Showing papers in "Desalination and Water Treatment in 2019"
100 citations
TL;DR: A detailed survey on dye removal methods, and scope for the improvement can be done on the removal of dyes from industrial wastewater can be found in this paper, where the attention has moved to select the low-cost and efficient adsorbents which are alternative to the existing activated carbon.
Abstract: Water is one of the most important components in the environment. This is essential for all forms of life and leisurely plays a vital role in the world economy. The discharge of large amount of dye wastewater from different industries such as textile, leather, pulp, rubber pharmaceuticals, food processing, electroplating cosmetics, plastic, paper industries, etc. to the aquatic system constitutes the major hazards to the living environment. Hence, the rapid removal of these dyes from wastewater before their discharge is an important necessity of day to day life as well as for environmental safety. Several traditional treatment methods were available for the removal of dyes from water/ wastewater such as chemical coagulation, filtration, flocculation, ozonation, oxidation, photocatalytic degradation, ion exchange, biodegradation, electrolysis and adsorption. Among all these treatment methods, adsorption process using activated carbon is one of the most important, effective and reliable method for the removal of dyes from aquatic system. However, the widespread application of activated carbon is restricted because of its high cost. Therefore, the attention has moved to select the low-cost and efficient adsorbents which are alternative to the existing activated carbon. Some of the natural materials, agricultural wastes, industrial wastes and biosorbents have been reported as an effective low-cost adsorbent for the removal of dyes from aquatic system by many researchers. The current review paper explains the detailed survey on the dye removal methods, and scope for the improvement can be done on the removal of dyes from industrial wastewater.
96 citations
TL;DR: In this paper, a novel visible-light-driven AgI/WO3/ZnO nanocomposite was synthesized for the photodegradation of methylene blue (MB).
Abstract: A novel visible-light-driven AgI/WO3/ZnO nanocomposite was synthesized for the photodegradation of methylene blue (MB). The composite was characterized by XRD, UV-Vis DRS, SEM, BET, electrochemical impedance spectroscopy (EIS) and photoluminescence (PL) techniques. PL results confirmed lower PL intensity for the composite confirming a lower e–/h+ recombination for it. Both PL intensity and photodegradation activity of the resulted composites depended on the mole ratio of AgI, WO3 and ZnO in the composite. The composite with a mole ratio of 2:1:1 (AgI:WO3:ZnO) showed a broad PL peak at 698 nm which is 11.3 times weaker than that of WO3 and ZnO and 3 times weaker than that of AgI alone. Among the composites with different mole ratios, this composite had also the lowest PL intensity. Initial photodegradation experiments showed that about 21%, 36%, 56% and 69% of MB molecules can remove by single ZnO, WO3, AgINps and the composite (with a mole ratio of 1:1:1), respectively. The composite with a mole ratio of 2:1:1 showed also the best photodegradation efficiency and it removed about 79% of MB molecules during 40 min photodegradation process. MB solutions before and after photodegradation process were subjected to FTIR analysis and the results showed appearance of new peaks at 3452 and 1655 cm–1, confirming degradation of MB molecules into the smaller fragments. The pseudo-first order reaction rate constants of 0.055 and 0.025 min–1 were estimated based on COD and UV-Vis results based on the Hinshelwood model. The catalyst showed good reusing applicability after 4 successive runs.
79 citations
TL;DR: In this article, an investigation into two non-toxic natural coagulants abundantly growing in different countries, cactus (Opuntia spp.) and okra was performed on monthly river water samples (one-year period).
Abstract: An investigation into two non-toxic natural coagulants abundantly growing in different countries, cactus (Opuntia spp.) and okra was performed on monthly river water samples (one-year period). The studied case was the Euphrates river/Al-Mashroo canal/Iraq. Six statistical models were interpreted and tested describing the residual turbidity after Coagulation-Flocculation for the three studied cases (Optimum-Coagulant-Dose, Optimum-Flocculator-Velocity-Gradient and Optimum-Flocculation-Time). According to the environmental parameters recorded during the study and the statistical analyses, two facts were concluded. The first fact was that controlling the Optimum-Flocculator-Velocity-Gradient of the Coagulation-Flocculation process gave the highest contribution ratio of the models. The second fact was that the most significant environmental parameter (statistically) in the Coagulation-Flocculation process was the initial turbidity. This was proved for the two natural coagulants under study. Also, from the results of the study, it was concluded that the two natural coagulants were of similar coagulation-flocculation properties, and they were competent for turbidity removal.
