Soh Kheang Loh - Independent Researcher (original) (raw)

Papers by Soh Kheang Loh

Biomass Conversion and Biorefinery, Oct 26, 2022

The hemicelluloses extracted from sunflower hulls by repeated alternating oxidative and alkaline ... more The hemicelluloses extracted from sunflower hulls by repeated alternating oxidative and alkaline treatments were purified by precipitation with Cetavlon and then ion-exchange chromatography on DEAE-trisacryl. The resulting fractions were examined by hydrolysis, methylation, GLC-MS, and NMR spectroscopy. The hemicelluloses are of the glucuronoxylan type with the following structure 4 4)-p-D-Xylp-(1-t 4)[4-O-Me-aD -GlcpA-(1 + 2)]-p-D-Xylp-(1 +. The polysaccharides differed in the amount of branching; the ratio of the main fraction 40MeGlcA : Xyl was 1: 8-9.

Journal of Oil Palm Research, Oct 18, 2018

Oil palm empty fruit bunch (EFB), being one of the lignocellulosic biomass forms generated from t... more Oil palm empty fruit bunch (EFB), being one of the lignocellulosic biomass forms generated from the palm oil milling process, has high contents of cellulose and hemicelluloses for bioethanol production. However, the conversion routes so far remain challenging and optimisation is necessary. This article aims at optimising the fermentable process variables in the production of bioethanol from EFB using response surface methodology (RSM). The EFB was firstly pre-treated with mild NaOH, then hydrolysed using diluted H 2 SO 4 to extract mainly xylose and subjected to enzymatic saccharification for glucose recovery prior to fermenting the sugars with Saccharomyces cerevisiae. A Central Composite Design (CCD) was used to optimise the three independent variables involved i.e. pH, temperature and agitation rate. The RSM data subjected to analysis of variance (ANOVA) and a second-order polynomial model revealed the optimised conditions: pH 4, 30°C, 150 rpm and 72 hr in batch fermentation. The validation experiment under these conditions gave a maximum bioethanol yield of 0.66 g g-1 glucose, which was very close to the predicted value (0.56 g g-1). These results confirmed that the model was adequate and reliable to optimise bioethanol production from the enzymatically hydrolysed EFB.

Bioenergy Research, Aug 14, 2021

Fuel quality is among the major issues encountered for commercial production and utilisation of o... more Fuel quality is among the major issues encountered for commercial production and utilisation of oil palm-based biomass pellets from empty fruit bunches (EFB). In this study, a physical treatment, namely sieving and water washing, was applied to EFB prior to densi cation using an industrial-scale plant. The physiochemical properties of the produced EFB pellets were compared with those without physical treatment as the control. The results showed that the physical treatment process had signi cantly enhanced the fuel properties of EFB pellets, particularly in reducing ash content. Both the treatments; sieving alone and a combined sieving and water washing of the feedstock managed to reduce the ash content of EFB pellets to < 4 wt.% and < 2 wt.%, respectively compared to > 5 wt.% of typical commercial EFB pellets. The reduction in ash content improved the calori c value of pellets to > 17.5 MJ kg-1 which signi ed achieving a milestone for oil palm biomass-based heat and power generation from technical, operational, economic and environmental points of view. The ndings also indicated that the combined sieving and water washing treatment method could potentially reduce further the unwanted ash-inducing elementals in EFB pellets, in particular chlorine and potassium. This study demonstrated that the employed physical treatment is an immediate and costeffective practical commercial approach to improve the fuel properties of EFB pellets.

Journal of Oil Palm Research, Oct 10, 2017

Empty fruit bunch (EFB) is a potential feedstock for the commercial production of biomass pellet ... more Empty fruit bunch (EFB) is a potential feedstock for the commercial production of biomass pellet fuel. In this study, the fuel properties of EFB pellets collected from four production plants were examined and the impacts of pellets production to the environment were determined using Life Cycle Assessment (LCA) approach. The fuel properties concerning moisture and energy content, bulk density and durability index were comparable to the European Standard (EN 14961-2) for solid biofuels except for the higher ash content i.e. > 6%. This high ash content contributed to the low energy content of the pellets. This was caused by contamination from soil and dirt, attributed due to poor handling of the raw material. The EFB pellets contained a high concentration of potassium, nitrogen, chlorine and sulphur compared to wood-based pellets. The presence of these elements affected biomass combustion at the furnace as well as emission generation. The Life Cycle Impact Assessment (LCIA) carried out showed that the main environmental impacts of the production of EFB pellets were fossil depletion, climate change and particulate matters emission. This was due to the plants' heavy dependence on the grid-connected electricity. The results can be used to identify approaches in upgrading EFB pellets quality and reducing the associated environmental impacts.

