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interesting properties of magnetic nanocomposites have attracted attention of both academic and industrial researchers. In this work, thermal, mechanical, morphological, and magnetic properties of polyethylene (PE) nanocomposites were inspected using carbon‐based magnetic fillers (CNi, CCo, and CFe). The melt mixing method was employed to prepare the nanocomposites using small amounts of filler ranging up to 2 wt%. Wood sawdust pyrolysis produces carbonized material activated by Ni, Co, or Fe salts and used as filler. The structural analysis was carried out using Fourier transform infrared spectroscopy indicating that the polymer chemical structure remains unaltered with the filler addition. Thermal stability of nanocomposites as well as the determination of metal amount in the carbon‐based fillers was investigated by thermogravimetric analysis. Filler introduction enhanced the onset and the maximum degradation temperatures up to 11°C and 8°C, respectively. The crystallization and melting temperatures examined by differential scanning calorimetry remained unchanged as compared to neat PE whereas the percent crystallinity was improved up to 8%. The incorporation of the filler leads to the improvement in the elastic modulus of the polymer matrix. The addition of 2.0 wt% of the metal‐carbonized filler in the diamagnetic polymer resulted in a thermoplastic nanocomposite with ferromagnetic behavior.

In the present study, polysulfone (PSF)-activated carbon nanocomposites were synthesized by a melt mixing technique. Here, 2 wt% activated carbon (CA, CA–Ni, and CA–Co) was used as filler, and effects on thermal, mechanical, magnetic, morphological, and carbon dioxide capture properties were studied. The pyrolysis of wood sawdust produced carbon materials activated by Co and/or Ni salt. The thermal degradation and the amount of metal in the carbon materials were investigated by thermogravimetric analysis. The maximum degradation temperature showed an improvement of up to 3 C, while the initial degradation temperature decreased up to 4 C with the addition of metal-activated carbons. The values of Tg estimated by differential scanning calorimetry appear to be practically identical for pure PSF and its nanocomposites. The elasticity modulus of the nanocomposite shows an enhancement of 17% concerning the neat PSF. The water contact angle showed a decrease with the incorporation of the fillers, indicating the hydrophilic nature of the composite. The carbon dioxide sorption capacity of the nanocomposite showed an enhancement of almost 10% in contrast to neat PSF. Ferromagnetic behavior of the thermoplastic nanocomposite was observed with the introduction of 2.0 wt% metal-carbonized filler. The exceptional magnetic properties, for a thermoplastic material such as polysulfone, make it promising for various industrial applications.

Eragrostis plana Nees leaves, abundant lignocellulosic biomass, was used as carbon source for preparation of activated carbon, by using microwave-assisted pyrolysis and chemical activation. The novel activated carbon (MWEPN) was characterised by FTIR, CHN elemental analysis, Boehm’s titration method, TGA, SEM, N2 adsorption/desorption curves and pH of the point of zero charge (pHpzc). Afterwards, the adsorbent was successfully employed for adsorption of the two emerging contaminants (caffeine and 2-nitrophenol). The results indicated that MWEPN had a predominantly mesoporous structure with a high surface area of 1250 m2 g−1. FTIR analysis indicated the presence of carbonyl, hydroxyl and carboxylic groups on the surface of MWEPN. The Boehm analysis showed the existence of the high amount of acid moieties on the surface of activated carbon. Adsorption kinetic indicated that the system followed the Avrami fractional order at the optimal pH of 7. The equilibrium time was attained at 30 min. The Liu isotherm model better described the isothermal data. Based on the Liu isotherm, the maximum sorption capacities (Qmax) of caffeine and 2-nitrophenol adsorbed onto activated carbon at 25 °C were 235.5 and 255.8 mg g−1, respectively.

