Iranian Journal of Chemistry and Chemical Engineering
Volume:41 Issue: 8, Aug 2022

Electrospun NanoFibers (ENFs) were fabricated from the mixture of Cellulose Acetate (CA), chitosan (CHI), and poly (ethylene oxide) using an acetic acid solution. The impact of CA/CHI ratio (0.5, 1, 1.5 wt %), CHI/PEO ratio (1, 1.5, 2 wt%), Sodium Dodecyl Sulfate (SDS) (0, 1.5, 3% w/w) and ammonium oxalate (3%, w/w) on the diameter, tensile strength, elongation, and porosity of the ENFs were optimized using Response Surface Methodology-Central Composite Rotatable Design (RSM-CCRD). The results revealed that ENFs were formed of non-woven fibers with a maximum diameter of 113 nm. Second-order polynomial models with high R2 values (0.996–0.99) were developed using Cubic analysis. The optimum condition was identified to be at the compounded level of CA/CHI 1.5 wt%, CHI/PEO 1 wt%, and SDS 3% (w/v). At the best point, the diameter, surface tension, elongation, and porosity of the fabricated ENFs were 96.07 nm, 0.054 N/mm2, 13.09 mm, and 52.29 respectively.

Malachite Green (MG) dye belongs to the triphenylmethane class and exhibits a noxious impact on the living being. Thus, it’s being immensely important to remove it from the environment matrix. Herein, the sonochemical synthesized adsorbent material -pyrophanite-MnTiO3/TiO2 NanoParticles (NPs) was utilized to expel the commercial Malachite Green (MG) dye from the solution. The adsorption efficacy data indicate the maximum removal of MG (90.2%) is obtained for the NPs calcinated at 1000 °C (MT1). The optimized adsorption material (MT1) is characterized by using different techniques including XRD, FE-SEM, EDX, FTIR, BJH, and BET. The XRD analysis indicates the formation of divergent phases viz. rutile TiO2 and MnTiO3. The FE-SEM indicates the formation of a nano-rod-like structure. The average size and percentage of void space of MT1 NPs are evaluated by using IMAGE J software. The hysteric loops obtain from BET and BJH plots reveal the existence of type H3 hysteresis indicating the MT1 NPs exhibit mesoporous structure. The surface area, pore volume, and pore size are 61.245 m2/g, 0.139 cm3/g, and 2.0178 nm respectively. The pH, dye concentration, and temperature of the solution are optimized for the removal of MG by using MT1 NPs. Further, the adsorption isotherms, kinetics studies, and intra-particle studies indicate that monolayered second-order diffusion occurs onto the surface of MT1 NPs. The adsorption process is endothermic, thermodynamically driven, and accompanied by an increase in entropy.

Determination of cholic acid concentration is a useful method to monitor liver diseases. We propose a rapid and simple method for measuring cholic acid. The development of a cholic acid electrochemical biosensor is described that is based on the modification of glassy carbon electrode surface using a mixture of carboxylated multiwalled carbon nanotube and titanium dioxide nanoparticles in chitosan solution and immobilization of 3α-hydroxysteroid dehydrogenase. The modification process of the sensing surface was characterized by Fourier transform infrared spectroscopy, Energy Diverse X-ray Spectrometry, Field Emission Scanning Electron Microscopy, and voltammetry techniques. A good correlation was demonstrated between cholic acid concentration and the peak currents in the presence of nicotinamide adenine dinucleotide. Using a carboxylated multiwalled carbon nanotube and titanium dioxide nanoparticles for electrode modification showed more effective area than an unmodified electrode at optimum pH of 6. Two linear ranges were obtained at 7.1 - 42.7, and 70.9-476.2 nM of cholic acid. Also, the detection limit was 6 nM and the sensitivities of the two ranges were obtained 956.9 and 28.7 µA/µM.

