Isothermal, kinetic, thermal, and economic characteristics of NaOH-modified charred–desiccated coconut waste as adsorbent for lead (II) in water phase

Abdul Rahman Abdul Rahim,Khairiraihanna Johari,Nurul Ekmi Rabat,Murid Hussain,Nasir Shezad,Young-Kwon Park 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.127 No.-

In this study, charred–desiccated coconut waste was treated with several chemicals, such as NaOH,NaOCl, H2O2, and HNO3, to prepare chemically modified adsorbents. Fourier transform infrared spectroscopyrevealed that chemical modification enhanced the surface chemistry of the adsorbent by introducingnew functional groups and increasing their concentration. The chemically modified adsorbentshad lower surface areas of 0.13–17.36 m2/g, which were substantially lower than that of the pristineadsorbent. Regardless of the surface area, all modified adsorbents exhibited higher Pb(II) adsorptioncapacities, wherein that of desiccated coconut-waste char (DCWC)-NaOH was the highest, with a removalefficiency of 96% (Q = 29.854 mg/g) for an adsorption time of 1 min. The equilibrium and kinetic data forthe DCWC-NaOH adsorbent best fit the Freundlich isotherm and pseudo-second-order kinetic models,respectively, with a maximum monolayer adsorption capacity of 1666.67 mg/g. The adsorption of Pb(II) ions was an exothermic process, with an optimum temperature of 40 C. Compared to existing commercialadsorbents, the proposed adsorbent was highly regenerable and considerably low-cost, showingpromising potential for commercial applications.

Effect of solvent and calcination process on physicochemical features of silica nanocapsule for CO₂ capture

Abdul Rahman Abdul Rahim,Khairiraihanna Johari,Murid Hussain 대한환경공학회 2024 Environmental Engineering Research Vol.29 No.6

Silica nanocapsules (SiNC) have gained considerable interest in their application as adsorbents due to its excellent physical structure and surface chemistry. The SiNC were synthesised via emulsion technique, whereby the effect of different solvents and calcination process were investigated. Diethyl ether as a solvent produced SiNC with the biggest surface area, 644 ㎡/g, followed by toluene and ethanol, 575 and 533 ㎡/g, respectively. The calcined SiNC had bigger surface area and pore volume, but smaller pore size as compared to their non-calcined counterparts. Diethyl ether and toluene as solvents produced SiNC with capsules or hollowed-core morphological structure, whereas by using ethanol, the SiNC was of solid core. The spectral analysis showed that the SiNC were of similar characteristics, whereby the ethanol-based SiNC had more intense hydroxyl (-OH) peaks and diethyl ether and toluene had an extra -CH₃ peak. The carbon dioxide (CO₂) adsorption measurement study showed that toluene-based SiNC performed the highest CO₂ adsorption capacity (Q = 2.59 mmol/g), followed by diethyl ether-based (1.45 mmol/g) and ethanol-based, (1.28 mmol/g). The sufficiently competent CO₂ adsorption capacity of the SiNC combined with their excellent physicochemical characteristics indicated their promising prospects for application as an adsorbent in CO₂ adsorption.

Conversion of coconut waste into cost effective adsorbent for Cu(II) and Ni(II) removal from aqueous solutions

Abdul Rahman Abdul Rahim,Iswarya,Khairiraihanna Johari,Nasir Shehzad,Norasikin Saman,Hanapi Mat 대한환경공학회 2021 Environmental Engineering Research Vol.26 No.4

Desiccated coconut waste (DCW) is an agricultural waste that originates from the coconut milk processing industry. In this study, it was utilized for the removal of copper (Cu(II)) and nickel (Ni(II)) via adsorption process. The physicochemical characterization of the DCW adsorbent shows that the adsorbent have a surface area of 6.63 ㎡/g, have high elemental carbon content and existences of important functional groups on its surface. The adsorptive capability of DCW adsorbent in removing the heavy metal were conducted in batch studies. DCW adsorbent performed highest Ni(II) and Cu(II) adsorption capacity at pH 6, where equilibrium is achieved at 450 minutes. The kinetic analysis showed the adsorption agreed with pseudo-second order kinetic model, indicating the Cu(II) and Ni(II) adsorption were a chemical adsorption, limited by the film diffusion. The DCW adsorbent still retained its effective adsorption capacity after 2 adsorption-desorption cycles, which is one of the excellent criteria of a good adsorbent for an adsorption process.

