Selective removal of heavy metals by hydrotalcites as adsorbents in diverse wastewater: Different intercalated anions with different mechanisms

Ali, Jawad; Peng, Li; Liang, Zongxia; Zhou, Zhi‐Hua; Shahzad, Ajmal; Ifthikar, Jerosha; Min, Zhao; Chen, Zhuqi

doi:10.1016/j.jclepro.2018.11.234

Cited by 97 publications

(34 citation statements)

References 62 publications

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“…Characteristic peaks were found at 7.8, 3.96, 2.62, 2.34, 1.99, 1.59, and 1.52 Å, which refer to the d 003 , d 006 , d 012 , d 015 , d 018 , d 110 , and d 113 values, respectively [39]. The basal reflection at 7.8 Å indirectly suggested the presence of CO 3 2− as an interlayer anion in the Mg/Fe LDH [40,41]. The XRD pattern of LDHM sample, apart from the presence of pyroaurite, also showed reflections characteristic for halite and calcite.…”

Section: Resultsmentioning

confidence: 99%

Removal of Chromates and Sulphates by Mg/Fe LDH and Heterostructured LDH/Halloysite Materials: Efficiency, Selectivity, and Stability of Adsorbents in Single- and Multi-Element Systems

Matusik

Rybka

2019

Materials

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Industrial wastewaters often contain mobile and toxic anions that cannot be removed by precipitation techniques and most known adsorbents. Layered double hydroxides (LDH) are excellent scavengers of anions; however, their use in real applications is of minor importance owing to their swelling behavior and high cost of production. The performed research shows the possibility of obtaining Mg/Fe LDH using natural magnesite. Moreover, heterostructured LDH/halloysite materials were synthesized. The adsorption efficiency of these materials was very high in both single- and multi-element systems, confirming the LDH selectivity. This was with the exception of wastewaters containing a high concentration of chlorides, which clearly hampered the removal of Cr(VI) and S(VI). The measurements indicated that LDH dissolution took place to a small extent (<10 wt%). The LDH/halloysite materials showed lower efficiency than the raw LDH; however, the clay presence has several benefits in terms of future applications: (i) it significantly reduces the pH, especially in contrast to the calcined LDH, which enables the reuse or safe disposal of purified water; (ii) it reduces swelling of the composite, which opens the possibility for applications in column adsorption; (iii) it induces dual adsorption properties through additional cation adsorption; and (iv) it substantially lowers the price of the adsorbent.

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Section: Resultsmentioning

confidence: 99%

Removal of Chromates and Sulphates by Mg/Fe LDH and Heterostructured LDH/Halloysite Materials: Efficiency, Selectivity, and Stability of Adsorbents in Single- and Multi-Element Systems

Matusik

Rybka

2019

Materials

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“…Its charge changes as a function of solution pH and is mostly negative due to –COOH deprotonation. Therefore, in this study for its removal, a different class of materials was tested, i.e., layered double hydroxides (LDHs), which are also applied in catalysis, polymer chemistry, biomedicine, and wastewater treatment [ 10 , 11 , 12 , 13 , 14 , 15 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

Fumonisin B1 Interaction with Mg-Al and Mg-Fe Layered Double Hydroxides: Removal Efficiency and Mechanisms

Matusik

Deng

2020

Materials

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Mycotoxins in feed and food are highly toxic and pose a serious danger even at very low concentrations. The use of bentonites in animal diet can reduce toxin bioavailability. However, some mycotoxins like fumonisin B1 (FB1) form anionic species which excludes the use of negatively charged clays. Layered double hydroxides (LDH) with anion-exchange properties, in theory, can be perfect candidates to adsorb FB1. However, fundamental research on the use of LDH for mycotoxins removal is scarce and incomplete. Thus, the presented study was designed to explore such a possibility. The LDH materials with differing chemistry and layer charge were synthesized by co-precipitation both from metal nitrates and chlorides and were then tested for FB1 removal. XRD, FTIR, XPS, and chemical analysis were used for the LDH characterization and to obtain insight into the removal mechanisms. A higher adsorption capacity was observed for the Mg/Al LDH samples (~0.08–0.15 mol/kg) in comparison to the Mg/Fe LDH samples (~0.05–0.09 mol/kg) with no difference in removal efficiency between Cl and NO3 intercalated LDH. The adsorption capacity increased along with lower layer charge of Mg/Al and was attributed to the lower content of bonded carbonates and the increase of non-polar sites which led to matching between the adsorption domains of LDH with FB1. The FTIR analysis confirmed the negative effect of carbonates which hampered the adsorption at pH 7 and led to the highest adsorption at pH 5 (FB1 content ~15.8 ± 0.75 wt.%). The fast surface adsorption (1–2 min) was dominant and XRD analysis of the basal spacing indicated that no FB1 intercalation occurred in the LDH. The XPS confirmed a strong interaction of FB1 with Mg sites of LDH at pH 5 where the interaction with FB1 carboxylate moieties COO− was confirmed. The research confirmed a high affinity and selectivity of LDH structures towards anionic forms of FB1 mycotoxin.

