Sorption Of Diethyl Phthalate Research Articles

Honeycomb-like porous carbons derived from multistep pyrolysis of artificial humic acids as efficient sorbents for removing diethyl phthalate

The uprecycling of hydrothermal liquid waste-derived artificial humic acids into stable carbon materials is helpful for advancing the development of hydrothermal carbonization technology, but it has rarely been investigated. For the first time, a multistep pyrolysis method was designed to convert artificial humic acids into honeycomb-like porous carbons (PCs). The obtained PCs exhibited a high specific surface area, reaching 1728.55 m2/g, while nonactivation treatment still provided a high value of 1425.14 m2/g. The high-pyrolysis process yielded graphite-like structures and maintained surface functional groups. PCs have been applied as sorbents to remove the emerging plasticizer diethyl phthalate (DEP) in water environments and exhibit promising sorption capabilities (as high as 993.30 mg/g), which are much higher than those reported for other sorbents. The sorption rate was controlled by mass transfer and chemical-like sorption, whereas the sorption capability was controlled mainly by the adsorption process, especially pore filling. Partitioning, hydrogen bonding, pore filling and π–π stacking are possible sorption mechanisms. In addition to the specific surface area, the pore volume is a suitable parameter for assessing the sorption capability. Exogenous dissolved organic matter can affect the sorption of DEP onto PCs through cosorption and coverage of their surface, but its influence is limited. Excellent sorption performance can cover a wide range of pH conditions. The prepared PCs also showed notable reusability and practicality. In this study, an excellent method was proposed for recycling hydrothermal liquid waste and preparing PCs, and the prepared PCs exhibited great potential for environmental remediation.

Sequential carbonization of pig manure biogas residue into engineered biochar for diethyl phthalate removal toward environmental sustainability

Manure biogas residue has attracted increasing attention in waste recycling but faces substantial challenges because of its low carbon content, high ash content, and high heavy metal content. A novel sequential carbonization approach was proposed for recycling biogas residue; this approach consisted of pre-pyrolysis, activation with Ca(OH)2, and then activation with KOH. Pig manure-derived biogas residue was upcycled into engineered biochar (EB) with a high yield (26 %) and showed excellent performance in removing a typical plasticizer, diethyl phthalate (DEP). The proportion of carbon content greatly increased from 18 % (biogas residue) to 67 % (EB); however, the ash content decreased from 50 % (biogas residue) to 24 % (EB). The concentration of heavy metals decreased, and Zn had the largest decrease from 713 mg kg−1 to 61 mg kg−1 (p < 0.001). The sorption of DEP onto EB was rapid and reached equilibrium within 20 h. The developed specific surface area of EB was 1247 m2/g and provided abundant sorption sites for DEP; additionally, the sorption quantity reached 309 mg/g. The sorption capacity was dominated by surface adsorption. The oxygen-containing functional groups, graphene structure, porous structure, and hydrophobicity of EB contributed to the pore filling, hydrogen bonding, π–π stacking, and partitioning processes. Furthermore, the EB showed excellent practical application potential and great cycling stability. A sequential carbonization strategy was proposed to upcycle manure biogas residue into the EB for DEP removal; moreover, this strategy can aid in the attainment of environmental sustainability, including sustainable waste management and environmental pollution mitigation.

Aquatic invasive plant biomass-derived magnetic porous biochar prepared by sequential carbonization and coprecipitation for diethyl phthalate removal from water

Low-cost multifunctional sorbents are urgently needed, especially for the treatment of emerging pollutants that are widely distributed in various water environments. This work transformed an aquatic invasive plant, Pistia stratotes, into magnetic porous biochars (P-MPBs) based on a proposed strategy involving sequential carbonization to increase porosity and subsequent coprecipitation with ferric salts. Both the porous structure (specific surface area of up to 996.86 m2/g) and high Fe3O4 loading (saturation magnetization of up to 23.48 emu/g) were maintained. A typical plasticizer, diethyl phthalate (DEP), was selected as a model emerging organic pollutant, and the sorption quantity of the P-MPBs reached 490.04 mg g−1, which is much higher than that of many reported sorbents, especially magnetic sorbents. P-MPBs can be reused multiple times due to their excellent separation characteristics and stable structure. On the basis of kinetics and isotherm analysis, multilayer sorption, including pore filling, hydrogen bonding, π–π stacking, and partitioning, was the main DEP sorption process for the P-MPBs. Our study suggested that the proposed method could be promising and inspiring for the transformation of biowaste into excellent magnetic porous biochar that is recyclable and highly efficient at removing pollutants in water.