Nifedipine is a dihydropyridine derivate calcium channel blocker, suitable as first-line therapy for patients with hypertension. When blood pressure is high, nifedipine will prevent calcium to pass into cardiac and vascular smooth muscle cells. Nonetheless, nifedipine has a low elimination half-life that makes nifedipine needs to be consumed repeatedly to enhance its bioavailability, and thus, gives rise to nifedipine concentration in blood. Hence, a controlled drug delivery system is needed wherein the drug could be delivered at the desired time. One of the options in drug delivery is drug microencapsulation using a polymer as a coating material. In this study, nifedipine was coated with poly(D-L lactic acid) (PDLLA)/poly(ethylene glycol) (PEG) polyblend also polycaprolactone (PCL)/PEG polyblend using solvent evaporation technique. The effect of the mass composition of the polyblend and molecular weight of PEG on the encapsulation efficiency and drug release was investigated. Microcapsules with the variation of PDLLA/PEG and PCL/PEG composition and PEG molecular weight had an encapsulation efficiency of about 90%-92%. Microcapsules with PDLLA/PEG600 (9/1) exhibited the highest drug release of 43.2% with an encapsulation efficiency of 91.96% whereas microcapsules with PCL/PEG400 (7/3) had the highest drug release of 44% with an encapsulation efficiency of 90.64%.

A blood Serum Separator Tube (SST) containing separator gels is widely used for clinical laboratory tests. This study aims to optimize the condition of a newly formulated serum separator gel and to investigate the impact of this gel on some clinical chemistry assays. Design Expert statistical software was used to predict the optimum condition of filler content and to achieve a desired density range. The newly developed polymeric (silicone oil) gel was prepared by using 8 and 10 phr di cumyl peroxide and silica in formulation, respectively. The results reveal that this new gel shows thixotropic behavior with the desired density of 1.05 g/mL. Afterward, a total of 22 clinical assays was performed on samples that were collected in newly developed gel-based serum tubes and commercial SSTs with and without separator gel. In all selected clinical assays, the results of samples collected in SSTs with newly developed gel and commercial gels were more or less the same. Moreover, the experimental data shows this new gel interacts less with blood samples in comparison with commercial gel tubes in some tests. Consequently, the new SST gives satisfactory performance and minimum interference in selected clinical assay results.

Hydrogels have excellent biocompatibility and are widely used in biomedical applications. However, it is still a challenge to build a hydrogel with outstanding mechanical properties and multiple functions. In this study, a polyacrylamide (PAM) hydrogel with a uniform network structure was achieved through an UltraViolet (UV)-responsive organic crosslinking agent and a higher mechanical strength PAM-Ag+ hydrogel was designed through the introduction of silver ion by metal coordination interaction. Various contents of N'N-bis(acryloyl)cysteamine (BACA)  as cross-linker, acrylamide (AM) as a monomer, and Irgacure 2959 as initiator were investigated to have an optimal combination of high strength. Thus, the PAM-Ag+ hydrogel exhibited excellent adhesive behavior that could be fixed to the human forearm and any part of the skin, such as the finger and elbow joint. In addition, the properties and biocompatibility evaluations of the tough hydrogel in medical wound dressing were investigated. Meanwhile, these results showed that PAM-Ag+ hydrogels possess high stretchable (2600%) and mechanical robust (2.55 MPa) properties. Excitingly, the release of colchicine (Col) of more than 95% in 48 h demonstrated the hydrogel's high potential in medical dressing and drug release applications by virtue of the excellent moisture retention, permeability, water tightness, swelling ratio, and biocompatibility.

The reaction of 4-phenylazo-phenylamine and benzaldehydes with dimethyl phosphite resulted in three new α-azoaminophosphonates in excellent yields. Molecular identification of synthesized compounds were probed using NMR, FT-IR, and elemental analysis techniques. The single crystal X-ray diffraction studies were used to determine the molecular structure of dimethyl [(4-methoxyphenyl ((4-phenyl diazenyl) phenyl) amino) methyl] phosphonate. The synthesized molecule was crystallized in the monoclinic space group P21/c with a=11.213(2), b=19.205(4), c=11.429(2) Å, β = 116.95(3), V= 2193.8(8) Å3. Density functional theory calculation with B3LYP/6-311++G (2d, 2p) basis set has been used to determine geometry parameters and harmonic vibrational frequencies. The optimized geometrical parameters calculated by density functional theory show satisfactory agreement with experimental values.

