Thiago Marinho Duarte, 33, has a solid background to work in teaching and research. The Paraiban, born in Campina Grande, did a bachelor’s, master’s and doctorate in Chemistry, in addition to a specialization in teaching methodology in Chemistry and Biology. Thirteen years were dedicated to his scientific education.

However, since defending his doctorate in Chemistry at the Federal University of Paraíba (UFPB) in February this year, his plans to become a research professor have been put “in the freezer”. In order to pay the bills, he used the knowledge learned in his adolescence, in technical courses, and started to work as an electrician.

In September, he passed a selection process by the municipality of Conde, in the metropolitan region of João Pessoa, to work on the front to fight Covid-19, dealing with various issues, from analyzing water reports to raising awareness about the pandemic. In this way, he achieved financial stability for a few months (the contract ends at the end of December) while continuing to look for opportunities in order to return to his scientific career.

Usually, the step following the completion of a doctorate is a post-doctorate, which can be understood as a temporary job as a “junior scientist”. In Brazil, this phase of the career usually occurs in university research groups and is usually paid through scholarships, funded by government research agencies, either federal (such as CNPq or Capes) or state funded.

“I submitted research projects in two CNPq calls for selection of postdoctoral fellows,” says Thiago.  “In both cases I was evaluated with a score close to the maximum (above 9.5), but I was informed that I would not receive the scholarship due to budget limitations,” he laments. In fact, the number of postdoctoral fellowships from federal agencies has been decreasing consistently since 2015, as previously shown by B-MRS.

In the middle of the pandemic, Thiago participated in four selective processes of higher education institutions in the states of Paraíba and Rio Grande do Norte for substitute lecturer – a temporary position that would allow him to remain in his professional area and get an income. But he was not selected. “The competition was very strong,” he says. In addition, he enrolled in a selective process for effective professor at the campus of the city of Areia at UFPB, but the selection has not yet been carried out due to the pandemic.

Thiago also considered entrepreneurship. He looked fondly at his undergraduate memories, when he began to produce and sell detergents, and thought that producing sanitizers would not be a bad idea for a chemist in a time of pandemic infectious disease. But this idea also ended up “in the freezer” given the difficulties Thiago faced to obtain bureaucratic information, necessary to start the initiative.

First university student in the family

“My first vocation was teaching,” says Thiago. In high school, he was good in courses in the Exact Sciences area. In the last year, after helping some colleagues understand a subject and pass the exam, he realized that he could dedicate himself to teaching. So, even without any family references (Thiago’s parents are salaried employees without higher education and he was the first person who attended college among all his relatives), he decided for a degree in Chemistry at the State University of Paraíba (UEPB).

After his graduation, in 2011, Thiago noticed that there were many selection processes in universities and federal institutes, and that they all required a master’s and/or doctorate degree. So he believed he should leave Campina Grande for postgraduate studies at UFPB, always in the Chemistry area.

That decision brought him many rewarding experiences, as well as personal and professional growth. In the master’s degree, Thiago was delighted to discover that the concepts learned in class became palpable in the laboratory, and that he could make his own contribution to the advancement of knowledge. In his PhD, he immersed in the world of computer simulations to study semiconductor materials that can be used for environmental remediation, which gave him the opportunity to go abroad for the first time to carry out part of the research at a Spanish university, with financial support from Capes.

“The contact with the real world of experiments and with the ideal world of simulations made me mature,” reflects Thiago. “And the experience abroad allowed me to grow as a person and as a researcher; it is something I recommend to everyone who has the opportunity,” he adds.

Currently, in addition to working on the front to fight Covid-19, Thiago is writing a research project to work in a group in the state of São Paulo. Once again, he will try to get a postdoctoral fellowship. In addition, Thiago is preparing to participate in another substitute-lecturer selection process, this time at the Federal University of Pernambuco (UFPE).

“I want to exhaust all possibilities in the country, but I don’t rule out going abroad,” says Thiago. “It is a pity that the government of Brazil has no interest in investing in knowledge and technology generation.”

B-MRS participated in the ceremony in honor of the scientist and engineer Ricardo Rodrigues, held on the morning of November 9 in the Sirius building, organized by CNPEM. The emotional ceremony, which was broadcast live on YouTube, brought together some relatives and friends, who held demonstrations and presentations about Rodrigues’ extensive scientific career and personal aspects.

Representing the Board of B-MRS, Professor Daniel Mario Ugarte (UNICAMP), a member of the Society, handed a plaque to Rodrigues’ widow, Liu Lin, who is also a scientist. The B-MRS’s homage to Ricardo Rodrigues was conceived by members of B-MRS at the beginning of the year and would take place at the opening of the XIX B-MRS Meeting, which would be held in September this year in Foz do Iguaçu, but was postponed to 2021 due to the pandemic. The ceremony organized by CNPEM provided a new opportunity to perform the tribute.

Commemorative inscription in the plaque

“B-MRS homage to Antônio Ricardo Droher Rodrigues (1951 – 2020). The Brazilian Materials Research Society (B-MRS) pays homage to Ricardo Rodrigues’ fundamental contribution to the successful development and implementation of Brazilian synchrotron light sources (UVX and Sirius), which have placed Brazil at the forefront of materials research worldwide. November 2020.”

Ricardo Rodrigues

Ricardo Rodrigues was one of the main leaders responsible for the construction of the first synchrotron light source in the Southern Hemisphere, UVX, inaugurated in 1997. Starting in 2009, he led the engineering team that developed Sirius’ electron accelerators, the second light source synchrotron of Brazil. He passed away on January 3, 2020, at the age of 68.

