scholarly journals Layered Double Hydroxides as Effective Adsorbents for U(VI) and Toxic Heavy Metals Removal from Aqueous Media

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
G. N. Pshinko

Capacities of different synthesized Zn,Al-hydrotalcite-like adsorbents, including the initial carbonate [Zn4Al2(OH)12]·CO3·8H2O and its forms intercalated with chelating agents (ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), and hexamethylenediaminetetraacetic acid (HMDTA)) and heat-treated form Zn4Al2O7, to adsorb uranium(VI) and ions of toxic heavy metals have been compared. Metal sorption capacities of hydrotalcite-like adsorbents have been shown to correlate with the stability of their complexes with the mentioned chelating agents in a solution. The synthesized layered double hydroxides (LDHs) containing chelating agents in the interlayer space are rather efficient for sorption purification of aqueous media free from U(VI) irrespective of its forms of natural abundance (including water-soluble bi- and tricarbonate forms) and from heavy metal ions. [Zn4Al2(OH)12]·EDTA·nH2O is recommended for practical application as one of the most efficient and inexpensive synthetic adsorbents designed for recovery of both cationic and particularly important anionic forms of U(VI) and other heavy metals from aqueous media. Carbonate forms of LDHs turned out to be most efficient for recovery of Cu(II) from aqueous media withpH0≥7owing to precipitation of Cu(II) basic carbonates and Cu(II) hydroxides. Chromate ions are efficiently adsorbed from water only by calcinated forms of LDHs.

2011 ◽  
Vol 194-196 ◽  
pp. 2365-2375
Author(s):  
Jai Houng Leu ◽  
Li Fong Wu ◽  
Ay Su

This research investigated and explored the overall technical and legal suggestions on mixed ash (bottom ash + fly ash) from the first BOT(built-operation then transfer) incineration plant in south Taoyuan of Taiwan, with the hope of serving as the reference for treating ash from urban refuse incinerator and making sustainable operation management policies in Taiwan. Both bottom ash and fly ash contain high-content harmful metals like lead, chrome, and cadmium, with the lead content exceeding standard value. Plasma fusing technology may effectively settle toxic heavy metals and reduce their dissolution rate. The results show that the increase in percentage of bottom ash could maintain post-fusing strength and produce solidification effect, but this reduced the stability of toxic heavy metals and raised their dissolution rate. Suitable mixture ratio of bottom ash and fly ash was 2:1, volume reduction ratio 0.349, and weight reduction ratio 0.4936. The mixture was fulvous and dense with gloss and adequate strength. The dissolution test of lava products complied with national standards, and they might be used for recycling aggregates and solidifying cement.


Water ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 2659
Author(s):  
Muhammad Zaim Anaqi Zaimee ◽  
Mohd Sani Sarjadi ◽  
Md Lutfor Rahman

Natural occurrence and anthropogenic practices contribute to the release of pollutants, specifically heavy metals, in water over the years. Therefore, this leads to a demand of proper water treatment to minimize the harmful effects of the toxic heavy metals in water, so that a supply of clean water can be distributed into the environment or household. This review highlights several water treatment methods that can be used in removing heavy metal from water. Among various treatment methods, the adsorption process is considered as one of the highly effective treatments of heavy metals and the functionalization of adsorbents can fully enhance the adsorption process. Therefore, four classes of adsorbent sources are highlighted: polymeric, natural mineral, industrial by-product, and carbon nanomaterial adsorbent. The major purpose of this review is to gather up-to-date information on research and development on various adsorbents in the treatment of heavy metal from water by emphasizing the adsorption capability, effect of pH, isotherm and kinetic model, removal efficiency and the contact of time of every adsorbent.


Author(s):  
Khushboo Chaudhary ◽  
Suphiya Khan ◽  
Pankaj Kumar Saraswat

The heavy metal pollution problem is all over the world. Plant-growth-promoting bacteria (PGPB) has transformed heavy metals present in the soil, which removes and minimizes their toxic effects. This chapter highlights the role of plant-growth-promoting bacteria, chelating agents, and nanoparticles for remediation of heavy metals; their mechanism of action; and their applications approach of hyperaccumulation. Therefore, this chapter focuses on the mechanisms by which microorganisms, chelating agents, and nanoparticles can mobilize or immobilize metals in soils and the nano-phytoremediation strategies are addressed for the improvement of phytoextraction as an innovative process for enhancement of heavy metals removal from soil.


Processes ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 645 ◽  
Author(s):  
Mohamed A. Tahoon ◽  
Saifeldin M. Siddeeg ◽  
Norah Salem Alsaiari ◽  
Wissem Mnif ◽  
Faouzi Ben Rebah

The discharge of toxic heavy metals including zinc (Zn), nickel (Ni), lead (Pb), copper (Cu), chromium (Cr), and cadmium (Cd) in water above the permissible limits causes high threat to the surrounding environment. Because of their toxicity, heavy metals greatly affect the human health and the environment. Recently, better remediation techniques were offered using the nanotechnology and nanomaterials. The attentions were directed toward cost-effective and new fabricated nanomaterials for the application in water/wastewater remediation, such as zeolite, carbonaceous, polymer based, chitosan, ferrite, magnetic, metal oxide, bimetallic, metallic, etc. This review focused on the synthesis and capacity of various nanoadsorbent materials for the elimination of different toxic ions, with discussion of the effect of their functionalization on the adsorption capacity and separation process. Additionally, the effect of various experimental physicochemical factors on heavy metals adsorption, such as ionic strength, initial ion concentration, temperature, contact time, adsorbent dose, and pH was discussed.


2005 ◽  
pp. 3694 ◽  
Author(s):  
Gregory G. Wildgoose ◽  
Henry C. Leventis ◽  
Andrew O. Simm ◽  
John H. Jones ◽  
Richard G. Compton

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