Removal Of Chloride Research Articles

PHYSICO-CHEMICAL ANALYSIS OF TEXTILE EFFLUENT COLLECTED FROM TIRUPPUR BEFORE AND AFTER TREATMENT WITH CRAB (PORTUNUS SANGUINOLENTUS) SHELL CHITOSAN

Textile industries are one of the main sources of wastewater containing high amounts of colour, pH,BOD, COD, DO, TDS, TSS, alkalinity, chloride, phosphate, hardness, chemicals and heavy metals.They contaminate the water bodies and its ecosystem. In the present investigation, textilewastewater was collected from the discharge tank of a Tiruppur textile industry to investigateeleven physico-chemical parameters such as colour, total solids, TDS BOD, COD, Total alkalinity,Total hardness, chlorides, sodium, sulphates and iron. Chitosan extracted from crab shell is selectedas an absorbent to reduce most of the aforesaid parameters present from the textile industrial wastewater. The percentage removal of colour, total solids, TDS BOD, COD, total alkalinity, totalhardness, chlorides, sodium, sulphates and iron were 32.61 mg/l, 90.97 mg/l, 91.81 mg/l, 61.72mg/l, 55.66 mg/l, 91.57 mg/l, 45.90 mg/l, 96.76 mg/l, 66.73 mg/l, 80.77 mg/l and 94.79 mg/l respectively.

Thermal-resist hydro-charged air filters (HCAFs) with charge stability for long-term efficient fine particle removal

Fibrous air filters are widely equipped air freshening material in individual protective masks and air purifiers to regulate air quality and protect people from health hazards. To further improve filtration without increasing airflow resistance, electret technology is commonly used in combination with fibrous air filters due to electrostatic attraction caused by the charges on the fiber. However, constructing fibrous air filters with both charge stability and excellent filtration performance that could be used for long-term particle removal remains a challenge. Herein, hydro-charged air filters (HCAFs) that can be used in long-term high-efficiency removal of sodium chloride and paraffin oil aerosol particles is presented. Specifically, numerious positive and negative charges were dispersed in the HCAFs after hydro charging treatment, resulting in significantly enhanced filtration efficiency of 99.84 % (99.16 %) for sodium chloride (paraffin oil) aerosol particles. More importantly, the filtration efficiency of HCAFs for sodium chloride (paraffin oil) aerosol particles only had a decrement of 2.3 % and 0.35 % (6.1 % and 2.5 %) after 130 ℃ heat treatment and standing for two years, indicating that HCAFs possess charge stability and thermal resistance that can be used for long-term filtration. The successful fabrication of HCAFs shows a great promise for hydro charge technology and provides a new guideline for next-generation commercial air filters.

Removal of Hg2+ in wastewater by grafting nitrogen/sulfur-containing molecule onto Uio-66-NH2: from synthesis to adsorption studies.

The remediation of heavy metal deserves to be on the agenda, with the adsorbent design bearing the brunt of it. In this study, the molecule (4, 6-diamino-2-mercaptopyrimidine, DMP)containing thiol (-SH) and amino (-NH2) functional groups was grafted onto Uio-66-NH2, and a composite metal-organic framework nanomaterial (Zr(NH2)-DMP) was synthesized via a facile post-modification scheme. The morphological characteristics and structural features of the modified adsorbent were characterized by XRD, FT-IR, FE-SEM, EDS, BET, and XPS. The characterization results verified that the post-modification scheme was successfully achieved. The adsorption experiments were carried out to investigate the removal performance of the Zr(NH2)-DMP towards Hg2+ under different influencing parameters. The maximum adsorption capacity of 389.4mg/g was obtained, and the adsorption equilibrium was achieved within 30min at pH 6 at room temperature. Adsorption thermodynamic study indicated that the adsorption process was exothermic and spontaneous. The Zr(NH2)-DMP exhibited excellent selectivity for Hg2+, and also has the potential to remove Cu2+, Fe2+, and Zn2+ ions. The introduction of Cl- inhibited the removal of Hg2+ due to the formation of mercuric chlorides (removal efficiency reduced from 97.8 to 95.6%). The removal efficiency of up to 86.7% was obtained after four cycles. The Langmuir isotherm and Pseudo-second kinetic were more suitable for fitting the adsorption process of Hg2+ by Zr(NH2)-DMP. The main removal mechanism could be attributed to the chelation between Hg2+ (soft acid) and nitrogen/sulfur (soft base) elements. These findings convinced that the successful synthesis of Zr(NH2)-DMP provides an option for Hg2+ removal from wastewater.