In this investigation, a series of thiophene-based flavone Schiff base derivatives were synthesized starting from phloroglucinol. Initially, the acetophenone derivative of phloroglucinol, 2-hydroxy-4,6-di-O-methyl phloroglucinol (3) was prepared by acetylation followed by selective O-methylation. Later, compound 3 was condensed with thiophenealdehyde to obtain respective thiophene chalcone and was cyclized with I2/DMSO to get the corresponding thiophene-based flavones intermediate. In the final stage, the titled Schiff base derivatives were obtained by formulation at the 8th position of the flavone skeleton followed by condensation with various amines. All the synthesized compounds were tested for their antibacterial and anticancer activities. Among the tested compounds, compound 8h (3-Cl, 4-NO2) showed good to excellent antibacterial activity on four microorganisms. Further, the compounds were compared with corresponding Schiff’s base analogs of furan-flavone Schiff's bases.

In this research, the potential and capability of carbon NanoCones (NC) as an Olaparib carrier in the gas phase has been investigated using quantum mechanical calculations. The adsorption mechanism was studied systematically using a DFT approach and the basis sets of B3LYP/6-311+G, 6-311++G(d), and 6-311++G(d,p). According to the calculations data, the drug can be transported and carried by carbon nanocone with strong and powerful chemical adsorption with a suitable and high energy value. Coating Olaparib onto carbon nanocones will lead to more disability and reduced toxicity of the drugs in the human body, resulting in greater bioavailability. Chemical parameters like softness, hardness, chemical potential, and electrophilicity of olaparib have been calculated showing that olaparib has potent chemical activity in biochemical medium.

This study reports the synthesis of Co(II), Fe(II), Pd(II), and Ru(II) complexes with Schiff base obtained by the condensation of 2-amino-methyl-4,5,6,7-tetrahydrothieno[2,3-c]pyridine-3-carboxylate with salicylaldehyde. The characterization of the ligand and its complexes was arranged and studied by FT-IR, UV-Vis., 1H and 13C NMR, microanalyses (C, H, N, S), X-Ray Diffraction (XRD) analysis, magnetic susceptibility, mass spectra, and ThermoGravimetry Analysis (TGA) and further was screened for antimicrobial, antioxidant and antiradical activities. The antioxidant activity of the ligand and its metal complexes was examined by using different methods including the total antioxidant activity method, total reduction method, and DPPH. The antimicrobial activities of Schiff base and metal complexes were investigated on bacterial and fungal strains. DNA cleavage experiments of metal complexes with supercoiled pBR322 DNA were detected by gel electrophoresis in the being of H2O2.

Quinolinyl triazole derivatives 4-(4-chlorophenyl)-5-{[(5-chloroquinolin-8-yl)oxy]methyl}-2,4-dihydro-3H-1,2,4-triazole-3-thione (4-4CPCQMT), 4-(3-chlorophenyl)-5-{[(5-chloroquinolin-8-yl)oxy]methyl}-2,4-dihydro-3H-1,2,4-triazole-3-thione (4-3CPCQMT) and 4-(4-fluorophenyl)-5-{[(5-chloroquinolin-8-yl)oxy]methyl}-2,4-dihydro-3H-1,2,4-triazole-3-thione (4-4FPCQMT) are of great importance in pharmaceutical chemistry such as antifungal, antituberculosis, anticonvulsant, anticancer activities, etc. The present work highlights the synthesis of the quinolinyl triazole derivatives ((4-4CPCQMT, 4-3CPCQMTand 4-4FPCQMT). The substituents present and the compounds 4-4CPCQMT, 4-3CPCQMTand 4-4FPCQMT were confirmed by FTIR and NMR spectroscopy. These compounds having many reactive sites were used as inhibitors for mild steel in 1.0 M hydrochloric acid medium at 303 to 323K. An inhibition study was done by electrochemical measurement. The prevention efficiency is in the order 4-4FPCQMT>4-4CPCQMT>4-3CPCQMT. The surface morphology of the mild steel surface was done using SEM, AFM, and, EDX.

