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In this work, facile fabrication of lignin nanoparticles (L

Environmental remediation based on catalytic technologies has gained prominence as highly effective mean of removing toxic organic pollutants. Herein, mixed metal nanoparticles were decorated onto lignocellulose based support material, namely oil palm frond (OPF) biomass to fabricate a nanocatalyst (Cu + Co@OPF) via. facile chemical route. Various microscopic properties of as-prepared Cu + Co@OPF were examined using XRD, FTIR, FESEM, EDS and TGA. To check the universal applicability of as-prepared catalyst in wastewater decontamination, reduction of eight models pollutants was investigated such as dyes viz., Congo red (CR), Methyl orange (MO), Rhodamine B (RB), Methylene blue (MB) and different nitrophenols such as Ortho-nitrophenol (ONP), Meta-nitrophenol (MNP), Para-nitrophenol (PNP), 2, 4-dinitrophenol (DNP). Using Cu + Co@OPF heterostructure platform, complete reduction of organic pollutants was achieved in shorter time using NaBH4 as a hydrogen and electron source. The rate of catalytic reduction of pollutants followed order as; MO ˃ RB ˃ MB ˃ CR and PNP ˃ MNP ˃ ONP ˃ DNP in case of dyes and nitrophenols, respectively. The Cu + Co@OPF based heterostructure demonstrated multifunctional properties, for instance enhanced diffusion of pollutants, excellent catalytic activity as well as easy recovery. In addition to being renewable and eco-friendly, the porous and rough three-dimensional structure of biomass provided a large surface area for the formation of high-density of mixed metal NPs as possible catalytic sites, also allowing more contact between NPs and pollutant molecules in subsequent reduction reactions. The results reported herein present the potential of Cu + Co@OPF as highly efficient, cheaper, recoverable, universally applicable nanocatalyst and we advocate that its mass production would be highly useful in wastewater treatment.

Detailed investigation on the physicochemical characterization of Malaysian crop and agro-industrial biomass residues has been carried out to identify promising feedstock for thermochemical and biochemical energy yield. This study covered a wide range of biomass residues including oil palm frond (OPF), oil palm trunk (OPT), empty fruit bunches (EFB), palm kernel shell (PKS), rice husk (RH), rice straw (RS) and kenaf biomass (K). From the detailed characterization studies based on proximate composition, CHNS/O analysis, calorific value and lignocellulosic content determination, physicochemical properties of biomass residues were correlated with their potential for bioenergy generation. In addition, various analytical techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetry (TG) and X-ray fluorescence spectroscopy (XRF) were used to study various microscopic properties of biomass residues such as functional groups, crystallographic structure, thermal degradation and mineralogical composition, respectively. Results showed that in terms of volatile matter, the order followed was; EFB (83.42%) ˃ K (82.70%) ˃ OPT (81.46%) ˃ OPF (76.98%) ˃ RS (76.42%) ˃ PKS (69.66%) ˃ RH (66.65%). Proximate analysis revealed that RH has the highest ash content (18.82%). Notably, minimum undesirable ash material was generated by K (5.73%), EFB (6.56%) and OPT (7.71%) containing high fractions of catalytic species. PKS presented maximum thermochemical potential with higher heating value of 17.32 MJ/kg followed by K (16.66 MJ/kg), OPT (16.34 MJ/kg), RS (16.15 MJ/kg), EFB (16.07 MJ/kg), OPF (14.49 MJ/kg) and RH (14.37 MJ/kg). Due to highest apparent density and maximum content of fixed carbon as well as lignin, PKS can be an interesting energy resource in thermochemical processes. Compositional analysis revealed that OPF, OPT and K were rich in polysaccharide content with much less quantity of lignin. Based on XRD measurements, it was found that EFB and K would be more susceptible to enzymatic digestion due to lower crystallinity index (CrI) compared to other residues. We believe that these investigations could decisively contribute to a better understanding of the influence of different factors related to lignocellulosic biomass feedstock on the efficiency of conversion and biofuel potential.

In present study, magnetic chitosan-graphene oxide composite (ᶆC-GO) has been synthesized and used for the removal of two common textile dyes; acid red-17 (AR-17) and bromophenol blue (BPB). The effect of various parameters including pH (2–8), time (10–100 min), adsorbent dosage (2–10 mg), initial dye concentration (2–30 μg mL−1) as well as temperature (303, 313, and 323 K) was investigated. The point of zero charge of composite was determined using pH drift method in an attempt to better understand the adsorption process. Present work revealed fast adsorption kinetics with removal efficiency of around 79 and 97% for AR-17 and BPB, respectively, under optimized conditions. Besides, equilibrium relationships were studied using Langmuir and Freundlich models. Thermodynamic analysis uncovered the spontaneous and endothermic nature of dye-composite interation. Synthesized material showed profound stability after five successive adsorption-desorpion cycle of reuse. Importantly, spiked real water samples were used to check the suitability of composite adsorbent for practical applications. High % recoveries were obtained which indicated that complex matrix presented insignificant interference effects. Also, comparative study revealed that composite material offers superior performance for the removal of dyes relative to precursors (C, Fe3O4 nanoparticles, GO). Improvement in removal efficiency of synthesized composite toward selected dyes can be attributed to intrinsic qualities of C and incorporated functionalities; exceptionally high surface area as well as excellent mechanical properties of GO and convenience of magnetic separation because of Fe3O4 nanoparticles. POLYM. COMPOS., 2017. © 2017 Society of Plastics Engineers

