scholarly journals Insights into the Recent Use of Modified Adsorbents in Removing Heavy Metal Ions from Aqueous Solution

2021 ◽  
Vol 12 (2) ◽  
pp. 1884-1898

Natural water gets contaminated with heavy metal ions because of industrial effluents' discharge into the aquatic environment. As these heavy metal ions cause various health hazards, they should be removed from the aqueous solution. Heavy metal ion concentration in the aqueous solution is very less, so conventional metal removal and recovery processes cannot be applied here. The adsorption method is a great alternative to all these processes as it is a cost-effective and easy method. The use of natural, low-cost materials as adsorbents is eco-friendly also. However, metal uptake capacity of low-cost materials is very less. So, modification is required for low-cost materials to increase their efficiency. In the present review, different modification procedures adopted by different researchers have been discussed. Different low-cost materials used are sawdust, fruit and vegetable wastes, soil, minerals, etc. The modifying agents are heat, acids, bases, and other chemicals. Nevertheless, most of the studies are limited to batch tests only. Future research should be carried out on the extension of batch tests to column study for the large-scale treatment of contaminated water, and the cost of modification procedures and their impact on the environment should also be assessed.

2002 ◽  
Vol 20 (7) ◽  
pp. 607-617 ◽  
Author(s):  
Adil Denizli ◽  
Bora Garipcan ◽  
Sibel Emir ◽  
Süleyman Patir ◽  
Ridvan Say

Details of the adsorption performance of poly(2-hydroxyethylmethacrylate–methacrylamidocysteine) [p(HEMA–MAC)] beads towards the removal of heavy metal ions from aqueous solution were studied. The metal-complexing ligand and/or co-monomer MAC was newly synthesized from methylacrylochloride and cysteine. Spherical beads of average size 150–200 mm were obtained by the radical suspension polymerization of MAC and HEMA conducted in an aqueous dispersion. The p(HEMA–MAC) beads obtained had a specific surface area of 18.9 m2/g. p(HEMA–MAC) beads were characterized by swelling studies, FT-IR spectroscopy and elemental analysis. Such beads with a swelling ratio of 72%, and containing 3.9 mmol MAC/g, were used for heavy metal removal studies. The adsorption capacities of the beads for selected metal ions, i.e. CdII, AsIII, CrIII, HgII and PbII, were investigated in aqueous media containing different amounts of these ions (10–750 mg/l) and at different pH values (3.0–7.0). The adsorption rate was fast in all cases. The maximum adsorption capacities of the p(HEMA–MAC) beads were 1058.2 mg/g for CdII, 123.4 mg/g for AsIII, 199.6 mg/g for CrIII, 639.1 mg/g for PbII and 1018.6 mg/g for HgII. On a molar basis, the following affinity order was observed: CdII > HgII > CrIII > PbII >AsIII. The adsorption capacity of the MAC-incorporated beads was affected significantly by the pH value of the aqueous medium. The adsorption of heavy metal ions from artificial wastewater was also studied. In this case, the adsorption capacities were 52.2 mg/g for CdII, 23.1 mg/g for CrIII, 83.4 mg/g for HgII, 62.6 mg/g for PbII and 11.1 mg/g for AsIII at an initial metal ion concentration of 0.5 mmol/l. The chelating beads could be regenerated easily with a higher effectiveness by 0.1 M HNO3. These features make p(HEMA–MAC) beads potential candidates for heavy metal ion removal at high capacity.


This study showed that kaolinite clay modified with Moringa oleifera pods is a promising low cost adsorbent for the removal of metals from aqueous solution because the resultant composite has higher adsorption capacities, and hence a better metal ions removal efficiency. The efficiencies of these adsorbents for the removal of Pb (II) and Cd (II) ions from aqueous solutions were studied as a function of pH, time, adsorbate concentration and adsorbent dose. Adsorption results showed that pH did significantly affect removal of heavy metal ions between pH 3 and 6. Increasing contact time and initial metal ion concentration increased the sorption capacity of the adsorbent for the metal ions. Adsorbent dosage indicated mainly surface phenomena involving sharing of electrons between the adsorbent surface and the metal ion species. The adsorption of metal ions from aqueous solutions of both metal ions at different initial metal ion concentrations reduced the initial adsorption rates of the adsorption of Pb (II) and Cd (II) by unmodified and modified kaolinite clay.


