Showing papers in "Environmental Progress in 2013"
TL;DR: In this article, the degradation of antibiotics amoxicillin using sulfate radical-based advanced oxidation processes (SR-AOPs) was investigated, and the optimal conditions were found as follows: oxone concentration 0.01 mol·L −1, Co3O4 dosage 0.06 g, pH 6.0, reaction temperature 60°C, and reaction time 45 min.
Abstract: Sulfate radical-based advanced oxidation processes (SR-AOPs) are attracting considerable attention due to the high oxidizing ability of sulfate radical to degrade organic pollutants in aqueous environments. In this study, the degradation of antibiotics amoxicillin using SR-AOPs was investigated. This process is based on the generation of sulfate radicals through Co3O4-mediated activation of peroxymonosulfate (PMS). Several parameters affecting antibiotics degradation such as Co3O4, PMS, pH, and temperature were investigated. The optimal conditions were found to be as follows: oxone concentration 0.01 mol·L −1, Co3O4 dosage 0.06 g, pH 6.0, reaction temperature 60°C, and reaction time 45 min. Under these optimum conditions, it was found that the chemical oxygen demand (COD) removal efficiency of 91.01% was achieved. The effect of ultrasound in the Co3O4/PMS system for amoxicillin degradation was also studied. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 193-197, 2013
191 citations
TL;DR: In this article, the effect of initial solution pH, adsorbent dose, contact time, initial MB dye concentration, and temperature on the removal of MB dye was analyzed, and the adsorption equilibrium data were fitted to different adaption isotherm models such as Langmuir, Freundlich and Dubininin-Radushkevich.
Abstract: Kinetic, mechanism, equilibrium, and thermodynamic behavior of adsorption of methylene blue (MB) dye onto surface modified Strychnos potatorum seeds (SMSP), in an aqueous solution were studied. Batch adsorption experiments were carried out to analyze the effect of initial solution pH, adsorbent dose, contact time, initial MB dye concentration, and temperature on the removal of MB dye. The kinetics of MB dye adsorption onto SMSP follows a pseudo-second order kinetic model. The adsorption of MB dye onto SMSP was found to be controlled by both surface diffusion and pore diffusion. The diffusivity values were calculated from Boyd kinetic and Shrinking Core Model for varying initial MB dye concentration from 50 to 250 mg L−1. The adsorption equilibrium data were fitted to different adsorption isotherm models such as Langmuir, Freundlich, and Dubinin-Radushkevich. The equilibrium data fitted best with the Freundlich adsorption isotherm model, which indicates multilayer adsorption of MB dye onto SMSP. The maximum monolayer adsorption capacity estimated with Langmuir isotherm model was 78.84 mg of MB dye molecules per gram of SMSP. Thermodynamic studies showed that the adsorption of MB dye onto SMSP follows an exothermic process. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 624–632, 2013
75 citations
TL;DR: In this article, the authors investigated a processing strategy called hydrothermal carbonization (HTC) to convert wet algal biomass into a lipid-rich hydrochar and aqueous phase (AP) co-product.
Abstract: The high fertilizer demand for biodiesel production from microalgae is a significant challenge facing the commercialization of this promising technology. We investigated a processing strategy called hydrothermal carbonization (HTC) to convert wet algal biomass into a lipid-rich hydrochar and aqueous phase (AP) co-product. By reacting biomass at 200°C for 15 min, about 50% of the algae biomass became a solid hydrochar and roughly 40–70% of the C, N, and P in the reactant material dissolved into the AP. For the first time, an AP co-product of this nature was analyzed by HPLC, GC-MS and FT-ICR-MS to identify and characterize the dissolved organic matter. Using a unique marine bi-culture suspected to contain a green algae (Nannochloris) and a cyanobacteria (Synechocystis), we demonstrated that this AP co-product can support biomass growth better than a medium containing only inorganic nutrients. To manage unwanted contamination and optimize AP utilization, we employed a two-stage growth process and fed-batch additions of the AP co-product. The effect of media recycling and nutrient supplementation, as well as a production model for a large-scale facility, are discussed. Our work suggests that HTC can play a critical role in making algal biorefineries more sustainable by obviating biomass drying for fuel processing and recycling nutrients. © 2013 American Institute of Chemical Engineers Environ Prog, 32: 962–975, 2013
69 citations
TL;DR: In this article, it was shown that surface FeS particles became red and attached to the wall of reaction vessels within 3-4 days after contact with Se(IV), suggesting that a new solid phase, possibly Se(0), may have been produced.
