Regeneration Reuse Research Articles

Biomass-based perovskite/graphene oxide composite for the removal of organic pollutants from wastewater

Water pollution is a critical issue that affects both human health and the environment. Biomass-based LaFeO3 is prepared by the microwave-assisted method using rice straw as a cellulose source. Then LaFeO3/graphene oxide (GO) composite is prepared by ultrasonication to facilitate the perovskite-GO binding. Raman and FTIR spectra of the prepared composite identify the presence of the perovskite, biochar, cellulose and GO oxide phases and proves the surface functional groups interactions. Transmission electron microscope image shows that the GO sheets are homogeneous covered with the perovskite nanoparticles. The adsorption performance of the LaFeO3/GO composite for the removal of methylene blue (MB) and congo red (CR) dyes from aqueous solution is optimized. Adsorption follows pseudo 2nd order kinetic model and Freundlich isotherm, with maximum adsorption capacities of 319.5 and 416.7 mg/g for MB and CR, respectively. These values are higher than those reported for magnetic GO composites, indicating the excellent adsorption ability of the proposed perovskite/GO composite. A thermodynamic study shows that the adsorption of MB is exothermic, while it is endothermic for CR and combines physisorption and chemisorption characteristics for both dyes. The proposed adsorbent shows a good performance in the presence of NaCl interferent, with the possibility of regeneration and efficient successive reuse.

Artificial neural network modelling and experimental investigations of malachite green adsorption on novel carboxymethyl cellulose/β-cyclodextrin/nickel cobaltite composite

This study presents a novel polymer nanocomposite based on carboxymethyl cellulose and β-cyclodextrin crosslinked with succinic acid (CMC-SA-β-CD) containing nickel cobaltite (NCO) nano-reinforcement. Various analytical techniques have been employed to investigate the structural, thermal, and morphological features of the resulting nanocomposite. The CMC-SA-β-CD/NCO nanocomposite has been utilized as an adsorbent for the removal of bisphenol-A (BPA, R% <40 %), malachite green (MG, R% > 75 %)), and Congo red (CR, no adsorption) from the synthetic wastewater. The study systematically explored the impact of various parameters on the adsorption process, and the interactions between MG and CMC-SA-β-CD/NCO were discussed. The adsorption data were fitted to different models to elucidate the kinetics and thermodynamics of the adsorption process. An artificial neural network (ANN) analysis was employed to train the experimental dataset for predicting adsorption outcomes. Despite a low BET surface area (0.798 m2 g−1), CMC-SA-β-CD/NCO was found to exhibit high MG adsorption capacity. CMC-SA-β-CD/NCO exhibited better MG adsorption performance at pH 5.5, 40 mg L−1 MG dye concentration, 170 min equilibrium time, 20 mg CMC-SA-β-CD/NCO dose with more than 90 % removal efficiency. Moreover, the thermodynamic studies suggest that the adsorption of MG was exothermic with ΔH° value −9.93 ± 0.76 kJ mol−1. The isotherm studies revealed that the Langmuir model was the best model to describe the adsorption of MG on CMC-SA-β-CD/NCO indicating monolayer surface coverage with Langmuir adsorption capacity of 182 ± 4 mg g−1. The energy of adsorption (11.4 ± 0.8 kJ mol−1) indicated chemisorption of MG on the composite surface. The kinetics studies revealed that the pseudo-first-order model best described the adsorption kinetics with qe = 86.7 ± 2.9 mg g−1. A good removal efficiency (>70 %) was retained after five regeneration reuse cycles. The ANN-trained data showed good linearity between predicted and actual data for the adsorption capacity (R-value>0.99), indicating the reliability of the prediction model. The developed nanocomposite, composed predominantly of biodegradable material, is facile to synthesize and exhibited excellent monolayer adsorption of MG providing a new sustainable adsorbent for selective MG removal.

