Development of hybrid coconut shell-peek adsorbent for methane adsorption: optimization using response surface methodology

Adsorbed natural gas (ANG) provides efficient and clean combustion, with minimal emissions compared to diesel and gasoline. This article was designed to develop techniques of ANG for transportation application by apply RSM and CCD to identify the optimum preparation conditions for preparation of stable adsorbent for methane adsorption. Coconut shell and poly ether ketone (PEEK) was selected for synthesis of activated carbon (AC). The effectiveness of the parameters was determined using response surface method (RSM) couple with central composite design (CCD). The analysis of variance (ANOVA) was applied to identify the significant parameters. The quadratic model was adopted, as it has the highest F-value of 21.62 and P-value of less than 0.05, which relate the parameters and response. Microwave power has the highest F-value of 62.36. The maximum methane uptake of 5.12mmol g-1 was achieved. Overall, the hybrid coconut-PEEK adsorbent was found to be suitable for CH4 adsorption

Adsorption isotherm breakthrough time of acidic and alkaline gases on treated porous synthesized KOH-FeCl3.6H2O sustainable agro-based material

Poisoning gases are very harmful when smelled and even low concentrations of the gases are can be lethal. The gases are widely used in various industries. Activated carbon (AC) can be useful to filter the gases. AC derived from local agricultural by-product materials can be used as adsorbent instead of using commercial activated carbon (CAC) for application in safety respiratory devices like gas masks. The study was carried out to produce AC derived from palm kernel shell (PKS) and to determine the breakthrough and saturation time adsorption isotherm of SO2, NH3 and O2 on the AC produced. The preparation of AC involved two main steps which are carbonization and activation process. After carbonization process, the resulted char (PKS-char) was then impregnated with Potassium Hydroxide(KOH) and Ferric chloride hexahydrate (FeCI3.6H2O) followed by activation process using microwave heating. The prepared AC (PKAC-KOH-FECI3) was characterized by Thermo-gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Nitrogen adsorption isotherm. Breakthrough adsorption study was conducted in a stainless-steel reactor which loaded with 3.6 g of activated carbon for each run. The saturation time results were determined from the Yoon equation. From the adsorption breakthrough results, the PKAC-KOH-FeCI3 produced 51 s, 100 s, and 6.33 s breakthrough time for SO2, NH3, and O2 adsorption. The saturation time of PKAC-KOH-FeCI3 for SO2, NH3, and O2 adsorption were 16,947 s, 33,461 s, and 2,094 s. The results revealed that AC prepared from PKS treated with KOH-FeCI3 can be further developed as potential adsorbent for the gas phase applications

Sulphur dioxide and oxygen adsorption isotherm breakthrough time on surface porous palm shell activated carbon

Sulphur dioxide (SO2) releases from various industries can affect the environment and human health. Activated carbon has been widely studied in gas and liquid adsorption due to its capability in filtration to remove organic materials and particulate matter. Palm kernel shell (PKS) is an agricultural by-product from palm-oil processing mills. PKS has been used as the based material for the production of activated carbon (AC). The research is aimed to produce AC derived from sustainable palm solid waste and to study the breakthrough time adsorption isotherm of SO2 and oxygen (O2) on the AC. In this study, palm kernel shell activated carbon (PKS-AC) was prepared via carbonisation, impregnation and activation. The dry PKS was carbonised at 700 °C for 2 h in a furnace and was then impregnated with ferric chloride hexahydrate (FECI3.6H2O) in 1 : 5 ratios (ferric chloride hexahydrate to PKS-char). The treated PKS-char was activated through microwave heating at 400 W power level and 6 min irradiation time. The prepared AC were characterised using Thermo-gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Nitrogen adsorption isotherm. Breakthrough adsorption of SO2 and O2 was investigated in a fixed-bed reactor. The results shows that the prepared AC produced 23 and 7.5 s breakthrough time for SO2 and O2 adsorption. In conclusion, AC that produced from agricultural waste via impregnation with ferric chloride and microwave induced can be a new promising method for the production of simple and good quality of AC

Effects of staggered array of cubical obstacles on near-ground wind environment and air quality

Deterioration of natural ventilation in outdoor environments due to rapid urbanisation has raised the issues pertaining to pedestrians' thermal comforts and pollutant exposures. There are substantial interests in the recent years to get an insight on how deficient these situations are and later propose the appropriate urban layout for optimum wind ventilation in a dense urban area. The objective of this paper is to numerically study the effects of urban layouts (i.e., staggered arrangements and cubes' densities) on wind ventilation and air quality near the ground subjected to one wind direction; perpendicular to the disposition direction. Computational fluid dynamics simulations were carried out by the use of standard k-ε turbulence model and found to be in fair agreement against the experimental data. Our result showed that loosely packed cubes exhibited lower pollutant concentration and higher wind speed near the ground compared to medium and densely packed cubes. Air quality was improved in closely packed cubes with staggered layout but did not show any improvement in medium and loosely packed cubes with staggered layout. Adversely, disposition of cubes exhibited lower wind speed compared to regular cubes for all street gap sizes. This paper also illustrates a practical strategy in optimising building layouts for wind flow enhancement and air quality improvement in an idealised urban area

CO2 adsorption isotherms on KOH, H3PO4 and FeCl3.6H2O Impregnated palm shell kernel activated carbon

