Adsorption Of Organic Matter Research Articles

A Study of Adsorption of an Organic Colouring Matter on Powdered Natural Plant Material

The present paper describes the study of the removal of organic matter (Astrazon Brilliant Red 4G) (ABR) from the solution by the adsorbent prepared from wheat straw. To measure the efficiency of adsorption, different parameters like effect of pH, effect of initial dye concentration and effect of adsorbent amount with respect to time were studied. Spectrophotometric technique was used for the measurement of amount of dyes before and after adsorption process. The Langmuir adsorption isotherm model and Freundlich adsorption model were studied for this adsorption. The study reveals that wheat straw powder (WSP) can be used as an efficient adsorbent for the removal of ABR.

Comparison of enhanced microsphere transport in an iron-oxide-coated porous medium by pre-adsorbed and co-depositing organic matter

The effects of two types of organic matter (OM) (humic acid and protein) on colloid transport in porous media were investigated with column experiments and numerical modeling. Colloid deposition was explored in double-pulse experiments (DPEs) by injecting a pulse of OM to allow its pre-adsorption to iron-oxide-coated sand, followed by a pulse of latex microspheres. These experiments were compared with single-pulse experiments (SPEs), where one mixed pulse of OM and microspheres was introduced to the column. The experimental results show that pre-adsorbed and co-depositing OM may, respectively, limit initial and transient colloid deposition. The DPE results can be interpreted with an existing colloid transport model (random sequential adsorption: RSA). SPE results were interpreted with an extended RSA model (RSAE) that couples the process of OM co-deposition and blocking to colloid transport by introducing a conversion factor (Kconv) that reflects the blocking efficiency of OM. The calculations with the verified model suggest a comparable site blocking capacity of pre-adsorbed and co-depositing OM with a blocking capacity that differs for different sources of OM. Traditionally described as a modification of the chemistry of the overall deposition surface for the suspended particles, OM adsorption can also be interpreted as blocking local colloid attachment sites by the OM. This second interpretation may be more useful in describing nanoparticle deposition where the particle size is comparable to the length scale where a molecule of OM modifies the deposition surface.

Continuous adsorption of natural organic matters in a column packed with carbon nanotubes

In the present study, continuous adsorption experiments were carried out in an adsorption column to survey the efficiency of the carbon nanotubes (CNTs) for removal of natural organic matters (NOMs) from aqueous solution. Parameters such as mass of CNTs, initial NOMs concentration were evaluated and also the breakthrough curves were obtained. Experiments performed with various initial NOMs concentration and various CNTs masses. The breakthrough period was longer at lower initial NOMs concentration. Increase of the initial NOMs concentration, expectedly, resulted in the faster saturation of the CNTs bed. The adsorption capacities for multi wall carbon nanotubes (MWCNT) and single wall carbon nanotubes (SWCNT) in highest initial NOMs concentration were 53.46 and 66.24 mg/g, respectively. The effect of amount of CNTs on breakthrough time and volume of treated water was investigated and resulted that with an increase in the mass of CNTs, breakthrough time occurs very late and the volume of treated water increased. These findings suggested that CNTs present a great potential in removal of NOMs from aqueous solutions.

Mechanisms of membrane fouling controlled by online ultrasound in an anaerobic membrane bioreactor for digestion of waste activated sludge

An anaerobic membrane bioreactor coupled with online ultrasonic equipment (US-AnMBR) was operated for sludge digestion under a high volatile solids (VS) loading rate of 3.7gVSL−1d−1 for 54d. The ultrasound intentionally used for membrane fouling control enhanced membrane filtration. Mechanisms of membrane fouling controlled by the ultrasound were investigated in this study. The results of digested broth properties, membrane filtration resistance distributions and the scanning electron microscope observation comprehensively indicated that the ultrasound primarily controlled the cake layer fouling, but did not modify the digested broth properties to enhance membrane filtration. The contents of extracellular polymeric substances (EPS) in the residual cake layer on the membrane surface signified that the loose cake layer was removed by the ultrasound, whereas the compacted cake layer strongly adhering to the membrane surface with higher EPS concentrations remained. Furthermore, the ultrasound slightly affected the gel layer, as demonstrated by a reduction in gel layer fouling resistance. Based on the analysis of gel layer compositions, the ultrasound was proven to be able to control the adsorption of the soluble organic matters rather than the deposition of the inorganic particles into the gel layer.