Abstract: The Se 3d XPS spectra showed evidence of reduction of Se(IV) by contact with the mackinawite surface when certain assumptions were made, but there was no clear evidence for reduction of Se(VI). A continuous oxidation of surface Fe(II) was observed for FeS in contact with Se(IV), as indicated by a decrease of intensities of Fe(II)-S XPS peaks. S 2p spectra showed some evidence of oxidation of surface S(-II) associated with Se reduction that resulted in formation of polysulfides. However, the apparent change in S 2p spectra could be the result of overlap between S 2p and Se 3p peaks. FeS particles became red and attached to the wall of reaction vessels within 3–4 days after contact with Se(IV), suggesting that a new solid-phase, possibly Se(0), may have been produced. The low signal-to-noise of the S 2p peaks observed after 15 and 30 days contact with Se indicates increased amounts of sulfur in solution. This supports the existence of a reaction of Se with FeS in which discrete precipitates are formed and sulfide is released to solution. These observations support the conclusion that Se(IV) sorbs onto the surface of FeS and oxidizes surface species of iron and sulfur. © 2011 American Institute of Chemical Engineers Environ Prog, 32: 84–93, 2013.
68 citations
TL;DR: In this article, the effects of recycling process water on hydrophobicity of the biocarbon are investigated. But the results suggest that the effect of water recycling on the hydrophobic properties of the bio-carbons is negligible.
Abstract: Hydrothermal carbonization (HTC) is a process to densify, homogenize, and stabilize diverse biomass feedstocks. The water requirements of HTC need to be assessed to determine commercial feasibility. This current research work focuses on the effects on HTC of using recycled process water for multiple process cycles. Loblolly pine was treated in hot, compressed water at 200, 230, and 260°C for 5 min with a 5:1 water:biomass mass ratio. Liquid product was separated and recycled for reuse in HTC, nine cycles at 200 and 230°C and five cycles at 260°C. The solid products (biocarbon) were characterized by their mass yields, higher heating values (HHVs), and equilibrium moisture content (EMC), whereas in the liquid samples, total organic carbon (TOC) content and pH were determined. With successive recycling, biocarbon mass yield increases by 5–10% above the yield recorded for the initial cycle at each temperature investigated, whereas biocarbon HHV is essentially unchanged. The aqueous TOC is increasingly concentrated with the number of cycles and reaches an equilibrium. The EMC results suggest that the effects of recycling process water on hydrophobicity of the biocarbon are negligible. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 1309–1315, 2014
66 citations
TL;DR: In this article, a robust optimization approach for the synthesis of integrated biorefineries that deals with uncertainties in raw material supply and product demand is presented, which makes use of a single-step mixed integer nonlinear programming formulation.
Abstract: This work presents a robust optimization approach for the synthesis of integrated biorefineries that deals with uncertainties in raw material supply and product demand. This approach makes use of a single-step mixed integer nonlinear programming formulation, which is generated and solved with data from multiple biomass supply and product demand scenarios. Based on the optimized result, detailed allocation of biomass, intermediates, and final products can be determined. The optimal capacity of each process technology can also be found. An illustrative case study is then used to demonstrate the effectiveness of the robust optimization approach to determine the optimum integrated biorefinery configuration and capacity with consideration of uncertainties. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 384-389, 2013
65 citations
TL;DR: Observed differences in settling and bioflocculation of the two algae species were attributed to differences in algal cell size and shape, culture density, and exudate type, which may explain the often varied results observed with mixed cultures in algae wastewater ponds.
Abstract: The settling and bioflocculation of two strains of algae were investigated in the laboratory to provide insights to help improve algae settling in large-scale, algae-based wastewater treatment systems with simultaneous algae biofuel production. Energy-efficient algae harvesting methods are needed for cost-competitive production of biofuels from algae. The use of bacterially derived exudates (bioflocculation) is promising, but its use in high-rate algae pond (HRAP) wastewater systems has not yielded consistently reliable settling. The settling of the algae species Scenedesmus sp. and Chlorella vulgaris was investigated in the laboratory with and without cultures of the bacterium Burkholderia cepacia to investigate environmental effects on the settling of pure algal cultures and to examine possible bioflocculation by bacteria and bacterial exudates. Scenedesmus sp. and C. vulgaris responded in opposite ways to changes in operating conditions such as culture age and bioflocculation. Scenedesmus sp. settled better in later stationary growth stages, while C. vulgaris settled better in its early exponential growth phase. Scenedesmus sp. settling was improved by bioflocculation during early exponential and late stationary growth stages, but not during early stationary growth. Scenedesmus sp. responded better to B. cepacia cells plus filtrate (filtered bacterial broth) than to filtrate addition alone. In contrast, C. vulgaris settling was not improved via bioflocculation with neither the addition of B. cepacia cells nor filtrate at any growth stage. Longer contact time between the algae cells and bioflocculants improved the settling of Scenedesmus sp., but not the settling of C. vulgaris. Observed differences in settling and bioflocculation of the two algae species were attributed to differences in algal cell size and shape, culture density, and exudate type (i.e., capsular versus dissolved EPS). The widely different settling behavior of the two species of algae used in this research may explain the often varied results observed with mixed cultures in algae wastewater ponds. © 2013 American Institute of Chemical Engineers Environ Prog, 32: 946–954, 2013
56 citations
TL;DR: In this article, a multi-period mixed integer linear programming model focusing primarily on physical and temporal considerations of CO2 source-sink matching is proposed, which takes into account important temporal issues that may be encountered in planning the CCS system, particularly when the operating lives of sources and sinks do not completely overlap.
