Application of electrocoagulation process for the removal of chloroquine from an aqueous solution

Using chloroquine (CQ) as a provisional treatment for COVID-19 patients generates more pharmaceutical waste, posing a potential environmental threat. The present study evaluates the feasibility of the electrocoagulation (EC) process in removing CQ from an aqueous solution. The experiment was performed in a laboratory-scale stirred tank reactor (STR). The effects of operating conditions were investigated. Equilibrium and kinetic experiments were also performed to describe CQ adsorption. The results showed that increasing both the applied current density and the EC reaction time increases the removal efficiency of CQ. The results showed that 95% of CQ removal efficiency was achieved at a current density of 66.89 mA/cm(2), 600 rpm of agitation rate, 60 min of electrolysis time, an initial CQ concentration of 3 mg/L, and a pH of 6.5. For equilibrium and kinetic studies, the Lang-muir isotherm and the pseudo-second-order provided the best fit to the experimental data. The optimal operating conditions led to a specific amount of dissolved aluminum electrodes and a specific energy consumption of 0.228 kg/m(3) and 12.243 kWh/ m(3). These results suggest that the EC process is an excellent tool for effectively degrading CQ from wastewater with a low operating cost (2.48 USD/m(3)).

Development and validation of convective‐diffusion models to analyse the transient behaviour of a packed bed: Factors influencing aqueous phase adsorption of a bisbiguanide

Chlorhexidine gluconate [CHG] in combination with cetrimide [CET], widely used in various pharmaceutical compositions, is potentially hazardous to aquatic ecosystems. Continuous removal of these compounds using commercial [GAC] and functionalized activated carbons [FACs] in a packed bed column, is reported. Transient forms of convective diffusion models are developed with depletion terms being represented by the first and second-order kinetics. Performance of the packed bed is analysed with varying bed height, flow rate, initial concentrations, and estimated Damköhler numbers. On the basis of minimum value of sum of the squares of residuals [SSQ], it is evident that the second-order model fits better for the removal of CHG and CET by FACHF and FACNH3, while the first-order model fits better for GAC. Damköhler number increases with a decrease in flow rate for both the compounds. Ratio of Damköhler numbers does not change with flow rate. Irrespective of flow rates, for GAC: Da2(CHG):Da2(CET) ≈ 0.0526;for FACHF: Da2(CHG):Da2(CET)=0.30;for FACNH3: Da2(CHG):Da2(CET) = 0.0076. Changes in the breakthrough volume (nBT,max), causing the analytes to migrate from the front of the adsorbent bed into the back, are in the order: for CHG: nBT,max(FACHF) >nBT,max (FACNH3) >nBT,max (GAC);for CET: nBT,max (FAC- NH3) >nBT,max (FACHF) >nBT,max (GAC).

Global trends in the research and development of medical/pharmaceutical wastewater treatment over the half-century.

The COVID-19 pandemic has severely impacted public health and the worldwide economy. The overstretched operation of health systems around the world is accompanied by potential and ongoing environmental threats. At present, comprehensive scientific assessments of research on temporal changes in medical/pharmaceutical wastewater (MPWW), as well as estimations of researcher networks and scientific productivity are lacking. Therefore, we conducted a thorough literature study, using bibliometrics to reproduce research on medical wastewater over nearly half a century. Our primary goal is systematically to map the evolution of keyword clusters over time, and to obtain the structure and credibility of clusters. Our secondary objective was to measure research network performance (country, institution, and author) using CiteSpace and VOSviewer. We extracted 2306 papers published between 1981 and 2022. The co-cited reference network identified 16 clusters with well-structured networks (Q = 0.7716, S = 0.896). The main trends were as follows: 1) Early MPWW research prioritized sources of wastewater, and this cluster was considered to be the mainstream research frontier and direction, representing an important source and priority research area. 2) Mid-term research focused on characteristic contaminants and detection technologies. Particularly during 2000-2010, a period of rapid developments in global medical systems, pharmaceutical compounds (PhCs) in MPWW were recognized as a major threat to human health and the environment. 3) Recent research has focused on novel degradation technologies for PhC-containing MPWW, with high scores for research on biological methods. Wastewater-based epidemiology has emerged as being consistent with or predictive of the number of confirmed COVID-19 cases. Therefore, the application of MPWW in COVID-19 tracing will be of great interest to environmentalists. These results could guide the future direction of funding agencies and research groups.