GOVPH

Sex: Male
Education:

• Doctor of Philosophy in Energy Science and Technology, Myongji University
• Master of Science in Energy Science and Technology, Myongji University
• Bachelor of Science in Chemical Engineering, Ateneo de Davao University

Field of Specialization
Material Characterization
X-Diffraction
Mechanical Properties
Advanced Materials
Materials Processing
Material Characteristics
Mechanical Behavior of Materials
Mechanical Testing

Researches:

Article title: Sulfur co-polymerization with hydrophilic co-monomer as polysulfides in microbeads for a highly efficient Hg 2+ removal from wastewater
Authors: Lawrence A. Limjuco, Hiluf T. Fissaha, Hern Kim, Grace M. Nisola, and Wook-Jin Chung
Publication title: ACS Applied Polymer Materials 2(11): 4677-4689, September 2020

Abstract:
Re-purposing of sulfur, a petroleum industry by-product, will not only address safety issue of its storage but also advance its valorization. Herein, sulfur was directly copolymerized with 2-carboxyethyl acrylate (CEA) to synthesize S-rich hydrophilic polysulfide (pS-CEA) for Hg²⁺ sequestration. Physico-chemical properties such as hydration number and S-content were correlated with the ability of pS-CEAs to capture Hg²⁺ in terms of binding capacity (q) and site utilization. Results reveal that S content in pS-CEA must be balanced carefully with its wettability to ensure an efficient Hg²⁺ sequestration. At optimized S:CEA molar ratio, pS-CEA(6:1) exhibited extremely high affinity towards Hg²⁺ with distribution coefficient (Kd ~ 26095 mL g⁻¹). It attained superior adsorption capacity qm ~ 989 mg Hg²⁺ g⁻¹ derived from Langmuir isotherm model and followed a pseudo-second order kinetics. pS-CEA was conveniently configured into microbeads via agar gelation and drop-in-oil method. At its highest acceptable pS-CEA loading (150 wt%), pS-CEA/agar microbeads attained qm = 527 mg g⁻¹. The microbeads were configured into a packed bed column and successfully filtered out 99.89% Hg²⁺ from atypically high concentration feed (Co = 50 mg L⁻¹). The filtration column can be easily regenerated by passing a stripping solution (0.5 M HCl/1 M thiourea) with nearly 100% Hg²⁺ elution efficiency. This work demonstrates the effective design and benefits of the developed polysulfide which can be synthesized from sulfur waste as a functional material for Hg²⁺ pollution remediation.
Full text available upon request to the author

Article title: Water-insoluble hydrophilic polysulfides as microfibrous composites towards highly effective and practical Hg2+ capture
Authors: Lawrence A. Limjuco, Grace M. Nisola, Khino J. Parohinog, Kris Niño G. Valdehuesa, Seong-Poong Lee, Hern Kim, Wook-Jin Chung
Publication title: Chemical Engineering Journal 378(2):122216, July 2019

Abstract:
Polysulfides (PS) are emerging S-rich materials with unique properties attractive for various applications including Hg²⁺ capture. However, PS have yet to offer competitive Hg²⁺ binding capacities (q) due to their poor hydration and intractable structures. Herein, neoteric PS were developed by reacting molten sulfur with oxygenous co-monomers containing acryl-, methacryl-, and allyl groups. The PS products were thoroughly examined in terms of their consistency, rheology, solvent solubility, hydrophilicity and morphology. Their composition and chemical structures were proposed based on elemental analysis, FTIR, GC-MS, 2D NMR (HSQC) and XPS analyses. The best PS achieved high q ~ 835 mg g⁻¹ (vs. q < 26 mg g⁻¹ of conventional PS) due to enhanced utilization of the sulfide-rich and hydrophilic regions for Hg²⁺ capture. The PS can be conveniently electrospun into microfibrous (MF) composites with polyacrylonitrile (PAN) matrix, which further increased the Hg²⁺ binding site utilization especially for the S-rich region (~92%). These highlight the combined benefits of simple yet very effective methods in overcoming the current limitations on PS-based Hg²⁺ capture. The PS/PAN MF is highly Hg²⁺-selective (KD ~ 1.10 × 10⁷ mL g⁻¹), can remove ~99.91% Hg²⁺ and can retain only 1.0 μg L⁻¹ even at low feed concentration (Co = 1 mg L⁻¹). It can be regenerated and re-used as a membrane filter, with consistent performance and Hg²⁺ stripping efficiency. Considering sulfur as an abundant industrial waste, inexpensive PS-based membrane filters can be developed for practical high-volume treatment of Hg²⁺ contaminated water.
Full text available upon request to the author

