Water, sanitation, and hygiene global research: evolution, trends, and knowledge structure.

Water, sanitation, and hygiene (WASH) services play a crucial role in promoting public and environmental health as well as social and economic development. At the global level, particularly in the developing world, WASH issues continue to present significant challenges. These challenges have been further intensified by factors such as the COVID-19 pandemic, escalating conflicts, climate change, water scarcity, and rising inequality. The scientific community has actively engaged in constructive discussions on these issues, as evidenced by the notable research findings. Therefore, the aim of this study was to comprehensively examine and evaluate global knowledge on WASH. To search for relevant publications, the Scopus database was utilized using specific terms associated with WASH. VOSviewer 1.6.18 software was employed to generate network visualization maps, which assessed collaborative patterns and research trends in the field of WASH. The research output of countries was adjusted considering their gross domestic product (GDP) and population size. The total number of WASH-related publications, including all types of documents, was 1805. By narrowing the search to articles and reviews, the overall global productivity yielded 1589 documents: 1367 (86.0%) original articles and 222 (14.0%) review articles. The USA had the highest number of WASH publications (n = 668; 42.0%), followed by the UK (n = 396; 24.9%), Switzerland (n = 151; 9.5%), and Australia (n = 141; 8.9%). Ethiopia emerged as the leading country in terms of GDP per capita and the number of publications, followed by Uganda, Malawi, India, and Bangladesh. The USA, the UK, and Switzerland exhibited the most extensive collaboration among countries. The main research areas encompassed the role of WASH in sustainable development, the impacts of inadequate access to WASH services on gender equality, children, infants, and the outbreak of COVID-19 and other diseases, as well as the significance of hygiene practices and community and school-based WASH interventions in reducing infections. This study provides a novel analysis of global WASH-related research and highlights the distribution of outcomes across nations. Continued and increased collaboration between developed and developing nations will facilitate the sharing of responsibility for WASH research outcomes and the implementation of effective policies.

Photocatalytic degradation of aqueous methylene blue using ca-alginate supported ZnO nanoparticles: point of zero charge role in adsorption and photodegradation.

A novel insoluble Ca-Alginate created from soluble Na-Alginate was used as a support substrate for ZnO nanoparticles producing ZnO@Ca-Alginate composite photocatalyst. Fourier Transform Infrared (FT-IR), Ultraviolet-Visible (UV-Vis), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDX), and X-ray Diffraction (XRD) analysis techniques were used in the characterization of the prepared ZnO@Ca-Alginate. The ZnO@Ca-Alginate was tested for its potential use in the photodegradation of Methylene Blue (MB) from an aqueous solution under solar-simulated light. This composite photocatalyst efficiency in MB removal was compared with naked ZnO potential considering different conditions and parameters (e.g. pH, MB concentration, amount of photocatalyst, and irradiation time). The MB concentrations were identified using UV-vis spectrophotometric methods. While, high-performance liquid chromatography (HPLC), Total organic carbon (TOC) analysis, and other elemental analyses were used to confirm the MB complete mineralization. The MB photodegradation results were performed by using UV-vis analysis., the results showed that up to 95% of MB (40 mL, 40 ppm) was removed within 30 min of irradiation using either ZnO@Ca-Alginate or naked ZnO. The pH and the zero-charge point (Pzc) values play a main role in the adsorption and photodegradation results. The Pzc values for Ca-Alginate, ZnO, and Zn@Ca-Alginate were 6.5, 8.8, and 6.8 respectively. The prepared composite catalyst showed a maximum adsorption and photodegradation in a basic to slightly basic medium, the MB completely removed at pH of 7.7 within an hour of irradiation. The complete miniralzation of MB at the end of the photodegrdation process was confirmed. Here it is proved that the ZnO@Ca-Alginate photocatalyst can be recovered and reused without any significant decrease in its effectiveness.

Correction: Optical properties and photoactivity of carbon nanodots synthesized from olive solid wastes at different carbonization temperatures.

