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Biochar is a promising pyrolysed carbon-enriched soil amendment and has excellent properties for agriculture production and to remediate environmental pollution. A set of reviews were conducted on biochar production by pyrolysis process from various waste biomass which has drawn extensive interest due to the low cost of production with several benefits. As many potential technologies have been developed, there are still several knowledge gaps that have been identified for some key points to contribute a comprehensive study towards soil fertility, nutrient and water retention, soil microbial activity, plant growth and yield, pollution remediation, mitigation of greenhouse gas emission and an improvement in the farmer's economy to achieve maximum profit by adopting environmentally friendly technique "pyrolysis". Therefore, this review explored a detailed study on food waste biochar production by the pyrolysis process and its impact on different applications as an amendment. Slow pyrolysis process at low and medium temperatures is a potential amendment for agriculture production and soil and water remediation by enhancing biochar properties like carbon, BET surface area, cation exchange capacity, zeta potential, and nutrient content, etc. with minimum ash content. The biochar enhances soil water and nutrient retention capacity, crop yield, and improved microbial community at different soil quality. Additionally, food waste to biochar is a realistic adsorbent and economical carbon sequester to mitigate GHG emissions. This review conducted a brief assessment of the knowledge gaps and future research directions for researchers, encouraging investigators, stakeholders, and policymakers to make the best possible decision for food waste valorization. Highlights: • Valorization of food waste to biochar is a promising amendment for agriculture and soil–water remediation. • Lower and medium pyrolysis temperatures qualitatively changed all aspects of biochar properties. • Biochar improves soil fertility, microbial activity, soil water and nutrient retention capacity, and plants growth. • Biochar is a good carbon sequestrator to mitigate greenhouse gas and a bioeconomy product for the farmer's community and policymakers. [ABSTRACT FROM AUTHOR]

In this study, an empirical model for the pyrolysis of major oil palm wastes (OPW) such as palm kernel shell (PKS), empty fruit bunches (EFB), and oil palm frond (OPF), and their blends is developed. Moreover, the techno-economic feasibility of the wastes is investigated to determine the type of waste that would be suitable for the commercialization of different types of products. According to the model results, the bio-oil dominates the pyrolysis process' product output, accounting for 59.21, 50.51, 56.60, and 55.65% of PKS, EFB, OPF, and their blend, respectively. Whereas biochar yield is 23.21, 23.1, 22.95, and 23.08%, gas yield is 17.57, 26.38, 20.44, and 21.27%. The findings demonstrate that the feedstocks under consideration are mostly suitable for producing bio-oil. According to the economic analysis, PKS-based pyrolysis has the highest capital expenses (CAPEX), while EFB-based pyrolysis has the lowest CAPEX of all tested feedstocks. Furthermore, PKS has the highest operating expenses (OPEX) due to its relatively higher market price as well as higher moisture content, which necessitates more energy input during the drying stage. Among the feedstocks, OPF has delivered the highest profit of USD 17 M/year, with a 22% return on investment (ROI). In terms of investment capital payback period, all OPW feedstocks demonstrated a reasonable period of 4–6 years. Bio-oil is the most valuable pyrolysis product, with the highest market value when compared to biochar and syngas. The established prediction model can be utilized as a solid reference for biomass pyrolysis modelling studies. Furthermore, the predicted values are reasonable enough to be used in industrial process design. [ABSTRACT FROM AUTHOR]

With ever-growing population comes an increase in waste and wastewater generated. There is ongoing research to not only reduce the waste but also to increase its value commercially. One method is pyrolysis, a process that converts wastes, at temperatures usually above 300 °C in a pyrolysis unit, to carbon-rich biochars among with other useful products. These chars are known to be beneficial as they can be used for water treatment applications; certain studies also reveal improvements in the biochar quality especially on the surface area and pore volume by imparting thermal and chemical activation methods, which eventually improves the uptake of pollutants during the removal of inorganic and organic contaminants in water. Research based on single waste valorisation into biochar applications for water treatment has been extended and applied to the pyrolysis of two or more feedstocks, termed co-pyrolysis, and its implementation for water treatment. The co-pyrolysis research mainly covers activation, applications, predictive calculations, and modelling studies, including isotherm, kinetic, and thermodynamic adsorption analyses. This paper focuses on the copyrolysis biochar production studies for activated adsorbents, adsorption mechanisms, pollutant removal capacities, regeneration, and real water treatment studies to understand the implementation of these co-pyrolyzed chars in water treatment applications. Finally, some prospects to identify the future progress and opportunities in this area of research are also described. This review provides a way to manage solid waste in a sustainable manner, while developing materials that can be utilized for water treatment, providing a double target approach to pollution management. [ABSTRACT FROM AUTHOR]

