Experimental Study of CO₂ Plasticization in Polysulfone Membrane for Biogas Processing

Polymeric membranes have emerged for biogas processing to remove CO2 from CH4. Nonetheless, it is also acknowledged that polymeric membranes have the tendency to sorb highly condensable CO2, which consequently swells the polymeric matrix, typically at operating condition higher than the plasticization pressure. The swelling increases void spaces for transport of gas penetrants, which results in an increment in permeability of all gas components at the cost of substantial decrease in membrane selectivity. Despite observations of the end results of plasticization, it is found that many transport property studies include only permeability measurements near ambient conditions. Complementary information on the individual contributions of the sorption and diffusion coefficients to the overall performance typically at non-ambient operating conditions is rarely reported. Therefore, in present study, experimental study has been conducted to fabricate polysulfone (PSF) film. Validity of the developed polysulfone membrane has been verified through characterization and validated with gas transport behavior of published results. Subsequently, transport properties of CO2 though the PSF membrane at varying operating temperatures has been elucidated. The dual mode sorption and partial immobilization models have been employed to quantify the gas transport properties of noncondensable CH4 and condensable CO2 through PSF membrane

Syngas-Enriched hydrogen production via catalytic gasification of water hyacinth using renewable palm kernel shell hydrochar

Syngas produced from biomass gasification has emerged as a highly promising substitute for conventional fossil fuel, catering to various industrial applications while ensuring minimal greenhouse gas emissions. Water hyacinth (WH) has been a major concern due to its invasive nature and uncontrollable growth which impedes aquatic growth and urban management. Fortunately, WH is a potential biomass feedstock due to the comparable cellulose and hemicellulose contents alongside high carbon content and high calorific value which reflects good biofuel properties. Therefore, this study aims to investigate the conversion of WH biomass via catalytic air gasification for syngas-enriched hydrogen production using palm kernel shell hydrochar (PKSH). A parametric study was conducted in a lab-scale fixed-bed downdraft gasifier based on the response surface methodology coupled with Box-Behnken design (RSM-BBD). The combined interaction effects of the influencing parameters investigated are temperature (600–800 °C), biomass particle size (2–6 mm), catalyst loading (0–10 wt%), and air flow rate (1–3 L/min). Temperature was revealed to be the primary factor with significant influence on the H2 and CO output. Maximum syngas (30.09 vol%) compositions of 11.14 vol% H2 and 18.95 vol% CO were obtained at 800 °C with a particle size of 6 mm and air flow rate of 2 L/min alongside 5 wt% PKSH catalyst loading

Thermal degradation behavior and kinetic modeling of green solvents-delignified biomass: a sustainable biomass-to-energy approach

The vast amount of empty fruit bunches (EFBs), which are generated in line with the huge production of crude palm oil in Malaysia, poses significant threats to the environment. In this sense, low-transition-temperature-mixtures (LTTMs) have been recognized as promising green solvents for the pretreatment of biomass as they are of low cost, easy to prepare, and environmental friendly with high delignification selectivity, which also improve the thermal degradation and hydrolysis performance of biomass. The delignification efficiency of LTTMs synthesized from malic acid-sucrose-water was investigated under various pretreatment temperatures, and the optimum temperature was identified to be 90°C. The delignified EFBs were applied in thermogravimetric analysis in order to study the effect of heating rates on their pyrolytic behaviors. Based on the differential thermogravimetric curves, the peaks of the maximum degradation temperature were moved to higher values with increasing heating rates. Iso-conversional Kissinger-Akahira-Sunose (KAS) model was applied in the kinetic modeling of the pyrolysis of delignified EFBs. The estimated activation energy for the untreated EFBs varied within the range of 42.27–254.16 kJ mol−1 while for the delignified EFBs were within the range of 57.73–262.12 kJ mol−1. This showed that the EFBs attained higher molecular stability after pretreatment using the LTTMs

Review of Adsorption Studies for Contaminant Removal from Wastewater Using Molecular Simulation

