Biosorbents have been highlighted as an alternative method for the removal of contaminants from spills or leaks of oil and its derivatives, since they are biodegradable, are highly available, low-cost, and have a good sorption capacity. This research investigated the sorption capacity of Calotropis procera fiber in natura (CP) and thermally treated (150 °C and 200 °C) for crude oil removal and recovery. The oil sorption tests were carried out in a dry and water (layer) static systems. The assays revealed that CP fiber has excellent hydrophobic-oil properties and good crude oil sorption capacity, about 75 times its own weight (76.32 g/g). The results of the treated fibers, CPT150 and CPT200, showed oil sorption capacities (in 24 h) higher than CP, between 94.31–103.37 g/g and 124.60–180.95 g/g, respectively. The results from sample CPT200 showed that it can be an excellent biosorbent for the removal of crude oil and other derivatives due to its high hydrophobicity, great reuse/resorption capacity, and ability to retain oil within the fiber lumens. Thus, it can be applied in the recovery, cleaning, and removal of petroleum products and its derivatives from spills and leaks in the future.

Calotropis procera (CP) fiber is a natural and renewable material with great lumen and hydrophobic-oleophilic characteristics, providing it with a good oil absorption capacity. In order to increase the absorption efficiency of organic oils and solvents, CP fiber was treated with either 0.1 M NaOH (CPNaOH), 1% NaClO2 (CPNaClO2), or hydrothermal conditions (CPHT) in an effort to improve its ability to remove crude oil from leaks or spills. The fibers were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with field emission (SEM-FEG), and wettability for water and diesel. The fibers CPHT, CPNaOH, and CPNaClO2 showed excellent hydrophobic-oleophilic properties and good crude oil absorption capacity in water 99.2 g/g, 103.9 g/g, and 92.0 g/g. The absorption after 60 min for most fibers in dry systems or with a layer of oil floating on water exceeded 90% of its absorption capacity for the time of 1440 min. The CPNaOH after 6 runs absorbed 445.8 g of crude oil per gram of fiber. Based on the results, the treated fibers can be considered an alternative for the removal of oil from leaks and spills due to the high availability and excellent absorption property for various oils.

The objective of this study was to evaluate the Calotropis procera fiber treated with NaOH combined with heat treatment as sorbent material for removal of petroleum and derivatives in cases of oil spill. The effects of oil viscosity, fiber/oil contact time, and the type of sorption system (oil and oil/water) were evaluated by experimental planning. The fiber obtained was characterized by Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (SEM-FEG), thermogravimetric analysis (TG/DTG), contact angle, and wettability. The fiber treated by combining NaOH and heat treatment (CPNaOHT) exhibited a large structure with an internal diameter of 42.99 ± 3.98 μm, roughness, and hydrophobicity on the surface with a contact angle of 101 ± 2°. The sorption capacity of oil ranged from 190.32 g/g to 98.9 g/g. After five cycles of recycling, the fiber still maintains about 70% of its initial sorption capacity and presented low liquid desorption (0.25 g). In this way, it can be used as an efficient sorbent to clean up spills of oil and oil products.

Calotropis procera fibres have been proposed for free-phase diesel removal in case of spillage into groundwater. For this, characterizations were carried out using Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FEG-SEM), wettability and contact angle measurements. Sorption oil capacity, kinetic, isothermal and recycling behaviour were evaluated. For initial optimization of the oil sorption capacity, an experimental design (DOE) was applied, with the optimized condition being 60 g L-1 of diesel in water and 0.01 g of fibre. Then, the results clearly indicated that the fibres have a hydrophobic and oleophilic character, quickly reaching more than 71.43 g g(-1) of diesel sorption, according to the adjustment (R-2 > 0.99) of the pseudo-second order and Langmuir models, governed by absorption mechanisms. It should also be noted that at the end of 8 reuse cycles, the fibre presented a total accumulated sorption capacity of about 252.6 g g(-1) of diesel. Furthermore, a laboratory-scale experiment was carried out to remove diesel from groundwater in gas station areas, the fibre removed 98.55% to 99.97% of removal efficiencies were achieved of the free phase over time. Therefore, the material demonstrates excellent characteristics for removing diesel spills in groundwater due to its fast, high and stable removal capacity. GRAPHICAL ABSTRACT

Biodiesel is considered a clean and renewable energy source, however it is important to know the environmental impacts caused by the water-soluble fraction (WSF) of this fuel, in the event of a spill. The objective of this research was to evaluate the seawater-soluble fraction of biodiesel (B100) compared to diesel (S500). A factorial design was used to carry out the experiments and evaluate the WSF's, varying the type of fuel and the contact time between oil and water (O/W) from 1h to 24h. The mortality rate (%) of Mysidopsis juniae and the concentration of total hydrocarbons (TPH) were used as response variables. The results obtained demonstrate that diesel showed greater toxicity, with an average mortality rate of 98.4 % and TPH concentration of 475.8 µg/L in the water-soluble fraction. On the other hand, biodiesel did not present significant toxicity in the exposure of organisms, even after 24 hours of contact, but it can still cause risks in cases of spillage (average mortality rate of 15.0%). The empirical models obtained using the experimental design methodology were able to satisfactorily estimate the TPH concentrations and the mortality rate in the WSF, with precision above 99%, with correlation coefficients (R²) of 0.9963 and 0.9970. Pure biodiesel, due to its low lethality of organisms, biodegradable and from a renewable source, is an ecologically favorable proposal as a fuel, causing less impacts in cases of spillage in seawater.

O derramamento de petróleo e seus derivados na água e no solo tem sido um desafio no mundo há décadas, devido à alta toxicidade e mobilidade dos hidrocarbonetos. Um dos métodos mais eficiente para minimizar esse tipo de contaminação é o uso dos processos de sorção. Atualmente, os sorventes sintéticos são os mais utilizados em derramamento de óleos, devido às suas ótimas propriedades oleofílicas e hidrofóbicas. Entretanto, devido seus custos elevados diversas pesquisas vêm buscando sorventes alternativos. Os biosorventes vêm se destacando como método alternativo na remoção de contaminantes orgânicos, pois além de serem biodegradáveis, apresentam alta disponibilidade natural, baixo custo, e uma boa capacidade de sorção. O objetivo desta pesquisa foi hidrofobizar o Madacaru (Cereus jamacaru DC.) com a cera de Carnaúba para uso como material sorvente na remoção de diesel em casos de derramamento. O material foi caracterizado pelas técnicas FTIR, TG/DTG, DSC, MEV, Molhabilidade/Ângulo de contato. A hidrofobização aumentou significativamente a afinidade do material por óleo com um ângulo de contato com a água de 94º; as micrografias e FTIR confirmaram que as superfícies do Mandacaru foram cobertas por cera de carnaúba, e os resultados de sorção para diesel foram satisfatórios sem diminuição da capacidade de sorção pela hidrofobização (1,65±0,01 g/g).