Abstract: Carbon capture and storage (CCS) involves capturing relatively pure carbon dioxide (CO2) from gaseous combustion products and storing it in various reservoirs. In this work, a multiperiod mixed integer linear programming model focusing primarily on physical and temporal considerations of CO2 source–sink matching is proposed. CO2 sources are assumed to be characterized by variable flow rates and fixed operating lives; on the other hand, CO2 sinks are characterized by finite injection rate and storage capacity limits, as well as earliest time of availability. The proposed approach takes into account important temporal issues that may be encountered in planning the CCS system, particularly when the operating lives of sources and sinks do not completely overlap. Two illustrative case studies are then solved to illustrate the use of the model to realistic CCS planning problems. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 411-416, 2013
56 citations
TL;DR: In this paper, the energy return on investment (EROI) and life cycle greenhouse gas (GHG) emissions for producing algal derived biodiesel and renewable diesel under different production pathways were modeled.
Abstract: Holistic evaluation via a life cycle based approach is critical for guiding the environmentally conscious development of emerging microalgal biofuel pathways. This study models the energy return on investment (EROI) and life cycle greenhouse gas (GHG) emissions for producing algal derived biodiesel and renewable diesel under different production pathways—consisting of a combination of algal cultivation, harvesting, extraction, and coproduct utilization scenarios. The results indicate that in the base-case scenario(s) the EROI for microalgae fuels range from 0.26 to 1.20 with GHG emissions ranging from 50 to 240 gCO2 equivalent/MJ-fuel depending on the choice of cultivation variables, coproduct utilization options, and processing technologies. In the improved scenario(s), algal fuels have an EROI ranging from 0.81 to 2.01 and GHG emissions ranging from 30 to 90 gCO2 eq./MJ-fuel. Furthermore, improved scenarios with favorable EROI and GHG emissions profile for microalgal biofuels are plagued with high technological uncertainty. This suggests that broad advances in algal technologies are required if algal fuels are to be competitive with other leading second generation and advanced biofuels. The choice of fuel conversion technology was found to have a comparatively small impact on overall life-cycle energy use and GHG emissions. Therefore, the choice of fuel product may be based on other criteria such as fuel storage stability and compatibility with transportation fuel infrastructure. © 2013 American Institute of Chemical Engineers Environ Prog, 32: 926–936, 2013
55 citations
TL;DR: Large quantity of oxygen evolves as a byproduct of photosynthesis in microalga cultivation, and effective deoxygenation mechanisms are required to maintain dissolved oxygen at a level that is not inhibitory.
Abstract: Large quantity of oxygen evolves as a byproduct of photosynthesis in microalga cultivation. As a result, dissolved oxygen of 100–400% air saturation or even higher is commonly observed in microalgal cultures. High concentration of dissolved oxygen may inhibit photosynthesis, cause photochemical damages to photosynthetic apparatus and other cellular components, result in reduction of cell growth or even culture collapse. Effective deoxygenation mechanisms are required to maintain dissolved oxygen at a level that is not inhibitory. This remains a significant challenge despite of the enormous technical advances in this field and information on large scale photobioreactors are scarce, which warrants systematic future studies, especially with controlled large-scale systems, in this important field. © 2013 American Institute of Chemical Engineers Environ Prog, 32: 982–988, 2013
52 citations
TL;DR: This is the first report of the utilization of Tequila's vinasses for the production of microbial oil by oleaginous yeast and this process could become a strategy to transform this highly contaminant wastewater into value added lipids.
Abstract: Oleaginous yeasts R. glutinis and C. curvatus were grown in batch culture on high strength distillery wastewaters from the Tequila production process (Tequila's vinasses). Both strains were able to grow either on decolorized charcoal or on naturally colored regular vinasses, with no extra nutrients addition. After 144 h of culture, lipids were accumulated up to 25.2 ± 1.98 and 27.02 ± 2.36% of cell dry weight, in C. curvatus and R. glutinis, respectively. At the same time, the chemical oxygen demand of vinasses (23,125 ± 5,557) was removed by C. curvatus and R. glutinis up to 78.98 ± 1.38 and 84.44 ± 3.52%, respectively. The fatty acid profile of the lipids accumulated by both strains was composed by myristic, palmitic, stearic, oleic, and linoleic. Linolenic acid was also found but only in the intracellular lipids of R. glutinis. This is the first report of the utilization of Tequila's vinasses for the production of microbial oil by oleaginous yeast. This process could become a strategy to transform this highly contaminant wastewater into value added lipids. © 2011 American Institute of Chemical Engineers Environ Prog, 32: 69–74, 2013.
TL;DR: In this paper, the influence of electrode distance and different electrode materials on power production and chemical oxygen demand (COD) removal using raw sago-processing wastewater were studied by varying it as 10, 12 and 15 cm.
