Modelling of Adsorption Kinetic Processes—Errors, Theory and Application

Adsorption has become a competitive method in the field of wastewater and air treatment. Adsorption kinetics is one of the main factors that must be understood before the applicability of any adsorbent. In every adsorption process, linear or non-linear analysis of the kinetics is applied. The goodness of fit index (coefficient of correlation or sum of squares) is applied to access the best model. The usage of linear or non-linear from of the adsorption kinetics has an impact on the distribution of error function. Almost in every adsorption study, linear forms have been used to conclude the best kinetic model that influence the adsorption mechanism—which might be an error. Therefore, this review highlights the mistakes in the usage of linear and non-linear models. The applicability of the adsorption kinetics in wastewater treatment is also illuminated

The Relationship Between Market Environment Dimensions and Availability of Malaria Pills in Uganda

Introduction: This study sought to examine the contribution of relationship building (in terms of collaboration, information sharing and supply chain interdependence) on the availability of malaria treatment pills in public hospitals in Sub-Saharan Africa using data from Uganda. Methods: By means of a cross-sectional survey research design, the study used a questionnaire strategy to collect quantitative data. Out of the 320 questionnaires that were distributed in 40 public hospitals, 283 were answered and returned, which yielded an 88% response rate. Structural equation modelling (SEM) was used to establish the relationship between measured variables and latent constructs. Results: Drawing on the survey results, the confirmatory factor analysist and the Structural Equation Modelling clearly demonstrate that relationship building (in terms of collaboration, information sharing and supply chain interdependence) significantly influences the availability of Artemisinin-based combination therapies in public general hospitals in Uganda. Conclusion: Policy-makers should focus on developing cheaper information technology tools to exchange information regarding stock levels, forecasting, quantification, orders, and dispensing. This study developed a measurement model for an inter-hospital relationship, using relational view theory, and it employs dimensions in terms of information sharing and supply chain interdependence to predict and explain the availability of malaria pills in government hospitals.Business Managemen

Offshoring-Outsourcing and Onshoring Tradeoffs: The Impact of Coronavirus on Global Supply Chain

The world has become a global village with companies investing in different nations to remain afloat and competitive. In the process of offshoring- outsourcing, companies and nations have become interdependent in their efforts to bridge the supply chain network. However, during a pandemic, such as the Coronavirus (COVID-19) that involved the closure of borders, and during which there was a high demand of lifesaving machines and personal protective equipment, many countries were left scrambling for critical medical products such as ventilators and personal protective equipment for doctors. Hence, the tendency away from offshoring and outsourcing to onshoring production. COVID-19 has elicited that countries need to invest in an onshore business if they are to remain afloat. However, investing in onshore (local) business calls for a tradeoff, which some countries cannot afford. Many countries lack skilled labour (developing countries), and where available, it is too expensive (developed countries) making onshore an expensive venture. Besides, promoting manufacturing companies means increased air pollution and greenhouse gases that are responsible for 4.2–7.0 million premature deaths every year, and which costs $4.6 trillion per year. Such death rates and cost can hinder the onshore business. Therefore, for countries to survive in the era of a pandemic, the best alternative is to build strong ties with offshore-outsource nations

Adsorption of Methylene Blue and In-situ Reactivation of Granular Activated Carbon (GAC) with Ozone

Granular activated carbon (GAC) is a porous, fine-grained adsorbent rich in carbon and it has been widely applied in water and wastewater treatment processes. For instance, GAC can be utilized in adsorption processes. Adsorption is a purification technique in which soluble impurities are removed from the solvent and adhere to the surface and pores of a solid material. Ozonation is extensively used in the treatment of wastewater as well. (Turhan, Durukan, Ozturkcan, & Turgut, 2012). Because of its high oxidizing power, ozone can break down colored substances like dyes in wastewater, which improves the aesthetics of water. However, to treat heavily colored industrial wastewater (e.g. textile wastewater), a high volume and concentration of ozone is necessary. This makes the application of ozone expensive. Adsorption using granular activated carbon (GAC) has been proven to be a superior method during the removal of methylene blue from water (Vargas, Cazetta, Kunita, Silva, & Almeida, 2011). When the adsorption capacity is reached, GAC is either regenerated or disposed to the landfill; the latter is the most common. This makes the application of GAC alone an expensive technology during the industrial treatment of dye. The purpose of this study is to concentrate methylene blue dye on GAC through column adsorption and perform in-situ regeneration of GAC using ozone. This will allow for repeated use of the GAC, and the process should be more efficient and less expensive than adsorption or ozone alone

Recent Advancements in the Removal of Cyanotoxins from Water Using Conventional and Modified Adsorbents—A Contemporary Review