[This corrects the article DOI: 10.1039/D1RA09273A.].

Effective and selective electroreduction of aqueous nitrate catalyzed by copper particles on multi-walled carbon nanotubes.

Drinking-water contamination with nitrate ions is inevitable and wide spreading, which demands feasible removal. Water de-nitration by potentiostatic electroreduction is described here. A novel electrocatalyst based on nano-copper particles, supported onto multi-walled carbon nanotubes (MWCNTs), and spray-deposited onto fluorine doped tin oxide-glass substrates, is described. The Cu/MWCNT/FTO electrode has been characterized by several methods and assessed as a working electrode in aqueous nitrate ion electroreduction, in comparison with MWCNT sprayed on FTO (MWCNT/FTO) with no copper. Comparison with earlier reported electrodes is also described. XRD patterns confirm the presence of nano-copper crystallites, in the electrode, with average size ⁓45 nm. Within 2 h of electrolysis, Cu/MWVNT/FTO exhibits more than 65% removal of nitrate at -1.80 V (vs. SCE). In longer time (7 h) the electrode completely converts the nitrate into N2 (∼65%) and (NH4+) ∼35% with no NO2- ions. The kinetics show 0.76 order with respect to nitrate, and a rate constant 4.53 × 10-2 min-1 higher than earlier counterparts. The new electrode functions under various conditions of temperature, pH, electrolyte type and concentration and inter-electrode spacing, only at ambient applied potential. Moreover, the electrode exhibits stability under nitrate electroreduction conditions, and can be recovered and reused for multiple times without efficiency loss. XRD and EDS results also confirm the electrode stability after multiple reuse. Compared to earlier systems, the Cu/MWCNT/FTO is environmentally stable, safe, non-costly with high nitrate removal efficiency and selectivity.

Mapping environmental impact assessment research landscapes in the Arab world using visualization and bibliometric techniques.

Interests and concerns on environmental issues have attracted much attention over the past few decades. This is in harmony with the growing understanding of environmental impacts associated with human activities and their role in degrading ecosystems. In line with these concerns, considerable advances in science and technology to assess, mitigate, or lessen these adverse impacts have emerged (i.e., environmental impact assessment (EIA) methodologies). The involvement of EIA in sustainable development has become a prevalent topic in research in either developed and developing countries. The present work investigated the research status, development trends, and hotspots of EIA in a region with massive environmental challenges; the Arab world. Bibliometric analysis and visualization mapping were utilized with an objective of revealing and evaluating the developments in knowledge on EIA from the Arab world. A sum of 595 documents was the productivity of the Arab world on EIA (2.1% of total global productivity). Most of the studies were performed by scholars in Egypt (143 documents; 24.0%), followed by Saudi Arabia (96 documents; 16.1%), and Tunisia (68 documents; 11.4%). France, the USA, and the UK were, respectively, the most collaborated countries with the Arab world on EIA. Most of the publications on EIA were in prestigious journals in relation to environmental sciences. King Abdulaziz University, Saudi Arabia and University of Kuwait were the most productive institutions (24 documents/institution). Topics in relation to assessing different environmental impacts on the quality and quantity of water will continue to be vital themes of research. While, the utilization of remote sensing, geographic information systems, risk assessment, life cycle assessment, bioaccumulation, and biomarkers techniques in assessing environmental impacts will continue to be dominant as efficient tools in conducting EIA related research. The outcomes displayed, in general, a rapidly and steadily rising interests on EIA. However, the development of regional experience, increasing of funds and advancing of competencies will further promote research activities on EIA.

Evaluating Solubility of Celecoxib in Age-Appropriate Fasted- and Fed-State Gastric and Intestinal Biorelevant Media Representative of Adult and Pediatric Patients: Implications on Future Pediatric Biopharmaceutical Classification System.

