Adsorption of heavy metals on conventional and nanostructured materials for wastewater treatment purposes: A review

Fruits and vegetables are the most utilized commodities among all horticultural crops. They are consumed raw, minimally processed, as well as processed, due to their nutrients and health-promoting compounds. With the growing population and changing diet habits, the production and processing of horticultural crops, especially fruits and vegetables, have increased very significantly to fulfill the increasing demands. Significant losses and waste in the fresh and processing industries are becoming a serious nutritional, economical, and environmental problem. For example, the United Nations Food and Agriculture Organization (FAO) has estimated that losses and waste in fruits and vegetables are the highest among all types of foods, and may reach up to 60%. The processing operations of fruits and vegetables produce significant wastes of by-products, which constitute about 25% to 30% of a whole commodity group. The waste is composed mainly of seed, skin, rind, and pomace, containing good sources of potentially valuable bioactive compounds, such as carotenoids, polyphenols, dietary fibers, vitamins, enzymes, and oils, among others. These phytochemicals can be utilized in different industries including the food industry, for the development of functional or enriched foods, the health industry for medicines and pharmaceuticals, and the textile industry, among others. The use of waste for the production of various crucial bioactive components is an important step toward sustainable development. This review describes the types and nature of the waste that originates from fruits and vegetables, the bioactive components in the waste, their extraction techniques, and the potential utilization of the obtained bioactive compounds.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/1541-4337.12330

Fruit and Vegetable Waste: Bioactive Compounds, Their Extraction, and Possible Utilization.

The fifth edition of "Numerical Methods for Engineers" continues its tradition of excellence. Instructors love this text because it is a comprehensive text that is easy to teach from. Students love it because it is written for them--with great pedagogy and clear explanations and examples throughout. The text features a broad array of applications, including all engineering disciplines. The revision retains the successful pedagogy of the prior editions. Chapra and Canale's unique approach opens each part of the text with sections called Motivation, Mathematical Background, and Orientation, preparing the student for what is to come in a motivating and engaging manner. Each part closes with an Epilogue containing sections called Trade-Offs, Important Relationships and Formulas, and Advanced Methods and Additional References. Much more than a summary, the Epilogue deepens understanding of what has been learned and provides a peek into more advanced methods. Approximately 80% of the end-of-chapter problems are revised or new to this edition. The expanded breadth of engineering disciplines covered is especially evident in the problems, which now cover such areas as biotechnology and biomedical engineering. Users will find use of software packages, specifically MATLAB and Excel with VBA. This includes material on developing MATLAB m-files and VBA macros.

Numerical methods for engineers

Surfactants And Interfacial Phenomena

Removal of heavy metals from water sources in the developing world using low-cost materials: A review.

Heavy metals are discharged into water from various industries. They can be toxic or carcinogenic in nature and can cause severe problems for humans and aquatic ecosystems. Thus, the removal of heavy metals from wastewater is a serious problem. The adsorption process is widely used for the removal of heavy metals from wastewater because of its low cost, availability and eco-friendly nature. Both commercial adsorbents and bioadsorbents are used for the removal of heavy metals from wastewater, with high removal capacity. This review article aims to compile scattered information on the different adsorbents that are used for heavy metal removal and to provide information on the commercially available and natural bioadsorbents used for removal of chromium, cadmium and copper, in particular.

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Heavy metal removal from wastewater using various adsorbents: a review

This paper reviews various kinds of heat storage materials, their composites and applications investigated over the last two decades. It was found that sensible heat storage systems are bulkier in size as compared to the latent heat storage systems. Latent heat storage system using phase change materials (PCMs) stores energy at high density in isothermal way. Various geometries of PCM containers used for enhancement of heat transfer area, materials used for the construction of PCM containers and their interaction with heat storage materials are studied. The choice of storage material depends on the desired temperature range, application of thermal storage unit and size of thermal storage system. Low temperature heat storage system uses organic phase change materials while inorganic phase change materials are best suited for high temperature heat storage. Heat transfer within the PCM can be enhanced by preparing composite of high thermal conductivity as well as by altering the geometrical design like addition of fins, use of straight and helical tubes etc. Shell and tube configurations were mostly used for thermal storage systems. Heat transfer enhancement using PCM composite is a promising approach as it reduces cost and bulkiness to the system.