Development of optimum waste water using network

The present study deals with three case studies are discussed in detail. All cases had been considered as retrofitting problems and solved very precisely considering existing fixed network costs, present cost of power consumption and recent market price of different sizes of pipes. The first case study involves four processes and single contaminant problem and three approaches of water minimization i.e. reuse, recycle reuse, regeneration reuse are applied. The GAMS software using CONOPT was used to mathematical programming. The second case study is identified as a multi contaminant, reuse problem. The results obtained from the present analysis is compared well and validated with the ASPEN WATER and WATER PINCH software's which uses mathematical programming and pinch technology. The third case study is also multiple contaminant problem which involves eight operations and only water reuse approach is applied. The results are also verified with both software's solutions. The initial fresh water consumption is 185 tph and after modification using mathematical programming it reduces to 90 tph (reuse), 90 tph (recycle reuse) and 46 tph (regeneration reuse).

Preparation of KHA/SA/MMT composites and their adsorption properties for Rhodamine B.

Two natural adsorbent materials, potassium humate (KHA) and montmorillonite (MMT), were successfully prepared by embedding them in sodium alginate (SA) gel spheres through physical cross-linking with CaCl2. And CaCO3 was used as a porogenic agent to prepare the porous composites, KHA/SA/MMT. The materials were characterized by using XRD, TGA, SEM, and N2 adsorption/desorption equipment. The results showed that MMT and KHA were successfully embedded in the SA gel; the introduction of MMT increased the thermal stability of the composites and the embedding of MMT, and the porogenic effect of CaCO3 increased the specific surface area of the composites substantially, which provided favorable conditions for adsorption and treatment of pollutants. In addition, a one-way exploratory experiment yielded a higher removal rate of Rhodamine B (RhB) at D = 0.6 g/L, pH = 5, C0 = 100 mg/L, and t = 360 min. The adsorption kinetics and adsorption isotherm conformed to the secondary kinetic model and Langmuir model, respectively, and the maximum adsorption of RhB by KHA/SA/MMT could reach up to 884.96 mg/g at 303 K. The adsorption mechanism for RhB was shown by FT-IR and XPS analyses to be possibly bound by non-covalent bonding forces. After seven consecutive adsorption-desorption cycles, the adsorption of RhB by KHA/SA/MMT still reached 80.75%. Therefore, the prepared gel spheres have the advantages of easy regeneration and efficient reuse and great potential for application in purifying RhB from wastewater.

Optimization of reaction variables in the sol-gel synthesis of Ni0.5Zn0.5Fe2O4 nanoparticles as a very fast adsorbent of methylene blue

An optimization study for the sol-gel synthesis of Ni0.5Zn0.5Fe2O4 nanoparticles and their performance for the adsorptive removal of the methylene blue (MB) dye was reported. The as-produced samples and their associated calcined corresponding ones in the range of 400–800 °C were systematically characterized for their structure and microstructure using different techniques. For the expected best candidate for the MB removal, the pure NiZn nanoferrite (optimized parameters: Fuel=Urea; pH=5; [Fe3+]:0.025 M; Total nitrate to fuel molar ratio=8/6.66) consists of ultrasmall nanocrystals with an average crystallite size of ∼4 nm. For the optimization study of adsorptive removal of the MB dye by selected ultrasmall NiZn ferrite nanoparticles, various critical physicochemical parameters were varied. Regarding the effect of calcination temperature, it was demonstrated that the nanoferrite calcined at 500 °C showed the best removal efficiency of MB (for instance ∼43% and ∼72%, for the as-prepared and the nanoferrite calcined at 500 °C, respectively). For the selected nanoparticles, the removal efficiency was found to increase in a monotonous manner in the pH range of 4–11. This increase was faster with pH values higher than the pHPZC (∼8). For instance, it is ∼10% for pH∼4, ∼18% for pH∼8 and ∼62% for pH∼11. Whereas, the uptake capacity of the dye onto the produced nanoparticles was found to decrease and increase, respectively, with the increase in the dosage and in the MB concentration. Whatever the dye concentration, almost of the removable amount of the dye takes place in the first 30 s. The very fast adsorption rate observed in the initial stage was mainly attributed to the external surface properties of the ferrite nanoparticles. Additionally, for an industrial, economic and environmental purposes, the reusability efficiency of the nanoparticles was tested. The nanoadsorbent was stable for up to five adsorption–desorption–regeneration–reuse consecutive cycles without obvious decrease in the removal efficiency for dyes.