2018 ◽  
Vol 18 (3) ◽  
pp. 472
Author(s):  
Venty Suryanti ◽  
Sri Hastuti ◽  
Tutik Dwi Wahyuningsih ◽  
Mudasir Mudasir ◽  
Dian Kresnadipayana ◽  
...  

The batch removal of Cu(II), Cd(II) and Pb(II) from individual heavy metal ion aqueous synthetic solution using biosurfactants produced by Pseudomonas aeruginosa with corn oil as substrate was investigated. The metal ion removal process of crude preparation biosurfactants (CPB) was established to be dependent on the initial pH and contact time. The optimum metal removal was observed at pH 6.0 of the initial metal solution and 10 min of contact time. The affinity sequence for metal ion removal was Pb(II)>Cd(II)>Cu(II). The removal capacity value of biosurfactant for Cu(II), Cd(II) and Pb(II) from single metal ions solution were 0.169, 0.276 and 0.323 mg/g, respectively. The removal capacity value of biosurfactant for Cu(II), Cd(II) and Pb(II) from multi metal ions solution were 0.064, 0.215 and 0.275 mg/g, respectively. The removal capacity of individual metal ion was diminished by the presence of other metal ions in multi metal ions from synthetic aqueous solution. The removal capacity value of biosurfactant for Cu(II), Cd(II) and Pb(II) from silver industry wastewater were 0.027, 0.055 and 0.291 mg/g, respectively. The results indicated that biosurfactants have potential to be used in the remediation of heavy metals in industrial wastewater.


2011 ◽  
Vol 236-238 ◽  
pp. 237-240 ◽  
Author(s):  
Xue Yi Guo ◽  
Sha Liang ◽  
Qing Hua Tian

In this study, orange peel (OP) was modified by KCl to prepare a novel orange peel adsorbent named as KOP. The adsorption behaviors of KOP for five heavy metals (Cu2+, Cd2+, Pb2+, Zn2+, Ni2+) were studied. The effects of pH, adsorption time and metal ion concentration on single heavy metal solution adsorption by KOP were investigated. All adsorption processes can attain equilibrium with 20min and kinetics data of five heavy metal ions were fitted to pseudo-second-equation; the maximum adsorption capacities for Cu2+, Cd2+, Pb2+, Zn2+and Ni2+were calculated as 59.77, 125.63, 141.84, 45.29 and 49.14 mg/g, respectively. Recycle and reuse experiments indicate that KOP could be used for more than 10 cycles. The effect of coexist metal ions on adsorption can be neglected.


Author(s):  
Zeynab Karimi ◽  
Reza Khalili ◽  
Mohammad Ali Zazouli

Abstract In this study, polythiophene/Al2O3 (PTh/Al2O3) and polyaniline/Al2O3 (PAn/Al2O3) nanocomposites in the presence of poly(vinyl alcohol) (PVA) as the surfactant were synthesized via in situ chemical oxidative polymerization method in aqueous medium. The synthesized nanocomposites were characterized by Scanning electron microscopy (SEM), Fourier transform-infrared (FTIR) spectroscopy and X-ray diffraction (XRD). Results indicated that the Al2O3 and poly(vinyl alcohol) influenced the properties of synthesized nanocomposites. The aim of this research was to investigate the sorption characteristic of polythiophene and polyaniline nanocomposites for the removal of heavy metal cations including Pb(II), Zn(II) and Cd(II) from aqueous solution. The factors that affected the adsorption equilibrium as well as the removal efficiency of the nanoadsorbents, i.e., contact time, metal ion concentration, pH and adsorption conditions were investigated in detail. From the kinetic results, it was concluded that the pseudo-second-order kinetic model was found to the best at describing the adsorption process for Pb(II), Zn(II) and Cd(II) on PTh-PVA/Al2O3 and PAn-PVA/Al2O3. In addition, thermodynamic analysis suggests the endothermic and spontaneous nature of the present adsorption process with increased entropy on PTh-PVA/Al2O3 and PAn-PVA/Al2O3. The results suggest polythiophene, polyaniline and their nanocomposites have great potential to be used as efficient absorbent for the removal of heavy metal ions from water.


Author(s):  
Gharde A. D. ◽  
Gharde B. D.

