Radioactive iodine isotopes especially ¹³¹I are used for diagnosis and treatment of different types of cancer diseases. Due to the leak of radioactive iodine into the patient’s urine in turn, the wastewater would be contaminated, so it is worth preparing a novel adsorption green material to remove the radioactive iodine from wastewater efficiently. The removal of ¹²⁷I and ¹³¹I contaminants from aqueous solution is a problem of interest. Therefore, this work presents a new study for removing the stable iodine ¹²⁷I⁻ and radioactive iodine ¹³¹I from aqueous solutions by using the novel nano adsorbent (Nano ZnO/MWCNTs) which is synthesized by the arc discharge method. It is an economic method for treating contaminated water from undesired dissolved iodine isotopes. The optimal conditions for maximum removal are (5 mg/100 ml) as optimum dose with shacking (200 rpm) for contact time of (60 min), at (25 °C) in an acidic medium of (pH = 5). After the adsorption process, the solution is filtrated and the residual iodide (¹²⁷I⁻) is measured at a maximum UV wavelength absorbance of 225 nm. The maximum adsorption capacity is (15.25 mg/g); therefore the prepared nano adsorbent (Nano ZnO/MWCNTs) is suitable for treating polluted water from low iodide concentrations. The adsorption mechanism of ¹²⁷I⁻ on to the surface of (Nano ZnO/MWCNTs) is multilayer physical adsorption according to Freundlich isotherm model and obeys the Pseudo-first order kinetic model. According to Temkin isotherm model the adsorption is exothermic. The removal efficiency of Nano ZnO/MWCNTs for stable iodine (¹²⁷I⁻) from aqueous solutions has reached 97.23%, 89.75%, and 64.78% in case of initial concentrations; 0.1843 ppm, 0.5014 ppm and 1.0331 ppm, respectively. For the prepared radio iodine (¹³¹I⁻) solution of radioactivity (20 µCi), the dose of nano adsorbent was (10 mg/100 ml) and the contact time was (60 min) at (pH = 5) with shacking (200 rpm) at (25 °C). The filtration process was done by using a syringe filter of a pore size (450 nm) after 2 days to equilibrate. The removal efficiency reached (34.16%) after the first cycle of treatment and the percentage of residual radio iodine was (65.86%). The removal efficiency reached (94.76%) after five cycles of treatment and the percentage of residual radio iodine was (5.24%). This last percentage was less than (42.15%) which produces due to the natural decay during 10 days.

The maximum limit for dissolved iron allowed to be in the drinking water is (0.3 mg/L). Ferric chloride is an important coagulant which used in drinking water treatment plants. The removal of residual Fe³⁺ is required after the treatment process. Therefore, the presented work studied the removal of Fe³⁺ from FeCl₃ aqueous solutions by using a novel nanocomposites (Nano ZnO/MWCNTs) which had been synthesized by the arc discharge method at (I_ac=15 A, 70 V and 25 °C) in deionized water. TEM, XRD, EDX and FTIR have confirmed the synthesizing success. The average nano size of Nano ZnO and outer diameter of MWCNTs were 15.68 and 18.03 nm, respectively. The optimum dose was (5.0 mg/100 mL) with shaking at 200 rpm in an alkaline medium for a contact time of 60 min. The Fe³⁺ concentration was reduced from 1.0120 to 0.1646 mg/L at (pH = 7.0) and from 4.020 to 0.9947 mg/L at (pH = 9.0) and from 6.060 to 0.6749 mg/L at (pH = 12.0). The high maximum adsorption capacity of Fe³⁺ on the surface of (Nano ZnO/MWCNTs) is 258.78 mg/g according to Langmuir isotherm model at (pH = 12.0). This adsorption is a multilayer physical process according to Freundlich isotherm model and an exothermic process according to Temkin isotherm model. Moreover, this adsorption obeys pseudo-first order kinetic model and Intra-particle diffusion kinetic model. Nano ZnO/MWCNTs is suitable for drinking water treatment from Fe³⁺ at pH = 7 and pH = 8. It can be used for polluted water treatment from Fe³⁺ before discharging it in to rivers or lakes at (pH = 9.0). Graphical Abstract

The correlations between the tilt angle (TA) of heliospheric current sheet (HCS) and the cosmic ray intensity (CRI), strength (B) of the interplanetary magnetic field (IMF), sunspot number (SSN), solar plasma speed (SWS) and density ( n ) have been studied before and after the reversal of IMF polarities. High sensitivity of the CRI of different rigidities to changes in the TA of HCS is observed during the qA < 0 epoch (when the IMF toward the Sun) as compared to the qA > 0 epoch (when IMF away from the Sun). The results of the present study are consistent with the drift model of cosmic rays, showing that the spectra of drift particles were harder after the reversal of IMF polarity state in (1999/2000). The reversal of IMF polarity state from (qA > 0 state to qA < 0 state) has a great effect on the rigidity-tilts dependence. The modulation of the lower energy particles of (median rigidity Rm < 22 GV) is more pronounced throughout qA < 0 epoch than that of qA > 0 epoch. The rate of sensitivity/modulation of CRIs to the HCS tilts is higher throughout the minimum solar activity years as compared to the maximum solar activity period. Keywords: Cosmic rays – Interplanetary magnetic field – Solar Activity – Solar wind – Heliospheric current sheet