Melamine is a key compound used as a clarifying agent for waste lubricating oil primarily due to its excellent adsorbent properties. Moreover, considerable interest exists for the further modification of melamine in order to provide a remediation agent with improved clarification capacity. In this study, hexamethylolmelamine was prepared using a solution of formaldehyde, which provided an agent capable of incorporation into a silicate polymer framework. Subsequently, the resultant monomer was added to a solution of silicate to produce the melamine-silica polymer. The melamine and melamine-silica polymer were characterized using the techniques of XRD, FTIR, SSA and thermal analysis to confirm structural and morphological characteristics. These characterizations indicated that the increase in the surface area of the 0.315 m 2 /g to melamine to 26.71 m 2 /g of melamine-silica suggests the effective introduction of silanols groups to hexamethylolmelamine and, therefore, corresponds to thehigh performance in relation to melamine as clarifying of waste lubricant oil.

Clay is a material that exhibits excellent adsorbent properties which can be applied for the clarification of used motor oils. We describe a comparative analysis between natural and chemically-modified clays as an environmentally sound method of clarification. Previously, a sample of clay was chemically treated with KOH and H2SO4 with a concentration of 2.0 M at 150 °C. Both the natural and chemically-treated samples were characterized using the techniques of XRD, FTIR, SSA, and thermal analysis to observe the structural change after the chemical treatment. These characterizations indicated that there was an increase in surface area and microporous space creation in the acid-treated sample as a result of the clay exfoliation. The acid-treated sample exhibited the potential of clarification of waste oil and high performance relative to the natural sample and the base-treated sample.

The disposal of textile waste in water bodies is exacerbating environmental problems, which led scientists to seek natural materials to develop more sustainable ways. Searching for low cost materials was used to remove the dye in two cellulosic sources (filter papers of different brands). The papers were characterized by XRD which confirmed crystallographic profile similar to cellulose. With the aim of optimizing the best conditions, various tests were performed, where the ideal time was 180 minutes for the paper 1 and 240 minutes for the second paper, both by adjusting the pseudo second-order model. The other parameters studied was the pH, adsorbate-adsorbent systems which have maximum adsorption capacity of 2.76 mg / g at pH 2.02 and 2 mg / g at pH 11 for the paper 1 and 10.57 mg / g pH 4 and 2 mg / g at pH 11 for the paper 2. Both adsorbents had the best fit to the Langmuir model in pHs 2 and 11 at the temperature of 298 K.

Vermiculite clays are adsorbent materials that have good chemical adsorption capacity, which makes them applicable in the removal of drugs from aqueous solutions. Their lamellar structure can be easily expanded and organophilized. To assess the efficacy and environmentally-tolerant capacity of the adsorption method, the organophilized vermiculite clay was compared to both natural and expanded vermiculite clays. To prepare the organophilized clays, a natural clay sample was expanded at 900 °C. The expanded clay was thus treated by immersion in a 1.0 M NaCl solution and organophilized using a cetyltrimethylammonium bromide (CTMA-Br) surfactant, for 24 h at 50 °C. Natural, expanded, and organophilized samples were characterized using the techniques of XRD, FTIR, TG/DSC, and SEM to observe structural changes after expansion and organophilization. These characterizations indicated that there was an increase in the interlamellar space of the expanded and organophilized sample. In addition, a study of the point of zero charge was performed to determine the surface changes of the samples and the amount of doxazosin adsorption in the samples was determined by the time adsorption test. Further, the organophilized sample showed potential adsorption of the drug doxazosin and high performance in relation to the expanded and natural samples.

The constant search for the removal of organic and inorganic pollutants has been largely intensified lately, as has the search for efficient techniques. With that, this work aims to test two filter papers of different origins to identify their interaction with the bright yellow dye and to determine the adsorption capacity of each paper. Various parameters were studied (pH, time, temperature, and concentration) and it was possible to verify that the best interaction conditions between the material and the dye were 180 minutes, pH 2, and temperature of 298 K, with a maximal capacity at approximately 7 mg of dye per gram of material, with a kinetic adjustment to the pseudo-second-order model. Thus, these results prove that the paper interacts with the dye, and it can be used as an adsorbent.