The prevalence of cyanobacteria is increasing in freshwaters due to climate change, eutrophication, and their ability to adapt and thrive in changing environmental conditions. In response to various environmental pressures, they produce toxins known as cyanotoxins, which impair water quality significantly. Prolonged human exposure to cyanotoxins, such as microcystins, cylindrospermopsin, saxitoxins, and anatoxin through drinking water can cause severe health effects. Conventional water treatment processes are not effective in removing these cyanotoxins in water and advanced water treatment processes are often used instead. Among the advanced water treatment methods, adsorption is advantageous compared to other methods because of its affordability and design simplicity for cyanotoxins removal. This article provides a current review of recent developments in cyanotoxin removal using both conventional and modified adsorbents. Given the different cyanotoxins removal capacities and cost of conventional and modified adsorbents, a future outlook, as well as suggestions are provided to achieve optimal cyanotoxin removal through adsorption

Application of Lanthanides in Wastewater Treatment and Water Reuse

Much of the world’s population feed on grains (wheat, rice, and corn). Corn is as sensitive as it is productive. This thirsty, fast-growing plant goes into thermal shock in drought. In 2014, California lost over $2.2 billion in crop production due to drought. The Horn of Africa (in 2011) and Sahel (in 2012) faced humanitarian disasters due to food and water scarcity. The higher frequency of climate change and the erratic nature of rain, combined with underlying economic and social vulnerabilities, has meant that food and water scarcity is here to stay. To improve food and water scarcity, water reclamation and reuse is a logical option. To alleviate food production, phosphorus is necessary to increase crop yield. Apart from the affordable phosphorus rock that is expected to last for less than 80 years, the primary source of phosphorus can be wastewater. Aluminum, iron, and magnesium coagulants (AIMCs) are expended to retrieve phosphorus from wastewater and deliver clean water to communities. However, AIMCs\u27 performance is affected by pH, making their application in wastewater a challenge. If excess phosphorus is not removed from wastewater, 1-2 mg/L of phosphorus can pollute water bodies triggering algal bloom and resource loss. Emerging lanthanide coagulants (LCs) were introduced in wastewater treatment plants to retrieve phosphorus (Task-1). LCs outperformed AIMCs, especially under extreme acidity conditions and enhanced removal of other contaminants like organic matter. LCs don’t require pH adjusters and produce less sludge which translates into cost-saving. The use of LCs in water means human/animal exposure, and there is a lack of information on lanthanide-associated health effects. Therefore, the study was extended to understand the cytotoxicity and genotoxicity of LCs (Task-2). This objective helps the World Health Organization and Environmental Protection Agency to establish exposure limits of LCs. Bioassays with human cells were used to fulfill this objective. At expected LC effluent concentrations (0.5 mg/L) from WWTP, LCs did not elicit any changes in mitochondria potential, reflective of continued cellular ability to generate energy. LCs did not activate the production of reactive species that can trigger cytotoxicity. Furthermore, no DNA damage was registered as a result of LCs exposure. Having secured that LCs are less harmful and possess a high affinity to retrieve phosphorus and treat wastewater, lanthanide-phosphorus (Ln-P) precipitates and lanthanide reclaimed wastewater (LRWW) were used to grow corn (maize), Task 3. LCs did not affect corn growth in terms of height, chlorophyll development, stomatal conductance, and electron transport rate. Lanthanides did not attenuate the availability of phosphorus to corn as anticipated. In addition, lanthanides increased calcium and magnesium uptake. Thus, full-scale implementation of LCs in wastewater treatment can help us bridge the following United Nations Sustainable Development Goals (UNSDGs): • UNSDG-6: Clean water and sanitation/public health: Treated wastewater can be recycled to communities while reducing community exposure to pathogens and emerging contaminants • UNSDG-2: No hunger: Treating wastewater and recovering vital nutrients boosts agriculture • UNSDG-1: No poverty: Boosting agriculture enhances crop yields, thus leading to poverty reduction for farmers • UNSDG-11: Sustainable communities and cities: Collecting and capturing nutrients from wastewater before they are discharged into the environment promotes community sustainability • UNSDG-14: Life below water: Removing nutrients like phosphorus protects water bodies from algae growth that affect the aquatic environment • UNSDG-15: Life on land: Preventing water contamination protects animals from toxins like cyanotoxin

Adsorption isotherms and kinetics of vanadium by shale and coal waste

The use of adsorption using nanomaterials has become a very competitive method for removal of hazardous materials from wastewater. With increasing consumption of fossil fuels and development of energy storage systems, the levels of vanadium pollution are expected to increase. Utilizing natural shale and coal waste as adsorbents, batch adsorption, isotherms, and kinetics of vanadium was studied. The adsorption characteristics of shale and coal waste were studied using Fourier Transform Infrared spectroscope and Scanning Electron Microscopy. The effect of pH, the amount of adsorbent, vanadium concentration, temperature, and contact time between adsorbate and adsorbents were also studied to obtain optimum conditions for maximum adsorption of vanadium. The Fourier Transform Infrared results show little distortion in the vibration of bands, and hence the surface properties remain unchanged for both sorbents after adsorption. The adsorption kinetics are best described by pseudo-second order, while Langmuir model fits the adsorption isotherm for both adsorbents. Maximum sorption capacity is 67.57 mg/g for shale while that of coal is 59.88 mg/g at 298 K and pH 3. For both adsorbents, the adsorption process is spontaneous, endothermic, and chemisorption in nature. Both adsorbents can effectively be recycled twice