In boilers and hot water heating systems, hydrazine is used as one of the powerful reducing agents for eliminating oxygen. Due to the toxicity and carcinogenicity of this material, a suitable replacement named diethylhydroxylamine (DEHA) can be used. DEHA has low acute toxicity and animal tests do not show mutagenic activity. In this study, hydrazine, and DEHA as deoxygenation materials were used in boilers of Tarasht power plant in Iran (Tehran). In different months (May to November), deoxygenation was examined by these two substances. The oxygen removal value of DEHA was equal to hydrazine and sometimes far better than it. The rate of deoxygenation reaction of DEHA was 40 ppb in most months of the year, but the number of peaks in hydrazine was greater (2 peaks with 50 ppb and 1 peak with 60 ppb). Hydrazine analysis is time-consuming, as well as pollutes the environment. On the other hand, DEHA of tests was completed sooner. Also, DEHA as an economical material with low toxicity can be a good alternative to hydrazine in boilers. This material can prevent boiler corrosion by oxygen removal.

Heavy metal contamination has become a global issue. In this study, the concentrations of arsenic (As), lead (Pb), nickel (Ni), zinc (Zn), chromium (Cr), copper (Cu), and cadmium (Cd) in the air of the Tehran metropolis were measured. Also, cancer and non-cancer risk assessments were performed to quantify the rate and effect of infection on health. Sampling was done every month from April 2019 to March 2020 for one year. Sampling points in the whole city were determined based on Municipality 22 districts of Tehran. The concentrations of the studied heavy metals in nanogram per cubic meter ( /m3) showed the following order: Zn (106.22) > Pb (31.65) > Cu (16.38) > As (5.83) > Ni (5.77) > Cr (5.62) > Cd (5.36). The results indicate that in non-carcinogenic risk assessment, the hazard index (HQ) of As (8.20E+00), Ni (8.67E+00), Cr (1.14E+00), and Cd (1.13E+01), and the total hazard index (HI) of 2.94E+01 are above the safe level of 1, indicating the potential threat of non-carcinogenic diseases through the inhalation of air. According to USEPA guidelines, the risk of carcinogenicity is unacceptable for Cr, acceptable for As, Cd, and Ni, and without any significant health effects for Pb. The total carcinogenic risk of metals was 1.10E-02, being in the high-risk range. Therefore, exposure to heavy metals through air inhalation increases the risk of cancer and mortality, so 61 people annually suffer from various cancer types due to the inhalation of air. The Monte Carlo simulation uncertainty results also confirm those of non-carcinogenic and carcinogenic respiratory risk analysis of heavy metals in the air. The obtained results indicate the need for improving the air quality in Tehran needs and taking into account the health risks to humans via inhalation exposure to heavy atmospheric metals.

In this research, several Ni/Y catalysts were prepared to perform kerosene aromatization. The Na+ cation of Y zeolite was exchanged with NH4+, and then Ni/HY catalysts were synthesized through the precipitation-deposition method. The properties of the samples were characterized by XRD, EDX, and BET. In addition, the Response Surface Method in combination with a three-factor Central Composite Design was employed to optimize the conditions of the reaction over Ni/HY catalysts. The three independent variables were: Ni content of the catalysts, reaction time, and temperature. Analysis of aromatic yield as the response was performed to survey the importance of these independent variables. Results of numerical optimization revealed that maximum operation conditions were 5%Ni-loading at a temperature 450ºC and a reaction time of 120min, in which aromatic yield was 55.74%. This was in agreement with the predicted aromatic content (52.62%) in this condition. Acceptable value for correlation coefficient (R2= 0.989), root mean square error (RMSE = 0.77), and standard error of prediction (SEP = 1.82) was obtained. These low values confirmed the adequacy and statistical significance of the model to predict an adequate response.

Recently, the demands for biodegradable and renewable materials for several eco-sustain applications have increased tremendously. This rise in demand is connected to the growing environmental concerns over the extensive use of synthetic and non-biodegradable plastic packaging and the dumping of plastic waste in landfills. Biodegradable bioplastics are polymers that are mineralized into carbon dioxide, methane, water, inorganic compounds, or biomass by specific microorganisms by enzymatic action. As a result, they could be a viable and environmentally friendly alternative to petrochemical plastics.  Bioplastic delivers precisely as per demand exhibiting several advantages: lower carbon footprint, energy efficiency, non-hazardous, stable, cost-efficient, and eco-friendly. Herein, a major focus is given to the discussion of bioplastic production from various sources, their type, and the role of additives to strengthen their chemical and physical properties.  This review article's goal is to provide information about bioplastic synthesis concerning the recycling of bioplastics, thermoplastic biocomposites, and their blends with a special focus on the mechanical recycling of bio-based materials. Additionally, the utilization of these bioplastics in various industries such as the food packaging industry, and the automotive industry has been enlightened.

