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The modification of kaolin with nano-size fillers has exhibited excellent performance in the adsorption process. Carbon quantum dots (CQDs) are the new generation of nanoparticles that have attracted interest for their utilization as modifiers. In this study, a composite of metakaolin(MK)/CQDs was synthesized and tested for methylene blue (MB) removal. The heating and acid-alkali treatment of kaolin transformed it into MK. The interaction between MK and CQDs was analyzed using XPS to detect the binding of pyridic NH2 and C-N. By loading CQDs into the kaolin matrix, the surface area was improved and the removal of MB increased. For a lower MB concentration at 5 ppm, the removal efficiency could reach 96%. The composite exhibited good regeneration through the recyclability test.

Numerous agricultural wastes are well-defined as low-cost sources and rich in silica content. The residue of oil palm wastes combustion seems a promising silica source and can be recovered through a straightforward method. In this study, the combustion followed by an alkaline extraction method was employed to extract high purity of silica. The oven-dried oil palm decanter cake (DOPDC) was heated at combustion temperatures of 600, 700, 800, and 900°C to produce OPDC ashes (OPDCA), followed by an alkaline extraction using 5M of NaOH solution. Thermogravimetric analysis (TGA) was used to observe the thermal behavior of DOPDC where the suitable combustion temperatures to produce silica ranged between 600 and 1000 ℃. X-Ray Fluorescence (XRF) analysis showed that silica contents were 31-36% after combustion, increasing to 76.95% after the chemical treatment. Moreover, the spherical shape of the silica was observed through electron microscope analysis. It was represented by the aggregation of silica after going through chemical treatment. The X-Ray Diffraction analysis also proved that the amorphous silica was produced, characterized by the hump-shaped spectrum. The infrared analysis confirmed that the silica had been successfully extracted from OPDCA by the presence of silica functional groups shown in the spectrum.

Usage of conventional energy sources such as oil, coal, and natural gas as an energy source for development has led to many economic, environmental, social, and political impacts worldwide. Due to this, the world has redirected its policies and investments towards producing clean energy which is based on renewable resources such as biomass. Due to the limitation of biomass which is low-density value, high moisture contents at the production place and non-uniform sizes and shapes, biomass was considered difficult to be utilized efficiently. To overcome this, pellet fuels were used to increase the density of the biomass. Since the enormous quantity of crops is produced from nipa palm, this paper focuses on studying the pelletizing properties of different parts of nipa palm seeds through the determination of the drying behavior, calorific value determination, CHNS determination, and TGA analysis and mechanical strength on the nipa palm seed. Husk was observed to have the highest calorific value which was 3843.5 kcal/kg and mixture nipa palm seed has a calorific value of 4092.7 kcal/kg which is in range with the industrial pellets’ calorific value. Based on the CHNS analysis, carbon content was found to be the highest in the husk as compared to the other parts. It was observed that all parts of the nipa palm seed exhibit almost similar thermogravimetric (TG) curve but slightly different differential thermogravimetric (DTG) curve peaks with different maximum mass-loss rates. Finer size particles were observed to have better pellets’ performance in terms of its strength due to the higher surface area of the particle. Pellets formed from nipa palm seeds could be used to form pellet fuels given the fact that they have high calorific values and almost similar compositions with the industrial pellets.

Due to a large amount of biomass remaining in Malaysia, biochar has recently received great attention. Biochar is extensively used worldwide to improve the environmental aspects of soil fertility and water quality. the Two raw biomass materials from different sources (aluminosilicate: rice husk and agricultural lignocellulosic waste: kenaf fiber). The properties of the optimal mixing ratio of biochar were investigated by using proximate analysis, ultimate analysis, thermogravimetric analysis, surface area and pore volume determination, Fourier Transform Infrared Spectroscopy analysis, X-ray diffraction, and Scanning Electron Microscopy. According to the proximate analysis, ash content is increasing while the moisture content fixed carbon and volatile matter decrease. Based on the BET characterization finding, the surface area is increased proportionally as increasing the mixing ratio RHB: KFB (0.8:0.2, 0.5:0.5, 0.2:0.8). The SEM images showed that both biochars are suitable sources of blending because of the differences and the availability of good adsorbents. Based on this study, RHB and KFB as pure biochar have a great potential to be applied as an adsorbent. However, blending is not giving the desired result to be used as an adsorbent.