Sains Malaysiana, Aug 31, 2017

Utilisation of sago pith residue (SPR) for fermentable sugar production using both acid and enzym... more Utilisation of sago pith residue (SPR) for fermentable sugar production using both acid and enzymatic hydrolysis was studied. In acid hydrolysis, the effect of solid and acid concentrations, temperature and reaction time was optimised. The effect of enzyme dosage was studied on enzymatic hydrolysis of SPR. Higher yield and conversion of 0.73 g g -1 (96% conversion) was achieved by treating 6% (w v -1 ) of SPR with 1% (v v -1 ) H 2 SO 4 at 125°C for 90 min as compared to 0.61 g g -1 (79% conversion) using 40 U g -1 biomass of Aspergillus niger amyloglucosidase incubated at 60°C and pH4 for 48 h. The fermentation of acid hydrolysate of SPR demonstrated that high ethanol yield of 98% can be achieved without supplementation of nitrogen and nutrients. The complete process showed that 470 L of bioethanol could be produced from 1 tonne of SPR. This figure makes SPR an ideal raw material for bio-conversion into bioethanol or other value-added products.

American Journal of Applied Sciences, Apr 1, 2014

With the increasing concern on fossil fuel depletion and environmental problems, the utilization ... more With the increasing concern on fossil fuel depletion and environmental problems, the utilization of renewable biomass resources is expected to play an important role in the future. Biomass can be converted into a variety of fuels and chemicals by different processes; one of which is pyrolysis that has been subjected to extensive research in recent years. In this study, pyrolysis of oil palm Empty Fruit Bunches (EFB) was investigated using a quartz fluidised-fixed bed reactor. The effects of pyrolysis temperatures on the yields and composition of gaseous products were investigated. The temperatures of pyrolysis used were in the range of 300-600°C. The gaseous products from pyrolysis of (EFB) were analyzed using a dual-channel micro-GC with Thermal Conductivity Detector (TCD). The highest and lowest gas yields obtained were 42.98 and 31.55% at 600 and 300°C, respectively. The gases detected were Carbon Monoxide (CO), carbon dioxide (CO 2), Methane (CH 4), Ethane (C 2 H 6) and Ethylene (C 2 H 4). At 300 and 400°C, the gas mixture comprised mainly CO 2 (20%) and CO (20%). Other gases such as CH 4 , C 2 H 4 and C 2 H 6 only evolved at higher temperature starting from 400°C with the yield of the latter two gases in very low concentration.

Journal of environmental chemical engineering, Aug 1, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Production and physico-chemical characterization of biochar from palm kernel shell

Nucleation and Atmospheric Aerosols, 2013

Renewable & Sustainable Energy Reviews, Nov 1, 2014

Climate change, food crisis, energy generation and environmental pollution are among the greatest... more Climate change, food crisis, energy generation and environmental pollution are among the greatest threats and challenges faced by mankind today. Biochar production from various biomass sources has gained a lot of interests since its addition to degraded agricultural soils not only improve soil fertility and biomass yield, but also mitigate climate change through soil carbon sequestration and reduction in greenhouse gas emissions. There are enormous amounts of oil palm biomass generated along with the main palm oil production streams. A lot of research has been carried out to convert oil palm biomass into value-added products, but none except biochar has come close to be labeled as carbon negative products. In this paper, a review about production and application potential of biochar from oil palm biomass in Malaysia is given. Besides, some of the challenges in promoting biochar production and application, such as nature of the feedstocks, economic and logistical factors and market acceptance are highlighted as well. Producing biochar from oil palm biomass can potentially lead to a healthier environmental, societal and economic growth for the oil palm industry specifically, and enhances sustainability in worldwide context.

Nutrient Recovery from Anaerobic Palm Oil Mill Effluent Using Palm Kernel Shell Biochar and Deoiled Spent Bleaching Earth and Their Effect on Oil Palm Growth

Advanced structured materials, 2023

ARPN journal of engineering and applied sciences, 2015

To sustain a greener image of the palm oil industry, the producing countries have been placing re... more To sustain a greener image of the palm oil industry, the producing countries have been placing remarkable efforts to promote palm oil as an environmental friendly product. This paper aims to report a study regarding the wastes generated in local palm oil mills. Study was conducted to seven palm oil mills of different capacity, years of operation commencement, and management background. Attention is given to milling wastes as they represent a wider potential for beneficial reuse and probably leads to monetary returns, large quantity, and more environmental hazardous. Milling wastes included lignocellulosic palm biomasses namely the empty fruit bunches (EFB), oil palm shells (OPS), mesocarp fibres, palm oil mill effluent (POME), and palm oil mill sludge (POMS), as well as the solid wastes generated as a result from further processing of these biomasses into the palm oil fuel ashes (POFA) and palm oil clinkers (POC). An agro-industrial waste profile for palm oil mills was computed based on the thirteen years operation and production data. Management approaches of these palm oil mills on the by-products were also summarised. The information will be attention-grabbing for estimation and later prediction of the oil palm wastes accessibility, hence offer a statistic for future references.