Article title: The potential of monocationic imidazolium-, phosphonium-, and ammonium-based hydrophilic ionic liquids as draw solutes for forward osmosis
Authors: Hana G. Zeweldi, Lawrence A. Limjuco, Anelyn P. Bendoy, Han-Seung Kim, Myoung Jun Park, Ho Kyong Shon, Eldin M. Johnson, Hanki Lee, Wook-Jin Chung, Grace M.Nisola
Publication title: Desalination 444: 94-106, July 2018

Abstract:
The widespread implementation of forward osmosis (FO) is highly constrained by the limited availability of suitable draw solutes (DS). Herein, monocationic hydrophilic ionic liquids (ILs) were probed as FO DS. Water (J v), reverse solute (J s), and specific reverse solute (J s /J v) fluxes were determined and correlated with IL properties: Van't Hoff factor (i), ionic strength, hydrated ionic radius (r H), diffusivity and membrane affinity. Most of the ILs have comparable J v with the benchmark draw solute NaCl but their J s were significantly lower, particularly under PRO mode. Their remarkably lower J s /J v (i.e. < 0.010 ± 7.45 × 10 −4 mol L −1) than NaCl (0.021 ± 0.003 mol L −1) validates their potential use as FO DS. Tetraethylammonium bromide ([N2222]Br) is the most suitable IL DS due to its high π, high ionic strength, small r H , least membrane permeability (B = 0.14 L m −2 h −1) and lowest J s /J v = 0.004 ± 5.53 × 10 −4 mol L −1. Moreover, [N2222]Br effectively de-salinated seawater (0.6 M NaCl). It is thermally stable and can be effectively regenerated through direct contact membrane distillation. The final permeated water had only trace [N2222]Br, which is safe for consumption as confirmed by in vitro toxicity tests. These results demonstrate that certain ILs like [N2222]Br can be identified as suitable draw solutes for FO desalination process.
Full text available upon request to the author

Article title: Aerosol Cross-Linked Crown Ether Diols Melded with Poly(vinyl alcohol) as Specialized Microfibrous Li+ Adsorbents
Authors: Lawrence A. Limjuco, Grace M. Nisola, Rey Eliseo C. Torrejos, Jeong Woo Han, Ho Seong Song, Khino J. Parohinog, Sangho Koo, Seong-Poong Lee, and Wook-Jin Chung
Publication title: ACS Applied Materials & Interfaces 9(49), November 2017

Abstract:
Crown ether (CE)-based Li⁺ adsorbent microfibers (MFs) were successfully fabricated through a combined use of CE diols, electrospinning, and aerosol crosslinking. The 14-16 membered CEs, with varied ring sub-units and cavity dimensions, have two hydroxyl groups for covalent attachments to poly(vinyl alcohol) (PVA) as the chosen matrix. The CE diols were blended with PVA and transformed into microfibers via electrospinning, a highly effective technique in minimizing CE loss during MF fabrication. Subsequent aerosol glutaraldehyde (GA) crosslinking of the electrospun CE/PVA MFs stabilized the adsorbents in water. The aerosol technique is highly effective in crosslinking the MFs at short time (5 h) with minimal volume requirement of GA solution (2.4 mL g⁻¹ MF). GA crosslinking alleviated CE leakage from the fibers as the CEs were securely attached with PVA through covalent CE-GA-PVA linkages. Three types of CE/PVA MFs were fabricated and characterized through FTIR-ATR, ¹³C CP/MAS NMR, FE-SEM, N2 adsorption/desorption, and UTM. The MFs exhibited pseudo-second order rate and Langmuir-type of Li⁺ adsorption. At their saturated states, the MFs were able to use 90-99% CEs for 1:1 Li⁺ complexation suggesting favorability of their microfibrous structures for CE accessibility to Li⁺. The MFs were highly Li⁺-selective in seawater. Neopentyl bearing CE was most effective in blocking larger monovalents Na⁺ and K⁺ while the dibenzo CE was best in discriminating divalents Mg²⁺ and Ca²⁺. Experimental selectivity trends concur with the reaction enthalpies from DFT calculations, confirming the influence of CE structures and cavity dimensions in their "size-match" Li⁺ selectivity.
Full text available upon request to the author