The Malaysia's wastewater treatment plant has yet to find an environmentally alternative for the sludge treatment before disposal. In majority of cases, the sludge containing a high amount of heavy metals including Fe, Ti, Mn, Zn, As, Cu, Ni, Zr, and Ga, is disposed to the environment through landfill. The recovery of valuable materials such as manganese from the sludge is an alternative path towards zero dumpings of schedule waste as well as a way of reducing the possible pollutant release to the environment. It can be achieved through adsorption, as it provides a cheap yet flexible, method which is simple and easy to implement. Kenaf derived from Hibiscus cannabis was proven as a good adsorbent material for the heavy metals recovery. This project aims at utilizing Kenaf fiber as activated carbon to recover heavy metals from wastewater sludge in batch adsorption. The optimum adsorbent preparation conditions were obtained from the research performed by Chowdhury [1]. The adsorbent surface area and pore characteristics and elemental analysis were observed under adsorbent characterization. The effect of contact time, sludge pH and temperature to the removal efficiency was investigated. The adsorption isotherm was also studied. The result showed that the developed kenaf activated carbon is a promising adsorbent which might be used for some heavy metals. From batch adsorption study, it was observed that KFAC is able to remove an average 30% of the heavy metal element from the sludge. It was also found that the best removal is achieved in a neutral pH solution, increasing the contact time will increase the equilibrium uptake, while the increasing temperature will increase the percent removal of heavy metals. It was concluded that the Kenaf based activated carbon can be used for the recovery of heavy metals from the wastewater sludge through batch adsorption.

A rotating biological contactor (RBC) is a type of attached-growth biological wastewater treatment system and a widely used biological wastewater treatment technology. It employs a series of rotating discs to support microbial growth and promote the removal of pollutants from wastewater. RBC is widely recognized for its simplicity of design, high reliability, and low energy consumption. It has been used in various applications, from small-scale decentralized systems to large municipal wastewater treatment plants. The current review provides an overview of RBC bioreactors, design parameters, and the factors that influence biological performance, such as hydraulic retention time, sludge retention time, organic loading rate, disc rotational speed, and temperature. The review also highlights the advantages and disadvantages of RBCs compared with other wastewater treatment technologies and discusses their role in sustainable environmental performance. The future prospects of RBC are also discussed, including integration with other technologies, such as membrane filtration and potential use in resource recovery. The review explores the application of RBC in decentralized wastewater treatment and the potential to provide sustainable solutions for wastewater management in rural and remote areas. Overall, RBC remains a promising option for effective and efficient wastewater treatment, particularly in situations where simplicity, reliability, and low energy consumption are desired.

The coconut desiccant industry produces wastewater with high concentrations of suspended solids and turbidity, resulting in negative impacts to the environment if discharged without adequate treatment. The wastewater produced requires appropriate flocculant and coagulant compounds for treatment via the clarification process. Commercial coagulants raise many environmental concerns pertaining to the release of toxic metal residues and traces of chloride and sulphate ions in the treated water. The use of eco-friendly coagulants as an alternative for commercial coagulants in wastewater treatment is on the rise. Several factors that influence clarification performance during treatment includes coagulant dosage, flocculant dosage, and mixing rate of coagulation–flocculation process. The aim of this research is to analyze the effectiveness of using a natural coagulant, Moringa oleifera extract in the removal of suspended solids and turbidity from the coconut desiccant industry wastewater. The Response Surface Methodology approach was used to optimize the concentration of coagulant and flocculant dosed along with mixing rate. The results were measured as maximum percentage removal of suspended solids and turbidity. Coconut desiccant wastewater was collected over a period of five days. Moringa extract was produced via dilution of fat free Moringa seed powder with salt solution at a fixed ratio. The percentage removal of both suspended solids and turbidity was in the range of 85.4–95.1% and 85.2 to 94.8% respectively, based on multiple jar tests conducted. The model generated for optimization is a quadratic model. The optimization produced an optimum point of treatment, which is 12.00 mg/L of Moringa extract as coagulant, 12.660 ml/L of anionic polymer as flocculant and a mixing rate of 90 revolutions per minute, resulting in 93.997% and 93.735% removal of suspended solids and turbidity, respectively, proving a successful treatment of coconut desiccant wastewater.

