Hanapi Mat

Extraction and characterization of lignin from oil palm biomass via ionic liquid dissolution and non-toxic aluminium potassium sulfate dodecahydrate precipitation processes.

The objective of this study is to extract and characterize lignin from oil palm biomass (OPB) by dissolution in 1-butyl-3-methylimidazolium chloride ([bmim][Cl]), followed by the lignin extraction through the CO2 gas purging prior to addition of aluminum potassium sulfate dodecahydrate (AlK(SO4)2 · 12H2O). The lignin yield, Y(L) (%wt.) was found to be dependent of the types of OPB observed for all precipitation methods used. The lignin recovery, RL (%wt.) obtained from CO2-AlK(SO4)2 · 12H2O precipitation was, however dependent on the types of OPB, which contradicted to that of the acidified H2SO4 and HCl solutions of pH 0.7 and 2 precipitations. Only about 54% of lignin was recovered from the OPB. The FTIR results indicate that the monodispersed lignin was successfully extracted from the OPT, OPF and OPEFB having a molecular weight (MW) of 1331, 1263 and 1473 g/mol, and degradation temperature of 215, 207.5 and 272 °C, respectively.

An ionic liquid treatment and fractionation of cellulose, hemicellulose and lignin from oil palm empty fruit bunch

This work reports on a complete isolation and characterization of lignocellulosic compounds from oil palm empty fruit bunch (OPEFB) by ionic liquid (IL) treatment and alkaline treatment processes. The fractionated lignocellulosic compounds were confirmed by FTIR and CP/MAS 13CNMR analyses. The yield of the cellulose, hemicellulose and lignin fractions was 52.72±1.50% wt., 27.17±1.68% wt. and 16.82±1.15% wt. with molecular weight of 1869g/mol, 1736g/mol and 2695g/mol, and degradation temperature of 325.65°C, 236.25°C, and 201.40°C, respectively. The SEM image illustrates the bundle-like fiber of cellulose fraction and smaller particle size of hemicellulose and lignin fractions with inconsistent shape. The XRD patterns depict the crystalline cellulose, amorphous lignin and partially amorphous hemicellulose fractions property. The IL could be recovered and reused with an overall recovery of 48% wt. after the fourth cycle.

Adsorption enhancement of elemental mercury onto sulphur-functionalized silica gel adsorbents

In this study, elemental mercury (EM) adsorbents were synthesized using tetraethyl orthosilicate (TEOS) and 3-mercaptopropyl trimethoxysilane as silica precursors. The synthesized silica gel (SG)-TEOS was further functionalized through impregnation with elemental sulphur and carbon disulphide (CS2). The SG adsorbents were then characterized by using scanning electron microscope, Fourier transform infra-red spectrophotometer, nitrogen adsorption/desorption, and energy-dispersive X-ray diffractometer. The EM adsorption of the SG adsorbents was determined using fabricated fixed-bed adsorber. The EM adsorption results showed that the sulphur-functionalized SG adsorbents had a greater Hg° breakthrough adsorption capacity, confirming that the presence of sulphur in silica matrices can improve Hg° adsorption performance due to their high affinity towards mercury. The highest Hg° adsorption capacity was observed for SG-TEOS(CS2) (82.62 μg/g), which was approximately 2.9 times higher than SG-TEOS (28.47 μg/g). The rate of Hg° adsorption was observed higher for sulphur-impregnated adsorbents, and decreased with the increase in the bed temperatures.

STUDY OF HG(II) REMOVAL FROM AQUEOUS SOLUTION USING LIGNOCELLULOSIC COCONUT FIBER BIOSORBENTS: EQUILIBRIUM AND KINETIC EVALUATION