Prediction of performance of traditional, reformulated, and novel oral formulations in adults and pediatrics is of great importance. This study was conducted to assess solubility of celecoxib in age-appropriate fasted- and fed-state gastric and intestinal biorelevant media, classify celecoxib into biopharmaceutical classification system (BCS), and assess the effects of age-related developmental changes in the composition and volume of gastrointestinal fluids on the solubility and performance of oral formulations containing celecoxib. Solubility of celecoxib was assessed at 37°C in the pH range specified by the BCS-based criteria in 13 age-appropriate biorelevant media reflective of the gastric and proximal small intestinal environment in both fasted and fed states in adults and different pediatric subpopulations. A validated HPLC-UV method was used to quantify celecoxib. Experimental and computational molecular descriptors and in vivo pharmacokinetic data were used to assign the permeability class of celecoxib. Celecoxib belonged to BCS class 2. The pediatric to adult solubility ratios were outside the 80-125% boundaries in 3 and borderline in 1 biorelevant media. Significant age-related variability could be predicted for oral formulations containing celecoxib intended for pediatric use. Findings of this study indicated that the criteria used in the adult BCS might not be directly applied to pediatric subpopulations.

Salivary Lead Levels among Workers in Different Industrial Areas in the West Bank of Palestine: a Cross-Sectional Study.

Saliva is a biofluid that can easily be obtained and used for biomonitoring lead levels in occupationally and environmentally exposed individuals. The aims of this study were to determine salivary lead levels among workers in different industrial areas in the West Bank of Palestine and investigate the association between sociodemographic and occupational characteristics of the workers and their salivary lead levels. Salivary samples were obtained from workers in different industrial areas in metal-free polyethylene tubes. The samples were analyzed for their lead contents using a pre-validated inductively coupled plasma-mass spectrometric method. A total of 97 salivary samples were analyzed. The median salivary lead level was 1.84 µg/dL an IQR of 5.04 µg/dL. Salivary lead levels were significantly higher in workers who were 40 years and older (p value = 0.031), had 3 children or more (p value = 0.048), worked in repair workshops (p value = 0.012), worked in industrial areas for 20 years or more (p value = 0.048), did not consume fruits on regular basis (p value = 0.031), and smoked for 30 years or more (p value = 0.013). Multiple linear regression showed that smoking of 30 years old or more was a significant (p value < 0.001) predictor of higher salivary lead levels. Salivary lead levels among workers from different industrial areas of the West Bank were comparable to those occupationally exposed to lead in more industrialized and urbanized areas of the world. Smoking was a predictor of higher salivary lead levels.

Self-assembly of diclofenac prodrug into nanomicelles for enhancing the anti-inflammatory activity.

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely prescribed for the treatment of various types of inflammatory conditions. Diclofenac is a very common NSAID that is utilized to relieve pain and reduce fever and, most importantly, inflammation. However, it suffers from low water solubility and a low dissolution profile. Therefore, we aim to develop a new drug delivery system based on the synthesis of amphiphilic structures that are capable of self assembling into nano-micelles which will be a water-soluble delivery system for the diclofenac. The amphiphilic structure consists of a hydrophilic moiety of triethylene glycol (TEG), polyethylene glycol PEG 400, or PEG 600 linked with the hydrophobic drug diclofenac through an ester linkage. The diclofenac derivatives were successfully synthesized as confirmed by nuclear magnetic resonance. Moreover, the formation of the micellar structure of the synthesized amphiphilic derivatives was confirmed by atomic force microscopy obtaining a spherical shape of the micelles with average diameters of 200 nm for Dic-PEG400-Dic, and 110 nm for Dic-PEG600-Dic. The critical micelle concentration has been determined as 2.7 × 10-3 mg mL-1 for Dic-PEG400-Dic, and 1 × 10-4 mg mL-1 for Dic-PEG600-Dic. The in vitro diclofenac release profile by esterase enzyme was conducted and showed almost complete conversion to free diclofenac within 35 h in the case of Dic-PEG400-Dic micelles and more than 85% of Dic-PEG600-Dic micelles. Then the anti-inflammatory activity was determined by testing the TNF-α production in LPS-stimulated Balb/c mice. Diclofenac micelles significantly suppressed TNF-α production after a 5 mg kg-1 dose was given. The developed micelles showed TNF-α inhibition up to 87.4% and 84% after 48 hours of treatment in the case of Dic-PEG400-Dic and Dic-PEG600-Dic micelles respectively in comparison to 42.3% in the case of diclofenac alone. Dic-PEG400-Dic micelles showed the most potent anti-inflammatory activity with improved TNF-α suppression through time progress. Therefore, the developed nano-micelles provide a facile synthetic approach to enhance diclofenac water solubility, improve the anti-inflammatory effect and achieve a sustained release profile to get better patient compliance.