Traditional fossil-based plastic usage and disposal has been one of the largest environmental concerns due to its non-biodegradable nature and high energy consumption during the manufacturing process. Poly(lactic acid) (PLA) as a renewable polymer derived from natural sources with properties comparable to classical plastics and low environmental cost has gained much attention as a safer alternative. Abundantly generated orange peel waste is rich in valuable components and there is still limited study on the potential uses of orange peel waste in reinforcing the PLA matrix. In this study, orange peel fine powder (OPP) synthesized from dried orange peel waste was added into PLA solution. PLA/OPP solutions at different OPP loadings, i.e., 0, 10, 20, 40, and 60 wt% were then casted out as thin films through solution casting method. Fourier-transform infrared spectroscopy (FTIR) analysis has shown that the OPP is incorporated into the PLA matrix, with OH groups and C=C stretching from OPP can be observed in the spectra. Tensile test results have reviewed that the addition of OPP has decreased the tensile strength and Young’s modulus of PLA, but significantly improve the elongation at break by 49 to 737%. Water contact angle analysis shows that hydrophilic OPP has modified the surface hydrophobicity of PLA with a contact angle ranging from 70.12° to 88.18°, but higher loadings lead to decrease of surface energy. It is proven that addition of OPP improves the biodegradability of PLA, where PLA/60 wt% OPP composite shows the best biodegradation performance after 28 days with 60.43% weight loss. Lastly, all PLA/OPP composites have better absorption in alkaline solution.

A large amount of wastewater is directly discharged into water bodies without treatment causing surface water contamination. Conventional treatment techniques produce lower effluent quality and are energy extensive. Rotating biological contactor (RBC) is an attractive biological wastewater treatment that offers a low energy footprint. However, its unstable removal efficiency makes it less popular. This study optimizes operating parameters in RBC combined with external membrane filtration (RBC-ME) in which the latter acts as a post-treatment step to stabilize the biological performance. Response Surface Methodology (RSM) was employed to optimize the biological and filtration performance by exploiting three parameters of disk rotational speed, hydraulic retention time (HRT), and sludge retention time (SRT). Results show that RBC-ME exhibits excellent biological treatment capacity and higher effluent quality. It attained 87.9 ± 3.2% of chemical oxygen demand, 45.2 ± 0.7% total nitrogen, 97.9 ± 0.1% turbidity, and 98.9 ± 1.1% ammonium removals. The RSM data demonstrated that the experimental data and model predictions agreed well. Under the most optimum parameters, the permeability of 144.6 L/m2 h bar could be achieved at 36.1 rpm disk rotational speed, 18 h HRT, and 14.9 d SRT. This work demonstrates the effective use of statistical modeling to enhance RBC-ME system performance to obtain a sustainable and energy-efficient treatment process to prevent human health and the environment.

Development of strategies for removing heavy metals from aquatic environments is in high demand. Cadmium is one of the most dangerous metals in the environment, even under extremely low quantities. In this study, kenaf and magnetic biochar composite were prepared for the adsorption of Cd2+. The synthesized biochar was characterized using (a vibrating-sample magnetometer VSM), Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The adsorption batch study was carried out to investigate the influence of pH, kinetics, isotherm, and thermodynamics on Cd2+ adsorption. The characterization results demonstrated that the biochar contained iron particles that help in improving the textural properties (i.e., surface area and pore volume), increasing the number of oxygen-containing groups, and forming inner-sphere complexes with oxygen-containing groups. The adsorption study results show that optimum adsorption was achieved under pH 5–6. An increase in initial ion concentration and solution temperature resulted in increased adsorption capacity. Surface modification of biochar using iron oxide for imposing magnetic property allowed for easy separation by external magnet and regeneration. The magnetic biochar composite also showed a higher affinity to Cd2+ than the pristine biochar. The adsorption data fit well with the pseudo-second-order and the Langmuir isotherm, with the maximum adsorption capacity of 47.90 mg/g.