The relationship between organic matter and specific surface area in <2 μm clay size fraction of muddy source rock

The adsorption of organic matter (OM) onto clay minerals has long been considered as a significant way of OM preservation in source rock. Here we analyzed the relationship between OM and the specific surface area (SSA) of <2 μm clay size fraction isolated from 13 source rock cores collected from Dongying depression. Rock-Eval pyrolysis and N2 adsorption experiment were employed to probe the characteristics of OM and SSA (denoted S BET) in samples before and after OM extraction using trichloromethane. The results indicate that various kinds of OM occurrence coexist in clay size fraction and their contributions to hydrocarbon are different in each period of OM evolution. The occurrence and amount of OM affect the S BET of clay size fraction, and a nonlinear negative correlation between total organic carbon (TOC) and SBET can be recognized. The soluble OM (chloroform extract “A”), mainly stored in the pore space of clay size fraction, shows a negative correlation in amount with S BET. Our data also indicate that free hydrocarbon (S1) was stored mainly in the pore space and/or the surface of clay size fraction, whereas pyrolysis hydrocarbon (S2) was mingled mainly with clay minerals. Therefore, to understand various OM occurrences and their relationship with S BET in the clay size fraction is significant in the study of generation, accumulation, and migration of hydrocarbon in muddy source rock.

Preparation of a novel magnetic resin for effective removal of both natural organic matter and organic micropollutants

Abstract A novel, bifunctional, hypercrosslinked, magnetic resin W2 was prepared using divinylbenzene (DVB) and glycidyl methacrylate (GMA) as comonomers in three steps ( i.e. , suspension polymerization, amination and post-crosslinking reactions). To evaluate the adsorption of natural organic matter (NOM) and organic micropollutants (OMPs) on the obtained resin W2, two magnetic resins W1 (the precursor of W2 before post-crosslinking) and W0 (the precursor of W1 before amination) were chosen for comparison. The results indicated that W2 would be a promising material for the removal of both NOM and OMPs from aquatic environments.

Adsorption kinetics and thermodynamics of hydrophobic natural organic matter (NOM) removal from aqueous solution by multi-wall carbon nanotubes

The objective of this research was to study the efficiency of Multi-Walled Carbon Nanotubes (MWCNTs) for the adsorption of hydrophobic natural organic matter (NOM) from aqueous solution under different operational conditions of contact time, pH, initial concentration of NOM and temperature. MWCNTs were synthesized via chemical vapor deposition (CVD) with average diameter of 10–50 nm. The results illustrated that both as-prepared and functionalized MWCNTs showed high adsorption capacity for the NOM studied. Functionalization of MWCNT affected the surface area and introduced oxygen-containing functional groups to the surface of MWCNT which depressed the adsorption of NOM onto MWCNTs-COOH. The obtained data were studied using Freundlich, Langmuir and BET isotherms; NOM adsorption data had the best conformity to the Freundlich isotherm. Kinetic studies were performed and the adsorption kinetics successfully followed the pseudo-second-order kinetic model. Thermodynamic parameters such as free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) were determined and evaluation of them showed that the adsorption process for NOM is general spontaneous, endothermic and thermodynamically favorable.

Adsorption of organic matter from industrial phosphoric acid (H3PO4) onto activated bentonite

The Tunisian industrial phosphoric acid (IPA) was obtained from the phosphate rock by the wet process. However, the organic matter (OM) contained in the acid may interact with organic solvents to form stable foams, preventing phase settling, or simply by forming cross layers and organic phases, and denaturing part of the solvent. Hence, removal of these organics seems to be an important step for the production of decontaminated phosphoric acid.In the phosphoric acid plant of M'dhilla, the OM can be found as colloidal suspension and soluble forms. The colloidal organics are coagulated and deposited with the gypsum precipitation during the aging of H3PO4, while the soluble part remains behind. The purpose of this work was to study the OM adsorption onto montmorillonite bentonite. Equilibrium data are analyzed by the Langmuir, Freundlich and Redlich–Peterson adsorption isotherm models.