Insights into the effect of hydrochar-derived dissolved organic matter on the sorption of diethyl phthalate onto soil: A pilot mechanism study

Biowaste-derived hydrochar is an emerging close-to-natural product and has shown promise for soil improvement and remediation, but the environmental behavior of the dissolved organic matter released from hydrochar (HDOM) is poorly understood. Focusing on the typical mulch film plasticizer diethyl phthalate (DEP), we investigated the effect of HDOM on the sorption behavior of DEP on soil. The relatively low concentration of HDOM (10 mg L−1, 25 mg L−1) decreases the sorption quantity of DEP on soil, while it increases by a relatively high concentration, 50 mg L−1. The transformation from multilayer to monolayer sorption of DEP on soil occurs as the concentration of HDOM increases. The tryptophan-like substance is the main component of HDOM sorbed to soil, reaching 49.82 %, and results in competition sorption with DEP. The soil pores are blocked by HDOM, which limits the pore filling and mass transfer of DEP, but partitioning is significantly enhanced. The surface functional groups in HDOM are similar to those in soil, and chemical sorption, mainly composed of hydrogen bonding, exists but is not significantly strengthened. We identified the specific impact of HDOM on the sorption of organic pollutants on soil and provide new insights into the understanding of the environmental behavior of hydrochar.

Inter-molecular interactions of phthalic acid esters and multi-stage sorption revealed by experimental investigations and computation simulations

Because of the benzene ring and carbon chain structures, inter-molecular interactions among phthalic acid esters (PAEs) molecules may be significant, but their role in controlling the sorption characteristics was not investigated. This work selected diethyl phthalate (DEP) and dibutyl phthalate (DBP) as the model pollutants and their sorption was investigated on biochars produced from chicken feathers (CFBCs). The planar structure of CFBCs facilitated a comparative study combining lab experiments and computation simulations. DEP sorption kinetics was well described by a second-order kinetics model. However, DBP showed a very fast and high initial sorption, followed by an obvious decrease and then re-equilibrated sorption. Molecular dynamics (MD) simulations and density functional theory (DFT)-based calculations revealed the lower binding energy and stronger interactions of DBP molecules than DEP molecules, thus, DBP may form more stable clusters in aqueous phase at low concentration. These DBP clusters may be adsorbed and desorbed as a unit. The sorption of DBP clusters on CFBCs may result in an apparently fast initial sorption and decrease of the aqueous phase concentration, resulted in the breakup of the cluster and a re-equilibration of the sorption. The inter-molecular interactions should be considered in investigating PAEs behavior and risks.

Insights into effects of ageing processes on Cd-adsorbed biochar stability and subsequent sorption performance

The conversion of agricultural biomass wastes into biochar has enormous potential to improve soil quality. Particularly, biochar particles introduced into the natural environment readily bind environmental pollutants. The interaction of biochar and adsorbed pollutants will, however, be impacted by long term ageing. The mechanism of biochar adsorption performance that could be affected by such early-adsorbed pollutant is not understood. Herein, we study the effects of different ageing processes on Cd-adsorbed biochar stability by K2CrO7–H2SO4 oxidation method for carbon loss evaluation, and sorption capacity towards diethyl phthalate (DEP). We adopted artificially accelerated ageing methods to simulate various processes: HNO3/H2SO4, H2O2 oxidative, leaching, high temperature, freeze-thaw cycles, and dry-wet cycles. The results showed that all the Cd-adsorbed aged biochars had more C–C/C–H functional groups and exhibited higher carbon stability than pristine aged biochars. Specially, the carbon loss (20.2–25.2%) of Cd-adsorbed biochar showed almost two times lower than pristine biochar (34.5–35.4%) after high temperature and leaching ageing due to enhancing Cd-π bonding, which could resist strong K2Cr2O7/H2SO4 oxidation. Such interaction synergistically promoted the sequestration of adsorbed Cd on biochars. The subsequent sorption performance for DEP on Cd-adsorbed biochars was slightly higher than pristine biochar after H2O2 oxidative and leaching ageing. Whereas, the dominate mechanism of DEP removal on Cd-adsorbed biochars changed to hydrophobic partitioning after high temperature, freeze-thaw cycles and dry-wet cycles ageing, leading to a decreased DEP sorption capacity. Hence, the biochar application must be comprehensively considered the susceptibilities due to reciprocal effects of early adsorbed pollutant and natural ageing environment, which helps us both assess and take measures to minimize potential risks in the environment. The present study suggests the continuous irrigation and tropical or temperature climate regions would be suitable for long-term biochar application in soil remediation and carbon sequestration.