This study involved the preparation of magnetized activated carbon (Fe3O4–HSAC) by first activating hazelnut shell waste, followed by coating it by Fe3O4 nanoparticles. The Fe3O4–HSAC thus prepared was evaluated as an adsorbent possessing the potential for fluoride to elimination, under a variety of conditions. From the findings, it is evident that by using the Fe3O4–HSAC as an adsorbent 100% fluoride removal could be accomplished under the optimum conditions cited (adsorbent dose = 0.75 g/L; pH = 3–5; and temperature = 323 K). The Halsey and Freundlich isotherm models both concurred strongly with the equilibrium adsorption data, and from the results of the Langmuir model, the maximum adsorption capacity was achieved at 146.2 mg/g when the temperature was 298 K and pH was 5. The pseudo-second-order kinetic model offered the best explanation for the adsorption process. Besides, both the intra-particle diffusion and liquid film diffusion models were found to control the kinetic mechanism of the fluoride adsorption onto the Fe3O4–HSAC. The quantity of adsorption energy provided using the Dubinin–Radushkevich model was 4.59 kJ/mol, indicating that the physical adsorption was predominant. Further, the negative values of Gibbs free energy change (ΔG° = -2.73 to -8.11 kJ/mol at temperature = 288 to 318 K, respectively) and the positive values of enthalpy change (ΔH° = 56.01 kJ/mol) and entropy change (ΔS° = 0.198 kJ/mol. K) suggest that the nature of the adsorption thermodynamics is endothermic, spontaneous, and physical. From this study, the observation of the outstanding performance of the Fe3O4–HSAC helped to conclude that this is a material of promise as a treatment agent in the fluoride elimination from contaminated water and wastewater. [ABSTRACT FROM AUTHOR]

Sorbent pads and films have been commonly used for environmental remediation purposes, but designing their internal structure to optimize access to the entire volume while ensuring cost-effectiveness, ease of fabrication, sufficient strength, and reusability remains challenging. Herein, we report a trimodal sorbent film from recycled polypropylene (PP) with micropores, macro-voids, and sponge-like 3D cavities, developed through selective dissolution, thermally induced phase separation, and annealing. The sorbent has hundreds of cavities per cm2 that are capable of swelling up to twenty-five times its thickness, allowing for super-fast saturation kinetics (within 30 s) and maximum oil sorption (97 g/g). The sorption mechanism follows a pseudo-second-order kinetic model. Moreover, the sorbent is easily compressible, and its structure is retained during oil sorption, desorption, and resorption, resulting in 96.5% reuse efficiency. The oil recovery process involves manually squeezing the film, making the cleanup process efficient with no chemical treatment required. The sorbent film possesses high porosity for effective sorption with sufficient tensile strength for practical applications. Our integrated technique results in a strengthened porous polymeric structure that can be tailored according to end-use applications. This study provides a sustainable solution for waste management that offers versatility in its functionality. [ABSTRACT FROM AUTHOR]

Effective removal of heavy metals from wastewaters can enable increased reuse of treated wastewater and reduce water scarcity worldwide. This paper describes the results of an initial study on zinc removal using waste-derived aluminosilicate-based material by binary ion exchange with calcium and potassium. About 2 mmol/g of zinc removal adsorption capacity was demonstrated using the aluminosilicate resin. Seven equilibrium isotherm models have been analyzed using the zinc adsorption data; the best fit to the experimental values based on the lowest SSE error was the SIPS model. A mechanism between zinc adsorption and the calcium and potassium desorption has been developed and modelled and is confirmed based on the mass balance analysis between the divalent calcium ions and the monovalent potassium ions exchanged with the divalent zinc ions adsorbed. Desorption studies using isotherm model equations for the calcium and potassium data further confirmed the mechanism. Regeneration was over 80% per cycle for three acid regenerations, indicating the zinc can be recovered for re-use. Furthermore, optimization using the SIPS model showed the minimum amount of adsorbent required using a two-stage reactor system is much lower, proving the need for a two-stage reactor to make the system more economical. Future experiments on multicomponent analysis and further optimization will help develop this adsorbent for real water systems. [ABSTRACT FROM AUTHOR]

Information on the pyrolysis degradation kinetics of feedstock is critical for the design and fabrication of pyrolysis reactors. In this study, the pyrolytic behaviour of a novel biomass, camel manure, has been studied in a non-isothermal thermogravimetric analyser. The thermal analyses were performed from room temperature to 950 °C at different heating rates (10, 20, and 50°C/min) in an N2 environment (100 ml/min). The kinetic parameters of the manure components are determined using an Arrhenius model equation, and the influence of heating rate on the pyrolytic characteristics and kinetic parameters of the manure components has been examined. The results indicated that the increase in heating rates increased the starting and ending temperatures (decomposition) of manure components. The increase in heating rates shifted the ignition, peak, and burnout temperatures to higher temperatures. At the same time, the increase in heating rates improved the char yield from 22.50 to 31.51%. However, the increase in heating rates showed an insignificant effect on the kinetic parameters of the camel manure components. [ABSTRACT FROM AUTHOR]

The properties of biochar produced by pyrolysis are strongly influenced by various factors such as feedstock. Cabbage makes up around 6.5% of global vegetable production with around 30% wasted from the farm to plate, making it a considerable and widely available biochar feedstock. This study investigates the optimization of three design factors, namely, pyrolysis temperature, feed particle size, and quantity of waste cabbage biomass to produce biochar. Feed particle size was selected due to its relevance to solar or other drying pretreatment, necessary for moisture reduction. To evaluate the influence of these parameters and find their optimum conditions, response surface methodology (RSM) with a central composite design of experiments was used. Optimum response for cabbage biochar was observed at lower temperature (360 °C) with particle size of 0.90 mm and a relatively low quantity, though this latter parameter had minimal influence on most response parameters. Temperature was the most influential parameter on all response variables, although particle size was important for nitrogen content, cation exchange capacity (CEC), and electrical conductivity. Biochar produced at an optimum pyrolysis temperature of 360 °C and nearest practical size of 1 mm was tested with Ipomoea purpurea in sandy soil. Two percent biochar loading provided an increase in water retention from 6.5% in the control to 10% in the biochar amended soil (p = 0.016). Increases were also observed in plant height and leaf production but were not statistically significant at α = 0.05. [ABSTRACT FROM AUTHOR]