Coronavirus disease-19 in environmental fields: a bibliometric and visualization mapping analysis.

A coronavirus disease-19 (COVID-19) caused by a novel coronavirus has appeared in China by the end of 2019 and later recognized as a global pandemic. This pandemic has evolved as a global public health menace. It has affected every aspect of human life. In line with these concerns, governments and the scientific community react promptly to the outbreak of this pandemic. These efforts are devoted to develop vaccine and curative medicines. Further efforts are dedicated to assessing the impacts of the pandemic in relation to socioeconomic, psychological, and environmental dimensions. In this regard, it is important to follow up developments and research activities on this global issue. The present work intended to tracking the current hotspots and research trends on COVID-19 in environmental fields. Bibliometric analysis and visualization mapping were utilized with the objective of revealing and evaluating the developments in knowledge on COVID-2019 and its impacts based on a collection of environmental sources. A sum of 729 documents were collected from Scopus database limiting to environmental sources only. Of all these publications, 563 (77.2%) were articles, 56 (7.7%) were reviews, and 110 (15.0%) were others. China has the highest share of publications (163; 22.4%). It is followed by the USA (139; 19.15), and Italy (110; 15.1%). Most publications on COVID-19 were in prestigious journals. The most productive institution at global level was Chinese Academy of Sciences, China (24 documents; 3.3%). The most prevalent topics are in relation to impacts of the pandemic on air quality, mental health, psychological, and economic aspects. The development of these topics is based on cross-sectional studies, evidence-based tools, remote sensing, satellite mapping, geographic information systems, market analysis and sampling. The progress of environmental research on COVID-19 will guide the development of global environmental strategies to control future global environmental risks.

Sub-chronic treatment with high doses of ascorbic acid reduces lead levels in hen eggs intentionally exposed to a concentrated source of lead: a pilot study.

BACKGROUND: Hen eggs contaminated with lead can be harmful to the health of children and adults. The objective of this pilot study was to investigate if sub-chronic treatment with ascorbic acid can reduce lead levels in the different parts of hen eggs after intentionally exposing the laying hens to a concentrated source of lead. METHODS: Clinically normal mixed-breed egg laying hens (n = 18) were used in this pilot study. Hens were exposed to a concentrated source of lead (200 mg/kgbody weight/day lead acetate) for 1 week. Subsequently, egg laying hens were either treated with sub-chronic doses of ascorbic acid (500 mg/kgbody weight/day) or left untreated for 4 weeks. Lead levels were assessed in egg-shell, egg-albumen, and egg-yolk samples using a graphite furnace atomic absorption spectrophotometer. RESULTS: Lead levels increased significantly (p-value < 0.01) from baseline in egg-yolk, egg-albumen, and egg-shell samples following 1 week exposure to lead acetate. Sub-chronic treatment of egg laying hens with high doses of ascorbic acid could bring statistically significant reduction (p-value < 0.01) in lead levels in egg-yolk, egg-albumen, and egg-shell samples after intentional exposure to a concentrated source of lead. CONCLUSIONS: Findings of this pilot study showed that sub-chronic treatment of egg laying hens with ascorbic acid can reduce lead levels in different egg parts after intentional exposure to a concentrated source of lead. Supplementing feedstuffs and water with sources of ascorbic acid could be beneficial in reducing lead levels in hen egg tissues following environmental exposure. Further studies are still required to investigate if ascorbic acid can reduce lead levels in other chicken tissues.