Abstract: Microbial fuel cells (MFC) are hybrid bioelectrochemical devices, which generate electrical energy through the oxidation of organic matter catalyzed by bacteria. In this research, the influence of electrode distance and different electrode materials on power production and chemical oxygen demand (COD) removal using raw sago-processing wastewater were studied. Effect of electrode distance on MFC performance was carried out by varying it as 10, 12 and 15 cm. This study revealed that electrode distance of 10 cm resulted in increased power production with a voltage of 900 mV (millivolts), current of 9.0 mA (milliamps) at 100 Ω and COD removal of 94% compared to electrode distance of 12 and 15 cm. Graphite electrodes were good in power production compared to aluminum, stainless steel, and iron electrodes. Biofilm examination on the anode showed the presence of gram-negative rod (E. coli) bacteria which might have contributed for power production. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 390-395, 2013
TL;DR: A series of nanostructured CeO2/Clinoptilolite catalysts with different loadings of ceria were prepared by redox reaction followed by wet impregnation method and tested for oxidation of xylene as mentioned in this paper.
Abstract: A series of nanostructured CeO2/Clinoptilolite catalysts with different loadings of ceria were prepared by redox reaction followed by wet impregnation method and tested for oxidation of xylene The catalysts were characterized by XRD, FESEM, BET, FTIR, and TG-DTG analysis XRD data confirmed the formation of CeO2 as the crystalline phase with an average crystallite size of about 116 nm for three ceria loading of 10, 20, and 30% FESEM and size distribution analyses showed that nanocatalysts have nanometric particles with an average size of 3746 nm Specific surface analysis revealed that the synthesized nanocatalysts had large enough surface area for catalytic oxidation of p-xylene Furthermore, the results showed that the catalytic performance of the supported CeO2 catalysts was much higher than that of treated clinoptilolite, in particular, CeO2 (30%)/Clinoptilolite exhibited the highest conversion, 98% at 350°C It is observed that increasing both the xylene concentration and GHSV results in decreasing of the xylene conversion; however, even at higher concentrations of xylene (3000 ppm), the nanostructured catalyst has still enough destruction ability to reduce the pollutant A simplified reaction mechanism was proposed with respect to the behavior of adsorbed species on the catalyst surface to clarify the path through which the reaction components interact with each other © 2012 American Institute of Chemical Engineers Environ Prog, 32: 587–597, 2013
TL;DR: In this paper, acid and acid-base modified carbons were developed from walnut shell, and batch experiments were carried out to study their adsorption behaviors toward Cu(II) and Cr(VI).
Abstract: In this work, acid and acid–base modified carbons were developed from walnut shell, and batch experiments were carried out to study their adsorption behaviors toward Cu(II) and Cr(VI). Boehm titration data, elemental analysis, and FTIR studies suggested that the surface chemistry of the activated carbons was significantly changed by both acid and acid–base modification. N2/77 K adsorption isotherm methods revealed a significant decrease in SBET with acid treatment, a dramatic decrease was also observed in SBET in acid–base modified carbon. Batch equilibrium adsorption tests including the effect of pH of the solution, metal initial concentration, and temperature were conducted to evaluate the solids adsorption performance. The process kinetics was evaluated by pseudo-first-order and pseudo-second-order models, and the kinetics data agreed well with pseudo-second-order model. The applicability of the Langmuir, Freundlich, and D–R adsorption isotherms has been tested for the interpretation of equilibrium adsorption data. The results revealed that the acid–base carbon exhibited excellent copper (II) adsorption performance with a maximum adsorption capacity of 204.08 mg/g. The mean free energy value evaluated from D–R model indicated the adsorption of Cu(II) onto acid–base carbon involved chemical ion-exchange process. Thermodynamic studies illustrated adsorption of Cu(II) onto ACHN was endothermic and spontaneous. According to the overall results, the solution pH and the surface chemistry of the carbons were found to play a critic role in the uptake of copper ions from aqueous solutions rather than the carbon texture characteristics, while the adsorption of Cr(VI) closely related to the solution pH and its texture properties. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 688–696, 2013
TL;DR: In this paper, an activated carbon with high surface area was prepared from olive stone by microwave heating (MHOS) for the removal of a group of heavy metals Fe2+, Pb2+, and Cu2+ from synthetic wastewater.
Abstract: Activated carbon with high surface area was prepared from olive stone by microwave heating (MHOS) for the removal of a group of heavy metals Fe2+, Pb2+, and Cu2+ from synthetic wastewater. As a comparison, activated carbon was also prepared by conventional heating (CHOS) method. The effects of different reaction parameters, such as adsorbent dosage, contact time, stirring speed, and initial pH, on pollutant removal efficiency were determined. The microwave heating requires significantly lesser holding time as compared to conventional heating method to produce activated carbon of comparable quality, with higher yield. The BET surface area of carbon using microwave heating is noticeably higher than the conventional heating. Although the mesopore surface area of carbon is not vary significantly, the activation time and power consumption are considerably lower than the conventional heating rendering that the activation process via microwave is more economical than that via conventional heating. The adsorption capacity was found higher using microwave heating as compared with conventional heating. The adsorption equilibrium data were best represented by the Langmuir model and the adsorption capacity for Fe2+, Pb2+ and Cu2+ were found to be 62.50, 23.47, and 22.73 mg/g for MHOS; while 57.47, 22.37, and 17.83 mg/g for CHOS, respectively at pH 5, 3 h contact time and 200 rpm shaking speed. Regeneration studies showed that MHOS and CHOS could be used several times by desorption with an HCl reagent. A pseudo second-order model sufficiently described the adsorption kinetics for both carbons, which indicates that the adsorption process was controlled by chemisorption. Both carbons can be used for the efficient removal of Fe2+, Pb2+, and Cu2+ (>99%) from contaminated wastewater. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 1074–1085, 2014
TL;DR: In this paper, a gliding-arc plasma reformer for tar decomposition was developed to address the problem of coal tar in the thermal decomposition gas from pyrolysis and/or gasification process.