Lignocellulosic coconut wastes such as pith and fiber, which are abundantly available and cheap, have the potential of being used as low-cost biosorbents for heavy metal ion removal. In this study, pristine (CF-Pristine) and NaOH-treated (CF-NaOH) coconut fibers were used as a biosorbent for Hg(II) removal from an aqueous solution. The coconut fiber biosorbent (CFB) was characterized by scanning electron microscopy (SEM) and Fourier transform-infrared (FTIR) spectroscopy. The Hg(II) sorption capacities obtained for CF-Pristine and CF-NaOH were 144.4 and 135.0 mg/g, respectively. Both the equilibrium and kinetic data of Hg(II) sorption onto CFB followed the Langmuir isotherm model and a pseudo-second-order kinetic model, respectively. A further analysis of the kinetic data suggested that the Hg(II) sorption process was governed by both intraparticle and external mass transfer processes, in which film diffusion was the rate-limiting step. These results demonstrated that both pristine- and alkali-treated coconut wastes could be potential low-cost biosorbent alternatives for the removal of Hg(II) from aqueous solutions, such as water containing Hg(II) produced in the oil and gas industry.

The catalytic activity enhancement and biodegradation potential of free laccase and novel sol-gel laccase in non-conventional solvents.

The catalytic activity of free laccase and a novel sol-gel laccase (SOLAC) in ionic liquids and organic solvents was demonstrated by using 2,6-dimethoxyphenol (2,6-DMP) as a substrate. The enhancement of the catalytic activity of the SOLAC was observed and compared to the free laccase in both media. The oxidative biodegradation of o-chlorophenol as a model of phenolic environmental pollutants in organic media shows that the degradation was observed only when using water pre-saturated organic solvents or reverse micelle system. The SOLAC gave higher biodegradation rate in either aqueous or organic solvents, in which the optimum temperature was observed at 40 °C for the reverse micelle system as a reaction medium. All results demonstrated the potential use of the SOLAC for biodegradation of phenolic environmental pollutants in non-conventional media.

High removal efficacy of Hg(II) and MeHg(II) ions from aqueous solution by organoalkoxysilane-grafted lignocellulosic waste biomass

An effective organoalkoxysilanes-grafted lignocellulosic waste biomass (OS-LWB) adsorbent aiming for high removal towards inorganic and organic mercury (Hg(II) and MeHg(II)) ions was prepared. Organoalkoxysilanes (OS) namely mercaptoproyltriethoxylsilane (MPTES), aminopropyltriethoxylsilane (APTES), aminoethylaminopropyltriethoxylsilane (AEPTES), bis(triethoxysilylpropyl) tetrasulfide (BTESPT), methacrylopropyltrimethoxylsilane (MPS) and ureidopropyltriethoxylsilane (URS) were grafted onto the LWB using the same conditions. The MPTES grafted lignocellulosic waste biomass (MPTES-LWB) showed the highest adsorption capacity towards both mercury ions. The adsorption behavior of inorganic and organic mercury ions (Hg(II) and MeHg(II)) in batch adsorption studies shows that it was independent with pH of the solutions and dependent on initial concentration, temperature and contact time. The maximum adsorption capacity of Hg(II) was greater than MeHg(II) which respectively followed the Temkin and Langmuir models. The kinetic data analysis showed that the adsorptions of Hg(II) and MeHg(II) onto MPTES-LWB were respectively controlled by the physical process of film diffusion and the chemical process of physisorption interactions. The overall mechanism of Hg(II) and MeHg(II) adsorption was a combination of diffusion and chemical interaction mechanisms. Regeneration results were very encouraging especially for the Hg(II); this therefore further demonstrated the potential application of organosilane-grafted lignocellulosic waste biomass as low-cost adsorbents for mercury removal process.

Removal performance of elemental mercury by low-cost adsorbents prepared through facile methods of carbonisation and activation of coconut husk.

The preparation of chars and activated carbon as low-cost elemental mercury adsorbents was carried out through the carbonisation of coconut husk (pith and fibre) and the activation of chars with potassium hydroxide (KOH), respectively. The synthesised adsorbents were characterised by using scanning electron microscopy, Fourier transform infrared spectroscopy and nitrogen adsorption/desorption analysis. The elemental mercury removal performance was measured using a conventional flow type packed-bed adsorber. The physical and chemical properties of the adsorbents changed as a result of the carbonisation and activation process, hence affecting on the extent of elemental mercury adsorption. The highest elemental mercury (Hg°) adsorption capacity was obtained for the CP-CHAR (3142.57 µg g−1), which significantly outperformed the pristine and activated carbon adsorbents, as well as higher than some adsorbents reported in the literature.