Article title: Design of lithium selective crown ethers: Synthesis, extraction and theoretical binding studies
Authors: Rey Eliseo C. Torrejos, Grace M. Nisola, Ho Seong Song, Lawrence A.Limjuco, Chosel P. Lawagon, Khino J. Parohinog, Sangho Koo, Jeong Woo Hand, Wook-Jin Chung
Publication title: Chemical Engineering Journal 326(15): 921-933, October 2017

Abstract:
Lithium-selective (Li⁺) di-hydroxy crown ethers (CEs 3a-3h) were efficiently synthesized via intermolecular cyclization of bulky bis-epoxide with 1,2-dihydroxybenzene. Bis-epoxides were produced by etherifying allyl bromides with bulky diols to afford diene intermediates, which were subsequently epoxidized. Optimized cyclization reactions were established by changing the solvent, catalyst, and reaction temperature. Complexation abilities of CEs 3a-3h with Li⁺ and other alkali metals (Na⁺, K⁺, Cs⁺) were assessed by liquid-liquid extraction in dichloromethane-water system. Among the CEs, the highest Li⁺/Na⁺ selectivities were obtained from 3d (αLi/Na=2519) and 3e (αLi/Na=1768). DFT calculations reveal that 3d (1.28-1.37 Å) and 3e (1.23-1.38 Å) had the closest cavity sizes with Li⁺ diameter (1.36 Å). This result affirms that the size-match selectivity of CEs with Li⁺ was due to the presence of bulky tetramethyl (3d) or bicyclopentyl (3e) subunits with the rigid benzo groups. Complexation with larger cations like Na⁺, K⁺ and Cs⁺ greatly distorted the 3d and 3e rings as indicated by the larger O-M⁺ distances on their bulky sides than on their benzo sides. Thus, their (3d, 3e) superior selectivities were due to their Li⁺ preference and unstable complexation with larger M⁺. Enthalpy exchange reaction mechanisms reveal the tendency of all CEs to form 2:1 CE-M⁺ complexes with larger cations except for 3d, which mainly forms 1:1 CE-M⁺ hence it is considered most suitable for Li⁺. The efficient synthesis of di-hydroxy CEs widens their application not only as extractants but also as solid-supported Li⁺ adsorbents given the amenability of their OH- groups to further functionalization.
Full text available upon request to the author

Article title: Continuous lithium mining from aqueous resources by an adsorbent filter with a 3D polymeric nanofiber network infused with ion sieves
Authors: Wook-Jin Chung, Rey Eliseo C. Torrejos, Myoung Jun Park, Eleazer L. Vivas, Lawrence A. Limjuco, Chosel P. Lawagon, Khino J. Parohinog, Seong-Poong Lee, Ho Kyong Shon, Hern Kim, Grace M. Nisola
Publication title: Chemical Engineering Journal 309, February 2017