78 citations
TL;DR: The results revealed that the concentrations of the studied heavy metals in the water of the Great Al-Mussaib channel were less than the pollution levels and followed the order: Pb < Ni < Cu < Cr < Mn < Zn < Fe < Co and Cd were below the detectable limits as discussed by the authors.
Abstract: The Great Al-Mussaib channel (GMC), in Babylon province, Iraq, has been selected as a case study to measure the concentration of nine heavy metals (Pb, Ni, Zn, Fe, Cd, Cr, Cu, Mn and Co) in both water and sediments of the GMC. The channel is used as a raw water source for two cities, which reveals the importance of the current study. Where, any heavy metals pollution could cause significant health problems for the population of these cities. The obtained results revealed that the concentrations of the studied heavy metals in the water of the GMC were less than the pollution levels and followed the order: Pb < Ni < Cu < Cr < Mn < Zn < Fe. It is noteworthy to highlight that the concentrations of Co and Cd were below the detectable limits. Additionally, the results obtained from the analyses of the studied sediment samples showed, according to the values of pollution load index and geo-accumulation index (Igeo), that the concentrations of studied metals were less than the pollution levels (except for a few cases) and followed the order: Cd < Co < Cu < Pb < Ni < Cr < Zn < Mn < Fe.
75 citations
74 citations
TL;DR: In this paper, the authors have assembled Ag2S carbon quantum dots (CQDs) onto CaTiO3 nanocuboids (NCs), aimed at creating a composite photocatalysts with superior performance.
Abstract: In this work, we have assembled Ag2S carbon quantum dots (CQDs) onto CaTiO3 nanocuboids (NCs), aimed at creating Ag2S@CaTiO3 composite photocatalysts with superior photocatalytic performances. Scanning/transmission electron microscopy observation confirms the uniform decoration of Ag2S CQDs (7–17 nm) on the surface of CaTiO3 NCs with size of 0.8‒1.1 μm in length and 0.3–0.5 μm in width. Photoluminescence, photocurrent response and electrochemical impedance spectroscopy investigations reveal that the Ag2S@CaTiO3 composites manifest highly efficient separation of photoexcited electron/hole pairs. The photocatalytic degradation activity of the Ag2S@CaTiO3 composites was assessed by the removal of rhodamine B from aqueous solution. It is demonstrated that the composites exhibit photocatalytic degradation performance much superior to that of bare Ag2S CQDs and CaTiO3 NCs under ultraviolet irradiation. This can be explained as the result of efficient separation of photoexcited electron/hole pairs induced by the Z-scheme electron transfer. In addition, the composites also manifest enhanced visible-light photocatalytic performance when compared with bare CaTiO3 NCs, implying that they can make the best use of the solar energy in the practical photocatalytic applications.
72 citations
TL;DR: Hybrid cross-linked chitosan-glyoxal/TiO2 nanocomposite (Chi-Gly/TNC) was prepared and employed for the adsorption of reactive orange 16 dye (RO16) from aqueous solution as mentioned in this paper.