A comparative study on dynamic Hg(II) and MeHg(II) removal by functionalized agrowaste adsorbent: breakthrough analysis and adsorber design

Norasikin Saman,Helen Kong,Safia Syazana Mohtar,Khairiraihanna Johari,Azmi Fadziyana Mansor,Onn Hassan,Noorhalieza Ali,Hanapi Mat 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.7

The adsorption dynamics of inorganic mercury, Hg(II) and organic methylmercury, MeHg(II) removal by low-cost reactive agrowaste adsorbents namely CP-Pure, CP-MPTES and CP-RR was investigated in a fixed-bed adsorber. The results show that the breakthrough and saturation times were delayed with decreasing flow rate (F) and initial concentration (Co), and increasing bed height (Z). The Hg(II) possessed better adsorption performance than MeHg(II). The isotherm and kinetic model analyses of adsorption data followed the Temkin isotherm and the pseudosecond order kinetic models, respectively. The breakthrough curve was simulated well by the Thomas and Yoon-Nelson models, and then was further used for scale-up studies. The empty bed contact time (EBCT) concept was successfully demonstrated for the adsorber design and scale-up studies. The regeneration studies showed that the regenerated CP-Pure and CP-MPTES have a high regeneration efficiency up to third adsorption cycle

Adsorption behavior of Ag(I) onto elemental sulfur-encapsulated silica nanocapsules for industrial applications

Norasikin Saman,Gamal Abdulaziz Mohammed Alaghbari,Safia Syazana Mohtar,Helen Kong,Khairiraihanna Johari,Noorhalieza Ali,Hanapi Mat 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.4

Pure silica nanocapsules (SiNC-P) and elemental sulfur-encapsulated silica nanocapsules (SiNC-ES) as Ag(I) adsorbents were successfully synthesized by a one-step water-in-oil microemulsion polymerization process. The characterization of the synthesized materials, such as surface morphology, surface area, porosity, functional groups and thermal characteristics, was carried out using various analytical techniques. The SiNC-P and SiNC-ES have nearly similar morphology, but the surface area and pore size of the SiNC-ES are higher than SiNC-P. The Ag(I) adsorption study showed that it increased with increasing elemental sulfur (ES) amount in the SiNC-ES. The SiNC-ES shows high adsorption capacity, independent of pH, and higher adsorption rate as compared to SiNC-P. The maximum Ag(I) adsorption capacity of SiNC-P and SiNC-ES was 50.49mg g1 and 98.51mg g1, respectively. The adsorption isotherm data were best described by the Langmuir model. The diffusion modeling analysis of the kinetic data indicated that film diffusion is the controlling step, while chemical reaction modeling obeys the pseudo-second-order kinetic model. The SiNC-ES was reusable and good adsorption performance up to four adsorption cycles was observed. The practical capability of the SiNC-ES to adsorb Ag(I) was successfully demonstrated using an industrial waste solution in which a high removal efficiency was observed (>90%). This demonstrates that the SiNC-ES can be a potential adsorbent for Ag(I) recovery from industrial wastes.

Coagulant bath medium effect towards polylactic acid membranes structure and methylene blue dye removal

Amira M. Nasib,Stephen Simon,Syahmie M. Rasidi,Siti Kartini E. Ab. Rahim,Hoo Peng Yong,Ng Qi Hwa,Khairiraihanna Johari Techno-Press 2024 Advances in materials research Vol.13 No.3

The asymmetric polylactic acid (PLA) membrane was prepared via phase inversion method using non-solvent induced separation (NIPS) technique. This study aims to synthesized as well as to characterize the PLA membrane and evaluating the membrane performance on water flux and permeability. In addition, this research also studied the removal performance of methylene blue dye. The polymer solution has been prepared using 12 wt.% of PLA and dissolved in 88 wt.% of Dimethylacetamide (DMAc) as a solvent. Then, the cast film was immersed in different ratio of coagulant bath medium (distilled water: methanol: ethanol) ranging from 100:0:0, 75:25:0, 75:0:25 and 75:12.5:12.5, respectively). Several characterizations were performed which include, membrane contact angle and membrane porosity. Performance PLA membranes were determined in terms of water flux and permeability at 1 bar transmembrane pressure using dead-end permeation cell. Finally, methylene blue (MB) removal efficiency was tested at the same transmembrane pressure. The findings revealed that the increase of alcohol concentration in coagulant bath resulted in higher porosity and lower contact angle. In short, MB dye rejection efficiency is also closely related to the amount of alcohol ratio used in coagulant baths. Increases in concentration of methanol and ethanol in coagulant bath medium increases the membrane porosity thus increased in efficiency of methylene blue rejection.