Abstract: The pyrolysis and gasification technology uses diverse waste resources, including biomass, urban solid waste, and sewage sludge, to produce synthetic gases for industrial use The tar in the thermal decomposition gas from the pyrolysis and/or gasification process, however, damages synthetic gas facilities and causes operation trouble In this study, a gliding-arc plasma reformer for tar decomposition was developed to address the aforementioned problem In addition, experiments were performed on the variables that affect the tar removal efficiency, and the optimal operation condition was presented The experimental variables included the steam flow rate, input benzene concentration, total gas feed rate, specific energy input (SEI), gas nozzle diameter, electrode length, electrode gap, and electrode shape With the increase in the total gas feed rate, the benzene decomposition efficiency slightly decreased, and with the increase in the SEI, the energy efficiency increased In the stable plasma discharge condition, a smaller nozzle diameter, a longer electrode gap, and a longer electrode length led to better decomposition and energy efficiencies © 2012 American Institute of Chemical Engineers Environ Prog, 32: 837–845, 2013
TL;DR: In this article, a seawater spray scrubber was set up and tested with focus to desulfurization of marine engine exhaust gas, and the results indicated that seawater performed better than distilled water, by exploiting its inherent alkalinity.
Abstract: A seawater spray scrubber was set up and tested with focus to desulfurization of marine engine exhaust gas. Experimental tests were carried out simulating typical exhaust conditions of a marine diesel engine burning heavy fuel oil and using real seawater. Different flue gas flow rates, seawater flow rates, and SO2 concentrations were tested. Liquid-to-gas ratios were in the range 1–10 × 10−3. A comparison between seawater and distilled water was also carried out to elucidate the effect of seawater alkalinity. In all conditions, the liquid phase was analyzed for alkalinity, pH, and sulfate content before and after the tests. Finally, the spray droplet size distribution was measured as a function of liquid flow rate.
Experimental results indicated that seawater performed better than distilled water, by exploiting its inherent alkalinity. The desulfurization performance was improved by increasing the liquid flow rate and the gas residence time and by decreasing the SO2 concentration. SO2 capture efficiencies up to 93% were measured under the present operating conditions. The experimental data were further compared with calculations performed with an available model for SO2 absorption in fall-down droplets within a simple plug-flow reactor. Model calculations were carried out by using all parameters' values as measured in the present experimental campaign. Model results well fit the experimental data, even if a slight underestimation of the desulfurization efficiency is reported. The likely reasons are the assumed plug flow of gas as well as the neglected contribution to SO2 capture by water film falling at the wall. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 1179–1186, 2013
TL;DR: In this article, two case studies were carried out: Electrocoagulation (EC) of a reactive textile dye solution and a textile wastewater Stainless steel (SS) and iron (Fe) electrodes were used as sacrificial electrodes in parallel connection modes.
Abstract: In this study, two case studies were carried out: Electrocoagulation (EC) of a reactive textile dye solution and a textile wastewater Stainless steel (SS) and iron (Fe) electrodes were used as sacrificial electrodes in parallel connection modes Effects of pH, current density, and operating time on performance of EC were investigated Optimum parameters obtained from dye experiments were applied to treatment of the textile wastewater According to the experimental results, SS electrodes were found to be superior compared with Fe electrodes for treatment of both the dye and the textile wastewater By using SS electrodes, the textile wastewater was electrocoagulated successfully with 897% of COD, 912% of TOC, 903% of turbidity, and 941% of TSS removal efficiencies as well as 243 kWh/m3 of energy and 005 kg/m3 of electrode consumptions, 1061 kg/m3 of sludge production, and 062 $/m3 of total operating cost © 2011 American Institute of Chemical Engineers Environ Prog, 32: 60–68, 2013
TL;DR: In this paper, the adsorption enthalpy was −16.37 kJ/mol, the Gibbs-free energy was −28.73 to −27.04 kJ /mol, and the entropy was about 35 J mol−1 K−1, which showed that the adaption process was both exothermic and spontaneous.