Abstract: Hybrid cross-linked chitosan-glyoxal/TiO2 nanocomposite (Chi-Gly/TNC) was prepared and employed for the adsorption of reactive orange 16 dye (RO16) from aqueous solution. Response surface methodology (RSM) with 4-level Box–Behnken design (BBD) was applied to optimize RO16 removal efficiency. Various process parameters, viz., loading of TiO2 nanoparticles into Chi-Gly polymeric matrix (A: 0–50%), adsorbent dose (B: 0.04–0.14 g/50 mL), solution pH (C: 4–10), and temperature (D: 30–50°C) were selected for optimization process. Analysis of variance (ANOVA) was incorporated to judge the adequacy of model. The significant simultaneous interactions between input variables on RO16 removal efficiency were clearly observed by interactions between AB, AD, BC, and BD. Applying the method of the desirability function, optimization of TiO2 loading (50% TiO2: 50% chitosan labeled as Chi-Gly/TNC-50), adsorbent dose (0.09 g/50 mL), solution pH ~ 4.0, and temperature at 40°C gave a maximum of 93.2% RO16 removal efficiency by Chi-Gly/TNC-50. The adsorption of RO16 from aqueous solution at optimum input variables by using Chi-Gly/TNC50 in batch mode was evaluated. The kinetic results were well described by the pseudo-first order kinetic, and the equilibrium data were in agreement with Langmuir and Freundlich isotherm models with maximum adsorption capacity of 390.5 mg/g. The adsorption mechanism was attributed to the dipole-dipole hydrogen bonding interactions, Yoshida H-bonding, n-π stacking interactions, and electrostatic attractions.
63 citations
TL;DR: A boosted photocatalytic activity was obtained for the as-synthesized Cu2O-CdS nanocomposite (NC) with respect to single CdS nanoparticles in the photodegradation of sulfasalazine (SFSZ) in aquatic media as discussed by the authors.
Abstract: A boosted photocatalytic activity was obtained for the as-synthesized Cu2O-CdS nanocomposite (NC) with respect to single Cu2O and CdS nanoparticles in the photodegradation of sulfasalazine (SFSZ) in aquatic media. X-ray diffraction (XRD) spectroscopy, scanning electron microscope (SEM) and UV–Vis diffuse reflectance spectroscopy were characterization techniques used in this work. The best mole ratio was 2:1 for the Cu2O/CdS in the composite to achieve the best photodegradation efficiency. After 15 min, 230, 410, 585, 760 and 450 nano-moles of SFSZ molecules were degraded for concentrations of 10, 20, 30, 40 and 50 ppm of SFSZ solutions, respectively. The optimal conditions were CSFSZ: 30 mg L–1, pH 5, 25 min irradiation time and 0.5 g L–1 of the Cu2O-CdS composite. Degradation extents of 94%, 94.7% and 82% were, respectively, estimated for the degradation of SFSZ molecules based on the results obtained by UV–Vis spectroscopy, high-performance liquid chromatography and chemical oxygen demand measurements.
61 citations
TL;DR: Changani et al. as mentioned in this paper proposed a method to improve the quality of the air quality of air quality in Iran by using air quality index (AQI) scores.
Abstract: aDepartment of Civil Engineering, AMU, Aligarh, UP, India, email: sohailayub@rediffmail.com bDepartment of Environmental Health, Neyshabour University of Medical Sciences, Neyshabur, emails: mohammadi.eng73@gmail.com, mohammadia3@nums.ac.ir cDepartment of Environmental Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran, emails: changani_f@yahoo.com, changani39@gmail.com (F. Changani), Mahmood_yousefi70@yahoo.com (M. Yousefi)
57 citations
TL;DR: In this paper, a cross-sectional study was conducted in 2016 on the ground water resources of Baradaskan city, where the minimum and maximum values of nitrate and fluoride concentrations were between 0.0-77.2, 0.2-1.036 mg/l, respectively.
Abstract: In recent decades, harmful contaminants such as nitrate and fluoride have become more common. This cross-sectional study was conducted in 2016 on the ground water resources of Baradaskan city. In order to investigate the concentration fluoride and nitrate, sampling was done in 30 drinking water resources, then chemical parameters were analyzed according to standard method. The purposes of this investigation was (1) to provide an overview of present drinking water quality and compare it with the national standard (2) to determine spatial distribution of groundwater quality fluoride and nitrate concentrations, (3) to map groundwater quality in the study area, using GIS (V10.3), and (4) human health risk assessment was performed by calculating the chronic daily intake (CDI) and hazard quotient (HQ) of fluoride and nitrate through oral intake for infants, children, teenagers and adults. The minimum and maximum values of nitrate and fluoride concentrations were between 0.0– 77.2, 0.2–1.036 mg/l, respectively. Spatial distributions of nitrate and fluoride concentrations showed that highest nitrate and lowest fluoride concentrations occurred in the north-east region of the study area. HQ values of nitrate for children, teenagers and adults 3, 1, 2 villages were more than one. In contrast, mean HQ values of fluoride were lower than 1, which was mostly acceptable.
