Polymer-based nanocomposites for heavy metal ions removal from aqueous solution: a review

The rapid increase in industrialization and globalization in the last few decades has led to increased disposal of heavy metals in the environment leading to severe water and soil contamination. Among all known pollutants, heavy metals are especially notorious due to their high toxicity, persistent and bioaccumulative nature. Heavy metal toxicity is a major threat and therefore its removal and remediation require special attention to protect human, animal and plant health and to restore soil and water quality. Waste tea leaves (Camellia sinensis) are low-cost adsorbents and their use for the removal of heavy metal ions is likely to address the problems of waste management and heavy metal ion toxicity. In the present study, we have tested the efficacy of waste tea leaves for the quantitative removal of heavy metal ions like Ni(II) and Pb(II) from their aqueous test solutions using spectrophotometric and titrimetric methods respectively. With 5 g tea leaves in the Ni(II) solution, the removal percentage of the ion was found to be 85.56%. From a Pb(II) containing test solution, 286 ppm of the ion was adsorbed by the same amount of tea leaves. The amount of adsorbent dose was found to be directly related to the removal percentage of the metal ion. However, after reaching a threshold, increasing the adsorbent dose has only a negligible effect on adsorption. The adsorption was found to be primarily physisorption and follows Freundlich's adsorption isotherm. The zero-cost and easy availability of waste tea leaves make it a substrate of interest that can be used for the cost-effective removal of heavy metal ions from water and soil.

ABSTRACTA hyper‐crosslinked resin chemically modified with thiourea (TM‐HPS) was synthesized, characterized, and evaluated for the removal of heavy metal ions (Pb2+, Cd2+, and Cu2+) from aqueous solutions. The structural characterization results showed that a few thiourea groups were grafted on the surface of the resin with a big BET surface area and a large number of narrow micropores. Various experimental conditions such as pH, contact time, temperature, and initial metal concentration of the three heavy metal ions onto TM‐HPS were investigated systematically. The results indicated that the prepared resin was effective for the removal of the heavy metal ions from aqueous solutions. The isotherm data could be better fitted by Langmuir model, yielding maximum adsorption capacities of 689.65, 432.90, and 290.69 mg/g for Pd2+, Cd2+, and Cu2+, respectively. And the adsorption kinetics of the three metal ions followed the pseudo‐second‐order equation. FTIR and XPS analysis of TM‐HPS before and after adsorption further revealed that the adsorption mechanism could be a synergistic effect between functional groups and metal ions and electrostatic attraction, which may provide a new insight into the design of highly effective adsorbents and their potential technological applications for the removal of heavy metal ions from aqueous solutions. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45568.

The possibility of using the sorption technology to reduce the levels of metal ions present in urban storm-water runoff was investigated in this study. Seven sorbent materials including Amberlite XAD7, chitosan, crab shell, peat, Sargassum, sawdust, and sugarcane bagasse were initially examined for removal of 11 metal ions (Na, K, Ca, Mg, Mn, Co, Ni, Cu, Zn, Cd, and Pb) from simulated storm-water runoff at different concentrations. Among these sorbents, crab shell performed well with removal efficiencies exceeding 93% for all heavy metal ions examined and thus selected for further studies. Based on scanning electron microscopy/energy-dispersive x-ray analysis, microprecipitation of metal carbonates followed by adsorption onto the surface of crab shell was identified as the major mechanism responsible for removal of heavy metal ions by crab shell. Crab shell exhibited rapid removal of meal ions with attainment of biosorption equilibrium within 20 min. A crab-shell-packed column was used to study the continuous metal retention process. The column performed very well in the removal of heavy metal ions and was able to operate up to 192 h at a flow rate of 10 mL/min before outlet concentrations of Mn and Co reached 0.3 times of their respective inlet concentrations. Other metal ions such as Pb, Zn, Ni, Cd, and Cu were only in trace levels in the final effluent until 192 h. These findings would form the basis for the future development of crab-shell-based biofilters for removal of dissolved heavy metal ions from storm-water runoff.