Commercial sorbents available are expensive as a result of using high cost and non-renewable materials as precursors. It is imperative to select cheap, viable and sustainable carbon source for production of adsorbents for subsequent use in adsorption applications. Palm kernel shell char was obtained by carbonisation process at 730 °C ± 20 °C for 2 h with 10 °C/min heating rate under inert gas flow. The bio-char obtained was further grinded and sieved to 0.5 to 0.85 mm, then treated and synthesised separately each sample by KOH, H3PO4 and FeCl3.6H2O solution with ratio 1 : 1 weight ratio and followed by microwave treatment technique. Samples treated with chemicals used were named as PKS-POT (Palm Kernel Shell with Potassium Hydroxide ), PKSPAP (Palm Kernel Shell with Phosphoric acid) and PKS-FER(Palm Kernel Shell with Ferric chloride hexahydrate). CO2 gas was used during the adsorption and desorption study. Samples were characterised by Brunauer-Emmett-Teller (BET), scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). PKS-POT showed highest BET surface area (208.7037 m2/g) and pore volume (0.06580 cm3/g). PKS-POT's SEM result also confirms large surface area, pores and more compact of the shell structure which related to high adsorption capacity compared to PKS-PAP and PKS-FER. CO2 PKS-POT, PKS-PAP and PKS-FER adsorption capacities were 2.19, 0.62 and 1.25 mmol/g and no CO2 gas left for the end desorption phase. From the study concluded that sustainable palm kernel shell material was successfully achieved to obtain the high surface area, high porosity and high adsorption sorbent capacity

Kinetic equilibrium and isotherm modelling adsorbed methane assessment on synthesized peek-porous sorbent carbon of sustainable coconut shell kernel

It is important to understand methane (CH4) adsorption onto available biomass surfaces quantitatively for its storage as Adsorbed Natural Gas (ANG). Coconut shell being among the abundant agro-waste in Malaysia has chosen with polyetheretherketone (PEEK) as a precursor for preparation of hybrid activated carbon via microwave induced potassium hydroxide activation for methane storage. M33P15 Porous carbon prepared at 300 Microwave power with 3 min irradiation and 15 wt% amount of PEEK and M33P0 was prepared under the same condition as M33P15 but without addition of PEEK. The porous carbons were used for CH4 adsorption as the interactions between carbon and methane is based the pore diffusion and partly film diffusion. The ideal CH4 adsorption capacities of the activated carbons were conducted using volumetric adsorption equipment at pressures (5-30 bar). The obtained experimental data at initial pH of 8.0 and 9.0 were correlated using linear regression analysis with common adsorption kinetic (Pseudo-first order, Pseudo-second order, Elovich) and isotherm models (Freundlich, Langmuir, Sip, and Toth). The pseudo-second-order kinetics describe the best fitness with a correlation coefficient of 0.9998 for sample M33P15. For adsorption isotherms, Sip model shows better fitness for sample M33P15 with the regression coefficient (R 2 ) 0.9800 and with lowest RSMD value (0.1438) than other models. The findings revealed the potential of kinetic and isotherm models in methane adsorption applications

Methane and natural gases kinetic equilibrium adsorption comparison on synthesized porous coconut shell kernel activated carbon

Instability of diesel and gasoline market price with the generation of environmental pollution attracted world attention in looking towards natural gas (NG) as a means of alternative fuel. This research work presents an investigation of experimental adsorption uptake of pure methane (CH4) and NG onto a hybrid of coconut shell and polyetheretherketone (PEEK) porous carbon. The hybrid porous carbon was prepared by KOH microwave-assisted activation of a coconut shell with PEEK. The Porous carbon (M33P15) was used as a potential sorbent to investigate the adsorption characteristics of the two gasses. The adsorption is applied at an ambient and 5 °C adsorption temperatures and at a pressure of 3.5 MPa. The comparison is based on measuring adsorption uptake differences between the two gases onto porous carbon. The ideal CH4 and NG adsorption uptake on porous carbon are investigated using volumetric adsorption method. The CH4 adsorption capacity of 9.7045 and 9.9958 mmol CH4 adsorbed/g adsorbent was achieved at an ambient and 5 °C adsorption temperature. While NG adsorption capacity of 9.9432 and 10.0901 mmol NG adsorbed/g was achieved at an ambient and 5 °C adsorption temperatures. In conclusion, the results show that NG adsorption uptake is slightly higher than CH4 adsorption uptake. This is due to the ability of the adsorbent to adsorb other components of the NG other than CH4. It is also suggested that applying heat management strategies, by lowering the temperature of adsorbent during the adsorption process, can significantly improve the storage capacity of CH4 and NG

Prevalence, associated factors and predictors of depression among adults in the community of Selangor, Malaysia

Introduction Depression is one of the most common mental health disorders and is an emerging public health problem. The objectives of this paper were to determine the prevalence of depression, its associated factors and the predictors of depression among adults in the community of Selangor. Methods A cross sectional study was conducted in three districts in Selangor, from 11th June to 30th December 2012. The sampling frame was obtained from the Department of Statistics Malaysia (DOS) in May 2012, using the National Population and Housing Census 2010. Adults aged 18 years and above, living in the selected living quarters were approached to participate in the study and requested to complete a set of questionnaires. Results A total of 1,556 out of 2,152 participants participated in this study, giving an overall study response rate of 61.90%. Patient Health Questionnaire 9 (PHQ-9) was used to determine the presence of depression. The prevalence of depression was 10.3%, based on the PHQ-9 cut off point of 10 and above. Based on multiple logistic regression analysis, the predictors of depression were presence of anxiety, serious problems at work, unhappy relationship with children, high perceived stress, domestic violence, unhappy relationship with spouse, low self-esteem, unhappy relationship with family, serious financial constraint and presence of chronic diseases. When reanalyzed after removing anxiety, high perceived stress and low self-esteem, additional predictors of depression were found to be serious marital problems and religiosity. Conclusion The prevalence of depression in this study is similar to that found in other studies. Findings from this study are being used as baseline data to develop an effective program to assist in the management of common mental health disorders in the community, in particular depression. The identification of predictors of depression in the community is important to identify the target population for the program