The recording of the ceremony can be watched at https://www.youtube.com/watch?v=hrmTDdnyv9s.

[PAPER: Bacterial Nanocellulose/MoS2 Hybrid Aerogels as Bifunctional Adsorbent/Photocatalyst Membranes for in-Flow Water Decontamination. Elias P. Ferreira-Neto, Sajjad Ullah, Thais C.A. da Silva, Rafael R. Domeneguetti, Amanda P. Perissinotto, Fábio S. de Vicente, Ubirajara P. Rodrigues-Filho, and Sidney J. L. Ribeiro. ACS Appl. Mater. Interfaces 2020, 12, 37, 41627–41643.]

A team of researchers from Brazilian universities has developed a new material capable of decontaminating water, simultaneously eliminating organic and inorganic pollutants, such as dyes and heavy metals, respectively. The material is in the form of a membrane with the potential to be used as an active filter: as water passes through the membrane, pollutants are adsorbed and degraded. The material can be reused several times, without losing its properties.

The membrane is composed of a three-dimensional network of cellulose nanofibers, coated with molybdenum disulfide (MoS2) nanosheets. Each material performs its function in the filter. Molybdenum disulfide is primarily responsible for adsorbing pollutants and degrading them through photocatalysis [see box]. Nanocellulose operates mainly as support for photocatalysts. Firstly, it allows the construction of an easy to handle macroscopic membrane. In addition, its structure of interwoven nanofibers with a rough surface offers an exceptionally large surface area to contain the photocatalysts. Finally, the flexibility and strength of the nanocellulose allows the membrane to withstand the water flow pressure.

“Although several excellent photocatalysts have been previously developed, one of their disadvantages is the difficult separation and recovery of nanometric materials, thus the idea of producing membranes,” says Elias Ferreira-Neto, postdoctoral fellow at the Laboratory of Photonic Materials, at the Chemistry Institute of UNESP Araraquara. “This study is a first step in the area,” adds Elias, corresponding author of the article reporting on the development of membranes, recently published in Applied Materials & Interfaces (impact factor = 8,758).

Membrane production: from bacterial hydrogel to hybrid aerogel

The “recipe” developed by the Brazilian researchers to produce the membranes involves several steps and requires mastering different processes for the synthesis of materials.

In the first step, bacteria from a non-pathogenic strain, placed in an appropriate medium, perform a metabolic process that generates the bacterial nanocellulose hydrogel as a by-product. This highly porous material is composed of 1% of interwoven cellulose nanofibers and 99% of water. The hydrogel is then washed in order to eliminate impurities.

Subsequently, the surface of the nanofibers is coated with controlled structured molybdenum disulfide nanosheets, regularly distributed on the surface of the nanofibers. Finally, this hybrid hydrogel is transformed into aerogel through a drying process, which replaces the pore water with air. The final result is an aerogel membrane composed of bacterial nanocellulose and molybdenum disulfide.

Decontamination assays

The researchers built a small photoreactor in order to verify the ability of the new membranes to remove the organic and inorganic pollutants in the water. In this device, the contaminated water passes through the membrane, which is illuminated to generate the photocatalytic effect. In the assays, the researchers used an organic pollutant (methylene blue, a compound used as a dye and as a drug) and an inorganic contaminant (hexavalent chromium, a toxic and carcinogenic compound, still used in various industries).

By measuring the presence of contaminants in the water after filtering, the researchers found that the membrane was able to eliminate approximately 96% of the paint and 88% of the heavy metal after 120 minutes of reactor circulation. “The efficiency achieved is in the range of photocatalytic materials of nanoparticulate-like molybdenum disulfide, which is excellent, given that in the supported material, the active surface area exposed to light is much smaller,” says Elias. However, to make the membranes suitable for real applications outside the laboratory, the researchers intend to further increase this efficiency. “The modification of the materials prepared with other photocatalytic nanostructures, such as titanium dioxide (TiO2) and bismuth vanadate (BiVO4), can greatly increase the efficiency of the materials we have already obtained,” says Elias. In addition, the researchers plan to test the action of the membranes against other organic and inorganic compounds that pollute waters, such as drugs, pesticides and other heavy metals.

Aggregated expertise

Entirely carried out in Brazil, more precisely in the state of São Paulo, the work gather the expertise in bacterial cellulose materials from the group led by Professor Sidney Ribeiro (Institute of Chemistry at UNESP Araraquara), and the experience in photocatalysis from the group conducted by Professor Ubirajara Rodrigues Filho (Institute of Chemistry of São Carlos – USP). The research also involved the collaboration of Professor Fábio Simões de Vicente, from the Physics Department of UNESP Rio Claro, to characterize the porosity and textural properties of the materials.

The study is part of Elias Ferreira-Neto’s post-doctoral project, funded by FAPESP. In his doctorate, under the guidance of Professor Ubirajara, and during the research internship abroad conducted with a researcher specialized in aerogels, Elias acquired great experience in the development of inorganic nanoparticles and aerogels for photocatalysis. In these studies, he could identified the great potential of these materials as photocatalysts, as well as their main limitation, the low mechanical resistance and, particularly, the low resistance to capillary pressure in liquid medium.

In the context of Elias’ postdoctoral fellowship, the collaboration between Brazilian research groups could overcome this limitation through the development of hybrid aerogels that combine the excellent mechanical properties of the cellulose support with the photocatalytic and adsorptive properties of the MoS2 nanosheets.