Levels of Pb(II), Cu(II), Zn(II), Mn(II), and Co(II) ion in aqueous solutions were determined by atomic absorption spectrometry (AAS) technique after preconcentration on diethyl dithiocarbamate supported by EDTA modified charcoal from Khaya senegalensis wood. The sorbed elements were eluted with acid and subsequently analyzed. The influence of pH, contact time and initial metal ion concentration by the modified charcoal was investigated. At 90 min contact time the uptake level of metal ions from solution was found to depend on the metal ion-substrate contact time, ion concentration and ion type. The percentage recovery of the metals ions retained by modified charcoal was highest at pH 5. The sorption recovery for the metal ions was within the range of 95.1-99.8%. It was observed that EDTA modification of charcoal significantly improved the percentage recovery of the metal ions. The results obtained from the study showed EDTA modified charcoal to be favourable for preconcentration and removal of heavy metal ions from aqueous solution. Key words: Preconcentration, removal, heavy metals, modified charcoal, environmental pollution.

The manuscript discusses the role of polysaccharides and their derivatives in the removal of metal ions from industrial wastewater. Quick modernization and industrialization increase the amount of various heavy metal ions in the environment. Heavy metals can cause various diseases in humans and also drastic environmental hazards. In this review, the recent advancement for the adsorption of heavy metal ions from wastewater by using different methods has been studied. Various natural polymers and their derivatives act as effective adsorbents for the removal of heavy metal ions from the wastewater released from the industries and the treated water released into the environment can decrease the probability of diseases in humans and environmental hazards. From the literature surveys, it was concluded that the removal of heavy metal ions from industrial wastewater is beneficial for humans as well as for environment. Graft copolymers act as the most efficient adsorbents for the removal of heavy metal ions and most of these follow the pseudo-first-order and pseudo-second-order model of kinetics.

The adsorption of heavy metal cations, Pb(II), Cd(II), Cu(II), Zn(II) and Fe(II) from aqueous solution by newly-synthesized tamarind 4-hydroxybenzoic acid (THBA) resin was investigated. The resin was characterised on the basis of FTIR, elemental analysis, ion-exchange capacity and physico-chemical properties. The distribution coefficients (Kd) and percentage adsorption of metal ions on resin were determined by batch methods using atomic absorption spectrophotometry (AAS). The effect of experimental parameters, such as pH, treatment time, temperature, adsorbent dose, initial metal ion concentration and flow rate, on the removal of metal ions was also studied. THBA resin proved to be an effective adsorbent for the removal of different heavy metal ions from aqueous solution; removal efficiency followed the order: Fe(II) > Cu(II) > Zn(II) > Cd(II) > Pb(II). These results suggest that the cation exchange resin THBA holds great potential to remove cationic heavy metal species from industrial wastewater.

Novel adsorptive PVC nanofibrous/thiol-functionalized TNT composite UF membranes for effective dynamic removal of heavy metal ions

Review: 157 refs.

