ABSTRACT: Colloid transport is believed to be controlled by their interactions with the porous media. The dominating forces are the electrostatic interactions that are determined by colloid surface charge density. Although it is well accepted that electrostatic interactions between colloids and the surrounding environment play a very important role in controlling colloid retention in porous media, it is not clear how pH and ionic strength impact the electrostatic forces and the subsequent colloid transport. To have a better understanding of the impact, column colloid transport experiments were conducted under variable pH and ionic strength conditions. Based on the column experiments, colloid deposition and transport were quantified using the advection-dispersion equation and linked to solution pH and ionic strength. Finally, the repulsive electrostatic interactions between the colloids and the sediments were evaluated for different pH and ionic strength conditions, which were related to colloid transport observations. Results of this research are of importance to advancing the understanding of colloid facilitated heavy metal and organic contaminant transport in the subsurface.

Provides detailed information about the use of nanotechnology in remediating waste and pollution in agriculture Nano-Technological Intervention in Agricultural Productivity explores sustainable, eco-friendly technologies for remediating wastes and contaminated areas in both water and land ecosystems. Focusing on nano-technological innovations that use microbes and microbial agents to improve the quality and pollutant discharge of contaminated sites, this comprehensive volume also discusses molecular approaches for the characterization of nanoparticles, the biosynthetic pathways of microbes, gene and protein expression studies for bio-deterioration techniques, and more. Organized into nine chapters, the book opens with a thorough overview of the functions, classification, properties, synthesis, and applications of nanoparticles. Following a discussion of the environmental and agricultural implications of nanotechnology, the authors examine the current role and future prospects of nanotechnology in managing plant diseases, improving agri-food production, and increasing agricultural productivity. Subsequent chapters cover lignin nanoparticles, various applications of nanotechnology in agriculture, and nano-based advances in plant and microbial science. Offering an up-to-date account of the role of nanotechnologies in agricultural bioremediation, this book: Explores biotechnological advances in the development of sophisticated green technologies for waste minimization and waste control Emphasizes the use of microbes for degradation and removal of various xenobiotic substances Discusses bioremediation approaches in relation to the impact of increased urbanization and industrialization on the environment Covers a variety of applications of nanotechnology in agriculture, including nano-fertilizers, nano-biosensors, nano-pesticides, and nanoparticle protection in plants Nano-Technological Intervention in Agricultural Productivity is a valuable resource for students in plant biotechnology and agricultural science and engineering, as well as an important reference for researchers in plant biotechnology and agricultural sciences, particularly those with interest in the use of nanomaterials for pollution remediation and sustainable development.

Colloid-facilitated migration of plutonium in fractured rock has been implicated in both field and laboratory studies. Other reactive radionuclides may also experience enhanced mobility due to groundwater colloids. Model prediction of this process is necessary for assessment of contaminant boundaries in systems for which radionuclides are already in the groundwater and for performance assessment of potential repositories for radioactive waste. Therefore, a reactive transport model is developed and parameterized using results from controlled laboratory fracture column experiments. Silica, montmorillonite and clinoptilolite colloids are used in the experiments along with plutonium and Tritium. The goal of the numerical model is to identify and parameterize the physical and chemical processes that affect the colloid-facilitated transport of plutonium in the fractures. The parameters used in this model are similar in form to those that might be used in a field-scale transport model.

This book covers the basics of abiotic colloid characterization, of biocolloids and biofilms, the resulting transport phenomena and their engineering aspects. The contributors comprise an international group of leading specialists devoted to colloidal sciences. The contributions include theoretical considerations, results from model experiments, and field studies. The information provided here will benefit students and scientists interested in the analytical, chemical, microbiological, geological and hydrological aspects of material transport in aquatic systems and soils.