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In the modern communication era, the disposal of printed circuit boards is ecologically of dire concern on a global scale. The two prevalent methods applied for the disposal of this waste are either incineration or landfilling both of which are viewed with skepticism due to their negative environmental impact. Activation of the nonmetallic fraction of this waste leads to the development of a mesoporous material with highly functional groups which can potentially be applied for heavy metal uptake. The removal of copper, lead, and zinc was studied employing a cost-effective novel adsorbent based on waste printed circuit boards. The results indicate that the modification of the original e-waste material has a considerable effect on its surface area enhancement. Adsorption experiments revealed that the modified novel material had uptake capacities of 2.9 mmol Cu, 3.4 mmol Pb, and 2.0 mmol Zn per each gram of the adsorbent which are significantly higher values than its commercial counterparts used in industry. [ABSTRACT FROM AUTHOR]

The combustion of wastes has very significant benefits in reducing the volume of waste materials and producing energy. However, combustion processes produce emissions, which must be below the Best Practical Means (BPM) specified legislative limits. Several wastes, such as tires and meat meal, have been successfully combusted in cement kilns, up to 20% w/w, while retaining emission standards well below legislative limits. In the case of municipal solid waste (MSW) the introduction of large amounts of MSW into cement kilns is not practical because the additional kiln volume required is too great, the large amounts of ash generated will affect the cement clinker quality, and it would be difficult to sustain the required very high clinkering temperature of 1500 °C with large quantities of low calorific value MSW. A completely novel process, termed the Co-Co process, has been developed, integrating MSW combustion in a synergistic fashion with the cement production. This process is based on combining the cement ‘front-end’ calcination reaction and incorporating it with a high temperature, at 1200 °C, combustion process, providing a giant acid gas scrubber. A pilot plant was designed, constructed, and operated to demonstrate the benefits of the Co-Co process. The pilot plant achieved emissions minimization: dioxins were typically 0.5–1% of the European BPM limits, HCl, SOx, NOx, and particulates were 15, 10, 20, and 25% of BPM limits, respectively. Heavy metals were typically below 25% of BPM limit values. [ABSTRACT FROM AUTHOR]

Determines the solid-phase loading for the removal of metal ion from effluents using fixed-bed adsorbers. Utilization of the film pore diffusion model; Prediction of theoretical breakthrough curves; Accuracy of equations for application in design models.

Altering the textural properties of activated carbons (ACs) via physicochemical techniques to increase their specific surface area and/or to manipulate their pore size is a common practice to enhance their adsorption capacity. Instead, this study proposes the utilization of the vacant sites remaining unoccupied after dye uptake saturation by removing the steric hindrance and same-charge repulsion phenomena via multilayer adsorption. Herein, it has been shown that the adsorption capacity of the fresh AC is a direct function of the dye molecular size. As the cross-sectional area of the dye molecule increases, the steric hindrance effect exerted on the neighboring adsorbed molecules increases, and the geometrical packing efficiency is constrained. Thus, ACs saturated with larger dye molecules render higher concentrations of vacant adsorption sites which can accommodate an additional layer of dye molecules on the exhausted adsorbent through interlayer attractive forces. The second layer adsorption capacity (60-200 mg·g-1) has been demonstrated to have a linear relationship with the uncovered surface area of the exhausted AC, which is, in turn, inversely proportional to the adsorbate molecular size. Unlike the second layer adsorption, the third layer adsorption is a direct function of the charge density of the second layer. [ABSTRACT FROM AUTHOR]

Thisreview covers the production of solid carbonaceous materialsat high temperatures (above 500 °C) and high pressures. The revieworders the high temperature/high pressure (HTHP) studies by theirfinal product categories, namely carbon spheres, prolate spheroids(also known as ellipsoids and olivaries), nanotubes, and others suchas diamonds, fullerenes, composites, and nanostars. The mechanismsas well as the properties of the products are discussed. In particular,the literature pertaining to the production of carbon ellipsoids hasbeen collected for the first time. On one hand, the review concludesthat, due to the existence of other conventional and more practicalmethods, the production of nanotubes and spheres via HTHP does notappear to be industrially feasible. On the other hand, using the HTHPmethod to produce olivary carbons and other new and exotic productsseems attractive due to the absence of conventional methods for theirproduction. [ABSTRACT FROM AUTHOR]

Presents a combined diffusion model for the sorption of cadmium, copper and zinc ions onto bone char. Measurement and analysis of the ability of bone char to remove three single-component metals from aqueous solution; Examination of the effect of sorbent mass and initial metal ion concentration for the three systems analyzed; Description of the sorptions of three types of ions onto bone char.