Lagergren First-order Equation Research Articles

Removal of heavy metals from wastewater using agricultural byproducts

AbstractThe use of agricultural waste to remove heavy metals from wastewater has attracted much attention due to its economic advantages and high removal efficiency which is attributed to different functional groups. The sorption mechanism of biomass can consist of several steps including chemisorption, complexation, adsorption on surface, diffusion through pores, and ion exchange. Heavy metals were removed in different rates depending on the adsorbent and metal itself. For instance, coconut waste showed adsorption capacities of 263 and 285 mg/g in removing lead and cadmium ions, respectively. Also, black oak bark has adsorbed mercury in an adsorption capacity of 400 mg/g, while wheat brans adsorption capacity for chromium was 310 mg/g. The adsorption capacity is commonly calculated by Lagergren's first-order equation, the Redlich Peterson model, and the Brunauer–Emmett–Teller (BET) model. However, Langmuir and Freundlich models were intensively used to calculate the adsorbed amount by a unit weight of solid sorbents. This review article aims to present the recently available information on utilizing the biomass materials for heavy metals removal. Here, we highlight the increasing use of these materials due to their low cost, regeneration ability, high adsorption efficiency, and small chemical or biological sludge with a possibility of metal recovery.

Simulated oil release from oil-contaminated marine sediment in the Bohai Sea, China

There is a high degree of heavy oil partitioning into marine sediments when an oil spill occurs. Contaminated sediment, as an endogenous pollution source, can re-pollute overlying water slowly. In this study, a static oil release process and its effects in marine sediment was investigated through a series of experiments with reproductive heavy oil-contaminated marine sediment. The oil release process was accurately simulated with a Lagergren first-order equation and reached equilibration after 48h. The fitted curve for equilibrium concentration (C0) and first-order rate constant (k1) for sediment pollution levels exhibited a first-order log relationship. The instantaneous release rate (dCtdt) was also calculated. The C0 increased with increases in temperature and dissolved organic matter (DOM), and decreasing salinity. The k1 increased with temperature, but was not affected by DOM and salinity. These results can be used to better understand the fate of heavy oil in contaminated sediments of the Bohai Sea.

Study on Fluoride Removal from Aqueous Solutions by a Novel Defluoridation Adsorbent NEWDEF®

Batch experiment was carried out to determine the effectiveness of the novel composite defluorinating agent NEWDEF® for fluoride removal from aqueous solution. The results showed that the maximum adsorption capacities for F- were 4.09mg·g-1. Kinetics data obtained for the adsorption process fitted the Lagergren First-order equation. The adsorption kinetics and isotherm were found well fitted by Langmuir isotherm models and a pseudo-second-order kinetic, showing F- removal belonged to monolayer adsorption process. The reaction of F- adsorption from aqueous solutions by NEWDEF® was an endothermic process. Micro-columnand home-used equipment defluoridation test indicated that NEWDEF® can be perfectly suitable defluorinating agent in F- removal for drinking water in small towns.

Dyeing properties of CI reactive violet 2 on cotton fabric in non-ionic TX-100/Span40 mixed reverse micelles

In order to improve the dyeing properties of reactive dyes onto cotton fabric in reverse micelles, non-ionic mixed reverse micelles were prepared using non-ionic TX-100 and Span40 as a dyeing media. The maximum water solubilization, diameter of water pool, aggregation density, and conductivity values of the reverse micelles with different concentrations of TX-100/span40 were measured and compared. The adsorption and dyeing capacity of reactive dyes on cotton fabric in reverse micelles were investigated. Additionally, the Lagergren first-order equation and the pseudo second-order equation were also employed to fit the experimental data. The results indicated that the diameter of water pool and packing density of reverse micelles were increased with an increasing amount of Span40, which caused lower conductivity. The repelling force and competitive adsorption between the dyes and cotton fabric were decreased with an increasing amount of Span40, and the higher adsorption and improved dyeing properties in reverse micelles were obtained. Moreover, the dye adsorption process in mixed TX-100/Span40 reverse micelles could be described using pseudo-second-order kinetic equations. The adsorption is a chemical process.

