Adsorptive capacity of spray-dried pH-treated bentonite and kaolin powders for ammonium removal

The effectiveness of ammonium (NH₄⁺) adsorption was investigated, using spray-dried, pH-treated bentonite, and kaolin as adsorbents. Each powder's adsorption capacity towards NH₄⁺ was examined after up to 120 min of sample exposure, and results were compared. The zeta potential values for bentonite samples were between ?1.1 and ?19.4 mV, while for kaolin samples, they were between ?35.7 and ?40.9 mV (pH range examined was 2–10). The adsorption isotherm for bentonite showed a fit with the Langmuir model. The pH 10-treated bentonite and as-received bentonite (dispersed as pH 10 in distilled water) showed the highest adsorption capacity towards NH₄⁺. Meanwhile, for kaolin, the adsorption capacity was low and observed only at low NH₄⁺ concentration (100 mg/L and 200 mg/L), with pH 10-treated kaolin showed the highest adsorption capacity.     

Hollow fiber nanofiltration membranes: A comparative review of interfacial polymerization and phase inversion fabrication methods

Membrane-based separation is now established as one of staple technologies used in water treatment and reuse applications. Nanofiltration, in particular, can be a cost-effective solution for removing large ions and low-molecular-weight compounds from water. Nanofiltration membranes have been manufactured mostly as flat sheets and used in spiral wound modules. Hollow fiber geometry, however, offers several advantages over flat sheet and other configurations. This paper overviews recent developments in the design of hollow fiber nanofiltration membranes and provides a comparative analysis of two main methods of their fabrication: interfacial polymerization and phase inversion.     

Institutions for Cyber Security: International Responses and Global Imperatives

Almost everyone recognizes the salience of cyberspace as a fact of daily life. Given its ubiquity, scale, and scope, cyberspace has become a fundamental feature of the world we live in and has created a new reality for almost everyone in the developed world and increasingly for people in the developing world. This paper seeks to provide an initial baseline, for representing and tracking institutional responses to a rapidly changing international landscape, real as well as virtual. We shall argue that the current institutional landscape managing security issues in the cyber domain has developed in major ways, but that it is still “under construction.” We also expect institutions for cyber security to support and reinforce the contributions of information technology to the development process. We begin with (a) highlights of international institutional theory and an empirical “census” of the institutions-in-place for cyber security, and then turn to (b) key imperatives of information technology-development linkages and the various cyber processes that enhance developmental processes, (c) major institutional responses to cyber threats and cyber crime as well as select international and national policy postures so critical for industrial countries and increasingly for developing states as well, and (d) the salience of new mechanisms designed specifically in response to cyber threats.