Lignocellulosic biomass waste is a cheap, eco-friendly, and sustainable raw material for a wide array of applications. In the present study, an easy, fast, and economically feasible route has been proposed for the preparation of different zero-valent metal nanoparticles (ZV-MNPs) based on Cu, Co, Ag, and Ni NPs using empty fruit bunch (EFB) biomass residue as support material. The catalytic efficiency of ZV-MNPs/EFB catalyst was investigated against five model pollutants, such as methyl orange (MO), congo red (CR), methylene blue (MB), acridine orange (AO), and 4-nitrophenol (4-NP) using NaBH4 as a source of hydrogen and electron. Comparative study revealed that among as-prepared ZV-MNPs/EFB catalysts, Cu-NPs immobilized onto EFB (Cu/EFB) exhibited maximum catalytic efficiency towards pollutant abasement. Degradation reactions were highly efficient, and were completed within a short time (4 min) in case of MO, CR, and MB, whilst AO and 4-NP were reduced in less than 15 min. Kinetic investigation revealed that the degradation rate of model pollutants accorded with pseudo-first order model. Furthermore, supported catalysts were easily recovered after the completion of experiment by simply pulling the catalyst from reaction system. Recyclability tests performed on Cu/EFB revealed that more than 97% of the reduction was achieved in case of MO dye for four successive cycles of reuse. The as-prepared heterostructure showed multifunctional properties, such as enhanced uptake of contaminants, high catalytic efficiency, and easy recovery, hence, offers great prospects in wastewater purification.

In realizing the vast potential of lignocellulosic biomass residues generated by oil palm industry under the regime of ‘one-size-fits-all’ biorefinery concept, supercritical carbon dioxide (SC-CO2) technology offers great promise. Herein, we demonstrated a new eco-friendly pretreatment of oil palm trunk biomass based on SC-CO2 under controlled conditions of pressure (25, 35 and 45 MPa), temperature (80, 100 and 120 °C) and moisture content (0, 20, 40 and 60 %), and investigated their effect on enzymatic hydrolysis yields of the pretreated fractions. During pretreatment, biomass sample reacted with hot water in SC-CO2 which led to high diffusivities, promoting its disruption and xylan solubilisation as supported by various characterization techniques. This study illustrates that hydrolysis yields are influenced by process parameters, particularly the moisture content played a crucial role in the biomass disruption. The SC-CO2 pretreatment resulted in enhanced digestibility for all the pretreated fractions compared to the untreated biomass.

Herein, self-assembled three-dimensional reduced graphene oxide (RGO)-based hydrogels were synthesized and characterized in detail. A thorough investigation on the uptake of three widely used pharmaceutical drugs, viz. Naproxen (NPX), Ibuprofen (IBP) and Diclofenac (DFC) was carried out from aqueous solutions. To ensure the sustainability of developed hydrogel assembly, practically important parameters such as desorption, recyclability and applicability to real samples were also evaluated. Using the developed 3D hydrogels as adsorptive platforms, excellent decontamination for the above mentioned persistent pharmaceutical drugs was achieved in acidic pH with a removal efficiency in the range of 70-80%. These hydrogels showed fast adsorption kinetics and experimental findings were fitted to different kinetic models, such as pseudo-first order, pseudo-second order, intra-particle and the Elovich models in an attempt to better understand the adsorption kinetics. Furthermore, equilibrium adsorption data was fitted to the Langmuir and Freundlich models, where relatively higher R2 values obtained in case of former one suggested that monolayer adsorption played an important part in drug uptake. Thermodynamic aspects were also studied and negative ΔG0 values obtained indicated the spontaneous nature of adsorption process. The study was also extended to check practical utility of as-prepared hydrogels by spiking real aqueous samples with drug solution, where high % recoveries obtained for NPX, IBP and DFC were of particular importance with regard to prospective application in wastewater treatment systems. We advocate RGO-based hydrogels as environmentally benign, readily recoverable/recyclable material with excellent adsorption capacity for application in wastewater purification.

In the present study, we decorated chitosan (©) with Fe3O4 nanoparticles followed by cross-linking with GO to prepare Fe3O4 supported chitosan-graphene oxide composite (Fe3O4©-GO). Different properties of synthesized material were investigated by SEM, XRD, FTIR, TGA and EDX. Batch adsorption experiments were performed to remove toxic cationic and anionic dyes from industrial wastewater. To maximize removal efficiency of composite material, effect of pH (4-12), time (0-80min), Fe3O4©-GO dosage (2-10mg), initial dye concentration (2-30μgmL̄ (1)) and temperature (303, 313, and 323K) were studied. The uptake of dyes presented relatively fast adsorption kinetics with pseudo-second-order equation as the best fitting model. To understand the interaction of dye with adsorbent, Langmuir and Freundlich isotherm were applied. Thermodynamic studies were conducted to calculate the changes in free energy (ΔG(0)), enthalpy (ΔH(0)) and entropy (ΔS(0)). In view of practical application, the influence of ionic strength, recycling as well as investigations based on percent recoveries from spiked real water samples were also taken into account.