β -Cyclodextrin polymer/zinc ferrite nanocomposite: Synthesis, characterization, and adsorption application for the removal of malachite green and Congo red

To address the worsening water scarcity resulting from the growing worldwide population's increased demand for potable water and restricted availability of potable water sources, it is necessary to eliminate contaminants from wastewater. This will enhance the quality of water available for use in various sectors and free up drinkable water. Adsorption is one of the simple, efficient, and cost-effective ways to remove contaminants from wastewater. However, many previously used adsorbent materials have issues such as low selectivity, poor regeneration ability, lack of functional modifications, and high swelling, to name a few. In this study, the authors aimed to enhance the adsorption of malachite green by using a novel nanocomposite (β-CDPZF) based on a β-Cyclodextrin (β-CD) based polymer containing Zinc ferrite (ZF) nanofiller. The study compared the adsorption efficiency of the nanocomposite for both malachite green (MG) and Congo red (CR). The β-CDPZF nanocomposite was characterized using various analytical techniques such as Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (XRD), dynamic light scattering (DLS), Brunauer–Emmett–Teller (BET) surface area analyzer, field emission scanning electron microscopy (FE-SEM), and thermogravimetry (TG) analysis. The study investigated the influence of various experimental conditions on the adsorption process, and the isotherm, kinetics, and thermodynamic parameters was determined for the adsorption. The results showed that β-CDPZF had a fourteen times higher adsorption capacity (Langmuir) for the removal of MG compared to CR. Additionally, β-CDPZF could be effectively used for up to five regeneration reuse cycles while retaining >90% removal efficiency for MG. Therefore, the β-CDPZF nanocomposite can serve as a cost-effective, less swellable, and efficient adsorbent for the removal of cationic MG dye.

High-efficiency recycling of spent lithium-ion batteries: A double closed-loop process

Due to the scarcity of raw materials and negative environmental effects, it is essential to selectively recover lithium and other transition metals from end-of-life lithium-ion batteries (LIBs). Here, we propose a dual closed-loop process for resource utilization of spent LIBs. As an alternative to strong inorganic acids, deep eutectic solvents (DESs) as green solvents are employed for the recycling of spent LIBs. The DES based on oxalic acid (OA) and choline chloride (ChCl) achieves efficient leaching of valued metals within a short time. Through the coordination adjustment of water, it can form high-value battery precursors directly in DES, changing wastes into valuables. Meanwhile, water as a diluent can achieve the selective separation of lithium ions via filtration. More importantly, DES can be perfectly re-generated and recycled many times, indicating that the process is cost-effective and eco-friendly. As experimental proof, the re-generated precursors were used to produce new Li(Ni0.5Co0.2Mn0.3)O2 (NCM523) button batteries. The constant current charge-discharge test revealed that the initial charge and discharge values of the re-generated cells were 177.1 and 149.5 mAh/g, respectively, corresponding to the performance of commercial NCM523 cells. The whole recycling process is clean, efficient, and environment-friendly, realizing the double closed loop of spent battery regeneration and deep eutectic solvent re-use. This fruitful research demonstrates DES has excellent potential for recycling spent LIBs and provides an efficient and eco-friendly double closed-loop solution for the sustainable re-generation of spent LIBs.

Bentonite-layered double hydroxide composite as potential adsorbent for removal of Abamectin pesticide from wastewater

This research study has proposed the preparation of bentonite-supported CuAl-LDH (B-CuAl) via co-precipitation technique with bentonite incorporation. The prepared B-CuAl has been investigated for adsorption of Abamectin pesticides (ABM) from wastewater in batch mode experiments. The prepared B-CuAl structures and morphology were identified by BET, FTIR, XRD and SEM. For the adsorption process, the impact of initial pH, shaking speed, contact time, ABM initial concentration, temperature, adsorbent dosage and particle size as well as, the thermodynamic, isotherm and kinetics have been studied. The Langmuir isotherm model fits the B-CuAl adsorption data better than the Freundlich isotherm model, suggesting mono-layered adsorption phenomena. The kinetics of ABM adsorption are described by a pseudo-second-order model (R2=0.9898). The thermodynamic study revealed that adsorption of ABM onto B-CuAl was spontaneous and endothermic in nature. Furthermore, the regeneration capability and reuse of the prepared adsorbent have been studied. The adsorption efficiency was higher than 86.32%, suggesting that B-CuAl is an excellent adsorbent for effective pesticides removal from wastewater.