Seasonal Transport Characteristics of Suspended Particulate Organic Carbon in the Middle and Lower Yangtze River and the Relationship with Three Georges Reservoir

The suspended matter samples collected about 2 times every month in Datong of Yangtze River from May to November 2010 were used for determination of grain size and particulate organic carbon (POC) component. The results indicated that the size composition and organic carbon concentrations of Datong showed obvious seasonal characteristics. The median grain size of the suspended particulate matter ranged from 5.8 to 7.8Φ, decreased in summer (July to September) and increased in autumn (October to November). The POC% of the suspended particulate matter ranged from 0.87% to 1.18%, and was lower in summer, because high sediment discharge had dilution effect for organic carbon. The increase of the turbidity of water reduced the production capacity, and the organic matter correspondingly decreased. POC% decreased with the reduction of median grain size, which suggested that organic matter into the river in summer is mainly organic debris, but not mainly absorbed by the fine particles of clay. CaCO3 content ranged 3.7% to 7.6% and was higher in summer, which reflected the increased source contribution of the upper stream. It decreased in autumn, which reflected the increased source contribution of the middle and lower stream. Since the impoundment of the Three Gorges Reservoir, POC% in Datong were significantly higher than before, which showed the rise of fine particulate matter component and its stronger adsorption of organic matter. The Three Gorges Dam had significant influence on the grain size and organic composition of suspended matter of theYangtze River into the sea. Its potential environmental impact of bio-geochemical effects deserves more research attention.

Types of Uraniam Minerial and Its Occurrence State of the Sandstone-type Uranium Deposits in the Meso-cenozoic Basin

Because of its particular sedimentary characteristics,a lot of sandstone-type uranium deposits are discovered in the meso-cenozoic basin,and its host rocks are considered to be medium-to-fine sandstone. In order to find out uranium mineral types of the sandstone-type uranium deposits and its occurrence state,quantitative and qualitative analysis are carried out by electron probe Modern analysis test method.From the analysis results,it is found that the uranium minerals mainly include coffinite, swamboite, uraninite, brannerite, zellerite,uranothorite,and Uranium carbonate mineral. Uranium minerals are symbiotic with Quartz, Albite, Pyrite and so on. Another existance is adsorption of Clay mineral and organic matter. in addition,Precipitation and concentration of uranium mineral have a close relationship with pH and Eh value in a sandstone formation

Assessment of silt density index (SDI) as fouling propensity parameter in reverse osmosis (RO) desalination systems

Due to its simplicity, silt density index (SDI) is extensively used in reverse osmosis systems despite its limitations in predicting membrane fouling. Employing a reliable fouling index with good reproducibility and precision is necessary. The aim of this investigation is to assess the reliability of SDI in order to understand the reasons for the low level of precision and accuracy. Different commercial SDI membranes and feedwater quality were used in this study. Results showed the existence of membrane properties’ variation within manufacturers, which then causes a lack of accuracy in fouling risk estimation. The nature of particles during SDI filtration provides information that particle concentration and size play a significant role in SDI quantification with substantial representation given by particles with size close to membrane nominal pore size. Moreover, turbidity-assisted SDI measurements along with determination of ultrafiltration permeate and clean water fouling potential, establish the indication of nonfouling-related phenomena involved on SDI measurement such as natural organic matter adsorption and hydrodynamic conditions that alters during filtration. Additionally, it was found that the latter affects the sensitivity of SDI by being represented by some portions of SDI values.

Natural Products for Materials Protection: Corrosion and Microbial Growth Inhibition Using Capsicum frutescens Biomass Extracts

Extracts of the fruit of Capsicum frutescens (CF) were assessed for anticorrosion and antimicrobial activity. The anticorrosion effect of the ethanol extract on low carbon steel in acidic media was studied experimentally using gravimetric, impedance, and polarization techniques, while the antimicrobial efficacy of ethanol, methanol, water, and petroleum spirit extracts respectively against the corrosion-associated sulfate reducing bacteria (SRB), Desulfotomaculum species, was assessed using the agar disc diffusion method. CF extract effectively inhibited both corrosion and SRB growth due to the action of the phytochemical constituents present therein, including alkaloids (8.8%), tannins (0.4%), and saponins (39.2%). The corrosion process was inhibited by adsorption of the extract organic matter on the steel surface, whereas the antimicrobial effect results from disruption of the growth and essential metabolic functions of the SRB. Molecular dynamics (MD) simulations were performed to theoretically illustr...