TL;DR: In this paper, a column-type sequential batch reactor (SBR) was employed for treating pulp and paper wastewater, and the performance of SBR, seeded with acclimatized sludge, was optimized and analyzed for maximizing COD and AOX removal.
Abstract: Pulp and paper industry generates effluent containing harmful compounds like chlorophenols which are difficult to biodegrade. It requires an appropriate treatment in order to meet the stringent discharge standards. In this work, a bench scale column type sequential batch reactor (SBR) was employed for treating pulp and paper wastewater. The performance of SBR, seeded with acclimatized sludge was optimized and analysed for maximizing COD and AOX removal. The process parameters viz; pH, initial COD, cycle time and MLSS were optimized and their effects on response variables: COD removal efficiency, AOX removal efficiency and SVI were investigated. The optimum conditions were determined to be: initial COD 1200 mg/l, pH 7.5, MLSS 2100 mg/L and cycle time 15 h, for 73.2% COD removal, 57.6% AOX removal and 122.8 mL/g SVI. The complex compounds were broken down into numerous intermediate compounds thus enhancing COD and AOX removal with low SVI. The bio-kinetics of the optimized system was also analyzed in order to understand the bacterial nature towards substrate utilization. Two kinetic models namely Grau second-order model and Stover–Kincannon model were found to be fitwell with high correlation coefficients (R2 = 0.99) for COD as well as AOX.
TL;DR: Evidence that local residents in Bardaskan County may be at a high risk of health problems caused from fluoride and nitrate in drinking water is provided, therefore, it is important to take some remedial measures to prevent any health problem in this county.
Abstract: Fluoride and nitrate are the important factors that influence the drinking water quality. A health risk
assessment was performed for exposure to fluoride and nitrate via drinking water ingestion pathway
for the inhabitants living in Bardaskan County, Iran. In the present work, totally 30 drinking water
samples were collected from private wells, monitoring wells, and boreholes during June 2018, from
different previously unexplored rural and urban areas. The concentration of fluoride and nitrate
varied from 0.55 to 1.75 mg/L (mean 0.873 mg/L) and from 5.7 to 25.4 mg/L (mean 12.58 mg/L),
respectively. None of the 30 studied areas had fluoride, except one place, and nitrate concentrations
above WHO guidelines. Hazard index (HI) values for adults, children and infants varied from 0.4160
to 1.1886 (mean 0.6405), from 1.0921 to 3.1203 (mean 1.6813) and from 1.165 to 3.3283 (mean 1.7934),
respectively. HI estimated for groundwater in 3.3%, 100%, and 100% cases were found to be above the
safety limit of 1 for adults, children, and infants, respectively. This research provides evidence that
local residents in Bardaskan County may be at a high risk of health problems caused from fluoride
and nitrate in drinking water. It is, therefore, important to take some remedial measures to prevent any
health problem in this county.
TL;DR: Ghernaout et al. as mentioned in this paper presented a survey of chemical and industrial engineering departments at the University of Ha'il in Saudi Arabia, including chemical engineering departments, chemical engineering department, college of engineering, University of ha'il, PO Box 2440, Ha’il 81441, Saudi Arabia.
Abstract: dChemical Engineering Department, College of Engineering, University of Ha’il, PO Box 2440, Ha’il 81441, Saudi Arabia, Tel./Fax +213-25-433-631, email: djamel_andalus@hotmail.com (D. Ghernaout) bChemical Engineering Department, Faculty of Engineering, University of Blida, PO Box 270, Blida 09000, Algeria cIndustrial Engineering Department, College of Engineering, University of Ha’il, PO Box 2440, Ha’il 81441, Saudi Arabia dArchitectural Engineering Department, College of Engineering, University of Ha’il, PO Box 2440, Ha’il 81441, Saudi Arabia
TL;DR: A review of the research works available in the open literature on the electrochemical treatment of industrial effluent such as textile, pulp and paper, paint, food, electroplating, distillery, etc. is presented in this article.
