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Paper is one of the oldest and most abundant materials known to man. Recently, there has been a considerable interest in creating paper devices by combining paper with other functional materials. In this letter, we demonstrate a simple fabrication technique to create water-resistant ferro-patterns on wax paper using CO2 laser ablation. A resolution of about 100 mu m is achieved which is mostly limited by the cellulose fiber size (similar to 50 mu m) in the wax paper and can be improved by using a smaller cellulose matrix. Laser ablation results in modification of surface morphology and chemistry, leading to a change in surface energy. We also present a 2D model for ferrofluid deposition relating the size of the pattern to the amount of ferroparticles deposited on the surface. Finally, a paper gripper is presented to demonstrate advantages of our technique, which allows microscale patterning and machining in a single step.

Landfill gas contains numerous speciated organic compounds (SOCs) including alkanes, aromatics, chlorinated aliphatic hydrocarbons, alcohols, ketones, terpenes, chlorofluoro compounds, and siloxanes. The source, rate and extent of release of these compounds are poorly understood. The objective of this study was to characterize the release of SOCs and the regulated parameter, non-methane organic compounds (NMOCs) during the decomposition of residential refuse and its major biodegradable components [paper (P), yard waste (YW), food waste (FW)]. Work was conducted under anaerobic conditions in 8-L reactors operated to maximize decomposition. Refuse and YW were also tested under aerobic conditions. NMOC release during anaerobic decomposition of refuse, P, YW, and FW was 0.151, 0.016, 0.038, and 0.221 mg-C dry g(-1), respectively, while release during aerobic decomposition of refuse and YW was 0.282 and 0.236 mg-C dry g(-1), respectively. The highest NMOC release was measured under abiotic conditions (3.01 mg-C dry g(-1)), suggesting the importance of gas stripping. NMOC release was faster than CH4 production in all treatments. Terpenes and ketones accounted for 32-96% of SOC release in each treatment, while volatile fatty acids were not a significant contributor. Release in aerobic systems points to the potential importance of composting plants as an emissions source.

The optimization of supercritical fluid extraction using CO2 for the extraction of contaminants in 15 samples of recycled paper and board (P&B) has been studied. An experimental design was used for simultaneous optimization of the variables involved in both the extraction step and the collection of the extract. Methanol was used as modifier. Several plastisizers such as diethyl phthalate, diisobutyl phthalate, di-n-butyl phthalate, dioctyl adipate, and diethylhexyl phthalate (from 2 to 100 microg/g of paper) were found in the recycled P&B samples. A discriminate analysis applied to all results obtained allow us to classify the samples in three different groups according to the content of recycled pulp (0, 10-30, and > 80% of recycled pulp), the sample thickness (from 600 microm), and the surface treatment of the paper. The analytical behavior and the results are discussed.