Sulfonylurea Herbicides' Fate in Soil: Dissipation, Mobility, and Other Processes

Sulfonylurea herbicides used in turfgrass—including chlorsulfuron, flazasulfuron, foramsulfuron, halosulfuron, metsulfuron, rimsulfuron, sulfometuron, sulfosulfuron, and trifloxysulfuron—are all weak acids, with disassociation constants ranging from 3.3 to 5.2. Sulfonylureas are used at low rates ranging from 4 to 280 g ha−1. Although these use rates put their soil concentration in parts per billion, they still have residual activity with variable persistence. They have limited susceptibility to soil leaching with weak adsorption to soil clay minerals. Sulfonylurea herbicides used in turfgrass have variable soil organic matter adsorption, which is soil dependent. The persistence and activity of these sulfonylureas are affected by soil pH. At soil pH of 7.0 and greater, some of these sulfonylurea herbicides tend to persist for longer periods with half-lives extending into years rather than days. In normal use patterns with soil pH of 7.0 and less, dissipation occurs via chemical hydrolysis and microbial degradation with half-lives ranging from days to months. Overall, sulfonylurea herbicide adsorption is negatively correlated to increasing pH (increased persistence) and positively correlated to increased organic matter (decreased activity).

Application of aqueous extracts of coffee senna for control of mild steel corrosion in acidic environments

Abstract Background The inhibitive effect of the aqueous extract of Coffee senna (CS) on the corrosion of mild steel in 1 M HCl and 0.5 M H2SO4 solutions was investigated by weight loss measurement as well as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. Result The extract was found to efficiently inhibit the corrosion process in both environments and inhibition efficiency increased with extract concentration as well as rise in temperature. Data from electrochemical measurements suggest that the extract functioned by adsorption of the organic matter on the metal/corrodent interface, inhibiting both the anodic and cathodic half reactions of the corrosion process. Adsorption of the extract organic matter was approximated by the Langmuir isotherm. The adsorption behavior of selected organic constituents of the extract on the metal surface was assessed at the molecular level, in the framework of the density functional theory. Conclusion This study clearly shows the potentials of CS extract for control of mild steel corrosion in acidic environment.

Natural Products for Materials Protection: Mechanism of Corrosion Inhibition of Mild Steel by Acid Extracts of Piper guineense

The adsorption and corrosion inhibiting effect of acid extracts of Piper guineense (PG) leaves on mild steel corrosion in 1 M HCl and 0.5 M H2SO4 was investigated using gravimetric, potentiodynamic polarization and electrochemical impedance spectroscopy techniques as well as scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The polarization and impedance results revealed that PG inhibited the cathodic and anodic partial reactions of the corrosion process via adsorption of the extract organic matter on the metal/solution interface. The mechanism of adsorption deduced from the variation of inhibition efficiency with temperature as well as kinetic and activation parameters suggest significant chemisorption of the extract constituents on the metal surface. Density functional theory calculations were performed to model the electronic structures of some extract constituents, including chemisorptive interactions with the Fe surface.

Influence of Suwannee River humic acid on particle properties and toxicity of silver nanoparticles

Adsorption of natural organic matter (NOM) on nanoparticles can have dramatic impacts on particle dispersion resulting in altered fate and transport as well as bioavailability and toxicity. In this study, the adsorption of Suwannee River humic acid (SRHA) on silver nanoparticles (nano-Ag) was determined and showed a Langmuir adsorption at pH 7 with an adsorption maximum of 28.6mgg−1 nano-Ag. It was also revealed that addition of <10mgL−1 total organic carbon (TOC) increased the total Ag content suspended in the aquatic system, likely due to increased dispersion. Total silver content decreased with concentrations of NOM greater than 10mg TOCL−1 indicating an increase in nanoparticle agglomeration and settling above this concentration. However, SRHA did not have any significant effect on the equilibrium concentration of ionic Ag dissolved in solution. Exposure of Daphnia to nano-Ag particles (50μgL−1 and pH 7) produced a linear decrease in toxicity with increasing NOM. These results clearly indicate the importance of water chemistry on the fate and toxicity of nanoparticulates.