Abstract: Electrocoagulation (EC) treatment can be used as an effective alternative to the existing treatment methods. It is a distinct, economical and an environmental friendly choice for meeting water treatment discharge standards and compliance requirements. Due to improved material of construction and process design, the EC process is widely accepted. Presently, this process has gained attention due to its ability to treat large volume of effluent with low cost. The EC process includes the in-situ generation of coagulants via the electro-dissolution of a sacrificial anode, which is usually made up of iron or aluminum. This paper presents a review of the research works available in the open literature on the electrochemical treatment of industrial effluent such as textile, pulp and paper, paint, food, electroplating, distillery, etc. The mechanism and design consideration for electrochemical treatment of wastewater is also presented.
TL;DR: In this article, a modified one-stage Phoredox (SOP) reactor was used to remove nitrogen and phosphorus from a pilot plant with a wall thickness of 0.5 cm and dimensions of 100 × 20 × 20 cm along with four sample valves and a dual valve.
Abstract: Nowadays, eutrophication is considered as one of the disturbing environmental phenomena, which its main cause is the discharge of nutrients into receiving waters. The main problematic chemicals in this regard are nitrogen and phosphorus. Considering the undesirable effects of these two nutrients on the receiving waters, the application of a biological process with high removal efficiency, such as modified Phoredox, is essential to ensure the removal of nitrogen and phosphorus. In this context, a pilot plant (made of Plexiglas) with wall thickness of 0.5 cm and dimensions of 100 × 20 × 20) along with four sample valves and a dual valve were provided and utilized in order to allow the entrance of flow and the discharge of the reactor for the purpose of flexibility in operation. With regard to the structure of modified one-stage Phoredox reactor, in this study, 20% of the total volume of the reactor was dedicated to the anaerobic region which was embedded on the base of the reactor with the help of a porous network by assuming an up-flow. Investigating the data obtained in the present research revealed that the modified one-stage Phoredox reactor was able to provide the highest removal of chemical oxygen demand (COD) (95.5%) at the organic loading rate of 400 mg/L, inlet phosphorus concentration of 10 mg/L, hydraulic retention time (HRT) of 8 h, and media filling rate of 60%, while the biochemical oxygen demand (BOD)5 removal efficiency by studied system was 94.9%. The remaining COD in this optimized phase was 15.04 mg/L. Moreover, the highest total phosphorus (TP) removal by this system was obtained to be 96.5 at organic loading rate of 500 mg/L and the inlet TP of about 15 mg/L, the HRT of 8 h and filling rate of 60% filling. The remaining TP in this optimized phase was obtained 0.54 mg/L which was extremely lower than the standard limit specified by the Department of Environment for discharging the sewage into the environment. This low rate indicates the effective performance of the modified one-stage Phoredox reactor to achieve environmental standards.
TL;DR: In this article, the authors used date seed biomass as a cheap and efficient starting material to prepare activated carbon for chromium removal from chromium polluted wastewater and showed that the ACDS could be used for a maximum of 3 times with a slight reduction in the Cr(VI) removal efficiency (< 10%).
Abstract: In this current work, activated carbon from date seeds (ACDS) was prepared through single step chemical activation using phosphoric acid. ACDS was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Thermogravimetric studies (TGA/DTA), surface chemistry and specific area analysis. Performance assessment of the ACDS was carried out through adsorption of chromium (VI) from its aqueous solution. Effect of adsorption parameters such as contact time (1–120 min), pH (2–8), operating temperature (10–50°C), adsorbent dosage (0.01–0.2 g/50 mL) and initial chromium concentration (5–50 mg/L) on Cr(VI) removal by ACDS was studied in detail. Maximum Cr(VI) adsorption of 42.57 mg/g was obtained for a contact time of 60 min and pH of 2 at 30°C using adsorbent dose of 0.1 g/50 mL for an initial feed concentration of 50 mg/L. The Cr(VI) adsorption efficiency of the ACDS was better as compared against commercial activated carbon. Experimental equilibrium data fitted well with Langmuir isotherm (R2 = 0.9958) and kinetics studies predicted the pseudo-second order for Cr(VI) adsorption on ACDS. Re-usability studies showed that the ACDS could be used for a maximum of 3 times with a slight reduction in the Cr(VI) removal efficiency (< 10%). Results indicated the promising use of date seed biomass as a cheap and efficient starting material to prepare activated carbon for Cr(VI) removal from chromium polluted wastewater.