Activated carbon (AC) was prepared from sapelli wood sawdust using a microwave heating process. The biomass was mixed with inorganic components (lime + ZnCl2 and FeCl3) to form a homogeneous paste. The AC samples are denoted as AC-1A (100 g sapelli wood sawdust + 20 g lime + 80 g ZnCl2), AC-2A (150 g sapelli wood sawdust + 20 g lime + 80 g ZnCl2), AC-1B (100 g sapelli wood sawdust + 20 g lime + 40 g ZnCl2 + 40 g FeCl3), and AC-2B (150 g sapelli wood sawdust + 20 g lime + 40 g ZnCl2 + 40 g FeCl3). The samples were placed in a microwave oven and pyrolyzed under nitrogen flow. To increase their porosity, the pyrolyzed samples were subjected to a leaching process (with 6 mol L−1 HCl) under reflux to eliminate inorganic components. Several analytical techniques such as Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and N2 isotherm and vapor adsorption analyses were performed to characterize the AC materials. The samples presented high Brunauer–Emmett–Teller (BET) surface areas, up to 941.08 m2 g−1 for AC-1A. The AC materials were tested for their o-cresol removal ability by determining the best fits to equilibrium and kinetic data using the Sips isotherm and fractional-order model, respectively. The maximum adsorption capacity of the AC samples as obtained from the Sips model was correlated with the surface area. The proposed adsorption mechanism suggests that hydrogen bonding, donor–acceptor complexation, and π–π interactions play key roles. The adsorbents were also tested for treatment of simulated industrial effluents, showing very good efficiency. Almost complete regeneration of the AC adsorbents was achieved using 10 % EtOH + 5 mol L−1 NaOH as eluent. These results demonstrate that sapelli wood sawdust is a promising precursor for preparation of AC to remove o-cresol from aqueous solution.