The application of biochar in agriculture is a developing means to improve soil water retention, fertility, and crop yield. The present work focuses on biochar preparation from mixed vegetable and fruit wastes, using cauliflower, cabbage, banana peels, corn leaves, and corn cobs. The biochar produced at 400 °C was applied to the soil as an amendment to observe the qualitative changes of soil quality, plant growth, and water retention capacity of the soil based on screening in a previous study. Pot experiments were conducted at a laboratory scale having 0%, 2%, and 6% biochar mixed with sand. Each pot was sown with seeds of chickpeas (Cicer arietinum L.) and monitored over 60 days. Two biochar application rates improved soil quality by increasing soil porosity from 49.3 to ≥ 53.4%, more than doubling cation exchange capacity to ≥ 21.1 cmolc.kg−1, providing a small reduction in bulk density of approximately 10% and decreasing electrical conductivity of the extract by at least 40% in comparison to control condition. The biochar application also increased key soil nutrients K, Mn, S, and P by a factor of 2–9 times. Application of biochar at 2% and 6% improved water retention from 55 to 77 and 91 mL respectively over the study and, more importantly, more than doubled the biomass yield for the same water application. The lower biochar application rate of 2% led to more germinated seeds (p = 0.0001), leaves (p = 0.0001), flowers, and fruiting chickpeas than the control condition. The 6% biochar application rate slightly improved plant height (p = 0.01) and provided a small reduction in water loss compared with the 2% biochar. Both biochar loadings increased the root and shoot biomass (p = 0.005) and nutrient content of the shoot and root biomass, particularly K, P, and S (p = 0.0001). This study demonstrates that biochar application at 2–6% is an effective means to increase chickpea yield and reduce water stress. Given small differences in performance within this application range, 2% application is recommended. The study establishes valorization of cellulose rich food waste in the form of biochar as a potential method for positive soil management and increased agricultural productivity in arid environments. [ABSTRACT FROM AUTHOR]

Industrial effluents and stormwater runoff pose a significant threat to the environment and public health. Consequently, the water quality guidelines set strict limitations on the heavy metal content due to their toxicity. Among heavy metals, cadmium is one of the most hazardous, and its maximum permissible concentration is 10 μg/L. Therefore, the improvement of wastewater treatment technology is a prominent and ongoing task. The present study deals with the adsorption of cadmium onto chitosan beads and nanochitosan, a natural polysaccharide polymer derived from seafood shell waste. The chitosan beads and the nanochitosan were derived from the same source chitosan in order to compare their capacities and their kinetic performances on an equal basis. Both cadmium adsorption capacities are extremely high with 1.65 mmol Cd/g chitosan beads and 1.90 mmol Cd/g on nanochitosan—with nanochitsosan showing a 15% higher uptake. Several kinetic models were compared and the kinetics of both chitosan beads and nanochitosan followed both the pseudo-second-order and the Elovich models very closely but the uptake of cadmium on nanochitosan was faster. A comparison of benefits and disadvantages of using the two chitosans is presented. [ABSTRACT FROM AUTHOR]

Heavy metal water pollution is a global concern in recent years. Copper is a toxic metal at higher concentrations (> 20 μg /g) and needs to be removed using ion exchanger systems. This study investigates the removal efficiencies of copper by the non-metallic fraction (NMF) waste printed circuit boards (PCBs). The high maximum adsorption capacity of copper by the PCB-derived material after activation with KOH was 2.65 mmol/g, and the experimental isotherm was best correlated by the Temkin model. Finally, this study presents a novel dual site adsorption/ion exchange mechanism, wherein the potassium (from the activation) and calcium (present in the structure) served as ion exchange sites for the copper in the solution. Therefore, this recycling study, focusing on cyclic environmental management, converts a major waste material to an activated ion exchange resin (high capacity) for the removal of copper from wastewater solutions and successfully regenerates the resin for re-use while producing an acidic copper solution for recovery by electrolysius or chemical salt precipitation. [ABSTRACT FROM AUTHOR]

Prior information on the pyrolysis product behaviour of biomass components-cellulose, hemicellulose and lignin is critical in the selection of feedstock as components have a significant influence on the pyrolysis products yield. In this study, the effect of biomass components on the yield of slow pyrolysis products (char, bio-oil and syngas) is investigated using a validated ASPEN Plus® model. The model is simulated at a temperature of 450 °C, a heating rate of 10 °C/min and a solid residence time of 30 min. The results indicated that at the given conditions, lignin contributed 2.4 and 2.5 times more char yield than cellulose and hemicellulose. The hemicellulose contributed 1.33 times more syngas yield than lignin while the cellulose and hemicellulose contributed 8.67 times more bio-oil yield than lignin. Moreover, the cost involved in the production of char using lignin (110 $/ton) is significantly economical than using cellulose (285 $/ton) and hemicellulose (296 $/ton). The net CO2 emission of lignin pyrolysis is 4.14 times lower than cellulose pyrolysis and 3.94 times lower than hemicellulose pyrolysis. It can be concluded that lignin pyrolysis is more advantageous than cellulose and hemicellulose pyrolysis. In the selection of feedstock for the slow pyrolysis, the feedstock with more lignin content is preferred. [ABSTRACT FROM AUTHOR]

