Selective Chelating Resin for Copper Removal and Recovery in Aqueous Acidic Solution Generated from Synthetic Copper-Citrate Complexes from Bioleaching of E-waste

This research focused on batch experiment using a new generation of chelating resins via an ion exchange process to describe the metabolic adsorption and desorption capacity onto iminodiacetic acid/Chelex 100, bis-pyridylmethyl amine/Dowex m4195, and aminomethyl phosphonic/Lewatit TP260 functional groups in bioleaching. The results showed that Dowex m4195 had the highest performance of adsorption capacity for copper removal in both H+-form and Na+-form. Results for Lewatit TP260 and Chelex 100 revealed lower adsorption performance than results for Dowex m4195. The investigation of desorption from chelating resins was carried out, and it was found that 2 M ammonium hydroxide concentration provided the best desorption capacity of about 64.86% for the H+-form Dowex m4195 followed by 52.55% with 2 M sulfuric acid. Lewatit with 2 M hydrochloric acid gave the best desorption performance in Na+-form while Chelex 100 using hydrochloric at 1 M and 2 M provided similar results in terms of the H+-form and Na+-form. As aspects of the selective chelating resins for copper (II) ions in aqueous acidic solution generated from synthetic copper-citrate complexes from bioleaching of e-waste were considered, H+-form Dowex m4195 was a good performer in adsorption using ammonium hydroxide for the desorption. However, chelating resins used were subsequently reused for more than five cycles with an acidic and basic solution. It can be concluded from these results that selective chelating resins could be used as an alternative for the treatment of copper (II) ions contained in e-waste or application to other divalent metals in wastewater for sustainable water and adsorbent reuse as circular economy.

Characterization of Waste Amidoxime Chelating Resin and Its Reutilization Performance in Adsorption of Pb(II), Cu(II), Cd(II) and Zn(II) Ions

The continuous expansion of the market demand and scale of commercial amidoxime chelating resins has caused large amounts of resin to be discarded around the world. In this study, the waste amidoxime chelating resin was reutilized as an adsorbent for the removal and recovery of Pb(II), Cu(II), Cd(II) and Zn(II) ions from aqueous solutions. The physical morphology and chemical composition of the waste amidoxime chelating resin (WAC-resin) from the factory was characterized by the elemental analyzer, X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. The influence of the initial metal ions concentration, contact time, temperature and the solution pH on the adsorption performance of the metal ions was explored by batch experiments. It was shown that the optimal pH was 4. Kinetic studies revealed that adsorption process corresponded with the pseudo-second-order kinetic model and the adsorption isotherm was consistent with the Langmuir model. At room temperature, the adsorption capacities of WAC-resin for Pb2+, Cu2+, Zn2+ and Cd2+ reached 114.6, 93.4, 24.4 and 20.7 mg/g, respectively.

RNA purification-free detection of SARS-CoV-2 using reverse transcription loop-mediated isothermal amplification (RT-LAMP)

Background Current diagnosis of SARS-CoV-2 infection relies on RNA purification prior to amplification. Typical extraction methods limit the processing speed and turnaround time for SARS-CoV-2 diagnostic testing. Methods Here, we applied reverse transcription loop-mediated isothermal amplification directly onto human clinical swabs samples to amplify the RNA from SARS-CoV-2 swab samples after processing with chelating resin. Results By testing our method on 64 samples, we managed to develop an RT-LAMP assay with 95.9% sensitivity (95% CI 86 to 99.5%) and 100% specificity (95% CI 78.2–100%). Conclusion The entire process including sample processing can be completed in approximately 50 min. This method has promising potential to be applied as a fast, simple and inexpensive diagnostic tool for the detection of SARS-CoV-2.