Rice husk is one of the best possible ingredients waste for producing a range of value-added goods, whether in the form of raw materials, ash, or char. Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and BET surface area measurements Characterization were used to describe the adsorbent that had been processed. The impact of initial concentration, solution pH, and rotation time was investigated in the batch study. The modified rice husk adsorbent obtained a larger surface area, showed a good removal rate, and highest adsorption capacity compared to the pure rice husk. The maximum removal rate of cadmium obtained by modified rice husk and pure rice husk were 78% and 67% at 25mg/L initial concentration, respectively. The optimal pH was found at a 6-pH solution and the removal rate and adsorption capacity were found high at an early stage of agitation time and reach the highest at 3 hours of agitation time then no significant improvement occurred.

A rotating biological contactor (RBC) offers a low energy footprint but suffers from performance instability, making it less popular for domestic wastewater treatment. This paper presents a study on an RBC integrated with membrane technology in which membrane filtration was used as a post-treatment step (RBC–ME) to achieve enhanced biological performance. The RBC and RBC–ME systems were operated under different hydraulic retention times (HRTs) of 12, 18, 24, and 48 h, and the effects of HRT on biological performance and effluent filterability were assessed. The results show that RBC–ME demonstrates superior biological performance than the standalone RBC. The RBC–ME bioreactor achieved 87.9 ± 3.2% of chemical oxygen demand (COD), 98.9 ± 1.1% ammonium, 45.2 ± 0.7% total nitrogen (TN), and 97.9 ± 0.1% turbidity removals. A comparison of the HRTs showed that COD and TN removal efficiency was the highest at 48 h, with 92.4 ± 2.4% and 48.6 ± 1.3% removal efficiencies, respectively. The longer HRTs also lead to better RBC effluent filterability. The steady-state permeability increased respectively by 2.4%, 9.5%, and 19.1% at HRTs of 18, 24, and 48 h, compared to 12 h. Our analysis of membrane fouling shows that fouling resistance decreased at higher HRTs. Overall, RBC–ME offered a promising alternative for traditional suspended growth processes with higher microbial activity and enhanced biological performance, which is in line with the requirements of sustainable development and environment-friendly treatment.

Cadmium is one of the most hazardous metals in the environment, even when present at very low concentrations. This study reports the systematic development of Kenaf fiber biochar as an adsorbent for the removal of cadmium (Cd) (II) ions from water. The adsorbent development was aided by an optimization tool. Activated biochar was prepared using the physicochemical activation method, consisting of pre-impregnation with NaOH and nitrogen (N2) pyrolysis. The influence of the preparation parameters—namely, chemical impregnation (NaOH: KF), pyrolysis temperature, and pyrolysis time on biochar yield, removal rate, and the adsorption capacity of Cd (II) ions—was investigated. From the experimental data, some quadratic correlation models were developed according to the central composite design. All models demonstrated a good fit with the experimental data. The experimental results revealed that the pyrolysis temperature and heating time were the main factors that affected the yield of biochar and had a positive effect on the Cd (II) ions’ removal rate and adsorption capacity. The impregnation ratio also showed a positive effect on the specific surface area of the biochar, removal rate, and adsorption capacity of cadmium, with a negligible effect on the biochar yield. The optimal biochar-based adsorbent was obtained under the following conditions: 550 °C of pyrolysis temperature, 180 min of heating time, and a 1:1 NaOH impregnation ratio. The optimum adsorbent showed 28.60% biochar yield, 69.82% Cd (II) ions removal, 23.48 mg/g of adsorption capacity, and 160.44 m2/g of biochar-specific area.

Rice husk, whether in the form of raw materials ash or char is one of the best potential materials for the production of a variety of value-added products. This study intends to optimize biochar from Malaysian rice husk, as a friendly low-cost adsorbent for removing cadmium from aqueous solution. Biochar production has been done using a tube furnace with different input parameters which are heating temperature, residence time, and impregnation ratio. The effect of pyrolysis process parameters was examined by using response surface methodology (RSM). Responses parameters, biochar yield, and removal efficiency were investigated. Depend on the Central Composite Design (CCD), three 2FI models were developed to compare three independent response variables. The optimum production condition for magnetic biochar was found as follows: a heating temperature of 395 °C, the residence time 120 min, and 0.5 g/g impregnation ratio. The optimum magnetic biochar showed 44.5% of biochar yield and 94.25% removal efficiency which was in agreement with the predicted values.