Sorption of diethyl phthalate and cadmium by pig carcass and green waste-derived biochars under single and binary systems

Potentially toxic elements (PTEs) and phthalic acid esters (PAEs) often coexist in contaminated soils. Their co-existence may affect the mutual sorption behavior, and thereby influence their bioavailability and fate in soils. To our best knowledge, the impacts of plant-and animal-derived biochar on the competitive sorption-desorption of PTEs and PAEs in soils with different organic carbon content have not been studied up to date. Therefore, in this study, batch sorption-desorption experiments were conducted to investigate the influence of biochars derived from pig carcass and Platanus orientalis branches on the mono- and competitive sorption of cadmium (Cd2+) and diethyl phthalate (DEP) in soils with high (HS) and low (LS) organic carbon content. The DEP sorption was well described by Freundlich isotherm model, while Cd2+ sorption fitted better with the Langmuir isotherm model. Application of both biochars enhanced soil sorption of DEP, which increased as the application doses increased. The HS showed a stronger affinity to both DEP and Cd2+ than the LS. In the LS, the pig carcass biochar (PB) addition was more effective to increase the sorption capacity of Cd2+ and DEP and to reduce their desorption than woody biochar (WB) treatments. Moreover, the co-existing of Cd2+ could reduce the sorption of DEP, especially in the LS. The presence of DEP enhanced Cd2+ sorption in LS treated by both biochars, but the sorption of Cd2+ was suppressed with DEP addition in the PB-amended HS. In conclusion, the soil sorption capacity of DEP and Cd2+ was affected by biochar type, application dose and soil organic carbon content. The reciprocal effect between DEP and Cd2+ was also a crucial factor influencing their sorption/desorption by biochar. Therefore, PB and WB, especially PB, can be used for metal/DEP immobilization due to enhanced sorption. This approach is applicable for future remediation of soils contaminated by PTEs and PAEs.

Selective sorption of diethyl phthalate on pH-responsive, molecularly imprinted polymeric adsorbents

ABSTRACT A novel synthetic route for preparation of pH-responsive molecularly imprinted adsorbents for separation of diethyl phthalate (DEP) is proposed. Polymers were synthesized using acrylic acid (AAc) and methyl methacrylate (MMA) crosslinked using ethylene glycol dimethacrylate (EGDMA) or divinylbenzene (DVB). The carried out tests revealed the pH-driven recognition of synthesized sorbents toward DEP. It was found that sorbents derived from mixture of 30% AAc:MMA (1:1) and 70 wt.% of DVB in the presence of 7 wt.% of template were the best. The DEP sorption took the highest value (85 mg g−1) at pH = 5, while desorption with extent of 92% was the most efficient at pH = 8.

Insight into mechanism of aged biochar for adsorption of PAEs: Reciprocal effects of ageing and coexisting Cd2+

Biomass derived biochar is a stable carbon-rich product with potential for soil amendment. Introduced into the natural environment, biochar will naturally experience ‘ageing’ processes that are liable to change its physicochemical properties and the mobility of sorbed pollutants over the longer term. To elucidate the reciprocal effects of biochar ageing and heavy metal adsorption on the affinity of biochar for organic pollutants, we systematically assessed the adsorption of diethyl phthalate (DEP), representative of phthalic acid esters (PAEs), to fresh and aged biochars with and without coexistence of Cd2+. Long-term oxidative ageing was simulated using 5% H2O2 and applied to biochar samples made from corn cob, maize straw and wheat straw made by pyrolysis at both 450 °C and 650 °C. Our results showed that biochar made at lower temperature (450 °C) and from straw exhibited the higher adsorption capacity, owing to their greater polarity and abundance of O-containing functional groups. The adsorption of DEP onto fresh biochars was found to be driven by van der Waals force and H-bonding. Biochar made at the higher temperature (650 °C) displayed higher carbon stability than that produced at lower pyrolysis temperature. Oxidized biochar showed lower adsorption capacity than fresh biochar owing to the formation of three-dimensional water clusters on biochar surface, which blocked accessible sites and decreased the H-bonding effect between DEP and biochars. The coexistence of Cd2+ suppressed the sorption of DEP, via competition for the same electron-rich sites. This indicates that cation/π-π EDA interactions are the primary mechanism for PAE and Cd2+ stabilization on biochar. Our study sheds light on the mechanism of organic pollutant sorption by biochar, as well as the potential susceptibilities of this sorption to ageing effects in the natural environment.