Hyaluronic acid (HA), as a high-value-added biological product, is one of the most widely used biopolymers in industry and medicine. This study aimed to increase HA production by carefully investigating the effect of glucose concentration, type and concentration of nitrogen source in batch culture, and control of glucose concentration in fed-Batch culture on HA production. The effect of two different nitrogen sources of hydrolyzed casein and tryptone soy broth on HA production was investigated in batch cultures of Streptococcus zooepidemicus. Then, the effect of glucose concentration on HA production was studied in batch and fed-batch cultures. Under optimal conditions, including hydrolyzed casein 20 g/L and an initial glucose concentration of 30 g/L in batch culture, 4.4 g/L HA was obtained. Also, constant feeding of 30 g/L of glucose increased HA production to 5.8 g/L. This amount is one of the highest HA production values ever reported in fed-batch cultures at a constant feeding rate. Weakening of the glycolytic cycle and slowing down the cell growth rate affect the increase of HA production. Also, controlling the concentration of glucose as a source of energy and carbon in the cells by the fed-batch culture can be directed the cell pathway to more hyaluronic acid production and higher yield.

In this study, the optimum conditions of the dissolution of colemanite (2CaO.3B2O3.5H2O) ore in ammonium bisulfate (NH4HSO4) solution were examined by using Taguchi fractional design methods, and an alternative reactant for boric acid extraction process from colemanite ore was specified. The studied parameters and optimum conditions for the dissolution process were the following; reaction temperature: 50˚C, solid/liquid ratio: 0.1 g/mL, particle size: -80 mesh, mixing speed: 600 rpm, and reaction time: 25 minutes. Particle size, mixing speed, and reaction time had the most significant effect on dissolution when compared to the others. Accordingly, the dissolution efficiency of colemanite was found to be 99.54% under optimum conditions and using NH4HSO4 as a solvent enabled the selective separation of boron from the colemanite ore. The ammonium sulphate formed as a by-product was converted into NH4HSO4 by the addition of the appropriate stoichiometric amount of sulfuric acid and fed back into the dissolution vessel.

The kinetics of methane hydrate formation in the presence of tetra n-butylammonium chloride (TBAC) and sodium dodecyl sulfate (SDS) is investigated in this research. The hydrate formation reactions are carried out in the isothermal condition of 278.15 K in a 169 cm3 stirred batch reactor. The amount of gas uptake and the storage capacity of methane hydrate formation are calculated. Results indicate that utilization of TBAC with a concentration of (3 and 5) wt% and SDS with a concentration of 400 ppm increases the amount of gas consumption and the storage capacity of methane hydrate formation. Utilization of TBAC along with SDS decreases the amount of gas consumption and storage capacity, compared to aqueous the solution of SDS. Investigation of the impact of pressure on the gas hydrate formation indicates that by increasing the initial pressure of the cell from 6 MPa to 8 MPa, the amount of gas consumption and the storage capacity of methane hydrate formation increases, considerably.

Water pollution, as a result of industrial development, has detrimental effects on aquatic organisms and human beings. In this research, Leucaena leucocephala biomass was modified using Fenton’s reagent and sodium hydroxide, and the performances of the native, Fenton-treated, and NaOH-activated adsorbents for removal of Ni(II) from aqueous solution were evaluated under various experimental conditions such as initial pH, contact time, initial concentration of Ni(II), adsorbent dosage, and temperature. The adsorbents were characterized using Fourier transform infrared spectroscopy and pH of the point of zero charge. Kinetic and equilibrium adsorption data were well described by Elovich and Liu models, respectively. The maximum adsorption capacities are 50.66, 56.72, and 75.17 mg/g for the native, Fenton-treated, and NaOH-activated L. leucocephala adsorbents, respectively. Desorption of Ni(II) from the surface of the adsorbents was done effectively with 0.03 mol/L of hydrochloric acid. Thermodynamic calculations show that the adsorption process was spontaneous, feasible, and favorable because the values of ΔGo were negative. Adsorption of Ni(II) onto the adsorbents was exothermic (ΔHo values were negative) and there was also a decrease in the randomness of the liquid-solid interface (ΔGo values were negative). Overall, the three adsorbents can be used for the treatment of water that is contaminated with Ni(II).