Landfilling is one of the most prevalent waste management strategies on a global scale. However, one major drawback of landfills is the production of highly contaminated leachate which can harm ecosystems and pollute water resources which municipalities depend on. Various treatment options have been explored for treating leachate throughout the years. This paper aims to investigate landfill leachate treatment studies through bibliometric and visual analysis of articles collected from the Scopus database from 1975 to 2019. The results show that more than one thousand papers have been published in 159 journals. Nearly 3000 authors have published on the topic, most commonly from China, the USA, Malaysia, and Brazil. The keywords co-occurrence network led to the formation of 5 topical clusters, after which they were closely examined and titled "oxidation processes," "nitrogen removal processes," "constructed wetlands/coagulation," "adsorption," and "membrane-based processes" based on their contents. Finally, the overlay network was used to discern the hottest research trends. The results showed that advanced coagulation-based processes (such as peroxicoagulation) and studies focusing on improving membrane-based processes through reduction of membrane fouling are focal points which will be trending into the future. [ABSTRACT FROM AUTHOR]

2,4-Dichlorophenoxyacetic (2,4-D) is a toxic herbicide used to control weeds in agricultural sector. However, its residuals in soil and water are harmful for human and aquatic life. Therefore, the aim of this study was to evaluate the photocatalytic degradation of 2,4-D from aqueous solution using the Fe-doped TiO2 nanoparticles in the presence of UV and sunlight irradiation. The nanoparticles were synthesized via a mild hydrothermal process. The characteristics of the synthesized nanoparticles were determined using powder X-ray diffraction, Fourier transform infrared and scanning electron microscopy techniques. The effects of different parameters, including pH, nanoparticle dosage, initial 2,4-D concentration and dopant percentage on the degradation of 2,4-D, were investigated. The results demonstrated that the successfully doped nanoparticles had likely pseudo-spherical morphology. The optimum conditions for photocatalytic degradation of 2,4-D obtained at pH 7, nanoparticle dosage = 0.4 g/l, initial 2,4-D concentration = 10 mg/l, dopant percentage = 1.5% and contact time = 120 min. Under the optimal conditions, the photocatalytic degradation efficiencies of 2,4-D under UV and sunlight irradiation were 65 and 72%, respectively. In addition, the findings showed that 2,4-D degradation efficiency increased with increasing dosage of nanoparticles, while it decreased with increasing initial concentration of 2,4-D and initial pH. Therefore, the Fe-doped TiO2 nanoparticles could be used for the photodegradation of 2,4-D, and it is recommended for the degradation of other organic pollutants from aqueous media especially in tropical areas where a free energy source, i.e., sunlight, is available. [ABSTRACT FROM AUTHOR]

Olive stones have been widely used as a renewable energy biowaste source. As they are rich in elemental carbon (40–45 wt%), much research focussed on effectively converting olive stones, as precursors, into activated carbon adsorbents. However, only a few studies have concentrated on summarising the various techniques used to produce activated carbon from olive stone. This article reviews the research undertaken on the production and application of activated carbon as an adsorbent from olive stones for wastewater treatment. Various physical, chemical and physico-chemical treatments to remove heavy metals, organics and dyes are discussed, and the resultant adsorption capacities are reported. In several cases, very high adsorption capacities are recorded. Finally, the future prospects of these materials as adsorbents are discussed, and after further development work, olive stone-derived activated carbons have great potential especially in the area of organic polluted wastewaters. [ABSTRACT FROM AUTHOR]

In the present study, electrospun nanofiber membranes (ENMs) of polyacrylonitrile (PAN) were modified by dispersing α-Fe2O3 nanoparticles, synthesized using a thermal solvent process, in a PAN solution. The morphology and physiochemical properties of the prepared ENMs and the α-Fe2O3 were characterized using FESEM, EDX, BET, XRD, FTIR, porosity, and contact angle measurement. XPS was used to investigate the interaction of ENM with arsenate (As(V)) during the adsorption. Moreover, the effect of pH, the equilibrium isotherm, and the kinetics were investigated in batch experiments. The Langmuir isotherm best correlated the experimental results, indicating monolayer adsorption on ENMs, and the kinetics was best fitted, R2 > 0.99, by the pseudo-second-order model. In addition, the effects of certain conditions on the filtration performance were examined, such as feed concentration and transmembrane pressure (TMP). By passing sodium hydroxide (0.1 M) for 20 min, the membrane was regenerated. The increase in TMP, along with the presence of co-ions including chloride, nitrate, and sulfate, had negative impacts on the removal of As(V). The results show that the modified ENMs with α-Fe2O3 nanoparticles are applicable for As(V) ion removal and possibly for eliminating other heavy metals from aqueous media. [ABSTRACT FROM AUTHOR]

In this study, arsenate (As-V) removal using micellar enhanced ultrafiltration (MEUF) modified by cationic surfactants was studied by a dead-end polyacrylonitrile (PAN) membrane apparatus. The UF membrane has been produced by a phase inversion process. The prepared membrane was characterized and analyzed for morphology and membrane properties. The influence of operating parameters such as initial concentrations of As-V, surfactants, pH, membrane thickness, and co-existing anions on the removal of As-V, surfactant rejection, and permeate flux have been studied. The experimental results show that from the two different cationic surfactants used the CPC (cetyl-pyridinium chloride) efficiency (91.7%) was higher than that of HTAB (hexadecyltrimethyl-ammonium bromide) (83.7%). The highest As-V removal was 100%, and was achieved using initial feed concentrations of 100–1000 μg/L, at pH 7 with a membrane thickness of 150 μm in a dead-end filtration system. This efficiency for As-V removal was similar to that obtained using a cross-flow system. Nevertheless, this flux reduction was less than the reduction achieved in the dead-end filtration process. The PAN fabricated membrane in comparison to the RO and NF processes selectively removed the arsenic and the anions, in the water taken from the well, and had no substantial effect on the cations. [ABSTRACT FROM AUTHOR]