Biodesalination performance of Phormidium keutzingianum concentrated using two methods (immobilization and centrifugation)

The biodesalination performance of the cyanophycean Phormidium keutzingianum concentrated using two methods (centrifugation and immobilization) was evaluated for the first time at NaCl concentrations of 10, 30, 50, and 70 g/L. In addition, the osmoregulation ability of P. keutzingianum was assessed at high salinities (50, 70, 85, and 100 g/L) over a relatively short time period. The pH, electrical conductivity, and chloride, nitrate, and phycocyanin concentrations were measured during all experiments. The immobilization method of concentration resulted in a chloride removal rate of up to 44 % during the osmoregulation experiment at a salinity of 100 g/L. For the centrifugation method, the chloride removal rate was 26 % on the 20th day of observation for 10 g/L. Thus, the immobilization method resulted in faster chloride ion removal than the centrifugation method. The findings demonstrate that biodesalination efficiency can be enhanced by the use of different P. keutzingianum preparation methods.

Construction of bismuth-based porous carbon models by 3D printing technology for light-enhanced removal of chloride ions in wastewater

The bismuth oxide (Bi2O3) based chloride (Cl−) removal method is one of the chemical precipitation methods possessing good selectivity and high removal efficiency of Cl− ions, but Bi2O3 often appears in the powder form, which is difficult to be recovered for regeneration. In this work, the combination of 3D printing technology and the Bi2O3 method was explored to construct the resin model including the Bi-precursors. In the optimum carbonization process at 400 °C for 30 min, the Bi3+ ions of the Bi-precursor were reduced into the metallic Bi0 nanoparticles, whose surfaces were covered by the thin Bi2O3 layers to form the heterostructured Bi0/Bi2O3 core/shell nanoparticles with an average size of 43 nm. These Bi0/Bi2O3 nanoparticles were tightly adhered to the internal and external surfaces of the hierarchical porous carbon model (Bi-PCM), which greatly facilitated their regeneration and ensured the stable Cl− removal performance. After five cycles of Cl− removal, the chloride removal efficiency over the multiple Bi-PCMs in the dark and pH 1 conditions maintained at about 26%, which then largely increased to 63.6% with UV light irradiation. The light-enhanced mechanism was related to the improved release rate of Bi3+ ions caused by photocorrosion and the Cl• radicals produced from the holes and the •OH and O2•− radicals, which quickly reacted with Bi2O3 to form BiOCl. The construction of Bi-PCMs by using 3D printing technology provides a very promising strategy for the removal of Cl− ions from wastewater.

Optimization of Water Leaching of Chlorides from Aluminum Salt Slag

Aluminum recycling generates large amounts of hazardous wastes, known as salt slags, consisting mainly of oxides, metallic aluminum, and salt fluxes. Water leaching is a common technique used for salt removal, being a decisive operation due to water usage and the need to achieve sufficient salt recovery. In this study, water leaching tests under varied operational conditions (water type, slag particle size, solid content, and leaching time) were carried out in salt slag samples obtained from a Brazilian aluminum scrap melting company. Leaching efficiency was assessed by the % chlorine leached. The optimal leaching condition, defined as the one that resulted in the highest chloride removal from the slag together with appropriate operational conditions (larger viable slag size, lower leaching time, etc.), was identified for a slag size below 2.8 mm, 30 wt% of solids in pulp, and a leaching time of 90 min. The results showed that it was possible to recover more than 92% of the salts initially contained in the raw slag, resulting in a leached material with less than 2.5% salts. The recovered salt characteristics showed potential for recycling and could be re-mixed to the salt flux used for aluminum melting. The possibility of achieving higher efficiencies and lower water consumption during leaching was also discussed, as was a preliminary flowsheet for salt slag treatment.