Pollution from dye containing wastewater leads to a variety of environmental problems, which can destroy plant life and eco-systems. This study reports development of a seaweed-based biochar as an adsorbent material for efficient adsorption of methylene blue (MB) dye from synthetic wastewater. The Eucheuma cottonii seaweed biochar was developed through pyrolysis using a tube furnace with N2 gas, and the properties were later improved by sulfuric acid treatment. The adsorption studies were conducted in a batch experimental setup under initial methylene blue concentrations of 50 to 200 mg/L, solution pH of 2 to 10, and temperature of 25 to 75 &deg, C. The characterization results show that the developed biochar had a mesoporous pore morphology. The adsorbent possessed the surface area, pore size, and pore volume of 640 m2/g, 2.32 nm, and 0.54 cm3/g, respectively. An adsorption test for 200 mg/L of initial methylene blue at pH 4 showed the best performance. The adsorption data of the seaweed-based biochar followed the Langmuir isotherm adsorption model and the pseudo-second-order kinetic model, with the corresponding R2 of 0.994 and 0.995. The maximum adsorption capacity of methylene blue using the developed seaweed‑based biochar was 133.33 mg/g. The adsorption followed the chemisorption mechanism, which occurred via the formation of a monolayer of methylene blue dye on the seaweed-based biochar surface. The adsorption performance of the produced seaweed biochar is comparable to that of other commercial adsorbents, suggesting its potential for large-scale applications.

Various types of activated carbon nanofibers&rsquo, (ACNFs) composites have been extensively studied and reported recently due to their extraordinary properties and applications. This study reports the fabrication and assessments of ACNFs incorporated with graphene-based materials, known as gACNFs, via simple electrospinning and subsequent physical activation process. TGA analysis proved graphene-derived rice husk ashes (GRHA)/ACNFs possess twice the carbon yield and thermally stable properties compared to other samples. Raman spectra, XRD, and FTIR analyses explained the chemical structures in all resultant gACNFs samples. The SEM and EDX results revealed the average fiber diameters of the gACNFs, ranging from 250 to 400 nm, and the successful incorporation of both GRHA and reduced graphene oxide (rGO) into the ACNFs&rsquo, structures. The results revealed that ACNFs incorporated with GRHA possesses the highest specific surface area (SSA), of 384 m2/g, with high micropore volume, of 0.1580 cm3/g, which is up to 88% of the total pore volume. The GRHA/ACNF was found to be a better adsorbent for CH4 compared to pristine ACNFs and reduced graphene oxide (rGO/ACNF) as it showed sorption up to 66.40 mmol/g at 25 &deg, C and 12 bar. The sorption capacity of the GRHA/ACNF was impressively higher than earlier reported studies on ACNFs and ACNF composites. Interestingly, the CH4 adsorption of all ACNF samples obeyed the pseudo-second-order kinetic model at low pressure (4 bar), indicating the chemisorption behaviors. However, it obeyed the pseudo-first order at higher pressures (8 and 12 bar), indicating the physisorption behaviors. These results correspond to the textural properties that describe that the high adsorption capacity of CH4 at high pressure is mainly dependent upon the specific surface area (SSA), pore size distribution, and the suitable range of pore size.

Polydopamine has been widely used as an additive to enhance membrane fouling resistance. This study reports the effects of two-step dopamine-to-polydopamine modification on the permeation, antifouling, and potential anti-UV properties of polyethersulfone (PES)-based ultrafiltration membranes. The modification was performed through a two-step mechanism: adding the dopamine additive followed by immersion into Tris-HCl solution to allow polymerization of dopamine into polydopamine (PDA). The results reveal that the step of treatment, the concentration of dopamine in the first step, and the duration of dipping in the Tris solution in the second step affect the properties of the resulting membranes. Higher dopamine loadings improve the pure water flux (PWF) by more than threefold (15 vs. 50 L/m2&middot, h). The extended dipping period in the Tris alkaline buffer leads to an overgrowth of the PDA layer that partly covers the surface pores which lowers the PWF. The presence of dopamine or polydopamine enhances the hydrophilicity due to the enrichment of hydrophilic catechol moieties which leads to better anti-fouling. Moreover, the polydopamine film also improves the membrane resistance to UV irradiation by minimizing photodegradation&rsquo, s occurrence.