Surfactant modification of banana trunk as low-cost adsorbents and their high benzene adsorptive removal performance from aqueous solution

The banana trunk was modified using cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulphate (SDS), poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (Pluronic 123), and 4-(1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol (Triton X-100) to develop novel low-cost adsorbents for benzene removal from aqueous solution. The surface morphology and functional groups of the synthesized adsorbents were determined by a field emission scanning electron microscope (FESEM) and a Fourier transform infrared (FTIR) spectrophotometer. The Brunauer, Emmett and Teller (BET) analysis and X-ray photoelectron spectroscopy (XPS) were also conducted to study adsorbent characteristics. The benzene adsorptive performance of the synthesized adsorbents was evaluated in a batch adsorption experiment at various experimental conditions. It was found that the highest benzene adsorption capacity (280.890 × 10−3 mmol g−1) was obtained for M-TX100-BT. The fundamental adsorption studies revealed that the benzene adsorption process was found to be thermodynamically non-spontaneous and all were fitted well by the Langmuir isotherm model. The adsorption kinetic data obeyed the pseudo-second kinetic model with the film diffusion as the rate-limiting step. The application prospects of the Triton X-100 modified banana trunk adsorbent were demonstrated through the regeneration study which revealed that it can also be repeatedly used for at least up to five-adsorption/desorption cycles and its adsorption capacity was comparable to the literature data of similar adsorbents. Thus, banana trunk agrowaste could be an alternative low-cost adsorbent precursor for the adsorptive benzene removal from an aqueous solution.

Silver Adsorption Enhancement from Aqueous and Photographic Waste Solutions by Mercerized Coconut Fiber

The mercerized coconut fiber (CF-NaOH) was prepared by treating the pristine coconut fiber (CF-Pure) with NaOH solution. The morphology and chemical composition of CF-Pure changed after mercerization process. The maximum Ag(I) adsorption capacity of the CF-Pure and CF-NaOH was 0.502 and 0.612 mmol/g, in which the equilibrium data fitted to the Freundlich and Langmuir isotherm models, respectively. The Ag(I) adsorption rate also increased by using CF-NaOH and the kinetic data of both CF-Pure and CF-NaOH obeyed the pseudo-second order kinetic model. The enhancement of Ag(I) adsorption selectivity from photographic waste solution was also observed for the CF-NaOH.

High removal performance of dissolved oil from aqueous solution by sorption using fatty acid esterified pineapple leaves as novel sorbents

This paper demonstrates the potential use of the lignocellulosic biomass of pineapple leaves (PALs) as an oil sorbent by mercerization and esterification with long chain fatty acids in order to enhance the surface hydrophobicity and thus the oil sorption capacity for the treatment of dissolved oil contaminated wastewater. The mercerized pineapple leaves (M-PALs) were esterified with lauric acid (LA) and stearic acid (SA) in pyridine–p-toluenesulfonyl chloride (Py–TsCl) solution to yield M-LA-PAL and M-SA-PAL sorbents, respectively, which were then characterized alongside the raw PAL (R-PAL) sorbent using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), CHNS/O analysis and Brunauer–Emmett–Teller (BET) surface area analysis to study the changes of the surface morphology, functional groups, elemental composition and specific surface area of the sorbents. It was found that M-SA-PAL gave the highest sorption capacity (138.89 mg g−1) followed by M-LA-PAL (107.67 mg g−1) and R-PAL (35.59 mg g−1), which are generally lower than dispersed oil sorption capacities. The oil sorption process was found to be exothermic in nature. The data analysis indicated that the sorption process obeyed the Langmuir isotherm and pseudo-second order kinetic models with film diffusion as the rate limiting step, which is similar to some of the reported dispersed oil sorption results. The sorbent regeneration was repeated four times using isopropanol–water (1:1, v/v) solution as a desorbing agent and the sorption results were found to be comparable with the freshly prepared sorbent. Finally, the present findings indicate that a lignocellulosic biomass such as PAL could be a potential alternative sorbent precursor for oil removal from oil contaminated wastewaters.