nodules to heavy-metal ions in aqueous solution
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/0175833b94b5474c86cd899c01a5e1cf
work_keys_str_mv	AT qili adsorptionfeaturesofloesscalcareousnodulestoheavymetalionsinaqueoussolution AT yananli adsorptionfeaturesofloesscalcareousnodulestoheavymetalionsinaqueoussolution
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Adsorption Features of Loess Calcareous Nodules to Heavy-Metal Ions in Aqueous Solution

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