Abstract: Attapulgite/activated carbon (ATP/AC) nanocomposites were prepared by the calcination of ATP and rice hull. ATP/AC nanocomposites were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy analysis. The kinetic and thermodynamic parameters of the adsorption of cationic yellow X-GL (CY) in aqueous solution on ATP/AC composites were studied. During all experiments, CY concentration was determined by UV–vis spectrophotometer. Research on the thermodynamic behavior indicated that the adsorption of CY obeyed the Langmuir isotherm model. The adsorption enthalpy was −16.37 kJ/mol, the Gibbs-free energy was −28.73 to −27.04 kJ/mol, and the entropy was about 35 J mol−1 K−1, which showed that the adsorption process was both exothermic and spontaneous. The kinetic parameters showed that absorption of CY on ATP/AC composites was best described by pseudo-second-order kinetics. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 655–662, 2013
TL;DR: In this paper, the use of restaurant waste for production of ethanol was investigated, and the results showed that using waste heat from restaurant waste could be used to drive flash vaporization to purify ethanol.
Abstract: This study focuses on the use of restaurant waste for production of ethanol. Food wastes (corn, potatoes, and pasta) were converted to ethanol in a two-step process: a two-part enzymatic digestion of starch using α-amylase and glucoamylase and then fermentation of the resulting sugars to ethanol using yeast. Because of the low initial composition of starch in the food waste, low ethanol concentrations were achieved: at best 8 mg/mL ethanol (0.8% by mass). Ethanol concentration increased with increasing enzyme dosage levels. Calculations were conducted to evaluate whether waste heat from restaurant waste could be used to drive flash vaporization to purify ethanol. If the solution produced by fermenting food waste is flashed at a temperature of 99.7°C, 77% of the ethanol is recovered in a vapor stream with 1.14 mol % ethanol (2.87 mass %). Waste heat could provide over a third of the energy for this vaporization process. If 4 mol % ethanol could be produced in the fermentation step by increasing the initial starch content in the waste solution and improving the fermentation process, then a single flash at 98.9°C will recover nearly 99% of the ethanol, giving a mass concentration of ethanol of 10.3%, which is similar to that achieved in industrial grain fermentation. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 1280–1283, 2013
TL;DR: In this paper, the adsorption of Pb, Zn, and Cd(II) in single and multi-element systems onto raw, acid-activated, and aluminum-pillared Tunisian smectite (RSM, ASM, and Al-SM, respectively) was investigated as a function of pH and species concentrations.
Abstract: Polluted water may contain more than one heavy metal species. Consequently, the behavior of a particular metal in a water system may be affected by the presence of the others. In this study, the adsorption of Pb(II), Zn(II), and Cd(II) in single and multi-element systems onto raw, acid-activated, and aluminum-pillared Tunisian smectite (RSM, ASM, and Al-SM, respectively) was investigated as a function of pH and species concentrations. Physico-chemical, Textural, XRD, and SEM analyses were investigated onto three different clay materials. The Al-SM samples, which were calcined at 450°C, presented the best results for the surface areas (267 m2/g) and for the Pb(II) adsorption capacity (75.35 mg/g). For instance, once they contained in a batch system at 25°C, pH 6, they retained more heavy metals due to their textural characteristics. The selected order of adsorption Pb(II) > Zn(II) > Cd(II) showed the importance of the competitive phenomenon onto clay materials' pores adsorption. At a higher pH, the precipitation phenomenon was possible. The two-site, Langmuir isotherm also yielded the best fit for Pb(II) and Zn(II) adsorption on RSM and Al-SM in binary and ternary solute-systems. However, it failed in the case of Pb(II), Zn(II), and Cd(II) on ASM, which had less heterogeneity than other samples. The obtained results can serve as baseline data to design an adsorption process using this local adsorbent for the wastewaters rich in heavy metals. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 229-238, 2013
TL;DR: In this article, the composition of syngas and process water from supercritical water gasification of macroalgae has been investigated and the potential for using the process water as a source of nutrients for microalgae cultivation was assessed.
Abstract: The composition of syngas and process water from the supercritical water gasification of macroalgae has been investigated. The potential for using the process water as a source of nutrients for microalgae cultivation was assessed. Saccharina latissima, harvested across the four seasons was gasified in a batch reactor at 500°C and 36 MPa to assess the influence of biochemical content and ash on syngas composition. In addition, summer harvests of four different macroalga were gasified with ruthenium catalyst (Ru/Al2O3). The molar yields of hydrogen and C1-C4 gases from S. latissima increased by 30% in the presence of Ru/Al2O3 with a maximum gasification efficiency of 92% compared with work without these catalysts. Following a series of dilutions, the process water from catalyzed gasification of S. latissima was used in cultivation trials of Chlorella vulgaris and compared to standard growth media. The results indicate the potential to recover process waters from gasification of macroalgae in nutrient management for microalgae.
TL;DR: In this paper, pyrolusite-modified activated carbons were used to develop effective adsorbents for the removal of Cu(II), Pb(II, and Cd(II) metal ions from aqueous solution.