Equilibrium sorption studies of anionic species of arsenite, As(III) ions and arsenate As(V) ions onto two biosorbents, namely, chitosan and nanochitosan, have been investigated and compared. The results and trends in the sorption behavior are novel, and we have observed during the sorption process of the As(III) and As(V) on chitosan, a slow process of desorption occurred after an initial maximum adsorption capacity was achieved, before reaching a final but lower equilibrium adsorption capacity. The same desorption trend, however, is not observed on nanochitosan. The gradual desorption of As(III) and As(V) in the equilibrium sorption on chitosan is attributed to the different fractions of the dissociated forms of arsenic on the adsorbent surface and in solution and the extent of protonation of chitosan with the changing of solution pH during sorption. The change of solution pH during the sorption of arsenite ions on chitosan was also influenced by the interaction between the buffering effect of the arsenite species in the aqueous medium and the physical properties of chitosan. The final equilibrium adsorption capacity of chitosan for As(III) and As(V) was found to be around 500 and 8000 μg/g, respectively, whereas the capacities on nanochitosan are 6100 and 13,000 μg/g, respectively. [ABSTRACT FROM AUTHOR]

In this work, CeO2-modified Pd/CeO2-carbon nanotube (CNT) electrocatalyst for the electro-oxidation of formic acid has been investigated. The support CNT was first modified with different amounts (5-30 wt.%) of CeO2 using a precipitation- deposition method. The electrocatalysts were developed by dispersing Pd on the CeO2-CNT supports using the borohydride reduction method. The synthesized electrocatalysts were analyzed for composition, morphology and electronic structure using x-ray diffraction (XRD), scanning electron microscopy with energy-dispersive x-ray spectroscopy (SEM/EDX), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA) techniques. The formation of Pd nanoparticles on the CeO2-CNT support was confirmed using TEM. The activity of Pd/CeO2- CNT and of Pd-CNT samples upon oxidation of formic acid was evaluated by using carbon monoxide stripping voltammetry, cyclic voltammetry, and chronoamperometry. The addition of moderate amounts of cerium oxide (up to 10 wt.%) significantly improved the activity of Pd/CeO2-CNT compared to the unmodified Pd-CNT. Pd/10 wt.% CeO2-CNT showed a current density of 2 A mg-1, which is ten times higher than that of the unmodified Pd-CNT (0.2 A mg-1). Similarly, the power density obtained for Pd/10 wt.% CeO2-CNT in an air-breathing formic acid fuel cell was 6.8 mW/cm² which is two times higher than Pd-CNT (3.2 mW/cm²), thus exhibiting the promotional effects of CeO2 to Pd/CeO2-CNT. A plausible justification for the improved catalytic performance and stability is provided in the light of the physical characterization results. [ABSTRACT FROM AUTHOR]

Oil spills over seawater and dye pollutants in water cause economic and environmental damage every year. Among various methods to deal oil spill problems, the use of porous materials has been proven as an effective strategy. In recent years, graphene-based porous sorbents have been synthesized to address the shortcomings associated with conventional sorbents such as their low uptake capacity, slow sorption rate, and non-recyclability. This article reviews the research undertaken to control oil spillage using three-dimensional (3D) graphene-based materials. The use of these materials for removal of dyes and miscellaneous environmental pollutants from water is explored and the application of various multifunctional 3D oil sorbents synthesized by surface modification technique is presented. The future prospects and limitations of these materials as sorbents are also discussed. [ABSTRACT FROM AUTHOR]

The study is a first-time investigation into the use of Eucalyptus leaves as a low-cost herbal adsorbent for the removal of arsenic (As) and mercury (Hg) from aqueous solutions. The adsorption capacity and efficiency were studied under various operating conditions within the framework of response surface methodology (RSM) by implementing a four-factor, five-level Box-Wilson central composite design (CCD). A pH range of 3-9, contact time ( t) of 5-90 min, initial heavy metal (As or Hg) concentration ( C ) of 0.5-3.875 mg/L, and adsorbent dose ( m) of 0.5-2.5 g/L were studied for the optimization and modeling of the process. The adsorption mechanism and the relevant characteristic parameters were investigated by four two-parameter (Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich) isotherm models and four kinetic models (Lagergren's pseudo-first order (PFO), Ho and McKay's pseudo-second order (PSO), Weber-Morris intraparticle diffusion, and modified Freundlich). The new nonlinear regression-based empirical equations, which were derived within the scope of the study, showed that it might be possible to obtain a removal efficiency for As and Hg above 94% at the optimum conditions of the present process-related variables (pH = 6.0, t = 47.5 min, C = 2.75 mg/L, and m = 1.5 mg/L). Based on the Langmuir isotherm model, the maximum adsorption or uptake capacity of As and Hg was determined as 84.03 and 129.87 mg/g, respectively. The results of the kinetic modeling indicated that the adsorption kinetics of As and Hg were very well described by Lagergren's PFO kinetic model ( R = 0.978) and the modified Freundlich kinetic model ( R = 0.984), respectively. The findings of this study clearly concluded that the Persian Eucalyptus leaves demonstrated a higher performance compared to several other reported adsorbents used for the removal of heavy metals from the aqueous environment. [ABSTRACT FROM AUTHOR]