Selective adsorption and fluorescence sensing of tetracycline by Zn-mediated chitosan non-woven fabric

Nowadays, numerous studies have focused on the newly developed technologies for the thorough removal of tetracyclines (TCs). The efficient removal of trace-amount pollutants requires the development of improved materials with higher adsorption capacity and increased adsorption selectivity. Zn(II)-mediated chitosan nonwoven fabric (Zn-CSNW) adsorbent with coordination capability was explored for the effective and selective removal of TC. The adsorption of TC to Zn-CSNW could reach equilibrium in about 30 min with a maximum adsorption capacity of 195.9 mg/g. It exhibited high anti-interference performance for TC adsorption at low concentrations, with good regeneration and effective reuse. Except for citrate, organic materials similar in structure to TC or common ions in aqueous solutions did not show obvious competition for the adsorption of low concentrations of TC. Additionally, the inherent fluorescence of chitosan and the fluorescence sensitization effect of Zn2+ for TC enabled function of Zn-CSNW as an indicator of the adsorption of TC by changes in fluorescence color and intensity under UV light (365 nm). It can indicate the saturation state of the Zn-CSNW, which will bring convenience to the use of the adsorbent. The Zn(II)-mediated coordination interaction plays a vital role in both the selective recognition of TC and the fluorescence sensing of adsorption amount, demonstrating an affordable and effective strategy for the treatment of water containing low amounts of antibiotics.

Simultaneous synthesis of heat-integrated water networks by a nonlinear program: Considering the wastewater regeneration reuse

Heat-integrated water network synthesis (HIWNS) has received considerable attention for the advantages of reducing water and energy consumptions. HIWNS is effective in water and energy sustainability. Mixed integer non-linear programming (MINLP) is usually applied in HIWNS. In this work, a novel nonlinear programming (NLP) was proposed for HIWNS by considering wastewater reuse and wastewater regeneration reuse. Integer variables are changed to non-linear equation by the methods for identifying stream roles and denoting the existence of process matches. The model is tested by examples with single and multiple regeneration unit problems. The testing results showed that the NLP is an alternative method for HIWNS with wastewater reuse and regeneration reuse.

Superabsorbent dewatering of refractory gold concentrate slurries

In this paper, superabsorbent polymer (SAB) dewatering behaviour of selected mineral pulps comprising low-grade, refractory gold flotation concentrate, bio-oxidation product and cyanide leach residue was investigated as an alternative to conventional, gravity thickening. The shear rheology of the resulting sediments was also investigated for pulp handleability. All slurries displayed better SAB-mediated dewatering performance, in terms of reduced processing time, volume minimization and greater water recovery for recycle, in comparison with gravity thickening. Specifically, SAB absorbed >94 wt.% water from the dilute slurries within 30 min of contact time. 45–76 wt.% more water was recovered after 60 min at high supernatant clarity using the SAB dewatering approach compared with gravity settling. The observed non-Newtonian, shear thinning rheological behaviour of SAB-dewatered consolidated slurries, reflecting low to moderate yield stresses in the range 1–40 Pa and shear thinning viscosities (<10 mPa⋅s), indicate their “handleability” in hydro-transport. The cost effectiveness of the SAB dewatering process engendered by its significantly greater water recovery and SAB polymer recovery, regeneration and multiple reuse capacity.

Removal of Estradiol from Water with a Hybrid MIP-TiO2 Catalytic Adsorbent

17β-Estradiol (E2) is one of the main compounds responsible for estrogenic activities in sewage and natural waters and has been found in these matrices all around the world, thereby justifying the development of technologies for its removal. In this work, pure or TiO2-containing molecularly imprinted polymers (MIPs) and non-imprinted polymers (NIPs) were prepared using E2 as template. The materials were characterized by infrared spectroscopy, X-ray diffraction, adsorption/desorption of N2, and scanning electron microscopy (SEM). The characterization analyses showed that TiO2 was incorporated in the polymers and that all materials could be characterized as mesoporous and had surface areas ranging from 238 to 279 m2g−1. Adsorption studies showed MIP-TiO2 had a high capacity to adsorb E2 from the water phase leading to qmax values of 15.16 to 26.49 mg g−1 at temperatures from 25 to 45 °C, respectively. In addition, the thermodynamic study showed that the adsorption process is endothermic, spontaneous, and entropically driven. The results also showed that the presence of TiO2 decreases the adsorption performance of MIP-TiO2 when compared with MIP (without the photocatalyst) during the adsorption. However, the application of MIP-TiO2 in a process of adsorption followed by photocatalysis resulted in 100% of E2 removal allowing the reuse of adsorbent. In addition, MIP-TiO2 maintained its E2 removal capacity even after five cycles of regeneration–reuse, which shows the ability of UV light to regenerate the specific adsorption sites. The results presented in this paper show MIP-TiO2 has potential to be applied in water treatment systems to remove E2.