Numerical modelling of electrochemical deposition techniques for healing concrete damaged by alkali silica reaction

Alkali silica reaction (ASR) is a long-term factor that causes concrete cracking, and the ingress of harmful agents such as chloride can then be promoted by the ASR-induced cracks. Electrochemical deposition method (EDM) is a promising nondestructive rehabilitation technique which has two-fold advantages of crack repair and chloride removal. In this study, the entire process from ASR-induced cracking to crack repair by EDM is studied for the first time by coupling three sub-models involving different disciplines: (1) multi-ionic transport model, (2) ASR cracking model, and (3) crack repair model. The consumptions and interactions among various ionic species during ASR and electrochemical deposition are quantitively reflected in multi-ionic transport model. The ASR cracking model is developed considering the local mechanical variances of concrete composites. The crack repair model can successfully visualize the crack closure status, and the time-dependent porosity and diffusion coefficients during the treatment have also been well reflected. The proposed model is calibrated and validated against experimental data to ensure the prediction accuracy. A subsequent parameter analysis shows that increase in alkali silica aggregates volume fraction can facilitate cracking process. Besides, for electrochemical deposition treatment on ASR-induced cracks, setting all exposed surfaces as anode can effectively improve the repair rate, and adoption of pulse current can ensure the continuous supply of magnesium ions from external anolyte. Other findings which have not been reported in existing studies are also highlighted, which is hoped to better guide the application in practical engineering.

Polymer-modified sulphoaluminate cement-based mortar anode and its optimal arrangement for electrochemical chloride extraction

Electrochemical chloride extraction (ECE) is becoming a common method for repairing reinforced concrete structures exposed to marine environments, and the development of more efficient and durable anode materials is important. Therefore, this study designed a polymer-modified sulphoaluminate cement-based mortar (PSCM) as an anode for ECE, which can effectively remove chloride ions and repair damaged concrete. The results show that the PSCM, prepared using sulphoaluminate cement as the main cementitious material with 2% ethylene–vinyl acetate (EVA) and 0.6% carbon fibre as additives, possessed strong bond performance, high conductivity, and good repair function. In addition, the chloride removal efficiency was improved to 58.9%, when the PSCM was used as an ECE anode. The grid-like PSCM anode arrangement and stainless steel mesh/PSCM double-anode arrangement could overcome the shortcoming of chloride ion enrichment between the concrete and PSCM anode, and the chloride removal efficiency could reach 64.3%.

Laboratory evaluation of operating conditions for chloride removal from diethanolamine using ion exchange resin and introduction of optimal parameters

In this study, a strong anionic resin was used to remove the chloride ion in the diethanolamine of sweetening unit of gas refinery. A laboratory pilot has been investigated as a resin-filled bed to evaluate the reaction temperature, chloride ion concentration, resin saturation, resin recovery rate, optimal reaction temperature, diethanolamine flow rate, hydrogen strength and resin performance in this work. The resin saturation time, capacity of resin, optimal reaction temperature and changes in chloride concentration of the output stream from resin were determined in this research. Finally, the optimal amount of water to regulate the pH of the resin and the optimal amount of 4% sodium hydroxide solution to recycle the resin were calculated. It was found that one liter of resin is able to absorb 20.77 g of chloride. The temperature of 50 °C was considered as the optimal temperature of ion exchange reaction by comparing the amount of caustic and water consumption for resin recovery and regulation of neutral acidity, respectively. In this study, the amount of 4 wt.% caustic and water at a temperature of 50 °C for recovery of 134 g of resin obtained was equal to 8.5 and 5 L, respectively.

Removal of chloride from waste acid using Bi2O3: Thermodynamics and dechlorination behavior