Study on Fluoride, Iron and Manganese Removal from Aqueous Solutions by a Novel Composite Adsorbent

Batch test had been carried out to determine the potential and the effectiveness of the novel composite adsorbent in removal of fluoride, iron and manganese from aqueous solution. It was found that the composite adsorbent could effectively not only remove Fe (II) and Mn (II) also fluoride from water, the maximum adsorption capacities for F-, Fe (II) and Mn (II) were 4.09mg·g-1 4.00mg·g-1 and 3.50mg·g-1 respectively. Kinetics data obtained for the adsorption process fitted the Lagergren First-order equation. The Langmuir adsorption isotherm was found to fit the experimental data derived from F- (R2= 0.9992), Fe (II) (R2=0.9858) and Mn (II) (R2=0.9876) removal. Both Fe (II) and Mn (II) removal increased with increase in solution pH, but F- removal remained relatively stable in pH 4.0~9.0. The process of adsorption of F-, Fe (II) and Mn (II) from aqueous solutions by the composite adsorbent was an endothermic process. The above results indicated the composite adsorbent can be possibly applied in F-, Fe (II) and Mn (II) removal from drinking water.

Ammonia-Nitrogen Sorptional Properties of Banana Peels

Using modified banana peel as a biosorbent to treat water containing ammonia-nitrogen (NH4(+)-N) was studied. Related parameters in the sorptional process, such as chemical modification, pH, and contact time were investigated. The experimental results showed that banana peel modified by 30% sodium hydroxide (NaOH) and mesothermal microwaves (NMBPs) can greatly improve the sorption removal for NH4(+)-N. The kinetics study revealed that the sorption behavior better fit the pseudo-second-order equation than the Lagergren first-order equation. Fourier transform infrared absorption spectrum analysis of banana peels and NMBPs before and after NH4(+)-N sorption revealed that the activity of hydroxyl groups at the surface of the banana peels was strengthened after modification, and nitrogenous groups appeared after biosorpting the NH4(+)-N. In the end, metallurgical wastewater containing a low concentration of NH4(+)-N was treated by NMBPs. The initial NH4(+)-N concentration of 138 mg/L was reduced to 13 mg/L in 25 minutes by 4 g/L NMBPs at pH 10.

Characteristics and applications of the Lagergren's first-order equation for adsorption kinetics

Adsorption kinetic curves of the Lagergren's first-order (LFO) equation were classified into four zones according to their rising characteristics. Of the 85 adsorption systems described by LFO equation, 46% of the kinetic curves belonged to zone II and 29% to zone III, these being good and fast. Activated carbons with a BET surface area of 626–1009 m 2/g and a micropore volume fraction of 57.5–88.0% were prepared from plum kernels, pinewood, pistachio shells, and Moso bamboo with steam activation. The adsorption kinetics of methylene blue, tannic acid, humic acid, and phenol on these activated carbons were studied. Normalized standard deviations were shown that the adsorption of methylene blue, tannic acid, and humic acid was better described by LFO equation and that of phenol by PSO equation. Also, the value of k 1 t ref was obviously affected by physical properties and particle sizes of the adsorbents as well as molecular weights of the adsorbates.

Adsorption of nuclease p1 on chitosan nano-particles

The sorption of nuclease P1 onto chitosan nano-particles is studied in this paper. The effect of some adsorption kinetics factors such as nuclease P1 concentration, chitosan nano-particles solution concentration, adsorption temperature, chitosan nano-particles size, solution pH, etc. is investigated. Adsorption of nuclease P1 onto chitosan nano-particles is fitted into Lagergren first-order equation at initial nuclease P1 concentration of 3.0 mg/mL. The first-order constant for nuclease P1 is 22.98 h-1. When nuclease P1 concentration is controlled into certain region, the adsorption fits into Freundlich isothermal linear equation. A mechanism of adsorption for nuclease P1 is proposed by analyzing IR spectra. The IR spectra shows that the hydrogen bond might be the main force between the hydroxyl group, the NH2 group and the nuclease P1.