TL;DR: In this paper, the authors investigated the pollution indices including enrichment factor (EF), geo-accumulation index (Igeo), and contamination factor (Cf) distribution and its pollution status in surface sediment samples collected in the Persian Gulf (South of Iran).
Abstract: Concentrations of Cd, Cr, Cu, Fe, Ni, Pb and Zn and geochemical controlling factors have been determined in surface sediment samples collected in the Persian Gulf (South of Iran) and were investigated using pollution indices including enrichment factor (EF), geo-accumulation index (Igeo) and contamination factor (Cf) distribution and its pollution status. Sediment samples were collected from 12 sites in a monitoring period of 4 months from September to December in 2014. The spatial distribution of heavy metals demonstrated that concentrations are much higher in the industrial areas in comparison with urban areas. Analytical results have been elaborated by using a geographical information system software to show metals accumulation areas. Based on the EF and Igeo, the order of heavy metal concentrations was Cd > Pb > Ni > Cr > Zn > Cu in industrial stations. For urban station, the order was as: Cd > Pb > Ni > Zn > Cu > Cr. EF and Igeo values showed that sediments were contaminated with Cd and Pb. Based on the EF, Cd was the heavy metal contaminant of most concern in urban and industrial surface sediments. Moreover, this study showed that Cd threshold concentrations to mostly be exceeded in the study area. Also, the concentration of heavy metals in the industrial areas was much higher than those of urban areas.
TL;DR: In this paper, the authors investigated the environmental impact of dairy effluents and their effective treatment using biological treatment technologies and found that the biological treatment method is the superior method for treating the dairy effluent.
Abstract: Dairy products are one of the richest sources of vital nutrients in the diet of human beings and it occupies an important place in satisfying their nutrient requirements. The dairy products possess a very short lifespan and during their decomposition create a huge nuisance to the environment. The dairy effluents discharged from the industries are mainly composed of complicated substances such as organic compounds, inorganic compounds, carbon, nitrogen, phosphorus, chlorides, sulphides, fats, oils, grease, etc. These organic loading present in the dairy effluent have a negative impact on the environment during its discharge to nearby water sources. The physical and chemical treatment of the dairy effluents is not as effective as the biological treatment. The biological treatment method is found to be the superior method for treating the dairy effluent. The biological wastewater treatment can be performed in two various conditions such as aerobic and anaerobic. The treatment methods such as aerobic lagoons, activated sludge, sequential batch reactor, trickling filter, completely stirred tank reactors, fluidized bed reactors, and anaerobic filters are some of the biological methods used in dairy effluent treatment. This review article has investigated in detail regarding the environmental impact of dairy effluents and their effective treatment using biological treatment technologies
TL;DR: In this article, the authors evaluated the relationship between fluoride and other chemical parameters (pH, Turbidity, EC, TDS, TH, ALK, Cl−, SO4, NO3−, NO2−, Ca2+, Mg2+, Na+, K+, PO4) in water bodies located in Showt, West Azerbaijan Province, Iran.
Abstract: Fluoride in drinking water is an important chemical species with regard to public health considerations, although a fluoride concentration of about 1.5 mg L–1 in drinking water can decrease tooth decay and higher concentrations cause health problems. The concentration of fluoride in water is affected by some chemical characteristics. This study aimed to evaluate the relationship between fluoride and other chemical parameters (pH, Turbidity, EC, TDS, TH, ALK, Cl–, SO4, NO3–, NO2–, Ca2+, Mg2+, Na+, K+, PO4) in water bodies located in Showt, West Azerbaijan Province, Iran. Sample preparation and analysis were performed according to standard methods. A wide range of fluoride concentrations was measured in this study (0.0–5.5 mg L–1). The results indicated that alkalinity and Na+ have a significant positive relationship with fluoride concentrations in water wells. Nevertheless, total hardness (TH) showed an inverse relationship with fluoride concentration. In addition, for a one-unit increase in alkalinity and Na+ concentration, the average amount of fluoride in water increased by 0.0028 and 0.16, respectively. Furthermore, for a one-unit increase in total hardness, the average amount of fluoride in water decreased by 0.005. In conclusion, fluoride concentration was affected by numerous factors such as hardness, alkalinity, and Na+ concentration. The findings of this study suggest that a suitable treatment of the groundwater is needed in contaminated areas before its use for drinking.