Resolution of industrial waste as thermal source is an effective way to transform the unwanted scheduled waste into renewable energy. Plant residues also contributed to enhance its utilization and considered a reliable resource for energy uses. Both sectors of feedstock are aimed to produce significant amount of thermal energy through combustion. Ash deposition behaviors of biomass fuel from industrial sludge and agricultural waste have been analyzed. Sludge and effluent were carefully taken from petroleum crude processing plant (PGB) and palm oil mill (POME), respectively. Rice husk and kenaf were obtained from local neighborhoods farm. The effective utilization of potential biofuel is evaluated based on its ash content, chemical composition and its ash slagging and fouling tendency. PGB and POME were evaluated to have energy content about 21.35 MJ/kg and 15.238 MJ/kg respectively. While kenaf and rice husk each has 16.14 MJ/kg and 15.19 MJ/kg, respectively. Ash content of PGB sludge was around 30.0% where POME sludge was about 38.0%. Kenaf showed a better biomass type as the ash content was only 2% ash, whereas rice husk ash content was 11%. To illustrate the realistic combustion condition under different temperature, the effect of ashing temperatures that are 525°C, 575°C and 625°C to the ash deposition characteristics is also examined. This variation of ashing temperature will also deflect the chemical composition especially the heavy metal element in the sludge ash. Furthermore, the physical ash deposition and deformation characteristics are observed by ash fusion test. Conclusively, PGB, POME, rice husk and kenaf biomass are feasible to produce sufficient thermal energy as well as stable at high temperature with their distinct chemical composition, but their individual range ashing temperature may deficient the thermal process differently.

In this study, a facile method was developed to prepare fibrous boron-selective adsorbent through introduction of poly(vinylamine) (PVAm) onto polyethylene/polypropylene (PE/PP) non-woven sheet by radiation induced graft copolymerization (RIGC) of N-vinylformamide (NVF) followed by hydrolysis, and glycidol immobilisation. The dependence of the degree of grafting (DG) on the reaction parameters (absorbed dose, monomer concentration, temperature, and reaction time) was investigated to control the content of hydrolysed poly(N-vinylformamide) (PNVF) grafts. The properties of the adsorbent were evaluated by Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), Scanning electron microscope (SEM), X-ray diffraction (XRD), differential scanning calorimeter (DSC), and thermal gravimetric analyser (TGA). The boron adsorption from solution on the prepared adsorbent was investigated under various pHs, contact times, initial boron concentrations, adsorbent dosages, and adsorption/desorption cycles. The adsorbent with a DG of 120% showed an adsorption capacity of 21.4 mg-B/g-adsorbent at pH 7 with an appealing stability. The overall properties and adsorption behaviour suggest that RIGC is highly effective method for preparation of glycidol-containing fibrous adsorbent with highly attractive properties for boron removal from aqueous solutions.

The aim of this paper was to study the moisture sorption characteristics of mixed biomass pellets. The pellets were developed using a mixture of woody (spruce or pine) and agricultural (reed canary grass or hay) biomass with a ratio of 1:1. The pellets were stored in a controlled environment until reaching the equilibrium moisture content. The temperature of the controlled environment was varied between 15 and 25 $$^{\circ }\hbox {C}$$ and relative humidity between 20 to 90%. The experimental results showed this temperature range had no effect on the moisture sorption isotherms. However, the equilibrium moisture content at higher relative humidity was found dependent on the type of the material and was higher for spruce-hay pellets compared to the other tested pellets. Oswin, Guggenheim-Anderson-de Boer, Henderson and Peleg models were tested for the prediction of the moisture isotherms. With a coefficient of determination varying between 0.998 and 0.995, a standard error between 0.054 and 0.071 and chi-square error ranging between 0.009 and 0.015, Oswin model was found more suitable to predict the moisture sorption isotherms of all biomass pellets. This result was further confirmed using the residuals plot, showing a more uniform distribution for Oswin model compared to the other models.