An ion exchange resin, based on the sodium diimidoacetate structure, has been tested for the removal of zinc ions from effluents. After employing three isotherm models, namely, Langmuir, Freundlich and Langmuir-Freundlich to measure and analyse equilibrium isotherms, a series of agitated batch experiments have been carried out to optimise the removal of zinc ions in a two-stage batch system. The first optimisation model involves minimising the total amount of resin required to achieve a specific percentage zinc removal. The second optimisation study involves minimising the total batch contact time to achieve a certain percentage zinc removal. [ABSTRACT FROM AUTHOR]

In the present study, multi-walled carbon nanotubes (MWCNTs) have been used for the rapid removal of four trihalomethanes (THMs) from aqueous solutions. The adsorption capacity of THMs onto MWCNTs was reasonably constant in the pH range of 5-7 but decreased as the pH exceeded 7. Four equilibrium isotherm models, namely, Langmuir, Freundlich, Temkin, and Sips, were applied to determine the best-fit equilibrium expressions. The results showed that all four experimental adsorption isotherms were best correlated by using the Sips model. The maximum adsorption capacities for the CHCl, CHClBr, CHClBr and CHBr were found to be 10.98, 6.85, 6.57, and 5.95 mg/g, respectively. The rate of adsorption followed the pseudo-second-order kinetic model. Furthermore, four nonlinear regression-based equations were also derived to model THM adsorption from aqueous solutions by MWCNTs. The modeling results clearly indicated that the empirical formulations satisfactorily described the behavior of the present adsorption process for CHCl ( R = 0.949), CHClBr ( R = 0.945), CHClBr ( R = 0.936), and CHBr ( R = 0.919). The overall results confirmed that MWCNTs could be a promising adsorbent material for THMs removal from aqueous solutions. [ABSTRACT FROM AUTHOR]

An oil absorbent material has been produced from waste biomass with an alkali treatment process. The simple yet effective process is carried out on the agricultural biowaste at 90 °C and ambient pressure. The present manuscript considers the transient behavior of the sorbent during application, in particular the oil sorption and desorption profiles with time. The kinetics data shows that this lignocellulosic sorbent reaches saturation in <2 min of contact with the spilled oily liquid (marine residual fuel). The results showed that the second order kinetic model accurately correlates with the experimental data. The rice-husk product is shown to significantly outperform a commercially available sorbent in terms of uptake capacity (more than 18 g/g by the husk sorbent compared to 10 g/g by Corksorb). However in gravimetric desorption experiments, the as-prepared husk exhibited less favorable behavior than the commercial competitor. [ABSTRACT FROM AUTHOR]

Rice is the third largest cultivated cereal crop in the world, making rice hulls one of the most abundant biowastes on Earth. In this manuscript, the rice husks have been subjected to alkali treatment at low temperatures aiming to produce a lignocellulosic sorbent material as well as removing their silica. This absorbent has been subsequently tested for marine diesel spill clean up. Various treatment conditions such as NaOH concentration, duration, and temperature have been investigated. The optimized cellulosic sorbents show high RMG380 marine diesel uptake due to low bulk density and their fluffy structure. It is argued that the bulk density is a critical factor in the excellent uptake capacity. As far as the authors are aware, these results (as high as 20 g of RMG380 sorbed per gram of sobent) show the highest oil sorption for rice husk derived materials reported in literature. Other advantages include higher yields and lower treatment temperatures compared to other studies. The proposed cheap and environmentally friendly method provides a simple and safe technique for the production of valuable products from lignocellulosic agricultural waste. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Municipal solid waste incineration (MSWI) ash is used in part as raw materials for cement clinker production by taking advantage of the high contents of SiO, AlO, and CaO. It is necessary for environmental reasons to establish a material utilization system for the incineration waste ash residue instead of disposing these ashes into landfill. The aim of this paper is to study the feasibility of replacing clinker raw materials by waste ash residue for cement clinker production. MSWI bottom ash and MSWI fly ash are the main types of ashes being evaluated. The ashes were mixed into raw mixture with different portions of ash residue to produce cement clinker in a laboratory furnace at approximately 1400°C. X-ray diffraction and X-ray florescence techniques were used to analyze the phase chemistry and chemical composition of clinkers in order to compare these ash-based clinkers with commercial Portland cement clinker. [ABSTRACT FROM AUTHOR]

novel activated carbon has been prepared by the activation of ground pine cones using phosphoric acid activation, and the nitrogen Brunauer-Emmett-Teller surface area was 869 m g. Equilibrium isotherms were performed to assess the capacity of the activated carbon using two acidic dyes, namely Acid Blue 113 and Acid Black 1. The monolayer equilibrium isotherm capacities of Acid Blue 113 and Acid Black 1 were 286 and 458 mg dye/g C, respectively. These capacities are significantly higher than commercial carbons and other literature carbons. For the first time, these carbons were tested in fixed bed experimental systems and data analysed using the bed depth service time model (BDST) and the carbon usage rate (CUR) model. In the fixed bed studies, the key parameters for a 20-cm bed depth for the BDST model at 50% breakthrough capacity are (a) for Acid Black, the BDST capacity is 149 mg dye/g carbon and operating time is 1,530 min and (b) for Acid Blue, the breakthrough capacity is 9 mg of dye/g of carbon and operating time is 195 min. The fixed bed study indicates that the BDST design models can be applied satisfactorily, and the pine cone carbon has significant potential but a more mesoporous pine cone carbon is preferable for the larger Acid Black dye. The CUR design method was not successful. [ABSTRACT FROM AUTHOR]