Biosorption of heavy metals from aqueous solutions is a relatively new technology for the treatment of industrial wastewater, which utilized naturally occurring waste materials derived from biomass. Generaly Heavy metals eliminated by biosorption are usually classified on three categories: toxic metals (such as Hg, Cr, Pb, Zn, Cu, Ni, Cd, As, Co, Sn, etc.), precious metals (such as Pd, Pt, Ag, Au, Ru etc.) and radionuclides (such as U, Th, Ra, Am, etc.), whose specific weight is usually more than 5.0 g/cm3 [Bishop, 2002; Volesky, 1990; Wang & Chen, 2006]. The heavy metal ions are stable and persistent environmental contaminants since they cannot be degraded and destroyed. These metal ions can be harmful to aquatic life and water contaminated by toxic metal ions remains a serious public health problem for human health. Numerous methods exist to remove heavy metals ions from aqueous solutions by chemical precipitation or by activated carbon as the most used adsorbent, nevertheless it is relatively expensive [Demirbas, 2008; Gabaldon et al, 1996]. The toxicity of heavy metals is apparent in reducing growth and development in microorganisms and plants, and seriously harming the health of animals and humans. In particular, heavy metals may disrupt the normal function of the central nervous system and cause changes in the blood content, and adversely affect the function of lungs, kidneys, liver and other organs. The long-term action of heavy metals may cause the development of cancer, allergy, dystrophy, physical and neurological degenerative processes, Alzheimer's and Parkinson's diseases. However, in small amounts, heavy metals are indispensable for many organisms, but their enhanced doses induce acute or chronic poisoning [Kvesitadze et al, 2006] Adsorbent materials derived from Biomass can be used for the effective removal and recovery of heavy metal ions from wastewater: from algae [Farooq et al, 2010; Hamdy, 2000], fungi [Kapoor et al., 1999], bacteria [Ozturk, 2007], sea-weeds [Elangovan et al., 2008], some higher plants (Rahman et al., 2005), and agricultural wastes[Demirbas, 2008; Park et al, 2006]. Several reviews articles have been published about the use of certain cellulosic agricultural waste materials for the removal of heavy metal ions [Sud et al., 2008], the use of microbial

Biosorption of heavy metal ions from aqueous solution by red macroalgae

Novel tyrosine-containing inorganic–organic hybrid adsorbent in removal of heavy metal ions

Removal of heavy metal ions from soils by electrokinetic treatment has several advantages. The extent of removal, however, is both soil specific and ion specific. The conditions to be maintained have to be established based on laboratory studies. With a view to maximize the removal of metal ions the trends of removal of heavy metal ions such as iron, nickel and cadmium form a natural Indian kaolinitic red earth during different conditions maintained in the electrokinetic extraction process are studied. A laboratory electrokinetic extraction apparatus was assembled for this purpose. Attempts are also made to elucidate the mechanism of removal of the metal ions from soil. The composition of the flushing fluid, voltage and duration of extraction are varied. While dilute acetic acid has been used to neutralize the alkalinity that develops at the cathode, EDTA solution has been used to desorb heavy metals from clay surface. Generally the extent of removal was proportional to the osmotic flow. Nickel and Cadmium are more effectively removed than iron. The percentage removal of Ni is generally proportional to the osmotic flow but shows sensitivity to the pH of the system. There is an optimum voltage for removal of metal ions from soil. The removal of iron was negligible under different conditions studied.

UiO series of metal-organic frameworks composites as advanced sorbents for the removal of heavy metal ions: Synthesis, applications and adsorption mechanism

Utility of chemically modified agricultural waste okra biomass for removal of toxic heavy metal ions from aqueous solution

A novel magnetic polysaccharide composite hydrogel was successfully constructed by using sodium alginate (SA) and carboxymethyl cellulose (CMC) as the backbone and filled with in situ Fe3O4 nanoparticles, which was then employed for removal of heavy metal ion from aqueous solution. The obtained magnetic SA/CMC composite hydrogel was characterized by Fourier transform infrared spectroscopy, fluorescence microscope, thermogravimetric and vibrating sample magnetometer. Effect of contact time, pH and adsorbent dosage on the adsorption of heavy metal ions by the magnetic SA/CMC hydrogel have also been studied. The results show that the prepared magnetic SA/CMC hydrogel can be effectively utilized in the removal of heavy metal ions from aqueous solution. The maximal adsorption capacity of Mn(II), Pb(II), and Cu(II) as calculated from the Langmuir model were 71.83, 89.49, and 105.93 mg/g, respectively. The adsorption process of the magnetic SA/CMC hydrogel on the heavy metal ions can be attributed to ion exchange and chemical adsorption. What’s more, the magnetic hydrogel exhibited high efficiency after four cycles, which indicating it offers great potential for practical application in the removal of heavy metal ions from aqueous solution.