Abstract:
Electrospun composite nanofiber (NF) was fabricated and employed as an adsorbent membrane filter in a continuous Li⁺ mining process from seawater. The filter was composed of a hydrophilic polyacrylonitrile (PAN) matrix infused with lithium ion sieves (LIS) H1.6Mn1.6O4. Characterization of the LIS/PAN NF confirmed its favorable structural and surface properties for effective Li⁺ adsorption. The LIS/PAN NF was mechanically suitable as a microfiltration membrane with high water flux and low pressure requirement. Breakthrough experiments at varied feed concentrations (Cf), seawater flowrates (F), and NF thicknesses (Z) revealed the dynamic adsorption behavior of the filter. The seawater residence time was most critical and must be kept ⩾0.12 min at any given Cf and Z to maximize the Li⁺ capacity of the filter. This can be conveniently achieved by adjusting the F of the process. Analogous to a packed bed system, the predictive power of nine breakthrough models were determined through non-linear regression analyses. Results reveal that bed-depth-space-time, Bohart-Adams (BA) and Thomas models adequately predicted the performance of the filter albeit BA exhibited the best agreement. Meanwhile, Wolborska failed to converge with any of the experimental results while Yoon-Nelson, Wang, Clark, dose-response, and modified dose-response were too simple to provide any meaningful information. Cycled Li⁺ adsorption-desorption runs successfully collected and concentrated Li⁺ in a mild acid stripping solution. After ten cycles, Li⁺ was separated 155–1552 times more efficiently than Na⁺, K⁺, Mg²⁺ and Ca²⁺. Overall results demonstrate the potential of LIS/PAN NF as an adsorbent membrane filter for continuous Li⁺ mining from aqueous resources.
Full text available upon request to the author

Article title: Polyethylenimine-modified mesoporous silica adsorbent for simultaneous removal of Cd(II) and Ni(II) from aqueous solution
Authors: Amit K. Thakur, Grace M. Nisola, Lawrence A. Limjuco, Khino J. Parohinog, Rey Eliseo C. Torrejos, Vinod K. Shahi, Wook-Jin Chung
Publication title: Journal of Industrial and Engineering Chemistry 49:133-144, May 2017

Abstract:
Nano-spherical amine-rich polyethylenimine (PEI) grafted on mesoporous silica (MCM-41) (PEI/MCM-41) was developed for Cd(II) and Ni(II) removal from water. Characterization of PEI/MCM-41 using various techniques confirms its successful fabrication. Adsorption results reveal that pH and adsorbent dosage must be controlled for maximum removals. The adsorption rate was pseudo-second-order, and fitted well with Langmuir and Freundlich isotherms at equilibrium. The adsorption was thermodynamically spontaneous, endothermic and favorable. Adsorption capacity of 156.0 mg g⁻¹ Cd(II) and 139.7 mg g⁻¹ Ni(II) were on par with other high performing reported adsorbents. The PEI/MCM-41 was successfully reused demonstrating its potential for HM decontamination application.
Full text available upon request to the author

Article title: H2TiO3 composite adsorbent foam for efficient and continuous recovery of Li+ from liquid resources
Authors: Lawrence A. Limjuco, Grace M. Nisola, Chosel P. Lawagon, Seong-Poong Lee Jeong Gil Seo Hern KimWook-Jin Chung
Publication title: Colloids and Surfaces A: Physicochemical and Engineering Aspects 504:267-279, September 2016

Abstract:
Metatitanic acid (H2TiO3) is a promising lithium ion sieve (LIS) that can supplant the traditional manganese oxide-based LIS. To materialize its potential use in continuous Li+ recovery, the H2TiO3 (HTO) was processed as pliant composite foams. Pre-synthesized HTO particles were incorporated in poly(vinyl alcohol) (PVA) matrix (HTO/PVA) via blending, lyophilisation, and chemical cross-linking. This approach ensured the high quality and convenient loading control of HTO in the foam. The composites were thoroughly characterized and evaluated in terms of Li+ adsorption performance and mechanical durability. At 200 wt% HTO loading, the HTO/PVA had minimal capacity loss (6%) and low retardation (8%) in Li+ uptake rate relative to the well-dispersed unsupported HTO powder. Such superior performance can be attributed to the high open pore network, uniform HTO distribution, and good wettability of the foam. Moreover, the composite maintained the Li+ selectivity of HTO in seawater suggesting minimal non-selective metal ion adsorption on the support matrix. The foam maintained its performance and mechanical integrity after several uses, demonstrating its high suitability for long-term application in Li+ mining from liquid resources like seawater.
Full text available upon request to the author