Comparative studies on the adsorption of various radioactive nuclides from waste aqueous solutions on graphene oxide, inorganic and organic ion exchangers

Adsorption of the radionuclides 141Ce, 140La, 140Ba, 137+134Cs, 131I, 125Sb, 103Ru, 95Nb and 95Zr are studied on graphene oxide from waste aqueous solution samples and their adsorption behaviors are compared to that on the inorganic ion exchanger Ceric tungstate as well as on the strong acidic cation exchanger Dowex-50X8 H+ form, the chelating resin Chelex-100 Na+ form and the strong basic anion exchanger AG-1X8 Cl− form. The waste samples are dilute aqueous solutions resulting from previous work. These solutions contained neither oxidizing nor reducing agents, consequently, it is expected that these radionuclides are existing in their most stable oxidation states, i.e. Ce(III), La(III), Ba(II), Cs(I), Ru(III) & (IV), Sb(III) & (V), Nb(V) and Zr(IV). The adsorption is studied under static conditions for all these radioactive nuclides in the presence of each other. Gamma radiometric analysis is carried out for these radionuclides. Effect of some factors on the adsorption is studied such as pH, graphene oxide particle sizes, contact time, temperature and other parameters. Complete removal of some radionuclides is achieved from these waste solutions by adsorption on graphene oxide. Some separation alternatives for some of these radionuclides are also achieved.

Amberlite IRC-718 ion chelating resin extraction of hazardous metal Cr (VI) from aqueous solutions: equilibrium and theoretical modeling

Under varied conditions, the IRC 718 ion-exchange resin is used to extract chromium (VI) ions from aqueous solutions. On chromium (VI) removal effectiveness, the effects of adsorption dosage, contact time, beginning metal concentration, and pH were examined. The batch ion exchange process reached equilibrium after around 90 minutes of interaction. With an initial chromium (VI) concentration of 0.5 mg/dm3, the pH-dependent ion-exchange mechanism revealed maximal removal in the pH 2.0–10 range . The adsorption mechanism occurs between Cr(VI) determined as the electron acceptor, and IRC 718 determined as the electron donor. The equilibrium ion-exchange potential and ion transfer quantities for Amberlite IRC 718 were calculated using the Langmuir adsorption isotherm model. The overall ion exchange capacity of the resin was determined to be 187.72 mg of chromium (VI)/g of resin at an ideal pH of 6.0.

Cyclotron production of 225Ac from an electroplated 226Ra target

Purpose We demonstrate cyclotron production of high-quality 225Ac using an electroplated 226Ra target. Methods 226Ra was extracted from legacy Ra sources using a chelating resin. Subsequent ion-exchange purification gave pure 226Ra with a certain amount of carrier Ba. The radium target was prepared by electroplating. We successfully deposited about 37 MBq of 226Ra on a target box. Maximum activation was achieved using 15.6 MeV protons on the target at 20 µA for 5 h. Two functional resins with various concentrations of nitric acid purified 225Ac and recovered 226Ra. Cooling the intermediate 225Ac for 2–3 weeks decayed the major byproduct of 226Ac and increased the radionuclidic purity of 225Ac. Repeating the same separation protocol provided high-quality 225Ac. Results We obtained 225Ac at a yield of about 2.4 MBq at the end of bombardment (EOB), and the subsequent initial purification gave 1.7 MBq of 225Ac with 226Ac/225Ac ratio of < 3% at 4 days from EOB. Additional cooling time coupled with the separation procedure (secondary purification) effectively increased the 225Ac (4n + 1 series) radionuclidic purity up to 99 + %. The recovered 225Ac had a similar identification to commercially available 225Ac originating from a 229Th/225Ac generator. Conclusion This procedure, which involves the 226Ra(p,2n)225Ac reaction and the appropriate purification, has the potential to be a major alternative pathway for 225Ac production because it can be performed in any facility with a compact cyclotron to address the increasing demand for 225Ac.

Preparation of side chain liquid crystal polyether chelating resin and its adsorption properties for Cu2+ in water

The authors have requested that this preprint be withdrawn due to erroneous posting.