TL;DR: In this paper, Salvia sclarea seeds (SSS) were used as adsorbent for the removal of Basic Violet 16 (BV 16) dye from aqueous solutions.
Abstract: The Salvia sclarea seeds (SSS) were used as adsorbent for the removal of Basic Violet 16 (BV 16) dye from aqueous solutions. The structure and surface characteristics of the SSS were investigated by field emission scanning electron microscopy, Fourier transform infrared spectroscopy, Brunauer– Emmett–Teller and pH point of zero charge (pHpzc) procedures. The effect of SSS dosage, pH of the solution, contact time and initial concentration of BV 16 dye on its removal was elucidated. The experimental data were analyzed by the Langmuir, Freundlich and Temkin isotherm models. The adsorption isotherm data were fitted well to Langmuir isotherm and the monolayer adsorption capacity was found to be 19.80 mg/g. The kinetic data obtained at different concentrations have been analyzed using a pseudo-first-order, pseudo-second-order equation. The kinetic studies showed that the pseudosecond-order kinetic model better described the adsorption of BV 16 dye onto the SSS. The findings reveal the feasibility of the SSS to be used as a potential and low-cost adsorbent in water and waste water industry for the removal of various pollutants, more specifically cationic dyes.
TL;DR: In this paper, the NaBH4 reduction method has been used to create surface disorder on Bi4Ti3O12 nanosheets with the aim of enhancing their photocatalytic activity.
Abstract: NaBH4 reduction method has been used to create surface disorder on Bi4Ti3O12 nanosheets with the aim of enhancing their photocatalytic activity. The NaBH4-treated Bi4Ti3O12 samples were systemati-cally investigated by XRD, TEM, BET, XPS, UV-vis DRS, EIS and transient photocurrent response. It is disclosed that disordered surface layer associated with oxygen vacancy defects is obviously formed on the surface of Bi4Ti3O12 nanosheets, and simultaneously surface defect states are introduced in the forbidden gap of Bi4Ti3O12. The NaBH4-treated Bi4Ti3O12 samples display enhanced visible-light absorption. The photocatalytic performance of the samples was investigated by the degradation of RhB under irradiation of simulated sunlight, UV light and visible light. It is found that the NaBH4-treated Bi4Ti3O12 samples exhibit a significantly enhanced photocatalytic activity under UV irradi-ation. The sample treated at 0.1 M NaBH4 solution shows the highest UV photocatalytic activity, about 1.9 times higher than that of pristine Bi4Ti3O12. This is ascribed to the fact that the induced sur-face defect states can act as electron acceptors and thus facilitates the separation of photogenerated electron-hole pairs. Moreover, the NaBH4-treated Bi4Ti3O12 samples also display a slightly enhanced photocatalytic performance under visible light irradiation, which is due to the enhanced visible light absorption induced by the surface defect states.
TL;DR: In this paper, the authors explored the use of palm oil fuel ash (POFA) as an adsorbent media for the treatment of a sewage wastewater and determined the optimum conditions for shaking at 200 rpm according to the adsorption of COD, ammonia nitrogen, nitrate and phosphorus by the media.