Purpose. This study was to develop and validate a new chiral HPLC-UV method for the quantitative analysis of enantiomeric ritalinic acid (RA) in human plasma. Methods. An α1-acid glycoprotein column was used with the mobile phase containing 0.4% acetic acid and 0.1% dimethyloctylamine, pH 3.4. The detection of enantiomeric RAs was at 220 nm. Results. A baseline separation for d- and l-RA was achieved by a separation factor of 2.08. Methylphenidate, the precursor of RA, was eluted with the front solvent, and thus does not interfere in the analysis of RA in our method. The assay was successfully applied for the in vitro analysis of enantiomeric ritalinic acids produced by human and dog plasma and dog liver. Conclusions. Data demonstrated that the esterase(s) in human plasma metabolize d-methylphenidate faster than its l-isomer. The yielded intrinsic clearances (Clint) are 1.02 and 2.17 µl/min/mg protein, respectively, for d and l-methylphenidate. KEY WORDS: ritalinic acid; methylphenidate; chiral separation; HPLC. [ABSTRACT FROM AUTHOR]

The sorption of acid dyes from aqueous effluents onto activated carbon has been studied. The effects of initial dye concentration and activated carbon mass on the rate of Acid Blue 80, Acid Red 114 and Acid Yellow 117 removal have been investigated. A three-resistance mass transport model based on film, pore and surface diffusion control has been applied to model the concentration decay curves. The model incorporates an effective diffusion coefficient Deff, which is dependant on the equilibrium solid phase concentration or fractional surface coverage. The results of the film-pore-surface diffusion model are compared with the data obtained from the basic film-pore diffusion model. It has been found that the film-pore-surface diffusion model provides a major improvement over the data correlated by the film-pore diffusion model. Also, the relationship between surface diffusion and fractional surface coverage has been investigated for the adsorption of acid dyes on activated carbon. [ABSTRACT FROM AUTHOR]

The single dose pharmacokinetics of fluphenazine (2 × 5 mg tablets, Prolixin) were studied in 21 drug free male psychiatric patients (12 black, 9 white). Plasma samples were harvested over a period of 48 h while the patients were on a strictly controlled diet. The results showed wide interpatient variations in all pharmacokinetic parameters including C, AUC, apparent oral clearance, and elimination half-life. It was determined for each of these parameters that the geometric mean gave a better estimate of central tendency than the corresponding arithmetic mean and the distribution was skewed and leptokurtotic. There was no significant difference between blacks and whites in any pharmacokinetic parameter examined. Considerable variations and marked undulations in the elimination portion of the plasma concentration versus time profiles were evident, possibly indicating biliary recycling of the drug. These undulations made it difficult to determine elimination rate constants for several of the patients. Hydrolysis or plasma samples from one patient demonstrated that the conjugate(s) of fluphenazine was present in three to four times the concentration of the unchanged drug. [ABSTRACT FROM AUTHOR]

The single dose pharmacokinetics of trifluoperazine (5 mg, Stelazine) were investigated in black ( n=25) and white ( n=32) healthy male subjects. Plasma samples were harvested over 24 h and analysed by a GLC-MS method. There were wide intersubject variations in all pharmacokinetic parameters examined, including C, AUC, apparent oral volume of distribution at steady state, and elimination half-life. For each of these parameters the distribution was positively skewed in both blacks and whites and the geometric mean gave a better estimate of central tendency than the corresponding arithmetic mean. In all pharmacokinetic parameters examined there was no significant difference detected between black and white subjects or between smokers and non-smokers. [ABSTRACT FROM AUTHOR]

Highly sensitive radioimmunoassays were applied to study the sulfoxidation of fluphenazine in 30 schizophrenic patients maintained on either 5 mg or 25 mg fluphenazine decanoate by intramuscular injection every 14 days over a period of 6 months. The presence of the sulfoxide metabolite was detected in all but one of the patients, such that 97% of the 340 plasma samples analysed contained the metabolite. Interpatient variations in plasma levels of fluphenazine, fluphenazine sulfoxide, and in drug to metabolite plasma level ratios were several fold higher than the corresponding intrapatient variations at both dosages. There were statistically significant tendencies for mean plasma fluphenazine levels to rise and mean plasma sulfoxide levels to fall over the 6-month period of study among patients on the high dose, consistent with our previously reported observation that it takes 3-6 months to establish a steady state of fluphenazine with this dosage regimen. By contrast, there were no statistically significant changes in mean plasma levels of either fluphenazine or its sulfoxide in patients on the low dose. Nevertheless, there was a significant rise in fluphenazine to fluphenazine sulfoxide mean plasma level ratios in both dosage groups. It is difficult to assess the significance of the changes in the drug to metabolite ratios with time, since there are no kinetic data on the phase II metabolism (conjugation) of fluphenazine or fluphenazine sulfoxide. This study shows that sulfoxidation is an important major pathway in the metabolism of intramuscularly-administered fluphenazine, and implies that metabolic sites other than gut wall are also involved in the process. [ABSTRACT FROM AUTHOR]

