The effects of PO43- removal from aqueous solution with varied concentrations of metal oxides in steel slag filter system

High amount of orthophosphate will accelerate the growth of autotrophs and eutrophication will occur. This phenomenon decreases the water quality and as a result may increase the cost of water treatment for drinking water. The overabundance of orthophosphate occurs when untreated or inadequately-treated wastewater from domestic and industrial activities is released into water bodies. Conventional treatment has been developed to treat wastewater. However, it is not effective for phosphorus removal, hence, high-cost advanced treatment is needed to remove phosphorus. Thus, alternative low-cost treatments for phosphorus removal are needed. Therefore, this study was conducted to understand and investigate the mechanisms of phosphorus removal using two different setups of steel slag filter, Set 1 for high Fe and Set 2 for high Ca. The study was operated at different pH values of 3, 5, 7, 9 and 11 under aerated and unaerated conditions. The samples of steel slag from 12 filters that has been run for three months for each set were semi-quantitatively analysed using scanning electron microscope-energy dispersive X-ray (SEM-EDX) to identify the adsorption of phosphate ion on the surface of the steel slag. The results of SEM-EDX studies showed that adsorption mechanism of phosphate removal takes place on the surface of the steel slag. The precipitates in the steel slag filters were collected and analysed for X-ray diffraction (XRD) for chemical compound identification and the precipitates were confirmed to be Fe3O4, a precursor of iron phosphate related compound

Efficiencies and mechanisms of steel slag with ferric oxides for removing phosphate from wastewater using a column filter system

The current study aimed to investigate the efficiencies and mechanisms of slag filter media for removing phosphorus from synthetic wastewater. The steel slag with high ferric oxides (Fe2O3) was subjected for the electric arc furnace (EAF) and selected as the filter media (HFe). The chemical characteristics of HFe were determined using pH, point of zero charge (PZC) and XRF. The phosphorus removal efficiency was studied in a designed vertical steel slag column rock filters in unaerated HFe (UEF) and aerated HFe (AEF) system. The microstructure of HFe was analyzed by FTIR, XRD and SEM-EDX analysis. The results of XRF revealed that ferric oxide (Fe2O3) ranged from26.1 to 38.2%. PZC for Filter HFe was recorded at pH 10.55 ± 0.27. The highest efficiencies were recorded by UEF and AEF systems at pH 3 and pH 5 (89.97 ± 4.02% and 79.95 ± 6.25% at pH 3 and 72.97 ± 8.38% and 66.00 ± 12.85% at pH 5 for UEF and AEF, respectively). These findings indicated that AEF exhibiting higher removal than UEF systems might be due to presence high Fe concentration in AEF which play important role in the phosphorus removal. The main elements available on the surface of HFe included carbon, oxygen, iron, calcium, magnesium, silicon, platinum, sulphur, manganese, titanium and aluminium. The XRD analysis indicated that the precipitation of orthophosphate as calcium and iron-phosphates was the removal mechanism as confirmed using FT-IR analysis. These findings demonstrated the efficiency of HFe in removing of phosphorus from wastewater

Removal of Phosphate from Wastewater by Steel Slag with High Calcium Oxide Column Filter System; Efficiencies and Mechanisms study

Background: The discharge of wastewater with heavy loads of phosphorus leads to the eutrophication in natural water systems. The current work investigated the removal of phosphorus from synthetic wastewater through the medium of a slag filtration system with a high content of CaO was selected as the filter media (HCa) and subjected to treatment in the electric arc furnace (EAF). The pH, point of zero charge (PZC) and XRF of the HCa filter medium was studied. The removal of phosphorus was investigated in a designed vertical column filters in aerated HCa (AEF) and unaerated HCa (UEF) systems. FTIR, XRD and SEM-EDX analyses was implemented for studying the microstructure of HCa. Results: The results of XRF revealed that CaO ranged from 20.2–49.5%. The PZC for the HCa filter was recorded at pH 17.75. The highest efficiencies recorded were 94.65 ± 3.46% and 96.13 ± 2.75% at pH 3 and 93.70 ± 2.59% and 97.15 ± 1.59% at pH 5 for AEF and UEF, respectively. These findings indicated that AEF performed greater removal than UEF systems might due to presence high Ca concentration in AEF, which plays an important role in the process of phosphorus removal. The main elements on the surface of HCa included oxygen, carbon, magnesium, calcium, aluminium and silicon. XRD analysis indicated that the precipitation of orthophosphate as calcium and Ca-phosphates was the removal mechanism, which was confirmed using the FT-IR analysis. Conclusion: These findings demonstrated the efficiency of HCa in removing phosphorus from wastewater

Comparative study of high calcium and high iron filter media of unaerated and aerated steel slag filter systems in removing phosphorus