Removal of diethyl phthalate via adsorption on mineral rich waste coal modified with chitosan

Phthalic acid esters or phthalates in wastewater are priority pollutants and demand efficient method for remediation. Here we present a novel utilization of low grade coal, which is otherwise a waste, modified by chitosan as adsorbent for removal of diethyl phthalate (DEP) via adsorption. A low carbon and high silicate content coal was chosen, characterized by CHN analyzer, energy dispersive X-ray analysis and by X-ray diffraction. A composite of mineral rich coal and chitosan is prepared via electrostatic interaction and hydrogen bonding between the hydroxyl groups of chitosan and the silicate group of coal; confirmed by Fourier transformed infrared spectroscopy, thermogravimetry analysis and zeta potential measurements. An optimized 9:1 weight ratio of coal-chitosan composite exhibited a positive zeta potential value in aqueous medium and corresponded to 91.1% DEP adsorption at an optimized condition e.g., pH5.8, adsorbent dose of 4mg/mL and contact time of 4h. The adsorption is thermodynamically favorable and followed pseudo-second order kinetics, and attributable to chemisorption process, is attributed to electrostatic interaction and hydrogen bonding between the DEP and the functional groups in the composite. The adsorption isotherm data was best fitted non-linearly by Sips isotherm model, which is consistent with Freundlich adsorption isotherm for lower concentration of DEP (5 to 100mg/L), while Langmuir adsorption was favored for adsorption of higher DEP concentrations (100 to 400mg/L). The qmax was 42.67mg/g, which is a significant improvement in DEP sorption from aqueous medium among the readily degradable adsorbents reported so far. The practical application of coal-chitosan composite as adsorbent has been demonstrated by its re-usability and ability for sorption of DEP from spiked municipal wastewater, supported by decrease in chemical oxygen demand value of treated wastewater.

SOC Effects on Diethyl Phthalate Sorption to Four Soils in China

Purpose: Phthalate esters (PAEs) are commonly detected in agricultural soils of China, which can post potential threats to human health. Understanding their sorption to soils is important in assessing their transport and bioavailability in environment. Limited research focuses on the influence of soil organic carbon (SOC) on PAEs adsorption to soils at different depths and increased dissolved organic carbon (DOC) after adsorption. Materials and Methods: Batch sorption experiments of diethyl phthalate (DEP) to four types of soils were conducted in this study, including black soil, fluvo-aquic soil, paddy soil, and red soil. Total concentration of solute DEP and the concentration of free DEP not sorbed to DOC were measured with HPLC. The UV absorbance of supernatant was measured and specific UV absorbance at 254 nm was calculated for DOC aromaticity. Sorption isotherms of DEP to soil particles were fitted to the Langmuir model and the Freundlich model. Results and Discussion: Partial SOC can dissolve to DOC in solution, and 47.4- 89.4% of total DEP can be sorbed to DOC. Increasing DEP in solution can enhance aliphatic SOC dissolving. The sorption coefficients of DEP are higher to fluvo-aquic soils (Koc for surface soils 1820 L kg-1 and subsurface soils 1388 L kg-1) than to other soils (<520 L kg-1), which indicates that SOC fractions of different soils have varied affinity to DEP. Conclusions: SOC plays an important role in DEP sorption to soil particles. Soil samples from surface layers have higher affinity than those from subsurface layers. DOC from SOC in solution is important for DEP transport in soil, and organic pollution can accelerate SOC dissolving.