Article title: Mixed matrix nanofiber as a flow-through membrane adsorber for continuous Li+ recovery from seawater
Authors: Myoung Jun Park, Grace M. Nisola, Eleazer L. Vivas, Lawrence A. Limjuco, Chosel P. Lawagon. Jeong Gil Seo, Hern Kim, Ho Kyong Shon, Wook-Jin Chung
Publication title: Journal of Membrane Science, 510: 141-154, July 2016

Abstract:
A polysulfone (PSf)-based mixed matrix nanofiber (MMN) dispersed with particulate lithium ion sieves (LIS) was developed as a flow-through membrane Li+ adsorber. The MMN was prepared via electrospinning, thermal annealing, and acid pickling (i.e. activated LIS: Li0.67H0.96Mn1.58O4 or MO). The unique dimensional property of the macroporous MMN promoted high MO exposure and distribution on the nanofiber surface. Minimal losses in Li+ adsorption capacity and kinetics, elicited by the PSf matrix, were observed. Moreover, the PSf matrix effectively improved the Li+ selectivity of MO as it alleviated the sorption of interfering cations. As membranes, the MMNs were highly permeable to water under minimal trans-membrane pressure. The convective flow of seawater through the highly accessible MMN facilitated the fast Li+ transport to the MO surface. Breakthrough studies revealed that a balance between kinetics and dynamic Li+ adsorption capacity could be obtained at optimal seawater/MMN contact time, which was easily achieved by adjusting the feed flow-rate or MMN thickness. Continuous flow-through operations were successfully controlled at a very short adsorption–desorption cycle time (one day) while maintaining the dynamic Li+ adsorption capacity of the MMN. Cycled operations confirmed the regenerability of the MMN and its adsorption performance consistency. Enrichment of Li+ was successfully done by repeated Li+ desorption in a small volume of acid solution. Overall results demonstrated the strong potential of the flow-through MMN membrane adsorber for continuous Li+ recovery from alternative resources like seawater.
Full text available upon request to the author

Article title: Macroporous flexible polyvinyl alcohol lithium adsorbent foam composite prepared via surfactant blending and cryo-desiccation
Authors: Grace M. Nisola, Lawrence A. Limjuco, Eleazer L. Vivas, Chosel P. Lawagon, Myoung Jun Park, Ho Kyong Shon, Neha Mittal, In Wook Nah, Hern Kim, Wook-Jin Chung
Publication title: Chemical Engineering Journal 110, June 2015

Abstract:
Macroporous polyvinyl alcohol (PVA) foam composites with high loading of uniformly distributed lithium ion sieves (LIS) were successfully fabricated and evaluated for Li+ recovery. Surfactant blending combined with cryo-desiccation effectively produced LIS/PVA foams with hierarchical porosity composed of macro- and mesopores. Glutaraldehyde cross-linking rendered the LIS/PVA foams insoluble in water but exhibited high water absorbency and flexibility. Relative to the LIS powder, the foams exhibited minimal reductions in adsorption capacity (qe) and kinetic properties due to: (1) high total porosity and surface area, (2) hydrophilicity of PVA matrix, and (3) high LIS loading, which promoted particle exposure on the foam surface. These features facilitated easy convective flow of water through the matrix and allowed intimate contact between the Li+ feed source and the LIS surface. Thus, LIS/PVA foams with high loadings (200-300 wt%) exhibited meager reductions in qe (7-13%) and kinetic properties compared to the LIS powder. With LIS loading increase, Li+ selectivity of LIS/PVA foams against other cations (i.e. Na+, K+, Mg2+, Ca2+) likewise approached that of the LIS powder. While 300 wt% LIS/PVA had low mechanical property, lower LIS loadings of 200- and 250 wt% were highly durable and exhibited no deterioration in adsorption performance and reusability. Among the prepared LIS/PVA, 250 wt% demonstrated the highest adsorption performance and can be repeatedly used for long-term application. The developed LIS/PVA foams are promising Li+ adsorbents for secondary Li+ sources; application of these foams via a simple “absorb and squeeze” mechanism could be more practical than the energy-intensive processes like packed bed and membrane systems.
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