Rapid growth in the oil and gas industry has led to the production of thick emulsion and oil spillage, leading to production issues. Also, these stable emulsions and hydrocarbon-contaminated wastewater pose a significant environmental challenge that must be immediately addressed (Zaman et al., 2019; Chen et al., 2021). Common methods of oil-water separation, like coagulation, gravity separation, thermal treatment, etc., have some disadvantages like consumption of high energy, longer separation time, and low separation efficiency (Chen et al., 2021; Xue et al., 2014), which make them commercially unviable.
Magnetic materials possess unique magnetic behavior resulting from complex multiphase structures (Zhang et al., 2015). Magnetic nanoparticles (NPs) have proved dominancy in various industries and research applications like drug delivery, electronics, separation, and purification (Yang et al., 2021a, Yang et al., 2021b; Nawaz et al., 2021; Ali et al., 2015a; Zhang et al., 2013), catalysis (Issaka et al., 2022; Yang et al., 2021a, Yang et al., 2021b; Khan et al., 2021) etc., owing to their strong magnetic domain and easy separation from stable emulsion system through external magnet (Ali et al., 2021; Dzumbira et al., 2021). Magnetite (Fe3O4) is considered a perfect candidate due to its minimum cytotoxicity and excellent compatibility (Ali et al., 2014; Nawaz et al., 2021). Evaluating NPs at liquid/liquid interfaces is significant in numerous research and industrial practices, including food processing, crude oil extraction, and mineral flotation (Ali et al., 2015b; Tian et al., 2015). Based on previous experimental and theoretical studies in this field, it is relatively easy to rationally describe the adsorbing phenomena of nanomaterials at liquid/liquid interfaces along with the emulsions stability as well as the formation of the foam resulting from the nanomaterials interface adsorption (Chu et al., 2022; Ali et al., 2019). Among these particles, stimuli-responsive polymers, together with nanoscale inorganic materials, have previously succeeded in the progress of composite materials with solvent, thermal, optical, and electronic characteristics (Hu et al., 2021; Ali et al., 2020; Cui et al., 2021).
The nanoscale inorganic materials hybridized with stimuli-responsive material may be demonstrated to utilize the water/oil interface (Liao et al., 2021). Previously, the integration of nanoscale, inorganic particles was used to fabricate multi-layered composite materials associated with individual nanoscale particle properties (Stefan et al., 2021; Zaman et al., 2019). Moreover, the composite of stimuli-responsive polymer with inorganic NPs have also been used for reversibly regulating the stability of the emulsion within stable oil-water systems through pH or temperature variation (Guo et al., 2022; Xu et al., 2022). In the stable emulsion, the emulsified water droplets are highly attractive regarding the development of facile inorganic NPs, with super hydrophilic wettability because NPs quickly migrate to the water phase in water, oil emulsion. Self-assembly of the inorganic NPs in the stable water, oil emulsion has been used to develop super hydrophilic multi-layered composites that effectively combine the properties of composite material and the individual nanoscale material (Ali et al., 2015c; Wang et al., 2021). Composite material formation by integrating stimuli-responsive polymers with magnetic inorganic NPs has also been used to reduce the emulsion stability via pH and temperature modulation (Zaman et al., 2019; Yue and Rahaman, 2022).
In this study, novel and recyclable magnetic composite NP, containing magnetic (Fe3O4) and an organic block copolymer of poly(methyl methacrylate acrylic acid) having strong hydrophilic wettability were developed. The magnetic composite NPs migrate to the emulsified water droplets due to the hydrophilic wettability of poly(methyl methacrylate-acrylic acid), thus efficiently detaching them through an external magnet (Scheme 1). The material is effective at 30°C temperature making 99% separation in about 30min. Furthermore, there is very low sludge formation and oil loss during separation. The prepared magnetic composite NPs can be recovered through external magnetic from the separated emulsion and can be recycled and used 8 times. Also, the treated emulsion is not contaminated with these NPs, presenting their green applications.
