Synthesis of a New Granulated Polyampholyte and its Sorption Properties

Currently, among various methods, polymer adsorbents are effective and widely used for the removal of non-ferrous and rare metal ions (Saad et al., 2011). Hence, polymer adsorbents are comparable to other recovery methods in terms of technical and economic efficiency, feasibility, and environmentally friendly technologies. Saad et al. (2011) crosslinked polyethylenimine (PEI) with epichlorohydrin (ECH) to afford a water-insoluble form and it was subsequently used as an adsorbent. As an extension of their study, (Saad et al., 2011; Saad et al., 2012), crosslinked polyethylenimine (CPEI) was phosphonated with phosphoric acid and formaldehyde for the selective removal of uranium ions. The binding affinity of phosphonated cross-linked polyethylenimine (PCPEI) with uranium ions as well as its regeneration for reuse were evaluated (Saad et al., 2012). The obtained polyampholyte exhibits up to 99% selectivity for uranium ions in the presence of competing metal ions (e.g. Mn, Ni, As).

Jeon and Kwon (2012) investigated the desorption characteristics of indium ions previously adsorbed on phosphorylated sawdust using various reagents such as HCl, HNO₃, NaCl, ethylenediaminetetraacetic acid, and nitrilotriacetic acid. Results revealed that HCl is the best desorption agent from an economic viewpoint, with an ~97% desorption efficiency for indium ions at an HCl concentration of 0.5 M. Moreover, an extremely high desorption efficiency (~94%) is observed for indium ions at a solid-to-liquid of 10.0, and desorption is rapidly completed in 60 min. Recycled phosphorylated sawdust maintains an 85% removal efficiency of indium ions in the 4th cycle. 

Elsharma et al. (2019) prepared a polyampholyte of nanocomposite bio-polymers, i.e., poly (N,N-diallyldimethylammonium chloride-co-acrylamide) grafted onto carboxymethyl cellulose/iron(III) oxide [P(DADMAC-AAM) CMC/Fe₂O₃] and poly(N,N-diallyldimethylammonium chloride-co-sodium acrylate grafted onto carboxymethyl cellulose/iron(III) oxide [P(DADMAC-SA)CMC/Fe₂O₃]], with various molar ratios of anionic groups and cationic groups using gamma radiation. The structure and morphology of the obtained materials were examined by Fourier transform infrared spectroscopy and scanning electron microscopy. Sorption batch sorption experiments were conducted using a radioactive indicator such as ⁶⁰Co to remove Co(II) P(DADMAC-AAm) CMC/Fe₂O₃ and P(DADMAC-SA) CMC/Fe₂O₃ were evaluated from aqueous solutions. Experimentally, P(DADMAC-AAm) CMC/Fe₂O₃ and P(DADMAC-SA) CMC/Fe₂O₃ exhibit high sorption capacities of 69.67 mg g^-1 and 75.17 mg g^-1 for Co(II), respectively, making them potential sorbents for the removal of Co(II) from water or wastewater.

Zeng and Li (2014) employed an ion-exchange resin method for the purification of heavy metal ions such as Cu²⁺ from chemical wastewater and investigated the effects of flow rate, pH, and temperature on Cu²⁺ removal using a microporous, strongly acidic cation exchanger of styrene type D001. Results revealed that at a flow rate of 1.5 mL/min, a pH of 6.0, and a temperature of 30°C, a 99.8% removal rate of Cu²⁺ is reported over D001. Chemical wastewater can reach wastewater discharge standard.

Smanova et al. (2011) investigated the efficiency of fibrous materials based on polyacrylonitrile (PAN) modified with hydroxylamine in organic and aqueous carriers, as well as with hexamethylenediamine and ethylenediamine. In addition, properties of the as-obtained fibrous sorbent for the sorption of iron(III) ions in an aqueous solution were examined.

Kiefer and Höll (2001) investigated the ion exchange of heavy metal ions (such as Cu²⁺, Ni²⁺, Cd²⁺, Zn²⁺, and Co²⁺) as well as Ca²⁺, Na⁺, and NH₄⁺, by two industrial processes using ion-exchange complex-forming resins comprising amino- and phosphate-containing functional groups (Purolite S 940 and S 950). The authors estimated sorption according to the theory of complexation of external surfaces, leading to a set of binary equilibrium sorption of ions, which remains unchanged in multi-ion systems. Kinetic parameters of the secondary, tertiary, and quaternary equilibria for sorption and the balance of complex agents in the industrial effluent formed during the processing of metal surfactants are proposed on the basis of equations that calculated theoretical values ??of sorption and compared with experimental data (Kiefer and Höll, 2001).

 Deepatana and Valix (2006) and Altun and Pehlivan (2007) independently investigated the release of trace amounts of non-ferrous and toxic metals using ion-exchange materials. Experiments were conducted using well-known industrial ion-exchange materials such as Lewatit CNP 80 and Lewatit TP 207 (Altun and Pehlivan, 2007). Authors investigated the effect of pH among solutions, sorption duration, metal ion concentration, and ion-exchanger amount during sorption. The examined complex media (Deepatana and Valix, 2006) exhibit a higher and more rapid sorption capacity for metal ions such as Pb(II), Cu(II), Zn(II), Cd(II), and Ni(II). The optimal pH range of solutions for the ion exchange of the above metal ions on Lewatit CNP 80 and Lewatit TP 207 is 7.0–9.0 and 4.5–5.5, respectively (Deepatana and Valix, 2006).

Olufemi and Eniodunmo (2018) examined the comparative adsorption removal of Ni(II) ions from an aqueous solution using coconut shells and a banana peel. The Adsorbate dose, adsorbent dose, pH, contact time, particle size, and temperature were varied, and their effects on the percentage removal of Ni(II) ions were evaluated. By using both adsorbents, the Maximum removal rate is observed at pH 8.0. The optimum conditions for both adsorbents include an adsorbent dose of 4.5 g, a contact time of 30 min, and a temperature of 25°C for the coconut shell, and an adsorbent dose of 4.5 g, a contact time of 120 min, and a temperature of 25°C for the banana peel.

        Previous studies reported the Preparation and identification of amino- and phosphorus-containing ion-exchange materials, as well as the study of selectivity for non-ferrous metal ions with the formation of stable chelates with these materials. In this study, the sorption of Cu(II), In(III), and Ni(II) ions from aqueous solutions of amino- and phosphite-containing polyampholytes is examined.