Plasma fluphenazine concentrations (FLU) were measured in 45 patients with schizophrenic disorders who participated in a double-blind comparison of 5 and 25 mg fluphenazine decanoate (FD). The rise in plasma level of FLU 24 h after a 'test dose' was significantly correlated with steady state FLU concentration at 12 weeks (for 5 mg patients, r=0.45, P=0.04; for 25 mg, r=0.78, P=0.005). Patients who had low FLU at baseline required nearly 6 months to reach a steady state when they received 25 mg. Patients who received 5 mg and had low FLU at baseline continued to demonstrate relatively low plasma levels for the entire 1st year. Although the mean FLU at 6 months was lower for patients who relapsed during the subsequent 18 months (0.57 ng/ml for relapsers vs 1.01 ng/ml for nonrelapsers), this difference was not statistically significant. When plasma levels from both dosage groups were combined, FLU at 12 weeks correlated significantly with factor scores for akinesia ( r=0.52, P=0.002) and BPRS cluster scores for retardation ( r=0.52, P=0.002). These results indicate that the measurement of fluphenazine plasma levels may be useful in determining when patients treated with FD are receiving drug doses which are likely to cause discomforting side effects. [ABSTRACT FROM AUTHOR]

A homogeneous solid phase diffusion model (HSDM) has been developed using a computer to predict the performance of a batch adsorber. The computer program utilises a semi-analytical solution for a two resistance model based on external mass transfer and homogeneous solid phase diffusion. The model has been successfully applied to four adsorption systems, namely, the adsorption of AB25, AR114, BB69 and BR22 onto pith. The method produces excellent correlations between experimental and theoretical concentration decay curves in batch adsorbers. The model developed presents a solution using a single solid diffusion coefficient and a single external mass transfer coefficient which are sufficient to characterise the system within a range of initial dye concentration, 25–300 mg · dm3 and solid/liquid ratios (w/v) 0.25–2. [ABSTRACT FROM AUTHOR]

This paper is, in a sense, a search for meaningful measurements of those internal and external forces or factors that shape the progress of water purification both in nature and in treatment works. Progress is related to time or distance. Internal factors are expressed in terms of (I) a fundamental reaction rate of a specific impurity exposed to a specific treatment process, (2) temperature itself or temperature-dependent properties of the water undergoing treatment, (3) longitudinal variation in treatment response, and (4) longitudinal change in the concentration of the impurity. External factors are measured in terms of (I) extent of contact surface relative to the volume of water treated or, for packed treatment columns or fixed contact media, relative to the volume of the contact media, and (2) contact opportunity in terms of the induced mobility of the contact surfaces or their sweep through the treatment unit as a product of time and velocity gradient. Structural longitudinal changes in relative contact surface and operational longitudinal changes in contact opportunity as well as relative contact surface require that these measurements be stated as functions to be evaluated specifically for each purification unit and its method of operation. Longitudinal change in interfacial activity itself is made part of the measurement of treatment response. The mounting competition for water by municipalities, agriculture, and industry has placed water in short supply in many parts of the world and led to its increased pollution by ever more numerous and complex waste substances. Water purification, both for the prevention of the pollution of receiving bodies of water and for the production of safe and satisfactory water supplies for home, farm, and industry, thereby, has become ever more pressing and important. Needed progress in purification methods and economy can be insured, in the long run, only by a more fundamental understanding of the kinetics of water purification. For this understanding, we must look to the research and observational talents marshalled in institutions such as the 'Eidgenössische Anstalt für Wasserversorgung, Abwasserreinigung und Gewässerschutz an der ETH Zürich' and to the leadership given these institutions by scientists such as Professor Dr. O. JAAG. The present special issue of this Journal pays tribute to the past accomplishments of this institution and its director and thereby expresses to both of them also the good wishes of sister institutions and their staffs for 'the years that are waiting before'. [ABSTRACT FROM AUTHOR]

Excess phosphate in water is known to cause eutrophication, and its removal is imperative. Nanoclay minerals are widely used in environmental remediation due to their low-cost, adequate availability, environmental compatibility, and adsorption efficiency. However, the removal of anions with nanoclays is not very effective because of electrostatic repulsion from clay surfaces with a net negative charge. Among clay minerals, halloysite nanotubes (HNTs) possess a negatively charged exterior and a positively charged inner lumen. This provides an increased affinity for anion removal. In this study, HNTs are modified with nano-scale iron oxide (Fe2O3) to enhance the adsorption capacity of the nanosorbent. This modification allowed for effective distribution of these oxide surfaces, which are known to sorb phosphate via ligand exchange and by forming inner-sphere complexes. A detailed characterization of the raw and (Fe2O3) modified HNTs (Fe-HNT) is conducted. Influences of Fe2O3 loading, adsorbent dosage, contact time, pH, initial phosphate concentration, and coexisting ions on the phosphate adsorption capacity are studied. Results demonstrate that adsorption on Fe-HNT is pH-dependent with fast initial adsorption kinetics. The underlying mechanism is identified as a combination of electrostatic attraction, ligand exchange, and Lewis acid-base interactions. The nanomaterial provides promising results for its application in water/wastewater treatment. [ABSTRACT FROM AUTHOR]

A series of experimental studies has been carried out using a novel, sustainable adsorbent to remove Tartrazine dye, namely, a steam activated carbon obtained from pecan nut shells. The dye also known as acid yellow 23 has been used in the food industry but is now classified as a carcinogen. The experimental equilibrium data has been used to test four equilibrium isotherm models and then the best fitting model was optimised to minimise the mass of adsorbent used to save costs in industrial applications using a two-stage batch adsorption system. The experimental contact time data has also been modelled and the best fit model has been used to optimise/minimise the contact time for a range of process conditions. [ABSTRACT FROM AUTHOR]