Zinc and cadmium adsorption on low-grade phosphate

A comprehensive assessment of the environmental risks posed by engineered nanomaterials (ENMs) entering the environment is necessary, due in part to the recent predictions of ENM release quantities and because ENMs have been identified in waste leachate. The technical complexity of measuring ENM fate and transport processes in all environments necessitates identifying trends in ENM processes. Emerging information on the environmental fate and toxicity of many ENMs was collected to provide a better understanding of their environmental implications. Little research has been conducted on the fate of ENMs in the atmosphere; however, most studies indicate that ENMs will in general have limited transport in the atmosphere due to rapid settling. Studies of ENM fate in realistic aquatic media indicates that in general, ENMs are more stable in freshwater and stormwater than in seawater or groundwater, suggesting that transport may be higher in freshwater than in seawater. ENMs in saline waters generally sediment out over the course of hours to days, leading to likely accumulation in sediments. Dissolution is significant for specific ENMs (e.g., Ag, ZnO, copper ENMs, nano zero-valent iron), which can result in their transformation from nanoparticles to ions, but the metal ions pose their own toxicity concerns. In soil, the fate of ENMs is strongly dependent on the size of the ENM aggregates, groundwater chemistry, as well as the pore size and soil particle size. Most groundwater studies have focused on unfavorable deposition conditions, but that is unlikely to be the case in many natural groundwaters with significant ionic strength due to hardness or salinity. While much still needs to be better understood, emerging patterns with regards to ENM fate, transport, and exposure combined with emerging information on toxicity indicate that risk is low for most ENMs, though current exposure estimates compared with current data on toxicity indicates that at current production and release levels, exposure to Ag, nZVI, and ZnO may cause toxicity to freshwater and marine species.

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“…However, Zn 2? can form precipitates with phosphate (Kandah 2004), which can reduce the dissolved Zn 2? concentrations.…”

Section: Dissolution In Watermentioning

confidence: 99%

Emerging patterns for engineered nanomaterials in the environment: a review of fate and toxicity studies

2014

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“…Significant product yield can also be observed depending on the origin of the carbon material [14]. The pH of the solution affects the surface charge of the adsorbents as well as the degree of ionization and speciation of different pollutants [15]. It is known that metal species (M) are present in deionized water in the form of M 2+, M(OH) 2 , and so on [16].…”

Section: Physico-chemical Characterisation Of the Activated Carbonmentioning

confidence: 99%

Physico-chemical Characterization and Comparative Studies of Some Heavy Metals Using Activated Carbon from Date Palm Seed

Uwem¹

2017

AAS

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Activated carbon from date palm seed was analyzed to ascertain the physicochemical parameters and conduct comparative studies [with industrial activated carbons-Powdered Activated Carbon (PAC) and Granular Activated Carbon (GAC)] of some heavy metals (Cd, Pb, Co, Mn and Cr) present using standard analytical techniques. The physicochemical parameters of the activated carbon as determined were: Bulk density (0.69 g/ml), Ash content (6.92%), Iodine value (10.38 mg/g), Volatile organic matter (7.63%), pH (6.92) and Moisture content (0.60%). The result also showed that date palm seed activated carbon adsorbed more of the Pb, as well as Cr better than the industrial activated carbon (GAC and PAC). The XRD result showed that the carbon has an amorphous structure which agrees with diffractogram of other activated carbons.

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“…There are several methods to treat the metal contaminated effluent, but the selection of the wastewater treatment methods is based on the concentration of waste and the cost of treatment [6][7][8][9][10][11][12][13][14][15]. However, these methods are either inefficient or expensive especially when the concentration of the heavy metal ion is low, in the range of 1-100 mg/L [16].…”

Section: Introductionmentioning

confidence: 99%

Activated and Nonactivated Date Pits Adsorbents for the Removal of Copper(II) and Cadmium(II) from Aqueous Solutions

Hilal

Ahmed

El-Sayed

2012

ISRN Physical Chemistry

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The present study aims to investigate the adsorption behavior of Cu(II) and Cd(II) ions from wastewater onto low-cost adsorbents either raw date pits (RDP), cheap agricultural and nontoxic materials, or chemically activated carbon (ADP) prepared by modified date pits using phosphoric acid. A series of experiments were conducted in a batch system to evaluate the effect of system variables. The adsorption process is affected by various parameters such as solution pH, contact time, initial concentrations of metals, and adsorbent dose. The optimum pH required for maximum adsorption was found to be 5.8 ± 0.5. The experimental data were tested using Langmuir, Freundlich, Dubinin-Radushkevich (D-R) isotherm equations. It was observed that the adsorption capacity of date pits increased after treatment with phosphoric acid. The maximum uptake capacities (Q m ) were 7.40 and 33.44 mg copper(II) per gram of RDP and ADP, respectively, while 6.02 and 17.24 mg cadmium(II) per gram of RDP and ADP, respectively. The results showed that although the equilibrium data could be described by the three models used, Langmuir model gave slightly better results while Freundlich model gave better results when using raw and activated date pits.

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Zinc and cadmium adsorption on low-grade phosphate

Cited by 115 publications

References 15 publications

Emerging patterns for engineered nanomaterials in the environment: a review of fate and toxicity studies

Emerging patterns for engineered nanomaterials in the environment: a review of fate and toxicity studies

Physico-chemical Characterization and Comparative Studies of Some Heavy Metals Using Activated Carbon from Date Palm Seed

Activated and Nonactivated Date Pits Adsorbents for the Removal of Copper(II) and Cadmium(II) from Aqueous Solutions

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