Photocatalytic degradation of phenazopyridine contaminant in soil with direct solar light.

Photocatalytic degradation of waste pharmaceutics, with solar radiation, is described here as a feasible method to purify pre-contaminated soils. Phenazopyridine has been used as a model soil contaminant. Two different nano-size powders have been first examined as catalysts, namely commercial TiO2 (anatase) and commercial ZnO. As the ZnO showed higher catalytic efficiency, the study was then focused on it. The commercial ZnO powder was then compared with lab-prepared ZnO powder, and the latter shows relatively higher efficiency. The ZnO was used in two different ways. In one way, dry ZnO catalyst powder was spread onto the soil, while in the other way the ZnO was sprayed onto the soil surface by a wet spray method. The spray technique shows slightly higher efficiency, in addition to being easier to apply at future large scale. Depending on conditions and type of photocatalyst used, up to 90% contaminant removal can be achieved in 30 min. In case of photocatalysis experiments, the reacted contaminant molecules undergo complete degradation with no detectable side reaction organic products. Possible evaporation or escape of organic contaminant, or other possibly resulting organics, is ruled out by a series of control experiments. Photodegradation process takes place only at the catalytic sites on the soil surface, where contaminant molecules that diffuse from the soil bulk are completely degraded. Other useful organisms inside the soil are not affected as they are kept away from catalyst sites. A plausible mechanism is proposed for the degradation process.

Physical and chemical behaviour of Nabali Mohassan single-cultivar olive oil during prolonged storage.

BACKGROUND: The effect of storage time on the fluorescence emission intensity and physico-chemical properties of olive oil from the Palestinian cultivar Nabali Mohassan was investigated. Olive oil samples stored up to 7 years were obtained from different olive orchards in Palestine, where prolonged storage is still in use. RESULTS: As a result of oxidation, all fluorescent minor compounds (tocopherols, chlorophylls, pheophytins and phenolic compounds) of olive oil significantly decreased as the storage time increased, whereas viscosity increased (P < 0.05). Until 1 year of storage, the physico-chemical properties of olive oil samples were within the limits of both Palestinian and European quality standards, and minor compounds, although affected by a marked decrease compared to freshly produced oil, were still detectable. After 5 years, a 90% decrease of the fluorescence attributed to tocopherols occurred and, after 7 years, phenolics reached a loss of 90%. CONCLUSION: The analysis of fluorescence, together with other physical measures, was demonstrated to be a useful tool for monitoring oil aging. This is the first report on fluorescent minor compounds of oils obtained from Nabali Mohassan olive cultivar. A better knowledge of this single-cultivar oil could enhance the adoption of the best practices by producers, improving the whole production chain. © 2018 Society of Chemical Industry.

Blood zinc levels in nursing women from different regions of the West Bank of Palestine.

Pregnant and nursing women are at higher risk of zinc deficiency which can have detrimental consequences on health. We assessed blood zinc levels in 72 nursing women from the West Bank of Palestine and investigated the association between sociodemographic variables and blood zinc levels. Blood samples were analyzed for their zinc contents using graphite furnace atomic absorption spectrophotometry. Blood and data collection were performed between July and December 2016. The median blood zinc level was 4.53 mg/L (interquartile range of 0.38 mg/L). In unadjusted analyses, blood zinc levels were higher in nursing women who lived in cities (p-value <.001), had higher household income (p-value <.001), whose husbands had a white collar job (p-value <.05), were nonsmokers (p-value <.05), did not use hair dyes (p-value <.05), and consumed energy beverages (p-value <.001). Multiple linear analysis showed that living in cities and consuming energy beverages remained significantly associated with higher blood zinc levels (p-value <.05). Blood zinc levels were in the range previously reported for similar non-malnourished populations. Nursing women living in cities and those consuming energy beverages tended to have higher blood zinc levels. Urbanized lifestyle might have enhanced blood zinc levels in nursing women.