Heat storage materials, geometry and applications: A review

Increased industrialization and motorization are the major cause of environmental pollution and diminishing petroleum reserves. Biodiesel being renewable and environment friendly is one of the alternate sustainable energy sources having similar fuel properties as that of petroleum diesel. The objective of this study is to produce biodiesel from cheap raw material (waste cooking oil) and to get optimum reaction conditions for both homogeneous and heterogeneous catalytic transesterification. A comparison is also made to make the transesterification process techno-economically feasible. Potassium hydroxide (KOH) was selected as a homogeneous catalyst and KOH loaded on alumina as a heterogeneous catalyst. A yield of 96.8% fatty acid methyl ester (FAME) was obtained with heterogeneous catalyst at the optimum conditions of reaction temperature 70 °C, reaction time 2 h, catalyst concentration 5%, catalyst loading 15 wt%, and methanol to oil molar ratio 9:1, whereas 98.2% yield was obtained with homogeneous KOH catalyst at the optimum reaction conditions of reaction temperature 70 °C, reaction time 1 h, catalyst concentration 1%, and methanol to oil molar ratio 6:1. The fuel properties were also measured for biodiesel to observe its competitiveness with conventional diesel fuel. Reusability test of KOH loaded on alumina catalyst gave reasonable yield up to 3 cycles.

Study of catalytic behavior of KOH as homogeneous and heterogeneous catalyst for biodiesel production

Lubricant oils are known to decrease the friction coefficient between two contacting surfaces. It is essential for the correct function of almost the totality of mechanical machinery working in the entire world. Lubricant oils consist of about 80% of oily base stocks which attributes to their properties of viscosity, stability, and pour point to the lubricant plus additives supplemented to improve these properties. Petroleum lubricants are usually environmentally unacceptable due to their low biodegradability and toxicity. These oils contaminate the air, soil, and drinking water and affect human and plant life to a great extent. Thus, the demand for environmentally acceptable lubricants is increasing along with the public concerns for a pollution-free environment. Plant oils are promising as base fluid for biolubricants because of their excellent lubricity, biodegradability, viscosity–temperature characteristics, and low volatility. The purpose of this paper is to present a survey of the current status of...

Lubricants from renewable energy sources – a review

In the present study, optimization of biodiesel production from mixture of edible and nonedible vegetable oils with low to high free fatty acid (FFA) has been investigated. The selection of oils was based on richness of particular fatty acid in it. The combination of oils has been optimized to get suitable mixture for production of biodiesel. The mixture was analyzed in terms of physical properties and accordingly two step esterification process was applied. For optimization study, the response surface methodology(RSM) based central composite design (CCD) was used in Design of Experiments (DOE) software to optimize the various process variables such as reaction time, methanol to oil molar ratio, reaction temperature and catalyst concentration for biodiesel production . A quadratic model was created for the prediction of the Biodiesel yield. The R 2 value of the model was 0.96 which indicates the satisfactory accuracy of the model. The optimum conditions were obtained as follows: reaction temperature of 43.50 °C, methanol to oil molar ratio of 8.8:1, catalyst concentration of 1.9 g/100 cc feed, reaction time of 58.4 min. At these reaction conditions, the predicted and observed biodiesel yield was 97.02% and 97.00%, respectively. These values experimentally satisfied the accuracy of the model. GC and FTIR analysis of biodiesel was also done for biodiesel characterization.

Madhu Agarwal

Papers

Heavy metal removal from wastewater using various adsorbents: a review

Heat storage materials, geometry and applications: A review

Study of catalytic behavior of KOH as homogeneous and heterogeneous catalyst for biodiesel production

Lubricants from renewable energy sources – a review

Optimization of biodiesel production from mixture of edible and nonedible vegetable oils