Improper wastewater treatment will accelerate eutrophication in waterbody due to phosphorus content in wastewater. However, to remove wastewater from requires a high and complex processes. This study was conducted to explore an alternative treatment of phosphorus removal using steel slag filter system in particular of affinity different chemical composition of steel slag. Therefore, this study has been designed for comparisons between steel slag of high composition of iron (Filter HFe) and steel slag of high composition of calcium (Filter HCa) when used as the filter media of unaerated (UEF) and aerated (AEF) lab-scale column filters in removing phosphorus. Both Filter HFe and Filter HCa were continuously running for three months using 25 mg/L synthetic phosphorus wastewater of different pH systems (pH 3, pH 5, pH 7, pH 9, pH 11 and control using distilled water) as the influents. Sampling was done weekly for analysis of pH values, phosphorus (in the form of orthophosphate) removal efficiency, and concentration of Ca, Mg and Fe in the effluents. The results showed that Filter HFe has excellent (>59%) orthophosphate removal efficiency at acidic systems (pH 3 and pH 5 systems) and average removal efficiency (21-87%) at pH 7, pH 9, pH 11 systems. Also, unaerated systems performed better compared to aerated systems. Meanwhile, for Filter HCa, orthophosphate removal efficiencies for all pH systems were better (80-100%) compared to Filter HFe

Effect of various operating parameters towards PVDF/HMO mixed matrix membrane performance

The development of antifouling membranes to separate oil/water emulsions in various environmental approaches is urgently needed. This work reports on the development of a mixed matrix membrane (MMM) using polyvinylidene fluoride (PVDF) incorporated with self-synthesized hydrous manganese oxide (HMO). The filtration performance was compared to the pristine PVDF membrane in terms of flux and rejection efficiency. The membranes were characterized and evaluated under various operating parameters: different oil/water emulsion feed concentrations (50, 100, 500, and 1000 ppm), cycle stability, long-term membrane stability, and flux recovery ratio (FRR). When tested with a 1000 ppm oil/water emulsion feed concentration, the fabricated MMM exhibited higher flux performance of approximately eight folds compared to the pristine membrane, with the FRRs of 87% and 56%, respectively. After the eighth cycle, the performance of the MMM decreased gradually. However, the pristine membrane had completely collapsed at the end of the recyclability test. Furthermore, the modified PVDF/HMO MMM was physically stable for up to 6 h during the long-term stability study, indicating the potential of HMO in improving separation performance and the lifespan of MMM

PVDF/HMO ultrafiltration membrane for efficient oil/water separation

In this research, hydrous manganese oxide (HMO) nanoparticles was adopted in polyvinylidene fluoride (PVDF) to improve the ability of the mixed matrix membrane (MMM) to separate oil/water emulsions. The MMMs – which were added with various amounts of HMO loading (3, 5, 7 and 10 wt%) – were characterized for its physicochemical properties, morphological structure, and nanoparticles dispersion of the PVDF/HMO membrane. Evidently, the presence of these nanoparticles increased the hydrophilicity and oleophobicity of the PVDF/HMO membrane as compared to those of the pristine PVDF. Concurrently, the water contact angle was reduced from 99 to 58 while oil contact angle increased from 0 to 35 . The presence of -OH groups and Mn element channeling the PVDF/HMO membrane wetting properties, which in turn improved the membrane’s affinity towards water molecules and aversion to oil droplets. The PVDF/HMO membrane that contained 10 wt% of HMO loading exhibited a water flux (402 L/m2 h) – 10 times greater than the pristine PVDF membrane with 93% oil rejection rate

Synthesis of zeolitic imidazolate framework-8 (ZIF-8) using different solvents for 2 lead and cadmium adsorption

The current study is focused on the facile synthesis of zeolitic imidazolate framework-8 (ZIF-8) at room temperature 14 using three different solvents: ammonia solution (ZIF-8 (N)), aqueous solution (ZIF-8 (H)), and methanol (ZIF-8 (M)). 15 The ZIF-8s produced have high crystallinity with different sizes and shapes. The morphology of ZIF-8 (H) resembled 16 the mixture of cubic and the rhombic dodecahedron with truncated corners, whereas ZIF-8(M) occurred as the most 17 stable rhombic dodecahedron, and ZIF-8(N) appeared as cubes with truncated corners. ZIF-8 (N) had the largest 18 average particle size of 573 nm, followed by ZIF-8 (H) and ZIF-8 (M) with average sizes of 108 nm and 62 nm, 19 respectively. ZIF-8 (N) showed a rapid Pb(II) and Cd(II) adsorption, within 15 min, while ZIF-8(H) achieved Pb(II) 20 and Cd(II) equilibrium within 240 min, and 300 min for ZIF-8 (M). The adsorption of Pb(II) and Cd(II) is best fitted 21 with the Langmuir isotherm and pseudo-second-order kinetic model. The maximum adsorption capacities for Pb(II) 22 and Cd(II) sorption were 454.55 and 312.50 mg/g for ZIF-8 (H), 434.78 and 277.78 mg/g for ZIF-8 (M), respectively, 23 and 476.19 and 263.16 mg/g for ZIF-8 (N), respectively. All of the prepared ZIF-8s showed a promising competency 24 as adsorbents for the removal of Pb(II) and Cd(II) from an aqueous solution