The bottleneck of conventional polymeric membranes applied in industry has a tradeoff between permeability and selectivity that deters its widespread expansion. This can be circumvented through a hybrid membrane that utilizes the advantages of inorganic and polymer materials to improve the gas separation performance. The approach can be further enhanced through the incorporation of amine-impregnated fillers that has the potential to minimize defects while simultaneously enhancing gas affinity. An innovative combination between impregnated Linde T with different numbers of amine-functional groups (i.e., monoamine, diamine, and triamine) and 4,4&prime, (hexafluoroisopropylidene) diphthalic anhydride (6FDA)-derived polyimide has been elucidated to explore its potential in CO2/CH4 separation. Detailed physical properties (i.e., free volume and glass transition temperature) and gas transport behavior (i.e., solubility, permeability, and diffusivity) of the fabricated membranes have been examined to unveil the effect of different numbers of amine-functional groups in Linde T fillers. It was found that a hybrid membrane impregnated with Linde T using a diamine functional group demonstrated the highest improvement compared to a pristine polyimide with 3.75- and 1.75-fold enhancements in CO2/CH4 selectivities and CO2 permeability, respectively, which successfully lies on the 2008 Robeson&rsquo, s upper bound. The novel coupling of diamine-impregnated Linde T and 6FDA-derived polyimide is a promising candidate for application in large-scale CO2 removal processes.

An adsorbent containing glycidolized poly(vinylamine) ligand with a remarkably high boron selectivity was prepared by modification of fibrous polyethylene/polypropylene (PE/PP) nonwoven sheet by radiation induced grafting (RIG) of N-vinylformamide (NVF) followed by hydrolysis and subsequent functionalization with glycidol. The variation of the absorbed dose and monomer concentration was used to control the content of the grafted P(NVF). Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) were used to verify the chemical and morphological changes accompanied the applied procedure and boron loading. The fibrous adsorbent with fully hydrolyzed poly(NVF) grafts of 120% exhibited a superior boron adsorption capacity of 21.4 mg/g compared to commercial and researched counterparts at pH 7.

An agricultural waste-based source of energy in the form of briquettes from rice husk has emerged as an alternative energy source. However, rice husk-based briquette has a low bulk density and moisture content, resulting in low durability. This study investigated the effect of initial moisture contents of 12%, 14%, and 16% of rice husk-based briquettes blended with 10 wt% of kraft lignin on their chemical and physical characteristics. The briquetting was done using a hand push manual die compressor. The briquette properties were evaluated by performing chemical (ultimate and proximate analysis, thermogravimetric analysis), physical (density, durability, compressive strength, and surface morphology) analyses. The durability values of all briquette samples were above 95%, meeting the standard with good compressive strength, surface morphology, and acceptable density range. The briquette made from the blend with 14% moisture content showed the highest calorific value of 17.688 MJ kg−1, thanks to its desirable morphology and good porosity range, which facilitates the transport of air for combustion. Overall, this study proved the approach of enhancing the quality of briquettes from rice husk by controlling the moisture content.

Membrane fouling is a major drawback of almost all pressure-driven membrane processes that limit their widespread application. This study compares the biological and the hydraulic performances of polyvinylidene fluoride (PVDF) and polysulfone (PSF) membranes when used as external filtration for polishing of a rotating biological contactor (RBC) effluent and as an integrated part in a membrane rotating biological contactor (MRBC). MRBC is an upgrade of the conventional RBC, in which the disk rotations are used not only to provide biological aeration but also as an inherent mechanism for membrane fouling control. Results showed that high biological performances were achieved irrespective of the membrane materials. The steady-state permeabilities of the membranes in MRBC are higher than external filtration by 92.4% and 19.7% for the PVDF and PSF membrane respectively. In the MRBC, smaller membrane-to-disk gaps and high disk rotational speed improve permeability for both membranes reaching the values of 297 and 173 L/(m2 h bar) for PVDF and PSF membranes, respectively. Full-scale energy consumption projection results show that the MRBC consumes only one-fourth of the energy of a referenced membrane bioreactor. The PVDF membrane outperforms PSF membrane thanks to the effective fouling control that maximize the throughput of a lower intrinsic resistance of the PVDF membrane. It implies that apart from membrane material, other operational parameters can still be optimized to further enhance the MRBC performance.