Heavy crude oil sample with diverse physical properties (Table 1) was obtained from the Gansu province Chang Qin oil field. NaAc, FeCl3·6H2O, and acrylic acid (AA) were provided by the reagent factory of Tianjin Hongyan Chemicals. Guang Zhou Jin Hua Da Chemical Co. Ltd provided Na3Cit, while methyl methacrylate (MMA) and ethylene glycol (EG) were provided by Fu Yu chemical reagent Co. Ltd Tianjin supplied by Jin Shan Hua Shi Chengdu chemical. Potassium peroxy sulphate was delivered by Shanghai,
TEM image of P(MMA-AA) precursor can be seen in Fig. 1. (a) and (b) as well as magnetic composite NPs in Fig. 1. (c) and (d). The TEM image in Fig. 1. (a) and (b) demonstrates the polymeric precursor NPs morphology to be uniform and almost monodisperse sphere-shaped particles having an average diameter of almost 140nm. Whereas images (c) and (d) show that the black Fe3O4 were appropriately adsorbed over the grey clour poly (methyl methacrylate-acrylic acid) polymer precursor nanoparticles
Demulsification capability at different concentration
To determine the hydrophilic wettability and demulsification capability of P(MMA-AA)/Fe3O4 magnetic composite NPs a number of successive experiments were performed via stable emulsions of crude oil having 24.7 °A PI. Fig. 8 image (a) for sample 01 (24.7 °API) describes the process of hydrophilic wettability and demulsification capability. Variant quantity of naphtha diluted (0.03, 0.04, and 0.05g) magnetic composite NPs had been added in 15mL 7:3 ratios (heavy crude) oil and water emulsion.
Comparison of magnetic composite NPs with commercial demulsifiers
After optimising different separation parameters such as time, temperature, pH, salt content and water content, the magnetic composite NPs were compared with various commercial demulsifiers available in the market (Fig. 13 a and b). Different commercial demulsifiers, i.e., hexyl amine and propylene oxide block copolymer, were used at 30°C for a stable emulsion of 24.7 °API. The separation efficiency for hexyl amine is 10%, and ethylene oxide–propylene oxide block copolymer is 23.3% at 30°C
In contrast to other commercial demulsifiers, the poly(methyl methacrylate acrylic acid)@Iron oxide (Magnetic) composite NPs were observed to increase the coalescence capability of water droplets, their kinetics, and their capacity of reusing after demulsification. Several demulsification trials were performed at 30°C by maintaining the demulsification for 30min to examine the magnetic composite NPs recycling ability. The recycle tests were performed 8 times. Fig. 14 (a) gives the image
Mechanism of demulsification performance of magnetic composite NPs
Two parts in the asymmetrical hybrids structure of P(MMA-AA)/Fe3O4 can be seen, one is organic polymer NPs with grey clour, and the other black clour is for inorganic iron oxide, which is appropriately deposited on the surface of the former. To know the water removal procedure from emulsions using P(MMA-AA)/Fe3O4 “magnetic composite NPs”, the emulsion system was analyzed through an optical microscope. Fig. 15 (a) confirms the presence of (water) droplets in the system in emulsions with droplets
Separated water physicochemical characterization for reuse
Water separation is the important step when oil is generated to remove replicated (produced) water with a number of organic and inorganic materials from chemicals. It is crucial to carry out the physicochemical characterization of (separated) water in large volumes and their suitable discarding or reuse for vital environmental concerns. Thus, physicochemical testing for the separated water from stable oil, water emulsion was performed through standard ASTM methods to confirm if the synthesized
P(MMA-AA)/Fe3O4 magnetic composite NPs with robust hydrophilic wettability and excellent demulsification application was prepared via a facile technique. The hydrophilic wettability of magnetic composite NPs permits them to efficiently move to the emulsified water droplets in emulsions, whereas the strong magnetic domain of Fe3O4 imparted quick separation of emulsified water from the heavy oil, water emulsion. The material was checked at different temperatures, time, pH, and salt contents and
Hira Zaman, Anwar ul Haq Ali Shah, Nisar Ali: Conceptualization, Formal analysis and curation, Project administration, Supervision, Validation, Writing – original draft, Writing – review & editing. Hira Zaman, Cao Zhou, Adnan Khan: Investigation, Methodology, Formal analysis and curation, Interpretation of results. Farman Ali, Chen Tian Tian: Conceiving and design of analytical methods, Validation, Writing – review & editing. Nisar Ali, Muhammad Bilal: Formal analysis, Formal analysis, Writing
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
The authors acknowledge the support from the International Joint Laboratory on Intelligent Preparation of High-end Mineral Salt Functional Materials, Key Laboratory of Regional Resource Exploitation and Medicinal Research, project numbers LPRK201909 and LPRK202101, National & Local Joint Engineering Research Center for Mineral Salt Deep Utilization, project number SF201801, Jiangsu Province College Students’ Innovation and Entrepreneurship Training program, project number 202111049338 and
Source, occurrence and risks of twenty antibiotics in vegetables and soils from facility agriculture through fixed-point monitoring and numerical simulation
Journal of Environmental Management, Volume 319, 2022, Article 115652
In this study, a universal method that combined fixed-point monitoring and numerical simulation was used to understand the source, fate and risks of antibiotics in environment. Results showed that the antibiotic concentration in vegetables, soil and manure from 53 fixed-point monitoring sampling sites were ND-18.47, ND-1438.50 and ND-24710.00μgkg−1, respectively. There were positive correlations between the antibiotic concentrations of vegetables and soil as well as between soil and manure. The average Amountsoil/manure values were 1.48–46.02, indicating that antibiotics built up pseudo persistent residues in soil due to repeated fertilization. The modified level-III fugacity model showed that tetracyclines and fluoroquinolones tend to remain in soil given their sorption and mobility, while sulfonamides were highly distributed in plants, especially in leaves. Norfloxacin, ofloxacin, sulfadiazine, sulfamethoxazole and sulfisoxazole were found to be risk factors in facility agriculture and should be continuously monitored during agricultural production. Most importantly, we used the inversion method to determine the recommended maximum residue limits of antibiotics in soil. This will not only allow for better control of the amount of the antibiotics in the environment, but also act as a potential method to assess the risks of pollutants without maximum residue limits in the environment.