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“…In this research, the Langmuir and Freundlich models [39,40] were used to describe the equilibrium relationship between Cu (II) adsorbed by ASHMA and the remaining ions in aqueous solution. The Langmuir model assumes that the surface of the adsorbent is uniform and the adsorption occurs in a monolayer.…”

Section: Adsorption Isothermmentioning

confidence: 99%

A Functionalized Silicate Adsorbent and Exploration of Its Adsorption Mechanism

et al. 2020

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Active silicate materials have good adsorption and passivation effects on heavy metal pollutants. The experimental conditions for the preparation of active silicate heavy metal adsorbent (ASHMA) and the adsorption of Cu(II) by ASHMA were investigated. The optimum preparation conditions of ASHMA were as follows: 200 mesh quartz sand as the raw material, NaOH as an activating agent, NaOH/quartz sand = 0.45 (mass fraction), and calcination at 600 • C for 60 min. Under these conditions, the active silicon content of the adsorbent was 22.38% and the utilization efficiency of NaOH reached 89.11%. The adsorption mechanism of Cu(II) on the ASHMA was analyzed by the Langmuir and Freundlich isotherm models, which provided fits of 0.99 and 0.98, respectively. The separation coefficient (R L ) and adsorption constant (n) showed that the adsorbent favored the adsorption of Cu(II), and the maximum adsorption capacity (Q max ) estimated by the Langmuir isotherm was higher than that of 300 mg/L. Furthermore, adsorption by ASHMA was a relatively rapid process, and adsorption equilibrium could be achieved in 1 min. The adsorbents were characterized by FT-IR and Raman spectroscopy. The results showed that the activating agent destroyed the crystal structure of the quartz sand under calcination, and formed Si-O-Na and Si-OH groups to realize activation. The experimental results revealed that the adsorption process involved the removal of Cu(II) by the formation of Si-O-Cu bonds on the surface of the adsorbent. The above results indicated that the adsorbent prepared from quartz sand had a good removal effect on Cu(II).The amorphous silica structure of active silicate materials makes their reactivity much stronger than that of crystalline silica and confers these materials with excellent adsorption properties for pollutants such as heavy metals [7][8][9]. Studies have shown that the silanol groups (Si-OH) in active silicate materials are the main determinants of surface chemistry [10] and can form covalent bonds and hydrogen bonds with some ions and molecules [11]. Heavy metals such as Cu(II), Cd(II), and Pb(II) in aqueous solution were found to be removed by forming surface adsorption complexes with surface silanol [12,13]. Our team used leaching residue from lead-zinc tailings with high silicon content as a raw material to prepare an active silicate heavy metal adsorbent, which showed a very high adsorption capacity for the heavy metals Cu, Pb, Cd and Zn. The saturated adsorption capacities were 3.40, 2.83, 0.66 and 0.62 mmol/g, respectively [14].Besides, when active silicate materials are applied to the remediation of heavy metals in soil, extractable heavy metals can be transformed into forms with relatively stable valence [15,16], and the heavy metal stress and accumulation in plants can be reduced [17]. Moreover, the active silicates can be absorbed by plants as nutrient elements to form phytoliths, which play an important role in increasing grain yield and enhancing photosynthesis, pest resistance, lodging resistance, and so on...

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Selective removal of heavy metals by hydrotalcites as adsorbents in diverse wastewater: Different intercalated anions with different mechanisms

Cited by 97 publications

References 62 publications

Removal of Chromates and Sulphates by Mg/Fe LDH and Heterostructured LDH/Halloysite Materials: Efficiency, Selectivity, and Stability of Adsorbents in Single- and Multi-Element Systems

Removal of Chromates and Sulphates by Mg/Fe LDH and Heterostructured LDH/Halloysite Materials: Efficiency, Selectivity, and Stability of Adsorbents in Single- and Multi-Element Systems

Fumonisin B1 Interaction with Mg-Al and Mg-Fe Layered Double Hydroxides: Removal Efficiency and Mechanisms

A Functionalized Silicate Adsorbent and Exploration of Its Adsorption Mechanism

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