In this study, the effect of variables including ashing temperature (525°C - 625°C), CaO additive (0 - 4 wt%) and blending ratio of rice husk blending (0 – 50 wt%) for the improvement of fusion slagging index of biomass is investigated. Response surface methodology (RSM) was used to identify influential factor and predict the interaction between process variables and responses. The results demonstrate that the rice husk blending is the most significant variable for the improvement of fusion slagging index of biomass in comparison with CaO additive and ashing temperature. The optimum parameters for obtaining the highest fusion slagging index of 1470°C were obtained at ashing temperature of 575°C, rice husk blending of 50wt% and without CaO additive.

Unprocessed biomass has low energy density and high transportation cost. The energy generated through biomass can be enhanced by the pelletizing technique. In order to evaluate the energy requirement for the pelletizing of agricultural biomass, three different particle sizes (150&ndash, 300, 300&ndash, 425, and 425&ndash, 600 &micro, m) of reed canary grass (RCG), timothy hay (TH), and switchgrass (SW) were selected in the present work. Furthermore, two woody biomasses (spruce and pine) were also considered under similar experimental conditions for comparison purposes. An Instron machine attached to an in-house built pelletizer unit was employed to produce a single pellet. The energy demand for compacting ground biomass (spruce) with a particle size of 150 &micro, m was lower (2.07 kJ) than those required for particle sizes of 300 &micro, m (2.24 kJ) and 425 &micro, m (2.43 kJ). The energy required for compacting ground reed canary grass, timothy hay, and switchgrass was lower (1.61, 1.97, and 1.68 kJ, respectively) than that required for spruce (2.36 kJ) and pine (2.35 kJ), evaluated at a 159-MPa load and at temperature of about 80 &deg, C. The energy demand for blended biomass was around 2 kJ with the pellet quality approaching that of the pellets made from woody biomass. Overall, blending helped to improve the quality of pellets and lower the compaction energy requirements.

The torrefaction of agriculture (switchgrass and timothy) and forestry (spruce and pine) biomass was studied using simultaneously thermogravimetric analyzer (TGA) coupled with Fourier transform infrared (FTIR), and mass spectrometer (MS). The chemical functional groups present in the gases were identified by FTIR and the quantification of gaseous products was determined using MS at different torrefaction temperatures ranging from 200 to 290 °C. TG-FTIR and TG-MS techniques are paired to refine the identification of gases. TGA results showed that the behavior of the agricultural and forestry biomass was not the same due to their composition variation. The decomposition of switchgrass took place at a lower temperature than other biomass. Both switchgrass and timothy have two peaks of degradation rate compared to only one peak present for forestry biomass. The FTIR analysis indicated that most of the chemical compositions present in the biomass are decomposed at torrefaction temperature of 290 °C. The mass spectrometric analysis at torrefaction temperature 200 and 230 °C quantified the degradation of combustible gases: CH4, C2H4, CO, and O2 around 20–30 %, whilst at torrefaction temperature 260 and 290 °C the degradation of combustible gases was more than 30 %. Moreover, all gaseous products evolved from the torrefaction of agricultural and forestry biomasses were almost similar in characteristics, but varied in proportions.

Woody biomass is densified in the form of pellets in order to improve its physical and mechanical properties during handling and storage. However, limited research work has been conducted on the mechanical properties of pellets made from agricultural and wood biomass blends. Two commonly available forestry biomass, spruce (S) and pine (P), and three agricultural biomasses, reed canary grass (RCG), timothy hay (H) and switchgrass (SW), were used to form pellets. The mechanical properties were evaluated for three different particle sizes (150-300, 300-425 and 425-600 μm). An Instron attached with an in-house built single unit pelletizer and temperature controlled die was employed to produce a pellet. The aim of this study is to investigate the effect of particle size and blending (agricultural and woody biomass) on the mechanical properties (density and intrinsic yield stress). For all biomasses, pellets made from lower particle size (150-300 μm) exhibited higher density (950-1178 kg/m3 for spruce and pine; 668-800 kg/m3 for RCG, H and SW; 900-970 kg/m3 for blended biomass). The intrinsic yield stress exhibited differences in values for individual forestry (40 MPa) and agricultural biomass (27-48 MPa), however after blending the values converged closest to that value for forestry biomass. In conclusion, blending low cost and abundant available agricultural biomass with woody biomass could not only result in better mechanical properties but would also help to meet the pellet market demand in future.