This work reports the characterization of intensive industrial and agricultural activity is the basic reason of enormous pollution of the environment. Heavy metals generally occur in water in low concentration as a result of metal industries and partly through geological processes, but these cause direct toxicity both to human and other living beings. Due to their presence obeyed the specified limit. Heavy metals in wastewater has emerged as focus of environment remediation efforts of industrialization, urbanization with new technological advantages. The natural bodies of water are polluted by means of different contaminant like organic refractories, heavy metal ions etc. The significant concentration of some of the heavy metal ions in water are toxic to human being, animals as well as aquatic organisms. Some heavy metal ions even at the trace level has been recognized toxic to the public health. Many metals have been evaluated toxic to aquatic life certain to threshold toxicity level. The effect of tree bark for Cu(II) from copper sulphate on the metal content of industrial wastewater was investigated in the pH of 4-6. It is observed that the method of binding follows the first order adsorption rate expression such as effect of pH, agitation time, doses of bark substrate, initial metal ion concentration, effect of varying temperature were also studied.


2002 ◽  
Vol 20 (2) ◽  
pp. 119-129 ◽  
Author(s):  
R. Saliba ◽  
H. Gauthier ◽  
R. Gauthier ◽  
M. Petit-Ramel

Eucalyptus barks harvested in Lebanon were used for the adsorption of pollutants such as heavy metal ions and dyes. Washing with water or pretreatment with formaldehyde was performed on the bark powder. The adsorption capacity of this material towards CuII, CrIII, CdII and NiII was evaluated in a batch process for various parameters. The results obtained showed that the retention capacity increased with contact time, pH and initial metal ion concentration but decreased with temperature. The adsorption capacities were 2.61, 0.71, 2.24 and 0.75 mmol/g adsorbent for CuII, CrIII, CdII and NiII, respectively. Eucalyptus barks are also very efficient for the adsorption of dyes (Acid Blue 25, Erichrome Blue Black B and Calmagite) because of interaction between the hydroxy and amino groups of the dyes and the phenolic moities of bark. This adsorption was modified when metal ions had already been adsorbed on to the barks as a result of the formation of a 1:1 complex between the dye and the metal ion. Desorption was achieved by treating with the sodium salt of ethylenediamine-tetraacetic acid (EDTA) for metal ions and by heating at 75°C in aqueous medium for dyes. After desorption, the recycling of the support was tested for potential use as a means of concentrating pollutants.


BioResources ◽  
2015 ◽  
Vol 11 (1) ◽  
Author(s):  
Ahmed H. El-Naggar ◽  
Abdalwahab K. R. Alzhrani ◽  
Mahtab Ahmad ◽  
Adel R. A. Usman ◽  
Dinesh Mohan ◽  
...  

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3946
Author(s):  
Mihai Negroiu ◽  
Anca Andreea Țurcanu ◽  
Ecaterina Matei ◽  
Maria Râpă ◽  
Cristina Ileana Covaliu ◽  
...  

Due to its valuable compounds, food waste has been gaining attention in different applications, such as life quality and environment. Combined with circular economy requirements, a valorization method for waste, especially banana waste, was to convert them into adsorbents with advanced properties. The banana waste, after thermal treatment, was used with high removal performances (100%) for the removal of heavy metals, such as Cr, Cu, Pb, and Zn, but their small particle size makes them very hard to recover and reuse. For this reason, a biopolymeric matrix was used to incorporate the banana waste. The matrix was chosen for its remarkable properties, such as low cost, biodegradability, low carbon footprint, and reduced environmental impact. In this research, different types of materials (simple banana peel ash BPA and combined with biopolymeric matrix, ALG–BPA, CS–BPA) were prepared, characterized, and tested. The materials were characterized by means of attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), optical microscopy (OM), scanning electron microscopy (SEM), and tested for the removal of metal ions from synthetic solutions using atomic absorption spectroscopy (AAS). The ALG–BPA material proved to be the most efficient in the removal of heavy metal ions from synthetic solution, reaching even 100% metal removal for Cr, Fe, Pb, and Zn, while the CS-based materials were the least efficient, presenting the best values for Cr and Fe ions with a removal efficiency of 34.14% and 28.38%, respectively. By adding BPA to CS, the adsorption properties of the material were slightly improved, but also only for Cr and Fe ions, to 37.09% and 57.78%.


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