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Adsorption stand out among other standard techniques used for water treatment because of its remarkable simplicity, easy operation, and high removal capability. Expanded graphite has been selected as a promising agent for oil spill adsorption, but its production involves the generation of corrosive remnants and massive amounts of contaminated washing waters. Although the advantageous use of the H2O2–H2SO4 mixture was described in 1978, reported works using this method are scarce. This work deals with the urgent necessity for the development of alternative chemical routes decreasing their environmental impact (based on green chemistry concepts), presenting a process for expanded graphite production using only two intercalation chemicals, reducing the consumption of sulfuric acid to only 10% and avoiding the use of strong oxidant salts (both environmentally detrimental). Three process parameters were evaluated: milling effect, peroxide concentration, and microwave expansion. Some remarkable results were obtained following this route: high specific volumes elevated oil adsorption rate exhibiting a high oil–water selectivity and rapid adsorption. Furthermore, the recycling capability was checked using up to six adsorption cycles. Results showed that milling time reduces the specimen’s expansion rate and oil adsorption capacity due to poor intercalant insertion and generation of small particle sizes.

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Mechanical alloying technique, such high energy ball milling process, is suitable for producing composite metal powders with a fine controlled microstructure. This method is crucial for obtaining homogeneous distribution of nano-sized dispersoids in a more ductile matrix (e.g. aluminium-or copper based alloys). The reinforcing particles Al4C3 have become an interesting reinforcing material because their high level of physical and mechanical properties, e.g. high temperature strength, thermal cyclic resistance, wear resistance and low linear expansion coefficient. Therefore, the reinforcement of the aluminum using Al 4 C 3 has recently become the subject of many studies and widely used for products and structures [1,2].The Al-based composites were produced by mixing Al powder (99.5 % purity) with 1 and 2 wt. % of Al 4 C 3 nanoparticle powder (previously synthetized by mechanical milling and subsequent heat treatment), each Al-Al 4 C 3 mixtures powder were mechanically milled in a high energy Simoloyer mill during 8 h. Argon was used as the milling atmosphere and ~4 ml methanol as a process-control agent. The device and milling media used were made from hardened steel. The milling ball to powder weight ratio was set to 50:1. Consolidated samples were obtained by pressing the powder mixtures during 20 s at 350 MPa in uniaxial load. The consolidate sample was sintered during 2h at 650°C. The Al4C3 reinforcing phase dispersed into the aluminum matrix also was observed by using electron microscopy analyses. Fig. 1a shows a STEM bright-field image of Al-20 sample (2 wt. % of Al 4 C 3 and not sintered), the image shows a graphite nanoparticle of about 10 nm long which is close to an Al4C3 nanoparticle that shows an irregular shape present in the aluminum matrix. Fig. 1b shows the simulated image that shows the interplanar distance of the A selected area of a Al 4 C 3 nanoparticle and the interplanar distance of the B selected area of a graphite nanoparticle. The Fig. 2a shows a STEM bright-field representative image of a rod-shaped aluminum carbide nanoparticle of about 100 nm long and 10 nm wide in the Al matrix of Al-22 sample (2 wt. % of Al 4 C 3 and sintered during 2 h). The HRTEM image of Figure 2b shows the interplanar distances of a rod shaped particle which correspond to Al 4 C 3 compound. At seems the Al 4 C 3 irregular shape nanoparticles dispersed into the Al matrix during the mechanical milling change to a regular rod-shaped after the sintering process.