Waste acid is an extremely hazardous acidic wastewater. Besides the toxic arsenic and fluoride, chloride in waste acid is a neglected but highly harmful substance which poses a threat to industrial equipment, the environment, and human health. In this study, bismuth oxide (Bi2O3) was used to remove chloride and detailed study of the dechlorination process and regeneration process was conducted on the basis of our team's arsenic and fluoride removal research. Thermodynamic investigations of the Bi3+–Cl−–H2O system showed the distribution regions of the single solid phase for bismuth oxychloride (BiOCl) and bismuth oxide are −1 ≤ pH < 5 and 9.6 ≤ pH ≤ 14, respectively. The effect of related factors on the removal efficiency, Bi residual concentration and final pH was explored experimentally. The removal efficiency of chloride reached 96.1 % under the temperature of 80 °C, the Bi2O3 dosage of the theoretical amount, and the reaction time of 60 min. The mechanism of Bi2O3 dechlorination is that Bi3+ generated by the dissolution of Bi2O3 is complexed with OH−, and Bi(OH)2+ decomposes to generate BiO+ which combined with Cl− to form BiOCl precipitation. The dissolution of Bi2O3 is the rate-controlling step. The regeneration efficiency reached 99 % under the optimal conditions. The dechlorination-regeneration cycling experiment showed that the regenerated Bi2O3 has almost the same dechlorination effect as the fresh Bi2O3. This study provides an important basis for the enhancement of chloride removal efficiency and process improvement of Bi2O3 method.

Preparation and Application of Calcined Mg/Al Layered Double Hydroxides in Organic Coatings and Chloride Removal

Preparation and Application of Calcined Mg/Al Layered Double Hydroxides in Organic Coatings and Chloride Removal

Solid fuel production from co-hydrothermal carbonization of polyvinyl chloride and corncob: Higher dechlorination efficiency and process water recycling

The hydrothermal carbonization (HTC) of polyvinyl chloride (PVC) and wet herbal agricultural wastes for solid fuel production remains bleak economics and sustainability because of high chloride residual, wastewater burden and low production capacity. In this study, the HTC dechlorination was investigated using the first-order reaction kinetic analysis. We found that the co-hydrothermal carbonization (co-HTC) of PVC and the typical biomass (corncob) achieved a staggering drop of dechlorination activation energy from 189.95 kJ/mol to 110.04 kJ/mol. The co-HTC process achieved rapid dechlorination and carbonization due to synergistic effect, to suppress the chlorine content in bituminous-coal-like hydrochar less than 0.05 %. The process wastewater (process water) from co-HTC was recycled four times to evaluate the reusability and chemical evolution. The organics in co-HTC environment enhanced the carbonization which was confirmed by the improved heating value (30.06 to 32.42 MJ·kg−1), hydrochar yield (33.33 % to 36.47 %) and energy recovery efficiency (57.73 % to 68.13 %). The Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) evidenced the process water recirculation maintained high chloride removal. Moreover, the possible formation pathways of two kinds of hydrochars were discussed through the chemical composition of the aqueous phase and the characteristic structures of hydrochar. The co-HTC and process water recycling strategies provide a more promising prospect to convert PVC and biomass wastes into solid fuels.

Extraction of chloride from slag flush wastewater using solvent N235

This work proposes a solvent extraction process for removal of chloride in slag flush wastewater using tri-n-octylamine (N235) as extractant. The single stage extraction and stripping efficiencies were 78.9% and 99.2% respectively under the optimal conditions. The McCabe-Thiele diagram and Kremser equation were utilized to predict the number of stages required to reduce the Cl− concentration to less than 350 mg/L. The results were authenticated utilizing a three-stage counter-current operation, that closely correspond the estimates of McCabe-Thiele diagram. The FT-IR spectra of organic phases indicate that the extractant N235 combines with H2SO4 first to form quaternary ammonium salt containing N-H+ after acidification by H2SO4, followed by an anionic exchange with Cl−. Further, the raffinate phase was stripped using a suitable stripping agent to increase the Cl− concentration up to 100,000 mg/L so as to facilitate precipitation of NaCl by addition of NaOH as salting-out agent. The XRD analysis was utilized to confirm the crystallinity and the purity of the precipitated NaCl.