Abstract: Sewage treatments are introduced in the country to protect the health of human and environment. In this study, palm oil fuel ash (POFA) was explored as an adsorbent media for the treatment of a sewage wastewater. The optimum shaking speed, shaking time, pH, and dosage for chemical oxygen demand (COD), ammonia nitrogen, nitrate and phosphorus removal were investigated using the adsorbent media of particle sizes ranging from 2.00 to 3.15 mm. POFA and composite POFA chemical composition and characteristics were then determined. Results indicated that sewage concentrations of COD (63.39 mg L–1), ammonia nitrogen (6.01 mg L–1), nitrate (0.63 mg L–1) and phosphorus (0.43 mg L–1). The optimum conditions for shaking were determined at 200 rpm according to the adsorption of COD, ammonia nitrogen, nitrate and phosphorus by the media. Optimum shaking time of 20 min for ammonia nitrogen, nitrate phosphorus and COD optimum shaking time is 30 min. The optimum pH value for COD, nitrate and phosphorus removal using composite POFA was obtained at pH 6 and for ammonia nitrogen is pH 9. Microstructures of the prepared composite POFA were analyzed using Brunauer–Emmett–Teller, scanning electron microscope, X-ray diffractometer and X-ray fluorescence measurements. These results suggest that composite POFA can be used as a potential effective, low cost and eco-friendly green adsorbent for the removal of COD, ammonia nitrogen, nitrate and phosphorus from sewage wastewater.
TL;DR: In this paper, various solar TESMs, especially phase change materials, tested by the researchers to improve the freshwater output as well as thermal performance of solar stills (SSs), are analyzed and discussed in detail.
Abstract: In recent decades, energy and water desalination using solar energy has played a vital role for the survival of human beings due to the cost and shortage of clean water; and gave considerable impetus to decrease greenhouse gas effects produced from burning fossil fuels. Thermal energy storage materials (TESMs) are used to store the energy through the daytime (sunshine time) and discharge this energy during nighttime (sunset time) and hence they have been used in water desalination systems to enhance its performance. TESM such as phase change materials (PCMs), myristic acid, sponge’s cubes, cotton, jute, cloth, porous materials and sponge sheet, quartzite and natural rock, coated and uncoated metallic wiry sponges, sand, gravels and aluminum filling are quite attractive in the solar desalination, especially in solar stills (SSs), to enhance thermal performance of SS by improving its thermal energy storage capability. We found from this review that the TESMs have a significant effect on enhancing the fresh water output from the SS especially when paraffin wax is used as PCM, which has large storage density with narrow range of temperature difference. In this review paper, various solar TESMs, especially PCM, tested by the researchers to improve the freshwater output as well as thermal performance of SSs, are analyzed and discussed in detail.
TL;DR: In this paper, a study was implemented to prove the sedimentation problem especially the formation of total suspended solid (TSS) and annual sediment load (SL) and the technique of analysis of primary data obtained which determine according with the procedure TSS and SL.
Abstract: Rivers, which provide 90% of the readily available freshwater, are key components of global water resource system. Terengganu River experienced deterioration in water quality, resulting from the sedimentation, anthropogenic, geomorphology problems and unsustainable development management around the river basin. This study was implemented to prove the sedimentation problem especially the formation of total suspended solid (TSS) and annual sediment load (SL). The technique of analysis of primary data obtained which determine according with the procedure TSS and SL. The results showed that the highest average of TSS (mg/L) is 67.2 (wet season) and 128.2 (dry season) which are class III. While the highest turbidity is 43.57 (wet season) and 21.57 (dry season) which are Class II based on National Water Quality Standard (NWQS). The highest annual average estimation for annual SL flow out from the Terengganu River Basin is 6,846.709 tonnes/km2/year (Manir River Basin) the lowest in the Pauh River Basin is 2.850 tonnes/km2/year. The statistical analysis proved the weak regression relationship between TSS, river discharges (Q), SL and area of catchment caused by the anthropogenic factors and uncertain climate changes. Furthermore, the water in the Terengganu River was classified under class III caused by the active land use activities especially industrial and development but it is still suitable for recreational activities and safe for body contact because its water quality index is not less than 65% which early stage of Class II. The contributors of sedimentation problems are from unsustainable land use such as sand mining activities which effectively trap the bed sediments, backflow that carries out high sediments, as well as sedimentation produced due to the river bank erosion. This study suggests the sedimentation management methods including land use settlement, cliff erosion problems, settlement and negotiable of uncontrolled development operations in Terengganu River and the integration of river management methods based on integrated river basin management in Terengganu River Basin is recommended.