Effect of aging process on adsorption of diethyl phthalate in soils amended with bamboo biochar

Biochar is a carbonaceous sorbent and can be used as a potential material to reduce the bioavailability of organic pollutants in contaminated soils. In the present study, the adsorption and desorption of diethyl phthalate (DEP) onto soils amended with bamboo biochar was investigated with a special focus on the effect of biochar application rates and aging conditions on the adsorption capacity of the soils. Biochar amendment significantly enhanced the soil adsorption of DEP that increased with increasing application rates of biochar. However, the adsorption capacity decreased by two aging processes (alternating wet and dry, and constantly moist). In the soil with low organic carbon (OC) content, the addition of 0.5% biochar (without aging) increased the adsorption by nearly 98 times compared to the control, and exhibited the highest adsorption capacity among all the treatments. In the soil with high OC content, the adsorption capacity in the treatment of 0.5% biochar without aging was 3.5 and 3 times greater than those of the treatments of biochar aged by alternating wet and dry, and constantly moist, respectively. Moreover, constantly moist resulted in a greater adsorption capacity than alternating wet and dry treatments regardless of biochar addition. This study revealed that biochar application enhanced soil sorption of DEP, however, the enhancement of the adsorption capacity was dependent on the soil organic carbon levels, and aging processes of biochar.

Sorption of Phthalates on Molecularly Imprinted Polymers

Porous beads of styrene divinylbenzene copolymer, S-co-DVB, imprinted with dimethyl phthalate, DMP, were obtained. Two solvents were applied for the formation of pores: n-hexane and n-octane. The sorbents were prepared by membrane emulsification of monomer mixtures containing DMP followed by suspension polymerization. The average diameters of the synthesized beads were 40 µm for beads obtained from mixtures with n-octane, and 30 µm for preparations with n-hexane as solvent. It was shown that almost all monodispersive sorbents were obtained; their SPAN parameter was as small as 0.7–0.9. Sorption properties of evaluated samples varied in relation to the kind of applied reaction mixture. Generally, imprinted materials showed higher sorption capacity towards DMP than their off-template analogues. For the sorbent obtained in the presence of n-octane and with 3 wt.% of DMP, sorption of dimethyl phthalate took the highest value - 89 mg/g. The sorbents imprinted with DMP were checked for sorption of diethyl phthalate, DEP, and dibuthyl phthalate, DBP also. It was shown that sorbability of synthesized materials towards other phthalates was much smaller than for DMP and was not related to the presence of dimethyl phthalate foot prints.

Adsorptive removal of phthalate ester (Di-ethyl phthalate) from aqueous phase by activated carbon: A kinetic study

Adsorptive studies were carried out on Di-ethyl phthalate (DEP) removal from aqueous phase onto activated carbon. Batch sorption studies were performed and the results revealed that activated carbon demonstrated ability to adsorb DEP. Influence of varying experimental conditions such as DEP concentration, pH of aqueous solution, and dosage of adsorbent were investigated on the adsorption process. Sorption interaction of DEP onto activated carbon obeyed the pseudo second order rate equation. Experimental data showed good fit with both the Langmuir and Freundlich adsorption isotherm models. DEP sorption was found to be dependent on the aqueous phase pH and the uptake was observed to be greater at acidic pH.

Sorption of diethyl phthalate by nitrocellulose fibers

AbstractThe manner in which diethyl phthalate (DEP) is absorbed into nitrocellulose (NC) fibers has been observed microscopically. The movement of pure DEP into dry fibers proceeds by capillary motion up the central canal (lumen) and through microcracks between fibrils. Attack, measured by a large change in birefringence, spreads from these foci, and within the time scale of the experiment there is little interaction with the primary (outer) wall of the fiber. If, however, the lumen and other capillary passages are blocked by water or other liquid, then attack proceeds evenly from the outer wall and a sharp boundary between swollen and unswollen material moves at a uniform speed towards the center of the fiber and appears to be unaffected by the fibrillar structure (Case II swelling). If the supply of DEP to the surface is interrupted, this boundary becomes immobile, and the concentration of DEP in the swollen layer is that which is just sufficient to saturate residual un‐nitrated hydroxyl groups on the NC. Reducing the activity of the DEP by admixture with benzene results in similar sharp boundaries, presumably because capillaries become blocked with spent diluent. Apart from capillary action, movement is always perpendicular to the fiber axis.