A Novel Approach for the Biological Desalination of Major Anions in Seawater Using Three Microalgal Species: A Kinetic Study

The global water shortage alert has been upgraded to a higher risk level. Consequently, a sustainable approach for ecofriendly, energy efficient water desalination is required for agricultural and municipal water reuse. In this study, an energy-efficient biological desalination process was used to treat chloride anions, which are the most abundant anion salt in seawater. Three algal species were studied: Scenedismus arcuatusa (S. arcuatusa), Chlorella vulgaris (C. vulgaris), and Spirulina maxima (Sp. maxima), under different operating conditions (saline concentrations, contact time, high light intensity, and CO2 supply), and two kinetic models were used. It was identified that under a high light intensity and CO2 supply, S. arcuatusa enhanced chloride removal from 32.42 to 48.93%; the daily bioaccumulation capacity (Qe), according to the kinetic models, was enhanced from 124 to 210 mg/g/day; and the net biomass production was enhanced from 0.02 to 0.740 g/L. The EDX analysis proved that salt bioaccumulation may be attributed to the replacement of Ca2+ and Mg2+ with Na+ and K+ through algal cells. The study’s findings provide promising data that can be used in the search for novel energy-efficient alternative ecofriendly desalination technologies based on algae biological systems with biomass byproducts that can be reused in a variety of ways.

Purification of zinc sulfate solutions from chloride ions using bismuth hydroxosulfate

ABSTRACT An efficient, simple and lowcost method for purification of zinc sulfate solutions from chloride ions by precipitation with bismuth hydroxosulfate BiOHSO4∙H2O was proposed. Chemical analysis, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to characterize the solid obtained. The studied parameters were reaction temperature, pH, concentrations of zinc sulfate and chloride, and the molar ratio between BiOHSO4∙H2O and chloride. Under optimal conditions, the chloride removal efficiency reached 94.5–95.8% and the residual concentration of Cl− in the purified solution was 65–85 mg/L, which meets the requirements for zinc electrolysis and allows the production of special high-grade zinc. Compared with the commonly used approaches, the method proposed has the advantages such as a higher degree of purification of zinc electrolyte, the short period of time required for the BiOCl precipitation (1 hour) and good filterability. Apart from that, the consumption of the precipitant is close to the stoichiometric molar ratio, which makes the purification process cost-effective.

Metal-organic framework ZIF-8 for exceptional HCl removal from Hydrogen gas by reaction

In the production of hydrogen gas, the removal of hydrogen chloride (HCl) is of particular relevance for the chemical industry. Here we report the HCl removal performance of ZIF-8 metal organic framework demonstrated via fixed-bed (dynamic) measurements under process conditions. The measurements revealed an HCl removal capacity of 1.02 g/g, outperforming by far all traditional materials and other metal-organic framework previously tested. The ZIF-8, before and after the HCl contact, was characterized via SEM-EDX, XRD, TGA, ATR-FTIR, XPS and Raman spectroscopy. The results showed a dramatic change in textural, structural and chemical properties of ZIF-8 after HCl contact, where the MOF material undergoes a reaction and re-crystalizes into a salt complex.

Fluoride pollutants removal from industrial wastewater

BackgroundThe main object of the present study is the industrial wastewater effluent treatment resulting from a solar cell manufacturing process, which is a Joint Egyptian Chinese Renewable Energy laboratory, in Sohag Governorate. Fluoric and hydrochloric acids are the main pollutants causing a pH of 1 to 3. The effluent is neutralized by the addition of both potassium hydroxide and calcium hydroxide to permit the precipitation of the resulting sparingly soluble calcium fluoride. The chlorides are partially precipitated as calcium chloride, and the further addition of hydrated aluminum sulfate is used to precipitate the remaining extra chloride as an insoluble complex to reach the allowable chloride concentration in the treated effluent. Set of experiments at bench and pilot scales were run to achieve the optimum conditions for defluorination and dichlorination taking into consideration not exceeding the allowable ranges of pollutants as soluble salts in the final effluent.ResultsExperimental results showed that the performance of a pilot scale was satisfactory in fluorides, chlorides, and dissolved solids by 97.64, 78.85, and 79.4% removal, respectively. Based on these results a full-scale industrial treatment unit was designed for construction and operation as a treatment unit for industrial wastewater contaminated with fluorides as main pollutant.ConclusionsThe recommended treatment procedure succeeded in the removal of fluorides and chlorides as main contaminants in the effluent which permit the use of treated water in the irrigation of non-edible plants, according to Egyptian Code No. (501/2015).

Reusable Extractant and Direct Catalytic Mediation of Water/Oil/Chlorodifluoromethane Nano-Emulsion in Natural Gas Condensate for Efficient Conversion of Chloride Impurities Into the Dicopper Chloride Trihydroxide Nanoparticles.