In this work, we tried to explore the review of CO2 capture using absorption and adsorption technologies. For this purpose, also, besides the literature review investigates the effect of some operational parameters such as temperature, pressure, amine concentration, solution flow rate, and the adsorbent loading on the CO2 removal efficiency and CO2 capture capacity. The results demonstrated that the flow rate of liquid and concentration of amine has a positive effect on the removal efficiency and the CO2 flow rate has a negative effect. The results in the adsorption part indicated the pressure had a positive effect on the equilibrium adsorption capacity and the adsorbent loading and temperature had a negative effect. Moreover, the absorption of CO2 into three ZrO2, TiO2, and ZnO nanofluids at Pz and DEA solution was investigated. The results represented that the loading of nanoparticles and speed of the stirrer have an optimum value for CO2 removal efficiency. The optimum value was 0.05 wt%, 0.05 wt%, and 0.1 wt%, for ZrO2, TiO2, and ZnO nanoparticles, respectively. Furthermore, the CO2 removal efficiency increased first with an increase of the stirring speed up to 200 rpm, and then begins to decrease as the stirrer speed increased above 200 rpm.

The textile industry produces a significant amount of liquid effluent pollutants due to the vast amounts of water used in fabric processing. This has resulted in significant water pollution worldwide. The reduction of these dye compounds from industrial wastewater has been achieved using chemical, physical, and biological methods. However, these approaches are time-consuming, costly, and pose disposal problems. Currently, photocatalytic degradation by nanoparticles is attracting significant attention.  In this regard, Activated carbon supported and unsupported SrO nanoparticles were synthesized by the wet chemical co-precipitation method. The nanoparticles were characterized by XRD, SEM, EDX, and FT-IR. The Strontium oxide (SrO) and Activated carbon-supported Strontium oxide (Ac/SrO) nanoparticles (NPs) were used as photocatalysts for the photodegradation of Congo red dye in an aqueous medium under UV irradiation. The unsupported SrO and AC/SrO NPs degraded about 93.3% and 97.6% of the dye, respectively, within 100 minutes of irradiation time. The maximum degradation of the dye was achieved at pH 4, 0.06 g of catalyst dose, 15 ppm dye concentration, and a temperature of 45℃. The data were best fitted with pseudo-first-order kinetics. The activity of the recovered catalyst was also examined.

Worldwide the broad usage of plastic has resulted in the massive production of plastic pollution, which is incinerated, and put in landfills and oceans. The technique of coating road aggregate with plastic has a good potential to deal with this global issue. The unique physical, mechanical and thermal properties of polymer offers effective binding, less moisture retention, and less susceptibility to void formation. This research will ultimately reflect plastic waste management and road enhancement. The main purpose of this experimental study is to predict and highlight the effect of varying plastic composition coating on an aggregate and select the best-performing sample. For this study, samples of polymer-coated aggregates of different ratios are created, and further tested for their enhancement in properties. To create polymer-coated aggregate, we have used recycled aggregates, Grade 70 bitumen, and polyethylene bags from waste. To coat the aggregates used the "dry-mix process". The effectiveness of the coating with varying plastic compositions was measured using seven different tests. It was hypothesized that incorporating plastic would enhance the properties of aggregate and increase the durability and workability of road materials. The test results supported the hypothesis. Standard ranges were used to perform a comparative study between polymer-coated aggregate and conventional aggregate. Nearly all tests' plastic compositions>8% and less than 15% have shown good results, but the optimum value for all tests is achieved by a sample with 12% plastic coating. Although this study supports that plastic incorporation is a better idea to enhance the longevity of roads, more research is required to explore the underlying mechanism of plastic coating and its long-term outcomes.