Nesta tese, carvões ativos (AC) oriundos de biomassa lignocelulósica foram preparados por pirólise assistida por microondas, caracterizados e aplicados na remoção de contaminantes orgânicos emergentes (EOCs) em meio aquoso. Foram estudadas as três etapas da preparação dos carvões ativos utilizando metais de transição como agentes de ativação. As misturas obtidas após a etapa de preparação foram pirolisadas num sistema de microondas em menos de 11 min. Em seguida, utilizou-se uma solução de HCl 6 mol L-1 para tratar os materiais pirolisados, sob refluxo, lixiviando os componentes inorgânicos e produzindo os carvões ativos. Esta tecnologia permitiu a produção de carvões ativos com alta porosidade. Análise elementar, FTIR, DR-UV, microscopia eletrônica de varredura, adsorção-dessorção de nitrogênio, TGA, DRX, FRX, pHpzc, propriedades hidrofóbicas e acidez e basicidade totais foram utilizados para a caracterização da biomassa, do material pirolisado e dos carvões ativos. Os resultados indicaram que os metais foram ligados em diferentes quantidades na superfície da biomassa através de interação iônica e interação de complexação superficial, durante a etapa de impregnação. Os carvões ativos (MWAC) obtidos a partir da impregnação com Zn2+ apresentaram maior volume de poros e maior área superficial específica. Esses dados foram relacionados com a capacidade de adsorção. Amostras preparadas com as misturas de biomassa : componentes inorgânicos em diferentes proporções (20% de cal+ 80% de ZnCl2 ou 20% de cal+ 40% de ZnCl2 + 40% de FeCl3) foram utilizadas para o estudo completo de adsorção de fenol (PhOH) e o-cresol. Os resultados indicaram que a cinética de adsorção para ambas as moléculas foi rápida e o tempo de contato em equilíbrio foi alcançado nos primeiros 10 minutos. Os modelos cinéticos de pseudo-primeira ordem, pseudo-segunda ordem e de ordem fracionária de Avrami foram utilizados para investigar a cinética de adsorção. Destes três modelos, o de ordem fracionária de Avrami descreveu melhor a cinética de adsorção de PhOH e o-cresol na superficie dos cavões ativos. As principais interações de PhOH ou o-cresol com os materias devem ser regida por interações hidrófóbicas, ligações de hidrogênio, interações polares e interação doadores e aceitadores de elétrons. Os estudos de dessorção mostraram que os carvões ativos podem ser regenerados facilmente utilizando-se uma mistura de EtOH (10 ou 50%) + NaOH (5 M). Além disso, o MWAC preparado com CuCl2, CoCl2 e NiCl2 também apresentou alta capacidade de adsorção. As capacidades de adsorção (qe) das moléculas seguiram esta ordem: 2-nitrofenol > bisfenol A > hidroquinona > 4-nitrofenol > 2-naftol > paracetamol > cafeína > resorcinol. Todavia, ZnCl2 parece ser o melhor agente ativador, permitindo o desenvolvimento de materiais de alta porosidade, bem como boas propriedades de adsorção, e essa tendência é seguida posteriormente por CuCl2, CoCl2 e NiCl2. In this thesis activated carbons from lignocellulosic biomass were prepared via microwave– assisted pyrolysis, characterized and applied into the removal of Emerging Organic Contaminants (EOCs) in aqueous media. A scientific understanding of the three-step preparation of activated carbons (AC) using first-row transition metals as activating agents by microwaves heating is also provided. The mixtures obtained after preparation step were pyrolysed in a microwave system in less than 11 min. Afterwards a 6 mol L-1 HCl was used to treat the pyrolysed materials, under reflux, to eliminate the inorganic components—producing activated carbons. This technology allows producing activated carbons with high porosity. Elemental analysis, FTIR, UV-Vis DRS, SEM, N2 adsorption/desorption curves, TGA, XRD Xray fluorescence, pHzpc, hydrophobic properties, total acidity and basicity groups were used to characterise biomass, intermediary materials and activated carbons. Results showed that the metals were bound successfully in different amounts with surface functional groups of the wood biomass through ion exchange and surface complexation interaction during the impregnation step. However, MWAC prepared with Zn2+ showed higher pore volumes and surface areas, which was related to their high adsorption capacity (qe). The samples prepared with the mixtures biomass: inorganic components (20% lime + 80% ZnCl2 or 20% lime + 40% ZnCl2 + 40% FeCl3) at different ratios were used for the complete adsorption study of phenol (PhOH) and o-cresol from aqueous solution. Results indicated that adsorption kinetic was very fast and equilibrium contact time was attained in the first 10 min for both molecules. Pseudo first-order, pseudo-second order and Avrami fractional-order kinetic models were used to probe the kinetic of adsorption. Among the three models; Avrami fractional-order kinetic model best described the adsorption kinetics of PhOH and o-cresol onto the activated carbons. The main interaction of PhOH or o-cresol with the activated carbons should be governed by hydrophobic interactions, hydrogen bonds, polar interactions and electron donor-acceptor interaction. While desorption experiment showed that activated carbons can be regenerated easily using a mixture of EtOH (10 or 50%) + NaOH (5 M). Additionally, MWAC prepared with CuCl2, CoCl2 and NiCl2 also exhibited high adsorption capacity. The adsorption order of the molecules is as shown: 2-nitro phenol > Bisphenol A > hydroquinone > 4-nitro phenol > 2-naphtol > paracetamol > caffeine > resorcinol. However, ZnCl2 demonstrate to be the best activating agent, which allows for the development of materials of high porosity as well as good adsorptive properties, and this trend is followed subsequently by CuCl2, CoCl2, and NiCl2.

A novel carbon composite was prepared from a mixture of coffee waste and clay with inorganic:organic ratio of 1.3 (CC-1.3). The mixture was pyrolysed at 700 °C. Considering the application of this adsorbent for removal of anionic dyes, the CC-1.3 was treated with a 6 mol L−1 HCl for 24 h to obtain ACC-1.3. Fourier transform infrared (FTIR), N2 adsorption/desorption curves, scanning electron microscope (SEM) and powder X-ray diffractometry (XRD) were used for characterisation of CC-1.3 and ACC-1.3 carbon adsorbents. The adsorbents were effectively utilised for removal of reactive blue 19 (RB-19) and reactive violet 5 (RV-5) textile dyes from aqueous solutions. The maximum amounts of RB-19 dye adsorbed at 25 °C are 63.59 (CC-1.3) and 110.6 mg g−1 (ACC-1.3), and 54.34 (CC-1.3) and 94.32 mg g−1 (ACC-1.3) for RV-5 dye. Four simulated dye-house effluents were used to test the application of the adsorbents for treatment of effluents.