In this study, cellulose nanocrystals with cellulose crystal structure I (CNCs I) and with coexisting cellulose crystalline structures I and II (CNCs I-II) were isolated from pine cellulose using acid hydrolysis with H 2 SO 4 . It was possible to obtain CNCs with different morphologies, crystallinities and crystalline structures adjusting only the reaction conditions. The thermal stability is directly related to the crystalline structure and the crystallinity. It was observed that CNCs composed mainly of CNC II have an initial degradation temperature higher than the CNCs I when comparing samples with similar crystallinity. The kinetic results allow us to conclude that activation energy (E a ) not only depends on the crystalline structure and crystallinity of the CNCs but may also be related to the presence of sulfate groups. Understanding the influence of crystallinity and crystalline structure on the thermal stability of CNCs can direct the studies of future applications for these materials.

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BACKGROUND In order to protect water resources and reduce the harmful effects of releasing contaminated wastewater to the environment, the textile industry has increasingly demanded improved water reclamation technologies, such as membrane distillation. In this work, theoretical and experimental investigations were carried out to evaluate the behavior of the operational parameters of a direct contact membrane distillation (DCMD) setting with a commercial membrane applied to synthetic dye solutions, simulating textile wastewater from the fabric dyeing stage. RESULTS The analytical model based on heat and mass transfer correlations specific to textile effluents implemented using Matlab® predicted the permeate flux with good agreement, with errors less than 10% when compared with the experimental values. There was a different trend for reactive and disperse dyes when input variables were changed. In general, increasing all variables led to an increase in permeate flux. An increase of 30 °C in the feed temperature increased by 2.0‐ to 2.3‐fold the permeate flux. Moreover, the simulation showed the influence of the permeate temperature and the membrane interface temperature on the permeate flux, which is not commonly achieved experimentally. CONCLUSIONS The hybrid modeling supported by extensive experimental validation accurately predicted the permeate flux in DCMD to recover water from synthetic dye solutions containing reactive and disperse black dyes. DCMD is a promising technology for recovering textile wastewater containing these dyes, as it can use the waste heat from the hot effluent discharge. Therefore, this work can contribute towards the scaling up of DCMD, aiding in predicting and optimizing the operational variables. © 2020 Society of Chemical Industry (SCI)

The gas separation is a very expensive step in the chemical industry and unquestionable relevance. In this work, was verified the efficiency of the use of type A-zeolites in the separation of CO2 in a gas mixture containing 25% CO2, 4% O2 and 71% N2. These concentrations are similar to the effluent gases from combustion processes. To this end, was synthesized type A-zeolites using commercial kaolin and mounted to an adsorption column to test the effectiveness of zeolites in the adsorption of CO2. The synthesized zeolites had surface area equal to 66.22 m2/g. The CO2 concentration was determined by gas chromatography with TCD detector. After adjusting the data to the Langmuir model, it was obtained the kinetic parameters of adsorption. Based on these parameters was found the ability of the zeolite to adsorb CO2, using a column of 0.461285 mg/g. The adsorption results have proved promising and showed maximum adsorption of 78.4% after a time of 10 seconds.