In the present work, ceramic-supported chitosan hybrid membranes were prepared for the pervaporation dehydration of ethanol. Mullite and combined mullite-alumina (50% alumina content) tubular low-cost ceramic supports were fabricated, and their influence on membrane performance was compared to a commercial α-alumina support. The membrane preparation parameters were different ceramic supports and the concentration of chitosan solution (varying from 2 wt.% to 4 wt.%). The supports and hybrid membranes were characterized by field emission scanning electron microscopy (FE-SEM) and contact angle measurements. The results show, with increasing chitosan concentration, the permeability decreases, and selectivity increases. It was also found that the separation factor decreases with increasing feed temperature and feed water content, while the permeation flux increases. The membrane that was coated on α-alumina support with a 3 wt.% chitosan concentration exhibited the best pervaporation performance, leading to a permeation flux and separation factor of 352 g·m−2·h−1 and 200 for 90 wt.% ethanol in feed at 60 °C, respectively.

This study provides a comparison of hydrothermal carbonization (HTC) char, starting from two different species of waste seaweed, namely the green algae Ulva pertusa and the brown algae Sargassum horneri. The effect of reaction temperature (180 ~ 250 ℃), biomass residence time (1 ~ 6 h), and water mass ratio (1 ~ 10) on HTC yield (38 ~ 57%) was investigated. Surface area (5 ~ 52 m 2 g −1 ), methylene blue removal efficiency (71 ~ 99%), methylene blue adsorption capacity (11 ~ 88%), and hydrochar composition have been assessed. An increasing residence time and HTC temperature led to an increase in surface area up to a maximum of 51 m 2 g −1 , while the yield in HTC hydrochar decreased around 35% for both HC. The van Krevelen diagram was extended to compare the variation in elemental composition of the waste seaweed derived hydrochars. Results of the methylene blue adsorption experiments are best described by a Langmuir model with maximal adsorption capacity values of 112 ± 7.63 mg g −1 for the Sargassum based char, produced at 180 ℃, with water/biomass ratio of 5 and 4 h residence time.

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Upgrading wet biomass to char via hydrothermal carbonization is a promising method to produce valuable resources for adsorption of organic impurities. In this work, a fresh green seaweed, Ulva pertusa, was investigated to demonstrate the effects of pre-drying and pre-washing on the process and the hydrochar production. Surface moisture and bound moisture were found to affect this process. Hydrochar produced from fresh seaweed with additional water showed similar adsorption capacity to fresh seaweed without additional water and 38% higher than hydrochar from soaked dry seaweed. This was supported by FTIR spectra analysis, which showed that these hydrochars produced from fresh seaweed without additional water have the highest proportion of carboxyl functional groups.