In recent years, simulation studies have emerged as valuable tools for understanding processes. In particular, molecular dynamic simulations hold great significance when it comes to the adsorption process. However, comprehensive studies on molecular simulations of adsorption processes using different adsorbents are scarcely available for wastewater treatment covering different contaminants and pollutants. Hence, in this review, we organized the available information on various aspects of the adsorption phenomenon that were realized using molecular simulations for a broad range of potentially effective adsorbents applied in the removal of contaminants from wastewater. This review was compiled for adsorbents under five major categories: (1) carbon-based, (2) oxides and hydroxides, (3) zeolites, (4) metal–organic frameworks and (5) clay. From the review, it was found that simulation studies help us understand various parameters such as binding energy, Gibbs free energy, electrostatic field, ultrasound waves and binding ability for adsorption. Moreover, from the review of recent simulation studies, the effect of ultrasound waves and the electrostatic field was elucidated, which promoted the adsorption capacity. This review can assist in the screening of classified adsorbents for wastewater treatment using a fast and cheap approach while helping us understand the adsorption process from an atomistic perspective

An atomistic simulation towards molecular design of silica polymorphs nanoparticles in polysulfone based mixed matrix membranes for CO2/CH4 gas separation

Incorporation of inorganic fillers into Polysulfone (PSF) to constitute mixed matrix membranes (MMMs) has become a viable solution to prevail over limitations of the pristine materials in natural gas sweetening process. Nevertheless, preparation of MMMs without defects and empirical investigation of membrane that exhibits characteristic of improved CO2/CH4 separation performance at experimental scale are difficult that require prior knowledge on compatibility between the filler and polymer. A computational framework has been conducted to construct validated PSF based MMMs using silica (SiO2) as inorganic fillers. It is known that nanosized SiO2 can coexist in varying polymorph configurations (ie, α‐Quartz, α‐Cristobalite, α‐Tridymite) but molecular simulation study of SiO2 polymorphs to form MMMs is limited. Therefore, this work is a pioneering study to elucidate feasibility in facile utilization of polymorphs to improve gas separation performance of MMMs. Physical properties and gas transport behavior of the simulated PSF based MMMs with different SiO2 polymorphs and loadings have been elucidated. The optimal MMM has been found to be PSF/25 wt% α‐Cristobalite at 55°C. The success in molecular simulation has shed light on how computational tools can provide understandings at molecular level to elucidate compatibility between varying pristine materials to MMMs for natural gas processing

A review on natural based deep eutectic solvents (NADESs): fundamentals and potential applications in removing heavy metals from soil

Natural based deep eutectic solvent (NADES) is a promising green solvent to replace the conventional soil washing solvent due to the environmental benign properties such as low toxicity, high biodegradability, high polarity or hydrophilicity, and low cost of fabrication process. The application of NADES is intensively studied in the extraction of organic compounds or natural products from vegetations or organic matters. Conversely, the use of the solvent in removing heavy metals from soil is severely lacking. This review focuses on the potential application of NADES as a soil washing agent to remove heavy metal contaminants. Hydrophilicity is an important feature of a NADES to be used as a soil washing solvent. In this context, choline chloride is often used as hydrogen bond acceptor (HBA) whereby choline chloride based NADESs showed excellent performance in the extraction of various solutes in the past studies. The nature of NADES along with its chemistry, preparation and designing methods as well as potential applications were comprehensively reviewed. Subsequently, related studies on choline chloride-based NADES in heavy metal polluted soil remediation were also reviewed. Potential applications in removing other soil contaminants as well as the limitations of NADES were discussed based on the current advancements of soil washing and future research directions were also proposed

Sustainable Biomass-to-Energy Transformation : Choline Chloride Based Deep Eutectic Solvent for Lignin Extraction and Liquefaction