Suitability evaluation of carrying capacity and utilization patterns on tidal flats of Bohai Rim in China
Journal of Environmental Management, Volume 319, 2022, Article 115688
Tidal flats in the Bohai Rim are facing threats from human activities. Quantifying the carrying capacity and suitability of tidal flats is of great significance to the regional environment and resource management. In this study, the existing social and natural data were collected and the natural conditions of tidal flats, e.g., the distributions and utilization patterns, were investigated through remote sensing image interpretation and field investigation in the Bohai Rim. Then, a multi-index evaluation system was developed with indexes organized under the framework of the analytic hierarchy process (AHP) and the Drivers-State-Impact (DSI) framework, processed by fuzzy evaluation, and weighted by the entropy method. The studies show that the rapid expansion of industry-port-town, salt pans or aquafarms in the Bohai Rim during 1990–2020 squeezed the space of tidal flats. Despite the limitation of the declining resource condition, the carrying capacity of tidal flats in the Bohai Rim increased slightly during 2000–2018 because of the great improvement in economic and ecological conditions. We estimate 59.93% of the land resources are suitable for economic development while others are temporarily unsuitable for reclamation due to their high ecological importance. The land use data and macro-evaluation system of tidal flat utilization patterns herein can provide references for coastal resource management and ecological restoration.
Differences in colonization strategies of three common pioneer woody species in post mining heaps
Journal of Environmental Management, Volume 319, 2022, Article 115668
Willow (Salix caprea), birch (Betula pendula) and aspen (Populus tremula) are common pioneer woody species, however little is known about colonization strategies in large-scale disturbances. Here we have compared the strategies of establishment of these pioneer woody species in unreclaimed sites on a large (1957ha) spoil heap in Czechia. For all species, seedlings numbers peaked in the 17 year old (successional age - time since overburden heaping) plot, suggesting that initial soil development promotes seedling establishment while covering of the surface by litter and organic layers reduces the establishment of pioneer species. The proportion of willow decreased from the edge of the heap and analysis of the age structure suggests that willow establishment was correlated with the presence of older willows in the vicinity of willows of certain ages (13 and 23 years being particularly important). The proportion of birch increased with its distance from the heap edge, and it is correlated with suitable weather conditions in the year of establishment, mainly July rainfall. Aspen proportion does not change significantly with its distance from the heap edge and year of establishment. It correlates with the number of trees in both surrounding and climatic conditions. Detailed analysis of young trees shows that vegetative propagation by root suckers (offspring) is rare in birch. In willow they represent about half of the trees while in aspen all of the young trees were root suckers derived from older aspen trees. This indicates a different colonization strategy of individual species. Birch is capable of long-distance seed transfer, which establishes most of the population, and its establishment is highly influenced by climatic conditions. Willow spreads massively over a short distance, and its establishment is highly influenced by the presence of 21–23 year old willow individuals in the vicinity. Only few scattered trees are able to establish at longer distances, where they can later spread locally by seeds. Aspen spreads over a long distance in low numbers but when some trees are established it spreads massively locally by clones.
