Efficient adsorption of chloroquine phosphate by a novel sodium alginate/tannic acid double-network hydrogel in a wide pH range.

In this work, a novel double-network composite hydrogel (SA/TA), composed of sodium alginate (SA) and tannic acid (TA), was designed and fabricated by a successive cross-linking method using Ti(IV) and Ca(II) as crosslinkers. SA/TA exhibited reinforced mechanical strength and anti-swelling properties because of the double-network structure. SA/TA was used as an adsorbent for removal of a popular antiviral drug, chloroquine phosphate (CQ), in water. The adsorption performance of SA/TA was systematically investigated, to study various effects including those of TA mass content, solution pH, adsorption time, and initial CQ concentration. Adsorption was also examined in presence of inorganic and organic coexisting substances commonly found in wastewater, and under different actual water samples. Batch experimental results indicated that SA/TA could maintain higher and more stable CQ uptakes within a wide solution pH range from 3.0 to 10.0, compared to its precursor, SA hydrogel, owing to the addition of TA-Ti(IV) coordination network. The maximum experimental CQ uptake exhibited by the 1:1 (by wt) SA/TA (SA/TA2) was as high as 0.699 mmol/g at the initial pH of 9.0. A high concentration of coexisting NaCl evidently reduced the CQ uptakes of SA/TA2 due to the electrostatic shielding effect, moreover, divalent cations including Ca(II) and Mg(II) also inhibited the adsorption of CQ due to competitive adsorption. However, humic acid had little effect on this adsorption. Considering the apparent adsorption performance, the aforementioned effects of various factors and the spectroscopic characterizations, multi-interactions are suggested for adsorption including chelation, electrostatic interactions, π-π electron donor-acceptor interaction and hydrogen bonding. SA/TA showed a slight loss in adsorption capacity toward CQ and sustained physicochemical structural stability, even after six adsorption-desorption cycles. In addition to CQ, SA/TA could be efficiently used for adsorption of two other antivirus drugs, namely, hydroxychloroquine sulfate and oseltamivir phosphate. This work provides an effective strategy for the design and fabrication of novel adsorbents that can effectively adsorb antiviral drugs over a wide pH range.

Upcycling waste polyethylene terephthalate (PET) bottles into high-performance activated carbon for electrochemical desalination.

Upcycling waste polyethylene terephthalate (PET) bottles has attracted intensive research interests. This simultaneously alleviates plastic pollution and achieves a waste-to-resource strategy. Waste PET water bottles were used to fabricate value-added activated carbon (AC) electrodes for capacitive deionization (CDI). The KOH activation temperature (greater than 700 °C) prominently affected the physi-chemical properties and desalination performance of PET-derived activated carbons (PET-AC). Profiting from a large Brunauer-Emmet-Teller specific surface area (1448 m2 g-1) with a good mesoporous structure (the ratio of the mesopore volume to the total pore volume was 41.3%), PET-AC-1000 (activated at 1000 °C) possessed a huge specific capacitance of 108 F g-1 for capacitive ion storage. Moreover, when utilized as the electrode material in single-pass CDI, PET-AC-1000 exhibited a maximum electrosorption capacity of 10.82±0.11 mg g-1 and a low level of energy consumption (0.07 kWh mol-1), associated with good electrochemical charging-discharging cyclic stability. The results provide a promising facile approach to tackle the challenge of plastic pollution and promote the advancement of electrode materials for economic affordable and energy-efficient electrochemical desalination process, which meets the United Nations (UN) sustainable development goals (SDGs).

Outbreaks of faecal-orally transmitted diseases in displacement camps: A scoping review of pathogens, risk factors, exposure routes, and drivers of transmission.

Many forcibly displaced people reside in camps characterised by precarious living conditions, exposing them to numerous health risks. This scoping review elucidated the risk factors and exposure routes implicated in outbreaks of faecal-oral pathogens in camps, as well as the context-specific drivers of transmission that shape these outbreaks. Journal articles were identified from PubMed, Embase, Scopus, and Web of Science. Portals for grey literature were also searched. A total of 48 records, published between 1937 and 2022, were included in the analysis. Cholera outbreaks were the most frequently reported. Risk factors included drinking water from shallow wells and rivers, consuming ice and leftover food, and inconsistent handwashing. These indicate exposure through vehicles of transmission in both public and domestic domains, emphasising the importance of a multipronged approach to outbreak prevention and control. Outbreaks were often exacerbated by extreme weather events and acute population influxes that damage or overwhelm water and sanitation facilities. Such shocks warrant explicit recommendations in preparedness and response guidelines. Development projects and outbreak response measures in surrounding areas may reduce the risk of importing pathogens into camps. Future research could further investigate faecal-oral pathogens other than Vibrio cholerae and analyse the co-occurrence of the identified transmission drivers.

Effluent toxicity study using biomarkers for ciprofloxacin photoelectrocatalytic degradation by bismuth-doped titanium dioxide nanotubes.