An iterative design method for regeneration reuse water network with internal water mains

AbstractCompared with the conventional water network, the water network with internal water mains has the advantages of simple structure, easy design and control. Regeneration reuse can avoid accumulation of contaminants compared with regeneration recycling. There are few studies on regeneration reuse water network with internal water mains. This paper analyzes the water‐using relationship between the water‐using unit and the internal water main and then provides an iterative design method for the regeneration reuse water network with internal water mains. Reasonably determining the flowrate of the internal water mains is the key to the design. The presented method is applicable to two types of regeneration units. Two cases are studied to demonstrate the applicability of the presented method.

High-efficient adsorption of phosphates from water by hierarchical CuAl/biomass carbon fiber layered double hydroxide

Phosphorus-contaminated wastewater is one of the main reasons for eutrophication. In this work, a hierarchical CuAl/biomass carbon fiber layered double hydroxide was synthesized successfully and applied to phosphates adsorption in simulated wastewater. The morphologies and structures of composites were characterized by Scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Fourier transform infrared (FTIR) and Raman spectrum (RS) analyses. The influences of pH, dosage of adsorbent, competitive anions, initial phosphates concentration and contact time on adsorption progress were studied. The adsorption of phosphates reached equilibrium quickly at about 50 min and the removal efficiency reached 99.6%. The results indicated that the major adsorption mechanism included anion-exchange, electrostatic attraction and ligand exchange were occurred during phosphates adsorption process. The results indicated that the phosphates removal kinetics is well fitted pseudo-second order model, and the adsorption isotherm is well described by Langmuir model. In addition, the regeneration potential and reuse of spent as-prepared adsorbents experiments showed the composites possess highly recyclable ability. It could be suggested that the prepared hierarchical composite was an efficient adsorbent for the removal of phosphates from wastewater.

A Mathematical Programming Method for Optimizing the Single-Contaminant Regeneration Heat-Integrated Water Networks

A superstructure-based mathematical model is established for single-contaminant heat-integrated water networks (HIWN), and the water loss of both wastewater regeneration recycling and regeneration reuse is considered. Furthermore, a sequential optimization procedure is established to achieve multi-objective optimization. The loss rate of water is taken into the mathematical model as there must have water loss in regeneration process, so that the optimization would be more realistic. Two cases are optimized using proposed model with regeneration recycling and regeneration reuse considered, respectively; the results show the differences between these two modes. Compared with the optimization method in the literature, the proposed method is more realistic.

Removal of fluoride from water by nanocomposites of POPOA/Fe3O4, POPOA/TiO2, POPOT/Fe3O4 and POPOT/TiO2: Modelling and optimization via RSM

The paper studies the synthesis, performance, and modeling of conducting copolymers of poly(o-phenetidine-co-o-anisidine/TiO2), poly(o-phenetidine-co-o-toluidine/TiO2), poly(o-phenetidine-co-o-toluidine/Fe3O4) and poly(o-phenetidine-co-o-anisidine/Fe3O4) on a stainless steel electrode in a batch reactor for removal of fluoride ions. As a safety method, the electrically switching ion exchange was used as the ion exchange process. In addition, modeling and optimization of the process was done by the response surface methodology (RSM) based on central composite design (CCD). The independent variables in the RSM were applied potential (V) and pH of fluoride solution. A real tap water was chosen as the water sample. The poly(o-phenetidine-co-o-anisidine/Fe3O4) has shown better results in the fluoride ions removal and regeneration–reuse process. Also, the other poly(o-phenetidine-co-o-anisidine/Fe3O4), under the controlled conditions of pH of 6.26 and the applied potential of 1.06V, shows a high ability in fluoride removal of 71.76% and after three successive cycles still has a fluoride removal ability of 16%.