Nanoscale organo-mineral reactions of biochars in ferrosol: an investigation using microscopy

Aims In this study, a chicken manure biochar (CM biochar) and a paper sludge biochar (PS biochar), prepared under similar treatment conditions, were amended into ferrosol as part of an agronomic field trial. The aim of this study is to investigate interactions between these biochars and the soil after a 3 month trial. Methods Soil samples following field trials were taken and biochar was separated from the soil, and studied for both surface oxidation and the degree of interaction with surrounding soil by X-ray photoelectron spectroscopy (XPS), SEM and TEM equipped with EDS for elemental analysis. Results Following incubation in field soil, both biochars showed that soil mineral incorporation on to their surfaces occurred within the first year, although the attachment was localized at specific sites on the surface. A relatively high concentration of Al was found at the interface between the biochar and mineral phases in both aged biochars, indicating a binding role of Al. For the CM biochar, a soil-iron redox reaction may be associated with the formation of biocharmineral complexes due to the relatively higher labile carbon content and higher pH value of this biochar. Conclusions Soilmineralattachmentmayoccurdirectly on to the biochar surface because of the formation of carboxylic and phenolic functional groups on the aged CM biochar surface by an oxidation reaction. For the PS biochar, adsorption of organic matter from the soil facilitated interactions between the biochar and mineral phases in the soil. Calcium is believed to be important in this process.

Investigation of the adsorption characteristics of natural organic matter from typical Chinese surface waters onto alumina using quartz crystal microbalance with dissipation

The adsorption of natural organic matter (NOM) from eight typical Chinese surface waters onto alumina was investigated using quartz crystal microbalance with dissipation monitoring (QCM-D). The adsorbed masses of NOM varied between 25ngcm−2 and 64ngcm−2, and these showed significant correlation with geographical location, and NOM character and concentrations. Adsorbed mass correlated with DOC concentration (slope k=0.0676, R2=0.61) and hydrophobic acid (HoA) and weakly hydrophobic acid (WHoA) (k=0.0342 and 0.0183; R2=0.49 and 0.52 for HoA and WHoA, respectively) constituents present in the water samples. The process of adsorbed layer formation was investigated from changes in the ΔD/Δf ratio and viscosity of adsorbed layer with injected time. The adsorbed layer viscosity increased exponentially with injected time (R2>0.99) for most samples. Samples with low DOC concentration (k=−1091.8, R2=0.55) and low content of HoA and WHoA (k=−524.33 and −322.76; R2=0.41 and 0.64 for HoA and WHoA, respectively), the slope of logarithm viscosity value is steeper, the property of adsorbed layer and NOM is more inconsistent. The QCM-D technique provides a method to view the process of complexation between NOM and coagulant, and can provide useful information to establish a quantitative calculation model of the coagulation process.

Corrosion Inhibition and Adsorption of Anthocleista Djalonesis Leaf Extract on the Acid Corrosion of Mild Steel

Aqueous extracts of the leaves of Anthocleista djalonesis (AD) have been investigated as non toxic corrosion inhibitors for mild steel in acidic environments (1 M HCl and 0.5 M H2SO4, respectively). Corrosion rates were evaluated at 30 o C using the weight loss, electrochemical impedance spectroscopy and potentiodynamic polarization techniques. AD extract was found to inhibit mild steel corrosion in both acidic media via adsorption of the extract organic matter on the metal/solution interface. Polarization data indicate that the extract functioned via a mixed inhibition mechanism, affecting both the cathodic and anodic partial reactions of the corrosion process. Molecular dynamics (MD) simulations were performed to illustrate the adsorption process of some specific components of the extract.

Experimental Study of Competitive Adsorption of Heavy Metals and Organic Matter for the Phosphoric Acid Purification

The program articulated around the experimental study of the effect of several parameters on the elimination of the cations: copper, cadmium and zinc, and the organic matter present in the phosphoric acid by using the bentonite, actived carbon and carbon of olives as supports, and on the other hand to show the effect of several parameters on this keeping back such as: the effect of the time (kinetic) of contact, speed of excitement, initial concentration of the pollutant, Solid report /liquid, the isotherms. At selected best parameters for better one capacity we calculated the capacity of purification for the different supports, the sawdust and the waste of cereal. The kinetic study of the keeping back of existing pollutants in the phosphoric acid is still presented.