Breast Milk Lead Levels in 3 Major Regions of the West Bank of Palestine.

BACKGROUND: Lead is a neurotoxic pollutant that is ubiquitously spread in our environment. Breast milk contaminated with lead poses a potential risk of exposing a recipient infant to lead. OBJECTIVES: The primary aims of this study were to evaluate the breast milk lead levels (BMLLs) in breastfeeding mothers in 3 major regions of the West Bank of Palestine and to investigate the effects of some sociodemographic variables on the BMLLs. METHODS: Breast milk samples were collected from 89 breastfeeding mothers from the Nablus, Ramallah, and Jerusalem regions and analyzed for their BMLLs using graphite furnace atomic absorption spectrophotometry. Breastfeeding mothers were interviewed and responded to a sociodemographic questionnaire. RESULTS: The median BMLL was 4.0 µg/L, ranging from 2.0 to 12.0 µg/L. Breast milk lead levels in 19.1% of the samples analyzed were higher than the World Health Organization's safety limits of 2.0 to 5.0 µg/L for an occupationally unexposed population. Breast milk lead levels were significantly higher in breast milk of mothers who lived in cities and refugee camps (P < .01), had lower monthly household income levels (P < .05), lived close to paint shops (P < .05), lived in houses with peeling or chipping paint (P < .05), used eye kohl (P < .01), and worked in agriculture for a duration longer than 3 years (P < .01). CONCLUSION: Breast milk lead levels were higher than the safety limits for occupationally unexposed populations. Authorities need to implement measures to eliminate or reduce lead exposure, especially in refugee camps and cities. Marketed eye kohl preparations should be tested for their lead contents.

Modes of tetra(4-pyridyl)porphyrinatomanganese(III) ion intercalation inside natural clays.

BACKGROUND: Metalloporphyrin ions, with planar shape, have been known to intercalate horizontally and diagonally between montmorillonite layers. Perpendicular intercalation inside montmorillonite has not been reported earlier. This work aims at achieving perpendicular intercalation inside montmorillonite in natural clays. Possible intercalation inside other forms of natural clay will also be investigated. METHODS: Natural clays were purified and characterized. The naked clay powder was then refluxed with tetra(4-pyridyl)porphyrinatomanganese(III) ion (MnTPyP(+)) solution in methanol with continuous stirring for different times. Electronic absorption spectra, atomic absorption spectra, Fourier Transform infrared spectra, scanning electron microscopy and X-ray diffraction were all used in clay characterization and in intercalation study. RESULTS: The natural clay involved different phases, namely montmorillonite, biotite, kaolinite, illite and traces of quartz. Montmorillonite clay allowed horizontal, diagonal and perpendicular intercalation of the metalloporphyrin ions. Biotite allowed only horizontal intercalation. The mode of intercalation was deduced by monitoring the clay inter-planar distance value change. Intercalation occurred inside both micro- and nano-size clay powders to different extents. The nano-powder (average size ~50 nm) showed uptake values up to 3.8 mg MnTPyP/g solid, whereas the micro-size powder (average size ~316 nm) exhibited lower uptake (2.4 mg MnTPyP/g solid). Non-expandable clay phases did not allow any intercalation. The intercalated MnTPyP(+) ions showed promising future supported catalyst applications. CONCLUSIONS: Depending on their phase, natural clays hosted metalloporphyrin ions. Montmorillonite can allow all three possible intercalation geometries, horizontal, diagonal and for the first time perpendicular. Biotite allows horizontal intercalation only. Non-expandable clays allow no intercalation. Graphical abstractMetalloporphyrin complexes can be intercalated into montmorillonite in horizontal, perpendicular and diagonal geometries.