Biological treatment of Climbing Hempweed biomass through optimized composting technologies - Toxicity assessment and morphological study of Abelmoschus esculentus
Journal of Environmental Management, Volume 319, 2022, Article 115631
Climbing Hempweed (CH) is one of the top ten most obnoxious weeds on the planet, as well as one of the most destructive weeds. Its disastrous spread on the agricultural field has hampered the production of a wide range of crops. Various management techniques have been used to eradicate the weed, but none have been completely successful. As a result, management through the use of weed biomass will aid in the eradication of the weed as well as the production of a value-added product. To utilize invasive weed CH for the production of rotary drum compost (R1) and rotary drum followed by vermicompost (V1), two composting technologies were used. These technologies are being compared on several physicochemical parameters to determine their efficacy. V1 compost had the highest total Kjeldahl Nitrogen (TKN) (3.01%), potassium (3.45%), and total phosphorus (16.42g/kg) levels, while R1 compost had 2.58% TKN, 2.8% potassium, and 14.25g/kg total phosphorus. Subsequently, the increasing trends in mitotic index (%) of R1 and V1 samples imply that the cytotoxic effects of CH were decreased due to composting and vermicomposting processes. Genotoxicity assessment revealed that an aberration percentage of 1.64 was observed in 100% concentration of V1 (after 30 days) and 4.34% in R1(after 20 days). R1 and V1 were used to evaluate the performance of Abelmoschus esculentus where the highest fruit harvest was seen at 25% amended R1 compost and 35% amended V1 compost. The application of 25–35% R1 compost and 35–40% V1 compost was found to be the most beneficial for the development of Abelmoschus esculentus. There was no significant difference in heavy metal (Mn, Fe, Cu, Co, and Zn) content in the fruit of Abelmoschus esculentus post-application of R1 and V1 compost.
Evaluating configuration of dual unit ceramic filter for arsenic removal from highly contaminated groundwater
Journal of Environmental Management, Volume 319, 2022, Article 115664
Iron (Fe) amended dual unit ceramic filters (DUCF) can be a viable treatment option for arsenic (As) removal from highly contaminated groundwater. The present field study investigated the effect of filter configurations, the separate-unit dual filter (SUDF) and connect-unit dual filter (CUDF), on As removal from groundwater having As concentration of 475μg/L. SUDF was configured by placing 1st and 2nd filter units side-by-side, whereas the 1st filter unit was placed on the top of the 2nd filter unit in CUDF configuration. Comparing the two filter configurations, SUDF achieving As concentration in the effluent below 50μg/L (standard value) was found more effective due to sufficient Fe2+ in the 2nd filter. Average As concentrations in the final product (effluent of 2nd filter) were 43μg/L from SUDF and 111μg/L from CUDF. The short hydraulic residence time (3.3min) in the 2nd filter of CUDF, along with limited contact between water and the iron net, lead to inadequate soluble Fe2+ resulting in poor As removal. Both filter configurations effectively removed Fe, P, and Mn with more than 90% reduction of these parameters by the 1st filter. Analysis of insoluble hydrous ferric oxides flocs through XAFS L3-edge spectra confirmed the oxidation of As(III) to As(V) in both the SUDF and CUDF systems resulting in enhanced As removal efficiency. The study results found SUDF as an appropriate configuration for filter design to treat highly contaminated groundwater in rural areas of developing countries.
Can digestate recirculation promote biohythane production from two-stage co-digestion of rice straw and pig manure?
Journal of Environmental Management, Volume 319, 2022, Article 115655
Digestate recirculation is often considered an important way to improve system stability (system acidification, ammonia inhibition, hydrolysis limitations, etc.) and gas production performance. However, it is not clear how the promotion of biohythane production works in anaerobic co-digestion with digestate recirculation of rice straw (RS) and pig manure (PM). Two sets of laboratory-scale two-stage continuous stirred tank reactors were operated continuously for 95d to investigate the performance of biohythane production in the first/second phase under mesophilic (M)/thermophilic (T) and digestate recirculation conditions. Firstly, biohythane was not produced by PM with RS under digestate recirculation. The main reasons were: 1) Digestive recirculation promoted the growth of hydrogenotrophic methanogenic bacteria; and 2) limitations in hydrolysis. Secondly, digestate recirculation has positive effects on the removal rates (removal rates of TS, VS, polysaccharide, protein and TCOD increased by 30.4%, 22.3%, 9.9%, 31.4%, and 11.9%, respectively) and energy yield (up to 68.7%). Finally, there was a higher abundance of hydrogen-producing bacteria (Fervidobacterium [44.9%] and Coprothermobacter [18.8%]) in T2, accounting for >80% of the total, and of which the huge hydrogen production potential cannot be ignored. The results provide new ideas for alleviating the energy crisis and developing green energy in the future.
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