Due to the traditional analysis method on the influence of soil nitrogen deposition on soil CO2 emissions during the freezing and thawing period, the initial impact of nitrogen deposition on soil CO2 emissions during the freezing and thawing incubation period was not analyzed, resulting in insufficient accuracy of the later analysis results. A new method was proposed to analyze the effect of nitrogen deposition on Soil CO2 emission during freeze-thaw cultivation. On this basis, the contents of soil temperature, moisture, inorganic nitrogen, and soluble carbon were determined. Three freeze-thaw models of nitrogen deposition levels were established. The influence of nitrogen deposition on Soil CO2 emission and the effect of nitrogen deposition on CO2 emission in alpine wetlands were studied by multivariate variance analysis. The effect of nitrogen deposition on CO2 emission of alpine wetlands was studied. The results showed that different soil temperatures and moisture content had a great influence on the seasonal variation of soil flux, which was generally consistent with the single peak of soil temperature, but highly consistent with the variation of soil moisture content in different growth periods. Nitrogen treatment changed the DOC content of soil organic matter. DOC content in the mineral layer and organic layer increased significantly in low and medium nitrogen treatments. The CO2 emission of soil in the freezing period is lower than that in a normal temperature period, and that in multiple freezing periods is less than that in one freezing period. The CO2 emission rate of soil under freeze-thaw conditions is the smallest, and the CO2 emission rate of soil after thaw is the largest. Appropriate nitrogen deposition can promote soil CO2 emission, while high nitrogen deposition can inhibit CO2 emission.

In the present study, the extraction of pectin from the banana peel (Musa sp.) was optimized using an artificial neural network and response surface methodology on the yield and degree of esterification obtained using microwave-assisted extraction methods. The individual, quadratic and interactive effect of process variables (temperature, time, the liquid–solid ratio, and pH) on the extracted pectin yield and DE of the extract were studied. The results showed that a properly trained artificial neural network model was found to be more accurate in prediction as compared to the response surface model method. The optimum conditions were found to be the temperature of 60oC, extraction time of 102 min, the liquid–solid ratio of 40 % (v/w), and pH of 2.7 and within the desirable range of the order of 0.853. The yield of pectin and degree of esterification under these optimum conditions were 14.34% and 63.58, respectively. Temperature, time, liquid–solid ratio, and pH revealed a significant (p < 0.05) effect on the pectin yield and degree of esterification. Based on the value of methoxyl content and degree of esterification the extracted pectin was categorized as high methoxyl pectin. Generally, the findings of the study show that banana peel can be explored as a promising alternative for the commercial production of pectin.

Due to the landfill leachate and the lack of drainage beds for collecting and directing leachate, especially in developing countries, the need to study Municipal Solid Waste (MSW) dryers is of particular importance. According to the technical literature, so far no comprehensive study has been performed on MSW dryers considering the actual components of the waste and the moisture content above 40%. Here a comprehensive study of wet MSW dryers consisting of three different parts is performed.  In the first part, a semi-theoretical mathematical model is developed to calculate the drying rate (internal) of wet MSW. For this purpose, with the laboratory results in the technical literature and Statistica software, a suitable mathematical model for drying MSW is validated and determined. Then, the external drying rate is determined according to the type of dryer selected and after its validation; it is compared with the internal drying rate. In the second and third parts, after validation of EES developed code, energy and exergy analysis are reviewed and finally, a parametric study is performed to investigate the effects of different parameters on energy and exergy efficiencies of the unsorted wet MSW drying process. The results show that the best model for drying the unsorted MSW is the logarithmic model with a corresponding  of 0.999. The internal and external evaporation rates are 0.157 and 0.165 kg/s and it is seen these two rates are well-matched together and differ by only 5%. The energy efficiency and exergy efficiency of the dryer are 13.92% and 2.91%, respectively. According to the parametric study, the inlet air temperature and the temperature of inlet MSW have the greatest effect on energy efficiency, respectively. Inlet air conditions such as absolute humidity of inlet air and atmospheric pressure have the greatest effect on the exergy efficiency of MSW drying.