Fermentation

Biomass deacetylation with alkali prior to dilute acid pretreatment can be a promising approach t... more Biomass deacetylation with alkali prior to dilute acid pretreatment can be a promising approach to reduce the toxicity of the resulting hydrolysates and improve microbial fermentation. In this study, the effect of mild alkaline treatment of oil palm trunk (OPT) biomass on succinic acid production was evaluated. Deacetylation was carried out under different conditions: NaOH loadings (1–5%, w/v) and reaction times (15–90 min) at 100 °C. Deacetylation using 1% (w/v) NaOH within 15 min was sufficient to achieve a high acetic acid removal of 5.8 g/L with minimal sugar loss. Deacetylation under this condition resulted in a total sugar concentration of 55.8 g/L (18.0 g/L xylose and 37.8 g/L glucose), which was 37% higher than that of non-deacetylated OPT. Subsequently, succinic acid production using Actinobacillus succinogenes was also improved by 42% and 13% in terms of productivity and yield, respectively, at 10% (w/v) solid loading. This further demonstrated that mild alkaline treatment...

BioResources

The exploitation of agroindustrial lignocellulose, such as oil palm trunk bagasse (OPTB), as a ra... more The exploitation of agroindustrial lignocellulose, such as oil palm trunk bagasse (OPTB), as a raw material in the production of succinic acid (SA) may serve as an effective strategy to propel the bio-based industry. This study aimed to optimise the recovery of fermentable sugar, i.e., glucose, from enzymatic hydrolysis of the dilute acid pretreated OPTB (DA-OPTB). The dilute acid pretreatment used in this study was able to remove 59.5% of hemicellulose and 13.3% of lignin. Response surface methodology (RSM) based on central composite design (CCD) was then applied to investigate four independent variables – enzyme loading (10 to 50 U/g), agitation speed (50 to 250 rpm), reaction time (0 to 96 h), and surfactant concentration (0.025 to 0.125%, v/v). The experimental glucose concentration of 21.7 g/L was in good agreement with the RSM-predicted value of 20.5 g/L. Among the parameters investigated, supplementation of a surfactant during enzymatic hydrolysis was significant in influenci...

Pilot-Scale Anaerobic Co-Digestion of Palm Oil Mill Effluent with Moringa Oleifera Filtrate in an Integrated Anaerobic–Aerobic Bioreactor

BioEnergy Research

Catalytic wet torrefaction of lignocellulosic biomass: An overview with emphasis on fuel application

South African Journal of Chemical Engineering

Journal of Physical Science, 2019

The coal bottom ash (CBA) sourced from thermal power plant was chemically treated using hydrochlo... more The coal bottom ash (CBA) sourced from thermal power plant was chemically treated using hydrochloric acid (HCl), namely CBA-HCl, and used as an adsorbent for palm oil mill effluent (POME) decolourisation. The treated CBA-HCl was characterised for surface property via Brunauer-Emmett-Teller (BET), surface chemistry via Fourier transform infrared (FTIR) and surface morphology via scanning electron microscopy (SEM). Its effectiveness for adsorption of POME colour was investigated via batch experiments as a function of pH, initial POME concentration, adsorbent dosage and contact time. The adsorption increased with increasing contact time until an equilibrium state was achieved within 18 h to 24 h. The maximum POME colour removal, 81.15% was achieved at pH 6 utilising 14% (w/v) adsorbent dosage for 24 h. The colour adsorption isotherm and kinetics of the CBA-HCl was well-fitted with Freundlich and pseudo-second order models with correlation coefficient, R 2 = 0.9991 and R 2 = 0.9996, respectively. Based on the results, CBA can be a potential adsorbent in removing POME colour before being discharged into a watercourse.

Oil palm biomass value chain for biofuel development in Malaysia: part I

Value-Chain of Biofuels, 2022

Effect of neutralizing agents in the preparation of succinic acid from oil palm trunk

IOP Conference Series: Materials Science and Engineering, 2021

Neutralization is an important process to control the pH required for enzymatic saccharification ... more Neutralization is an important process to control the pH required for enzymatic saccharification of pretreated biomass followed by fermentation for biochemical conversion. In this study, the production of succinic acid as a potential C4 building block was investigated by utilizing lignocellulosic biomass in the form of oil palm trunk (OPT). The effect of different neutralizing agents (NaOH, KOH and NH4OH) on the enzymatic saccharification of oxalic acid-pretreated OPT and subsequent succinic acid fermentation byActinobacillus succinogenesATCC 55618 was investigated. The results showed that all neutralizing agents tested were able to assist in the recovery of fermentable sugars with concentrations ranging from 38.1 to 39.6 g/L. However, during succinic acid fermentation, it was found that the soluble NH4-oxalate salt formed severely inhibited succinic acid fermentation compared to Na and K, thereby decreasing the succinic acid production from 14.0 g/L (using NaOH) to 1.0 g/L (using N...