This research introduces an oil-in-water (O/W) nano-emulsion (oil-water-) as the reusable extractant phase using liquid–liquid extraction methodology for the removal efficiency of Cl− and Hg(0) [between 90% and ∼100%, deepening on the nature of the natural gas condensate (NGC)] at a brief separation time (<3.0 min). The achieved safety of the NGC using this nano-emulsion results in efficient reduction in the corrosion rate during testing iron-based fragments (vs. the untreated ones as controls) and increase in the NGC economic value. Another advantage of the synthesized nano-emulsion is its capability and catalytic mediating behavior to efficiently separate and synthesize highly pure dicopper chloride trihydroxide nanoparticles. The synthesized nanoparticles were characterized by different analytical methods such as Fourier transform infrared spectrometry, X-ray diffraction, X-ray photoelectron spectrometry, and direct visualization by some electron microscopies. Direct synthesis, fast synthetic time (<3.0 min), high purity (>99%), and scalability are the main advantages of this synthetic method. This nanoparticle is not only safe but also is efficiently applicable in different industries, especially as an eco-friendly agricultural pesticide for different plants and tress such as pistachio. Consequently, this method is accepted as direct, simple, low-cost, and scalable conversion of some upstream industries with the downstream ones. All these possibilities are attributed to the intermediate transport properties of the introduced O/W nano-emulsion. At this condition, this reagent plays role as a recycled motor for the NGC purification and conversion of these impurities into the safe and usable products. To the best of knowledge, this research is considered as the first report that shows application of this O/W medium for both chloride and mercury removal from the NGC and its direct use as top element in the synthesis of eco-friendly nanoparticles. This system is applicable in some parts of the fuel and oil centers of the “Middle East.”

Hydrodechlorination of Aryl Chlorides Under Biocompatible Conditions.

Developing nonenzymatic chemistry that is nontoxic to microbial organisms creates the potential to integrate synthetic chemistry with metabolism and offers new remediation strategies. Chlorinated organic compounds known to bioaccumulate and cause harmful environmental impact can be converted into less damaging derivatives through hydrodehalogenation. The hydrodechlorination of substituted aryl chlorides using Pd/C and ammonium formate in biological media under physiological conditions (neutral pH, moderate temperature, and ambient pressure) is reported. The reaction conditions were successful for a range of aryl chlorides with electron-donating and -withdrawing groups, limited by the solubility of substrates in aqueous media. Soluble substrates gave good yields (60–98%) of the reduction product within 48 h. The relative toxicities of each reaction component were tested separately and together against bacteria, and the reaction proceeded in bacterial cultures containing an aryl chloride with robust cell growth. This work offers an initial step toward the removal of aryl chlorides from waste streams that currently use bacterial degradation to remove pollutants.

Extensive investigation and beyond the removal of micro-polyvinyl chloride by microalgae to promote environmental health

Microplastics (MPs) remediation via algae could be a prospective strategy to address MPs pollution concerns. In this study, Chlorella sp. GEEL-08 was exposed to different gradient concentrations ranging from 0 to 200 mg L−1 of polyvinyl chloride (PVC0.2μm). Microalgal growth, total nitrogen (TN), total phosphorus (TP), and cations (Cu, Zn, Na, and K) removal were investigated. The oxidative stress enzymes such as superoxide dismutase (SOD) and malonaldehyde (MDA) were also assessed. The addition of 50 mg L−1 mPVC resulted in the highest growth along with >99% removal of nutrients (TN and TP) and >80% removal of cations. However, the addition of 100–200 mg L−1 mPVC inhibited microalgal growth by 8.8–12.3%. The stress-induced by mPVC was highly observed at 200 mg L−1 mPVC on the 4th d with 70.8 U mgprot−1 and 62.3 nmol mgprot−1 of SOD and MDA, respectively. Fourier-transform infrared spectroscopy (FTIR) spectra confirmed that microalgal biomass retained mPVC. Thermogravimetric analysis/derivative thermogravimetric analysis (TGA/DTG) spectra showed that the organic matter of microalgal biomass attached with mPVC was decomposed faster than control, indicating the possibilities of using this biomass for pyrolysis and the formation of bio-products.