Adsorptive removal of heavy metal ions using graphene-based nanomaterials: toxicity, roles of functional groups and mechanisms

The endless introduction of toxic heavy metals through industrialization has worsened the heavy metal pollution in the environment. Thus, the need for its effective removal has become more crucial than before. Studies on graphene-based nanomaterials and their use in removing heavy metals are gaining tremendous traction over the past decade. The properties of graphene oxide (GO), such as large surface areas, desired functional groups and excellent mechanical properties are advantageous. Nevertheless, due to its tendency to agglomerate and difficulty in phase separation after treatment, the functionalization of GO using various materials of different surface functional groups is an ongoing study. The surface modification of GO is done by using various materials to introduce heteroatoms, which have high affinity for heavy metals. This review summarizes the utilization of different surface functional groups, such as oxygen-containing, nitrogen-containing, and sulphur-containing functionalized graphene oxide composites in the adsorption of cationic and oxyanionic heavy metals. The toxicity of these heavy metals is also addressed. Furthermore, the interactions between adsorbents and heavy metals which are influenced by pH and surface functional groups, are also discussed in detail. This is followed by the review in adsorption isotherms and kinetics. Future research needs are also offered

Synthesis of zeolitic imidazolate framework-8 (ZIF-8) using different solvents for 2 lead and cadmium adsorption

The current study is focused on the facile synthesis of zeolitic imidazolate framework-8 (ZIF-8) at room temperature 14 using three different solvents: ammonia solution (ZIF-8 (N)), aqueous solution (ZIF-8 (H)), and methanol (ZIF-8 (M)). 15 The ZIF-8s produced have high crystallinity with different sizes and shapes. The morphology of ZIF-8 (H) resembled 16 the mixture of cubic and the rhombic dodecahedron with truncated corners, whereas ZIF-8(M) occurred as the most 17 stable rhombic dodecahedron, and ZIF-8(N) appeared as cubes with truncated corners. ZIF-8 (N) had the largest 18 average particle size of 573 nm, followed by ZIF-8 (H) and ZIF-8 (M) with average sizes of 108 nm and 62 nm, 19 respectively. ZIF-8 (N) showed a rapid Pb(II) and Cd(II) adsorption, within 15 min, while ZIF-8(H) achieved Pb(II) 20 and Cd(II) equilibrium within 240 min, and 300 min for ZIF-8 (M). The adsorption of Pb(II) and Cd(II) is best fitted 21 with the Langmuir isotherm and pseudo-second-order kinetic model. The maximum adsorption capacities for Pb(II) 22 and Cd(II) sorption were 454.55 and 312.50 mg/g for ZIF-8 (H), 434.78 and 277.78 mg/g for ZIF-8 (M), respectively, 23 and 476.19 and 263.16 mg/g for ZIF-8 (N), respectively. All of the prepared ZIF-8s showed a promising competency 24 as adsorbents for the removal of Pb(II) and Cd(II) from an aqueous solution

Effects of operating parameters on cadmium removal for wastewater treatment using zeolitic imidazolate framework-L/graphene oxide composite

Water pollution due to heavy metal contamination has become a critical environmental issue. Thus, effective treatment for polluted water, such as simple adsorption to remove heavy metals, is gaining importance. Towards this end, zeolitic imidazolate framework-L (ZIF-L) with graphene oxide (GO) was successfully incorporated in the synthesis of novel ZIF-L/GO 20 and ZIF-L/GO 50 adsorbents using 20% and 50% loading percentages of GO, respectively, with ultrapure water as the solvent. The morphologies of ZIF-L changed to a flower-like structure with the introduction of 20% GO and turned into smaller irregular shapes when 50% GO was added. These novel adsorbents have demonstrated high adsorption capacities for Cd(II) adsorption at 172.42 mg/g (ZIF-L/GO 20) and 188.68 mg/g (ZIF-L/GO 50), with the optimum dosage of 0.2 g/L of adsorbents. The adsorption isotherms fit Langmuir isotherm, which suggested that adsorption occurred through uniform and monolayer sorption on the surface sites. The electrostatic attraction between the cationic Cd(II) and negatively charged surface played a crucial role as the main pathway in Cd(II) adsorption. Based on the investigated kinetic models, Cd(II) adsorption had a better correlation with the pseudo-second-order kinetic model, which showed that chemisorption occurred during the Cd(II) removal process. The findings of this study revealed that ZIF-L/GO has the potential of becoming the perfect adsorbent for cadmium removal from aqueous solutions