Plastic waste as a valuable resource: strategy to remove heavy metals from wastewater in bench scale application.

Single-use plastic waste is gradually considered a potential material for circular economy. Ion exchange resin obtained from polystyrene waste by sulfonating with H2SO4 was used for heavy metal removal from electroplating wastewater. Batch mode experiments of Cu2+, Zn2+, and Cd2+ were carried out to determine effect of pH, initial concentration, equilibrium time, and the isotherm and kinetic parameters; the stability of the resin in continuous operation was then evaluated. Finally, the longevity of the resin after being exhausted was explored. The results indicated that at pH 6, a pseudo-second-order kinetic model was applicable to describe adsorption of studied heavy metals by sulfonated polystyrene with adsorption capacities of 7.48 mg Cu2+/g, 7.23 mg Zn2+/g, and 6.50 mg Cd2+/g, respectively. Moreover, the ion exchange process between sulfonated polystyrene resin and Cu2+, Zn2+, Cd2+ ions followed the Langmuir isotherm adsorption model with R2 higher than 96%. The continuous fixed-bed column in conditions of a sulfonated polystyrene mass of 500 g, and a flow rate of 2.2 L/h was investigated for an influent solution with known initial concentration of 20 mg/L. Thomas and Yoon-Nelson models were tested with regression analysis. When being exhausted, the sulfonated polystyrene was regenerated by NaCl in 10 min with ratio 5 mL of NaCl 2 M per 1 g saturated resins. After 4 times regeneration, the heavy metal removal efficiency of sulfonated polystyrene was reduced to 50%. These aforementioned results can figure out that by sulfonating polystyrene waste to synthesize ion exchanging materials, this method is technically efficient and environmentally friendly to achieve sustainability.

Observing Phase Transition of a Temperature-Responsive Polymer Using Electrochemical Collisions on an Ultramicroelectrode.

Herein, a study on a new lower critical solution temperature (LCST) polymer in an organic solvent by an electrochemical technique has been reported. The phase-transition behavior of poly(arylene ether sulfone) (PAES) was examined on 1,2-dimethoxyethane (DME). At a temperature above the LCST point, polymer molecules aggregated to create polymer droplets. These droplets subsequently collided with an ultramicroelectrode (UME), resulting in a new form of staircase current decrease. The experimental collision frequency and collision signal were analyzed in relation to the concentration of the polymer. In addition, the degree of polymer aggregation associated with temperature change was also observed.

Determining mean corpuscular volume and red blood cell count using electrochemical collision events.

Blood tests (e.g., red blood cell (RBC) count) are crucial for detecting, diagnosing, and monitoring the progression of blood disorders. Here, we report the development of a new and rapid method for electrochemically detecting RBCs using single-particle collision events. The principle of this method relies on the electrochemical oxidation of an electroactive redox species (potassium ferrocyanide) hindered by an RBC attached to an electrode surface. A decrease in staircase current, caused by the collision of RBCs on the electrode, was observed. The magnitude of this current decrease could provide quantitative information on the size and concentration of RBCs, which could be converted into the mean corpuscular volume (MCV) and used for diagnosis. Anemia-related diseases caused by abnormal count of RBCs (e.g., erythrocytosis, pernicious anemia) or abnormal RBC size (e.g. megaloblastic anemia, microcytic anemia) could be detected easily and quickly using this electrochemical collision method, potentially leading to extensive applications in hematology and point-of-care blood testing devices.