Abstract: Activated carbons were prepared from sewage sludge by chemical activation with pyrolusite addition to develop effective adsorbents for the removal of Cu(II), Pb(II), and Cd(II) metal ions from aqueous solution. The transition metal compositions in pyrolusite were demonstrated to exhibit catalytic alike effects on the formation of pore structures, the carbon with pyrolusite addition showed 11.30% higher BET surface area than the one without pyrolusite addition. The XRD pattern showed the presence of MnO2 on the carbon surface by pyrolusite addition, and the accumulation of metal ions can also be seen on the carbon surface after adsorbing metal ions. The analyses of Boehm titration data, FTIR and XPS suggested that the surface chemistry of the activated carbons were modified by pyrolusite addition. Some acid functional groups (hydroxyl and carboxylate) were introduced to the carbon surface, which were responsible for the enhanced removal of Cu(II), Pb(II), and Cd(II). Adsorption experiments showed that the removal rate toward Cu(II), Pb(II), and Cd(II) were increased 30.2, 15.7, and 2.95% with pyrolusite modification, respectively. The adsorption selectivity in multi-ions solution was also studied for further understanding the adsorption affinities of pyrolusite modified adsorbents. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 1066–1073, 2013
TL;DR: In this paper, a quartz crystal microbalance (QCM) sensor was prepared for real-time monitoring of 17β-estradiol (E2) in water samples, through the attachment of E2 imprinted nanoparticles, synthesized by mini-emulsion polymerization, on the gold surface of QCM sensor.
Abstract: The 17β-estradiol (E2), natural steroid hormone, is one of the most potent endocrine disrupting compounds even at ng L−1 levels. Its rapid, selective and sensitive detection is intensively required. In this study, quartz crystal microbalance (QCM) sensor was prepared for real-time monitoring of E2 in water samples, through the attachment of E2 imprinted nanoparticles, synthesized by mini-emulsion polymerization, on the gold surface of QCM sensor. QCM sensor surface was characterized by atomic force microscopy (AFM), ellipsometer, and contact angle measurements. The specificity of the QCM nanosensor was shown by competitive adsorption of E2, stigmasterol and cholesterol. The results showed that QCM nanosensor has high selectivity and sensitivity for E2 even in a wide range of 3.67 nM–3.67 pM. The detection and quantification limits were calculated as 613 fM and 2.04 pM, respectively. According to the results, the proposed molecular imprinted QCM nanosensor is promising cost-friendly alternative for quantification of E2 from ground water. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 1164–1169, 2013
TL;DR: In this article, the uptake of arsenic from contaminated water using acetate functionalized zinc oxide (ZnO) nanomaterials was investigated and it was concluded from the study that ZnO of various sizes (6-60 nm) have been synthesized following different wet chemical routes.
Abstract: This research article deals with the uptake of arsenic from contaminated water using acetate functionalized zinc oxide (ZnO) nanomaterials. The ZnO nanomaterials of various sizes (6–60 nm) have been synthesized following different wet chemical routes. The arsenic removal efficacy of acetate functionalized ZnO nanomaterials was carried out at different pH and time interval. It has been concluded from the study that ZnO nanomaterials (<60 nm) prepared by zinc acetate precursor effectively removes arsenic, while ZnO of same size prepared from zinc chloride, zinc nitrate, zinc sulphate precursor could not remove arsenic considerably. However, ZnO of same size synthesized using other than zinc acetate precursor and functionalized with acetate ions removes arsenic effectively. It is also proposed that acetate ions over the surface of ZnO adsorb arsenic by an oxo-coordination mechanism and purifies water up to permissible limits of arsenic at pH 5.8–6.8. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 1023–1029, 2013
TL;DR: In this paper, the influence of air-flow rate on volumetric productivity of the micro alga was evaluated and the lipid content and fraction distribution of the biomasses produced under nutrient sufficient and nitrogen-starved conditions were analyzed and the neutral lipid fraction was fully characterized.
Abstract: The energy balance of microalgal biodiesel production is rarely considered. Besides, the actual potential of microalgae as triglyceride producers is often overestimated. This work was aimed at investigating these critical aspects using the marine eustigmatophyte Nannochloropsis sp. F&M-M24, a promising oil producing strain, as model organism and the “Green Wall Panel” as culture system. First, the influence of air-flow rate on volumetric productivity of the microalga was evaluated. At low and medium irradiances, no significant differences in productivity occurred at the three different mixing rates tested, while at high irradiances an increase in the air-flow rate resulted in significantly higher volumetric productivities. These results allow to foresee a strategy of air-flow rate tuning in accordance to radiation, that may lead to substantial energy savings and, consequently, to more favorable energy and economic balances in the cultivation process. Second, the lipid content and fraction distribution of the biomasses produced under nutrient sufficient and nitrogen-starved conditions were analyzed and the neutral lipid fraction was fully characterized. Finally, the alga was grown in bubbled-tubes using a culture medium prepared with an industrial wastewater, to evaluate its ability to use a free of charge source of nutrients, the exploitation of which may improve biomass production economics. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 846–853, 2013
TL;DR: In this article, the effect of operational parameters on the PEF process such as applied current, initial pH, flow rate, initial Fe3+ concentration and initial dye concentration was investigated.