Ciprofloxacin hydrochloride (CIP) is a broad-spectrum synthetic antibiotic often found in domestic sewage and industrial waste due to the inefficiency of conventional treatments. Given the potential risk of drug accumulation, this study presents coatings of titanium dioxide nanotubes (TiO2) doped with different bismuth (Bi) concentrations to degrade CIP through photocatalytic and photoelectrochemical processes. Characterization studies revealed that bismuth (Bi) doping affected the morphology of the materials, with concentrations of 0.01 and 0.05 mol L-1, resulting in collapsed materials with a smaller active surface area. Photocatalysis tests for all the materials exhibited a similar degree of efficiency to photolysis, approximately 33%. Ecotoxicity tests using the biomarkers Lactuca sativa L., Lemna minor, and Artemia salina indicated that, although they were similar to photolysis in terms of efficiency, the effluents generated when employing the doped catalysts showed lower levels of toxicity, with the best results achieved for the material doped with 0.005 mol L-1 of Bi, with a toxicity level approximately 40% lower. Photoelectrocatalysis proved to be the most efficient CIP degradation technique. The highest degradation rate was observed for materials doped with 0.005 mol L-1 of Bi, with an efficiency of 46%, which is 1.4 times more efficient than photolysis. These results demonstrate that materials doped with low amounts of Bi can be effectively used as photoanodes for drug degradation, as their performance is superior, and the final product generated exhibits low toxicity to living organisms.

Removal of the neonicotinoid insecticide acetamiprid from wastewater using heterogeneous photocatalysis.

Due to its high solubility in water, a large amount of the neonicotinoid insecticide acetamiprid persisting in the soil of treated crops enters surface water or groundwater. The aim of this study was to investigate the photocatalytic degradation of acetamiprid in an aqueous medium. The experiments were carried out in an annular suspension reactor operating in recirculated batch mode and using a UV-A lamp as the radiation source. An appropriate modification of the commercial TiO2-P25 photocatalyst was carried out to reduce its band gap energy and electron-hole recombination as well as to extend the visible light range of TiO2. The photodegradation study was carried out using a three-factor two-stage Box-Behnken experimental design to investigate the main effects and interactions between the operating variables, such as solution pH, initial concentration of acetamiprid, and amount of photocatalyst. The efficiency of the processes was determined by high performance liquid chromatography. The first-order pseudo-reaction kinetic model, as a simplification of the models of Langmuir-Hinshelwood under conditions of relatively low acetamiprid concentration, was applied and the reaction rate constants were estimated. The results of the study showed that the initial concentration of the pollutant was the most influential factor for the photocatalytic degradation process. Using ANOVA analysis, a linear model was established to predict the system behaviour at different operating conditions. The highest conversion and rate constant of acetamiprid degradation were recorded in the experiment with the lowest tested concentration of acetamiprid (2 mg/L), the average concentration of photocatalyst (60 mg) and at pH 8.

Accelerating urea hydrolysis in fresh urine by modifying operating conditions of a sequencing batch reactor.

A number of existing and emerging technologies can recover nitrogen from urine. A preliminary step in many nitrogen recovery processes is hydrolyzing urea to ammonium, a biologically-mediated process that can take days to weeks without intervention. The ability to achieve urea hydrolysis quickly and reliably would increase the feasibility of decentralized nitrogen recovery, especially where space and treatment time are constrained. The goal of this research was to determine whether urea hydrolysis could be accelerated by providing an inoculum containing microorganisms likely to have urease activity (feces or soil), providing a carrier to support attached growth (plastic carriers, granular activated carbon, or no carrier), and modifying the hydraulic retention time (HRT; 1.3, 2, and 4 days) and feeding frequency (Δt = 4, 24 h). Inoculated reactors achieved significantly more urea hydrolysis, and reactors inoculated with soil were able to sustain higher urea hydrolysis rates over time than those inoculated with feces. The mean zero-order rate constants (mM/hr) for reactors with a soil inoculum (15.1) were about three times higher than that of reactors with an inoculum of feces (4.9). A reactor with GAC and an inoculum of soil fed daily with fresh urine achieved greater than 90% hydrolysis with an HRT of 2 days; results suggest the HRT could be reduced to 16 h without reducing performance. No significant benefit was provided by increasing the frequency of feedings for the same HRT, likely because urease enzymes were saturated and operating at maximum hydrolysis rates during most of the reaction period.

Drinking Water Supply in the Region of Antofagasta (Chile): A Challenge between Past, Present and Future.

Since the mid-nineteen century, when the first mining companies were established in the region of Antofagasta to extract saltpeter, mining managers and civil authorities have always had to face a number of problems to secure a water supply sufficient for the development of industrial activities and society. The unique features of the region, namely the scarcity of rainfall, the high concentration of arsenic in freshwaters and the increasing pressure of the mining sector, have made the supply of drinking water for local communities a challenge. In the 1950s, the town of Antofagasta experienced a serious drinking water crisis. The 300 km long aqueduct starting from the Toconce catchment, opened in 1958, temporarily ended this shortage of drinking water but created an even more dramatic problem. The concentration of arsenic in the water consumed by the population had grown by approx. ten times, reaching the value of 0.860 mg/L and seriously affecting people's health. The water treatment plants (WTPs) which were installed starting from the 1970s in the region (namely the Old and New Salar del Carmen in Antofagasta and Cerro Topater in Calama, plus the two recent desalination plants in Antofagasta and Tocopilla), have ensured, since 2014, that the drinking water coverage in the urban areas was practically universal (>99.9%). However, the rural areas have continued to experience significant shortcomings regarding their capacity to ensure the quality and continuity of the water supply service in the long run. Presently, approx. 42% of the rural population of the region of Antofagasta does not have a formal supply of drinking water. The recent amendments to the Chilean Water Code (March 2022) and the interventions carried out in the framework of the Agua Potable Rural (APR) program were intended to reduce the socio-ecological inequalities due to the lack of drinking water in the semi-concentrated and isolated rural population.