Biomass is often renowned as one of the inexpensive and largest sources of non-depleting energy in the world, attributed to its great potential for continuous and sustainable supply of energy in the form of biofuels and various value-added products. With the increasing demand to preserve the environment, the use of green solvents, such as deep eutectic solvents (DESs), is desirable, given their capability to reduce the generation of hazardous substances. In this work, choline chloride based DESs have been used to extract lignin from biomass. The structure and thermal stability of the extracted lignin are analysed using Fourier-transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA), respectively. FT-IR spectra revealed that chemical properties of lignin were determined through absorbance peaks corresponding to hydroxyl and C-H stretching, as well as the presence of carbonyl moieties and phenolic groups. TGA analysis of lignin showed weight loss peaks at 66 °C, 256 °C, and 319 °C, with major weight loss at 200 - 350 °C due to lignin degradation and release of monomeric phenols, resulting in a final residue consisting of non-volatile solids associated with condensed aromatic structures and lignin ash at 740 °C. The extracted lignin was then subjected to subcritical water-supercritical CO2 hydrothermal liquefaction (HTL) and converted into bio-oil. In this context, HTL proves its benefits by providing the highest yield of 77.41 % using optimum parameters of lignin-to-water ratio (1:5), pressure (20 MPa), temperature (275 °C) and time (60 min). The functional groups of bio-oil derived from the extracted lignin were analysed using FT-IR, which proves the functional groups (phenols, carboxylic acid, ketones, carboxylic acid, esters and aromatic groups) present in the bio-oil. Detailed information regarding the HTL of lignin derived from biomass, which circumvents the need for energy-intensive drying procedures, is critical in mitigating the challenges posed by the abundance of biomass residues

Rethinking of the future sustainable paradigm roadmap for plastic waste management: A multi-nation scale outlook compendium

The myriad consumption of plastic regularly, environmental impact and health disquietude of humans are at high risk. Along the line, international cooperation on a global scale is epitomized to mitigate the environmental threats from plastic usage, not limited to implementing international cooperation strategies and policies. Here, this study aims to provide explicit insight into possible cooperation strategies between countries on the post-treatment and management of plastic. First, a thorough cradle-to-grave assessment in terms of economic, environmental, and energy requirements is conducted on the entire life cycle across different types of plastic polymers in 6 main countries, namely the United States of America, China, Germany, Japan, South Korea, and Malaysia. Subsequently, P-graph is introduced to identify the integrative plastic waste treatment scheme that minimizes the economic, environmental, and energy criteria (1000 sets of solutions are found). Furthermore, TOPSIS analysis is also being adapted to search for a propitious solution with optimal balance between the dominant configuration of economic, environmental, and energy nexus. The most sustainable configuration (i.e., integrated downcycle and reuse routes in a closed loop system except in South Korea, which proposed another alternative to treat the plastic waste using landfill given the cheaper cost) is reported with 4.08 × 108 USD/yr, 1.76× 108 kg CO2/yr, and 2.73 × 109 MJ/yr respectively. To attain a high precision result, Monte-Carlo simulation is introduced (10,000 attempts) to search for possible uncertainties, and lastly, a potential global plastic waste management scheme is proposed via the PESTLE approach

Life-cycle assessment of hydrogen production via catalytic gasification of wheat straw in the presence of straw derived biochar catalyst

The environmental footprints of H2 production via catalytic gasification of wheat straw using straw-derived biochar catalysts were examined. The functional unit of 1 kg of H2 was adopted in the system boundaries, which includes 5 processes namely biomass collection and pre-treatment units (P1), biochar catalyst preparation using fast pyrolysis unit (P2), two-stage pyrolysis-gasification unit (P3), products separation unit (P4), and H2 distribution to downstream plants (P5). Based on the life-cycle assessment, the hot spots in this process were identified, the sequence was as follows: P4 > P2 > P1 > P3 > P5. The end-point impacts score for the process was found to be 93.4017 mPt. From benchmarking analysis, the proposed straw-derived biochar catalyst was capable of offering almost similar catalytic performance with other metal-based catalysts with a lower environmental impact