Optimizing photo-mineralization of aqueous methyl orange by nano-ZnO catalyst under simulated natural conditions.

BACKGROUND: Photo-degradation of organic contaminants into non-hazardous mineral compounds is emerging as a strategy to purify water and environment. Tremendous research is being done using direct solar light for these purposes. In this paper we report on optimum conditions for complete mineralization of aqueous methyl orange using lab-prepared ZnO nanopowder catalyst under simulated solar light. RESULTS: Nano-scale ZnO powder was prepared in the lab by standard methods, and then characterized using electronic absorption spectra, photolumenscence emission (PL) spectra, XRD, and SEM. The powder involved a wurtzite structure with ~19 nm particles living in agglomerates. Photo-degradation progressed faster under neutral or slightly acidic conditions which resemble natural waters. Increasing catalyst concentration increased photodegradation rate to a certain limit. Values of catalyst turn over number and degradation percentage increased under higher light intensity, whereas the quantum yield values decreased. The photocatalytic efficiency of nano-ZnO powders in methyl orange photodegradation in water with solar light has been affected by changing the working conditions. More importantly, the process may be used under natural water conditions with pH normally less than 7, with no need to use high concentrations of catalyst or contaminant. The results also highlight the negative impact of possible high concentrations of CO2 on water purification processes. Effects of other added gaseous flows to the reaction mixture are also discussed. CONCLUSION: ZnO nano-particles are useful catalyst for complete mineralization of organic contaminants in water. Photo-degradation of organic contaminants with ZnO nano-particles, methyl orange being an example, should be considered for future large scale water purification processes under natural conditions.

Solid olive waste in environmental cleanup: enhanced nitrite ion removal by ZnCl2-activated carbon.

This communication describes how olive solid wastes can be used to prepare activated carbon (AC), with soundly high surface areas, suitable to remove nitrite ions from water. Solid olive wastes, so called Jeft, separated as unwanted bi-products from olive oil mills, have been converted into charcoal. The charcoal was then physically and/or chemically activated using different compounds namely conc. H3PO4 or ZnCl2. Charcoal carbonization was performed under inert atmosphere to avoid loss of heated carbon by oxidation with air. Surface area measurements and SEM micrographs showed that activation using ZnCl2 yields AC with highest surface area and more porous surfaces. The ZnCl2-activated carbon was then used to remove nitrite ions from water by adsorption. Effects of different parameters on value of surface area and adsorption capacity of the AC were investigated. Commercial AC materials were used as reference for comparison. The AC showed higher adsorption capacity toward nitrite than other reported adsorbents. The results suggest that using 5 g of the ZnCl2-activated carbon per liter of heavily nitrite-contaminated water (50 ppm) may bring the contaminant concentration down to the WHO accepted concentration limits within 60 min. This work highlights the future feasibility of using olive waste as feed stocks to produce useful renewable materials while keeping in mind the wisdom "make wastes work in environmental protection".

CdS-sensitized TiO2 in phenazopyridine photo-degradation: catalyst efficiency, stability and feasibility assessment.

Mineralization of phenazopyridine, 1, in water, under solar-simulator radiation was efficiently achieved using nanoparticle CdS-sensitized rutile TiO(2), TiO(2)/CdS, 2, as photo-catalysts. Despite that, 2 showed two main drawbacks. Firstly, the system was difficult to recover by simple filtration, and demanded centrifugation. Secondly, the sensitizer CdS showed relatively high tendency to leach out hazardous Cd(2+) ions under photo-degradation reaction conditions. In an attempt to solve out such difficulties, 2 was supported onto sand surface. The sand/TiO(2)/CdS system, 3, was easier to recover but showed slightly lower catalytic activity compared to 2. On the other hand, the support failed to prevent leaching of Cd(2+). This indicates limited future applicability of CdS-sensitized TiO(2) photo-catalyst systems, in solar-based water purification strategies, unless leaching out tendency is completely prevented.