Abstract: The electrochemical treatment of dye solution containing C.I. Direct Red 23 (DR23) has been studied under recirculation mode with an UV irradiation of 15 W. Decolorization experiments were performed in the presence of sulfate electrolyte media at pH 3.0 with carbon nanotube-polytetrafluoroethylene (CNT-PTFE) electrode as cathode. A comparison of electro-Fenton (EF) and photoelectro-Fenton (PEF) processes was carried out for decolorization of DR23 solution. Color removal efficiency was 66.22% and 94.29% for EF and PEF processes after 60 min treatment of 30 mg/L DR23, respectively. The effect of operational parameters on the PEF process such as applied current, initial pH, flow rate, initial Fe3+ concentration and initial dye concentration was investigated. Results indicated that the optimal conditions for decolorization process were applied current of 0.2 A, flow rate of 10 L/h, pH = 3, initial Fe3+ concentration of 0.05 mM and initial dye concentration of 10 mg/L. An artificial neural network (ANN) model was developed to predict the decolorization of DR23 solution, which provided reasonable predictive performance (R2 = 0.958). © 2012 American Institute of Chemical Engineers Environ Prog, 32: 557–563, 2013
TL;DR: The potential of geothermal water as an alternative water source was tested for the production of algal bio-fuels and the highest bio-crude oil yield was obtained with a Dunaliella Tertiolecta sample cultivated in a regular tap water medium.
Abstract: In this research, the potential of geothermal water as an alternative water source was tested for the production of algal bio-fuels Two algal species, Chlorella Sorokiniana and Dunaliella Tertiolecta were cultivated in a photo-bioreactor with tap water and geothermal water The freshly harvested wet algae samples were used to produce bio-crude oil samples in a high pressure reactor under a hydrothermal liquefaction (HTL) condition (300°C, 90 bar and solid loading of 9 wt %) Supernatant water obtained after harvesting was used in the HTL experiments A thermogravimetric analyzer was used to determine the moisture and ash content of the algal biomass It was observed that the bio-crude oil yield could be higher than the lipid content in the algae The GC-MS analysis of biocrude oils showed the contribution of both lipids and proteins to the yield of biocrude The highest bio-crude oil yield of 30 wt % (of dry algae) was obtained with a Dunaliella Tertiolecta sample cultivated in a regular tap water medium A similar amount of biocrude was achieved with a geothermal water medium Using a calorie meter, the high heating values of bio-crude oils were measured and these values ranged from 36 to 38 MJ/kg, which are close to that of crude petroleum oils © 2013 American Institute of Chemical Engineers Environ Prog, 32: 910–915, 2013
TL;DR: In this paper, the authors compared the various waste management strategies in Tabriz, Iran, and selected the best one by a decision-making method based on the Multi Criteria Analysis (MCA).
Abstract: This research compares the various waste management strategies in Tabriz, Iran, and selects the best one by a decision-making method. Selection the best strategy is conducted based on the Multi Criteria Analysis (MCA). In this regard, the Analytic Hierarchy Process (AHP), a mathematical technique for multicriteria decision making, and the Multi Criteria Analysis which is a developed decision-making tool have been used. This research compares four waste management strategies including various practices such as Source Separation (SS), Biological and Mechanical Treatment (BMT), Refused Derived Fuel (RDF), Incineration and Landfilling. There are mainly eight criteria weighted based on the AHP method to select the best strategy. These criteria consist of required land for waste management, energy recovery, investment and operation costs, income to cost ratio (benefit), environmental impacts, and complexity of implementation and operation of process, public acceptance, and recycling materials. The results of this study demonstrate that the first strategy provides the best solution for waste management which includes SS, Compost production, BMT, RDF and Landfilling. Finally, study suggests various solutions that minimize environmental impacts and social cost and improve the public acceptance. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 810–817, 2013
TL;DR: In this paper, the optimization of the methanol from glycerol and its integration in the production of biodiesel from algae is presented, where steam reforming and autoreforming are evaluated.
Abstract: In this article, we present the optimization of the production methanol from glycerol and its integration in the production of biodiesel from algae. We propose a limited superstructure where the glycerol from biodiesel is first reformed for which steam reforming and autoreforming are evaluated. The gas obtained is cleaned up and its composition is adjusted in terms of the ratio CO/H2 using three possible alternatives (bypass, PSA and water gas shift). Next, the removal of CO2 is performed by means of PSA and the syngas is fed to the methanol synthesis reactor and the products obtained are separated. This synthesis is coupled with the production of biodiesel from algae using heterogeneous catalyzed reaction based on previous results. The optimization of the system is formulated as a Mixed Integer Nonlinear Programming (MINLP) that is solved for the simultaneous optimization and heat integration of the production of biodiesel with recycle of methanol followed by water integration. The best process involves the use of autoreforming for a production cost of $0.66 gal−1, 3.65 MJ/gal of energy consumption and water consumption of 0.79 gal/gal. The integrated process is $0.2 gal−1 more expensive than the one that directly uses methanol but reduces in more than half the dependency of the process on fossil fuels. © 2013 American Institute of Chemical Engineers Environ Prog, 32: 891–901, 2013