Nickel-hydroxide-encapsulated polyacrylamide as a novel adsorptive composite for the capture of methylene blue from wastewater

The wastewater released from different industries is a major environmental issue that has grabbed significant attention lately. Thus, the implementation of suitable routes for the treatment of such water is strongly recommended to reach the level of possible reuse for either industrial or agricultural purposes. In line with such a concept, this research work introduces a new composite structure made via the coating of polyacrylamide by loading nickel hydroxide nanoparticles for use as an absorbent for the purification of wastewater from dye contaminants. High internal phase emulation (HIPE) polymerization was utilized to first prepare particles of polyacrylamide followed by their coating with particles of nickel hydroxide to ultimately obtain the designated adsorbent. The structural features and chemical composition of the synthesized composite were confirmed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and energetic dispersive X-ray (EDX) spectroscopy. Additionally, scanning electron microscopy (SEM) and N2 adsorption-desorption surface area analysis were employed to detect the textural characteristics of the composite. Subsequently, the efficiency of this structure, as an adsorbent for the disposal of methylene blue dye species from a wastewater sample, was studied. During the water purification process, several operating parameters, namely, retention time, solution pH, initial concentration, and absorbent dose, were investigated. The presented Ni-polyacrylamide composite achieved the promising removal of methylene blue dye. An increased adsorption capacity of 14.3 mg g-1 toward methylene blue was achieved by the composite, thanks to the presence of both organic and inorganic functional groups within its structure. Kinetic and isotherm studies for the adsorption of methylene blue species were found to fit pseudo-second-order and Langmuir models. Additionally, thermodynamic measurements indicated that the adsorption process of methylene blue is feasible, spontaneous, involves physisorption, and is endothermic.

Dry Reforming of Methane with Mesoporous Ni/ZrO2 Catalyst

Dry reforming of methane has exhibited significant environmental benefits as it utilizes two major greenhouse gases (CO2 and CH4) to produce synthesis gas, a major building block for hydrocarbons. This process has gained industrial attention as catalyst deactivation due to coke deposition being a major hindrance. The present study focuses on the dry reforming of methane over Ni-supported mesoporous zirconia support. Ni metal was loaded over in-house synthesized mesoporous zirconia within the 0–15 wt% range using the wet impregnation method. The physicochemical properties of the synthesized catalysts were studied using various characterization techniques, namely, XRD, SEM, FTIR, TGA, and N2 adsorption-desorption techniques. The activity of all the catalysts was evaluated at 750°C and gas hourly space velocity (GHSV) of 72000 ml/h/gcat for 9 hours (540 min). The deactivation factor indicating a loss in conversion with time is reported for each catalyst. 10 wt% Ni/ZrO2 showed the highest feed conversion of about 68.8% for methane and 70.2% for carbon dioxide and the highest stability (15.1% deactivation factor and 21% weight loss) for dry reforming of methane to synthesis gas.

Prospects and Technical Challenges in Hydrogen Production through Dry Reforming of Methane

Environmental issues related to greenhouse gases (GHG) emissions have pushed the development of new technologies that will allow the economic production of low-carbon energy vectors, such as hydrogen (H2), methane (CH4) and liquid fuels. Dry reforming of methane (DRM) has gained increased attention since it uses CH4 and carbon dioxide (CO2), which are two main greenhouse gases (GHG), as feedstock for the production of syngas, which is a mixture of H2 and carbon monoxide (CO) and can be used as a building block for the production of fuels. Since H2 has been identified as a key enabler of the energy transition, a lot of studies have aimed to benefit from the environmental advantages of DRM and to use it as a pathway for a sustainable H2 production. However, there are several challenges related to this process and to its use for H2 production, such as catalyst deactivation and the low H2/CO ratio of the syngas produced, which is usually below 1.0. This paper presents the recent advances in the catalyst development for H2 production via DRM, the processes that could be combined with DRM to overcome these challenges and the current industrial processes using DRM. The objective is to assess in which conditions DRM could be used for H2 production and the gaps in literature data preventing better evaluation of the environmental and economic potential of this process.