Characteristics of Elovich equation used for the analysis of adsorption kinetics in dye-chitosan systems

The Elovich equation has been widely used in adsorption kinetics, which describes chemical adsorption (chemical reaction) mechanism in nature. The approaching equilibrium parameter of Elovich equation ( R E) was used here to describe the characteristic curves of adsorption kinetics. Of 64 adsorption systems surveyed in this work, 80% of the R E values were between 0.1 and 0.3 with an adsorption curve belonging to “mild rising”. The results of three examples revealed that the characteristic curve of Elovich equation was between those of Lagergren's first-order equation and intraparticle diffusion model. Chitosans prepared from prawn, lobster, and crab shells were used for the adsorption of a reactive dye. The mean deviation obtained from the three kinetic models revealed that Elovich equation was the most suitable one. All the adsorption systems were in the “mild rising” zone. The R E value was related to the type of raw material but not to the particle size of chitosan, which agreed with chemical adsorption nature of the Elovich equation. According to an optimal adsorbent consumption of 85% coupled with its corresponding operating time ( t 0.85) proposed, these two parameters could be used for engineering design.

Adsorption Kinetics of Chromium (VI) onto an Anion Exchange Fiber Containing Polyamine

以聚丙烯腈纤维为原料,采用化学改性法,制备了多胺型阴离子交换纤维.研究该纤维对Cr（Ⅵ）的吸附特性.在研究的温度及浓度范围内,该纤维对Cr（Ⅵ）吸附的平衡数据符合Langmuir和Freundlich吸附等温方程,对Cr（Ⅵ）有较强的亲和力,吸附反应易于进行.重点研究了该纤维对Cr（Ⅵ）的吸附动力学特性,分别采用Lagergren一级动力学方程、修正伪一级动力学方程、伪二级动力学方程和颗粒内扩散方程进行拟合,计算相应的速率常数.研究表明,该吸附是一个快速吸附过程,20min即可接近吸附平衡,吸附过程符合伪二级动力学方程,以化学吸附为主,该纤维能够多次反复对Cr（Ⅵ）进行吸附.

Neutral lipase from aqueous solutions on chitosan nano-particles

The size of chitosan nano-particles had been prepared by ionic cross-linking of chitosan and tri-polyphosphate (CS-TPP), which were well dispersed and stable in aqueous solution. The physicochemical properties of nano-particles were characterized by IR spectra, SEM. Its sorption kinetics and sorption mechanism for neutral lipase were studied. The effect factors of adsorption kinetics were investigated, such as neutral lipase concentration, chitosan nano-particles solution concentration, adsorption temperature, size of chitosan nano-particles, stirring rate, solution pH, etc. Adsorption of neutral lipase on chitosan nano-particles was fitted into Lagergren first-order equation at initial neutral lipase of 3.0 mg/ml (pH 7.0). The first-order constant for neutral lipase was 23.34 h −1. When neutral lipase concentration was controlled under certain region, it was fitted into Freundlich isothermal linear equation. Mechanism of adsorption for neutral lipase was presumed by analyzing IR spectra. The hydrogen in the carboxyl group was connected with electronegative oxygen. Electron pair was attractive to oxygen, so hydrogen atom became cation and proton. When electronegative neutral lipase was closed to chitosan nano-particle, the hydrogen bond might be formed. It was the main force between hydroxyl group, NH 2 group and neutral lipase.

Adsorption of Neutral Proteinase on Chitosan Nano-Particles

ABSTRACTThe sorption kinetics and sorption mechanism for neutral proteinase on chitosan nano-particles were studied in the paper. The effect factors of adsorption kinetics were investigated, such as neutral proteinase concentration, chitosan nano-particles solution concentration, adsorption temperature, size of chitosan nano-particles, stirring rate, solution pH et al. Adsorption of neutral proteinase with chitosan nano-particles was fitted into Lagergren first-order equation at initial neutral proteinase of 3.0 mg/ml (pH 7.0). The first-order constant for neutral proteinase was 23.65 h−1. When neutral proteinase concentration was controlled under certain region, it was fitted into Freundlich isothermal linear equation. Mechanism of adsorption for neutral proteinase was presumed by analyzing IR spectra. The hydrogen in the carboxyl group was connected with electronegative oxygen. Electron pair was attractive to oxygen, so hydrogen atom became cation and proton. When electronegative neutral proteinase was closed to chitosan nano-particle, the hydrogen bond might be formed. It was the main force between hydroxyl group, NH2 group and neutral proteinase.