A stepwise optimal design of water network

In order to take full advantage of regeneration process to reduce fresh water consumption and avoid the accumulation of trace contaminants, regeneration reuse and regeneration recycle should be distinctive. A stepwise optimal design for water network is developed to simplify solution procedures for the formulated MINLP problem. In this paper, a feasible water reuse network framework is generated. Some heuristic rules from water reuse network are used to guide the placement of regeneration process. Then the outlet stream of regeneration process is considered as new water source. Regeneration reuse network structure is obtained through an iterative optimal procedure by taking the insights from reuse water network structure. Furthermore, regeneration recycle is only utilized to eliminate fresh water usage for processes in which regeneration reuse is impossible. Compared with the results obtained by relevant researches for the same example, the present method not only provides an appropriate regeneration reuse water network with minimum fresh water and regenerated water flow rate but also suggests a water network involving regeneration recycle with minimum recycle water flow rate. The design can utilize reuse, regeneration reuse and regeneration recycle step by step with minor water network structure change to achieve better flexibility. It can satisfy different demands for new plants and modernization of existing plants.

Effective Synthesis and Optimization Framework for Integrated Water and Membrane Networks: A Focus on Reverse Osmosis Membranes

Strict environmental regulations and social pressures have created the need for water and energy minimization in the process industries. Therefore, this work looks at the incorporation of a detailed reverse osmosis network (RON) superstructure within a water network superstructure in order to simultaneously minimize water, energy, operation, and capital costs. The water network consists of water sources, water sinks, and RO units for the partial treatment of the contaminated water. An overall mixed-integer nonlinear programming framework is developed that simultaneously evaluates both water recycle–reuse and regeneration reuse–recycle opportunities. The solution obtained from optimization provides the optimal connections between various units in the network arrangement, size and types of RO units, booster pumps, as well as energy recovery turbines. The paper looks at four cases to highlight the importance of including a detailed regeneration network within the water network instead of the traditional “bla...

Dispersion–precipitation synthesis of nanosized magnetic iron oxide for efficient removal of arsenite in water

Nanosized magnetic iron oxide was facilely synthesized by a dispersion–precipitation method, which involved acetone-promoted precipitation of colloidal hydrous iron oxide nanoparticles and subsequent calcination of the precipitate at 250°C. Characterization by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, nitrogen sorption, and vibrating-sample magnetometry revealed that the material was a composite of α-Fe2O3 and γ-Fe2O3 with primary particle size of 15–25nm and specific surface area of 121m2/g, as well as superparamagnetic property. The material was used as adsorbent for the removal of arsenite in water. Batch experiments showed that the adsorption isotherms at pH 3.0–11.0 fit the Langmuir equation and the adsorption obeys pseudo-second-order kinetics. Its maximum sorption capability for arsenite is 46.5mg/g at pH 7.0. Coexisting nitrate, carbonate, sulfate, chloride, and fluoride have no significant effect on the removal efficiency of arsenite, while phosphate and silicate reduce the removal efficiency to some extent. The As(III) removal mechanism is chemisorption through forming inner-sphere surface complexes. The efficiency of arsenic removal is still maintained after five cycles of regeneration–reuse.

PANI/GO as a super adsorbent for the selective adsorption of uranium(VI)

Abstract In this paper, polyaniline modified graphene oxide (PANI/GO) composites were synthesized by in situ polymerization technique, and applied to preconcentrate U(VI) from aqueous solutions. The PANI/GO composites have exceptionally capability in selective extraction of U(VI) from aqueous solution under a variety of conditions. The maximum adsorption capacities of PANI/GO composites for U(VI) achieve to 1960 mg/g at pH 5.0 and 610 mg/g at pH 3.5, which are two orders of magnitude higher than those of traditional adsorbents and today’s nanomaterials. PANI/GO composites also present ideal tolerance to high salt concentrations and excellent regeneration–reuse property. Thereby, PANI/GO composites have exceptional potential applications in the extraction of U(VI) from aqueous solution in nuclear fuel achievement and for U(VI) environmental pollution cleanup.