Papers by Keyword: Removal

Abstract: As a result of the ongoing hostilities on the territory of Ukraine, the waste situation has become significantly more complicated. The load on existing landfills has increased significantly, and the morphological composition of waste has changed significantly. Work on the reconstruction and construction of new environmentally friendly landfills is being carried out slowly and in insufficient quantities. Based on the research conducted, we proposed a scenario for the management of waste generated under martial law (in particular, destruction waste) using the example of the city of Kremenchug. The capacity of the local landfill and its ability to accept such waste were investigated. Recommendations have been developed to improve the system for monitoring the state of the environment in the area of ​​influence of the landfill. To increase the efficiency of using the landfill, measures have been proposed to compact waste, which will allow its continued operation and ensure safe waste management in war conditions.

Abstract: In Malaysia, there are some accumulation of sugar refinery byproducts with a lot of this material not being utilized in a productive manner, while, these byproducts had the great potential when mixed into agricultural soils as organic fertilizer with many of benefits that can improve soil health, and sustainable agronomic productivity. Pressmud or known as filter cake is a by-product of sugar industry and for every 100 tons of sugarcane crushed about 3 tons of pressmud cake is left behind as by-product. This studies carried out on this material have not properly summarized their characteristics properties that they can be used as aid for future works. Data from tests involving pressmud samples from Malayan Sugar Manufacturing (MSM) Prai Berhad, Penang which was part of a larger collection was analyzed. The physicochemical properties of pressmud characterization as well as leaching test were carried out. The physicochemical and engineering properties involved compaction behavior, permeability, cation exchange capacity (CEC), compressive stress test and its surface functional groups. The leaching test method included batch equilibrium test and column test. The optimum value of water content in pressmud was determined in the compaction test. It was found out that pressmud has higher optimum water content value was observed. The permeability test of pressmud gave value in ranges of 1.84 x 10^-5 cm/s. The Cation Exchange Capacity (CEC) of pressmud indicated value in the range of 99 to 101 meq/100 g. The high cation exchange capacity indicated that pressmud was believed to be primarily responsible for sorption of metal ions. It can be concluded that pressmud having the capability to remove heavy metals through CEC process. Pressmud also showed higher compressive strength value. Batch equilibrium test glaringly showed that pressmud have the capability to remove from 53.6%-93.8% metal removed from metal solutions for Chromium (Cr), Copper (Cu), Manganese (Mn), Nickle (Ni), Lead (Pb) and Zinc (Zn). From the result of column test, pressmud alone was able to retain efficiently all the heavy metals as these metals did not reach 1 (relative concentration) until 10 pore volume (PV.) indicating that pressmud was a good mixture material as it can assist in adsorption of heavy metals. Based on the characterization study, removal efficiency and column test, pressmud has great potentiality to be used as an additional material in soil amendments to enhance soil fertility and strength ability.

Abstract: Removal of Au(III) on a purified bagasse ash (BA) has been examined. The purified BA adsorbent was prepared through purification of a crude BA obtained from Madukismo sugarcane industry, Yogyakarta, Indonesia, using a mixed solution of HCl 0.1 M and HF 0.3 M and followed by HNO₃ 3 M. The HCl-HF-HNO₃ purified BA contained quartz with silanol (Si-OH) and siloxane (Si-O-Si) functional groups and aromatic component. Removal of Au(III) on the HCl-HF-HNO₃ purified BA was maximum at pH 4.2 with siloxane and silanol functional groups, but not aromatic component, took important role on the removal. At this optimum pH, the removal of Au(III) on the HCl-HF-HNO₃ purified BA fitter to the second order removal kinetics model than the pseudo-first and pseudo-second order kinetics models indicating that adsorption was not the only mechanism for the Au(III) removal. The second order removal rate constants (k₂) of Au(III) by HCl-HF-HNO₃ purified BA was 3.32 x 10² L/mol min. In fact, reduction of Au(III) to Au metal also occurred as an addition to adsorption for the removal of Au(III) from aqueous solution.

Abstract: Mesoporous carbon-doped TiO₂ (MCT) was synthesized via a template-free method in combination with solvothermal treatments. The structure, particle size and composition of this adsorbent were measured using XRD, TEM and XPS. Also, the usability of isothermal models for Cu (II) onto mesostructured adsorbent was implicated in these cases. The adsorptive capacity of MCT for Cu (II) was assessed using ICP-MS technique. The maximal adsorptive capacity was 16.9 mg g^-1, and the ion-exchange action of Cu (II) was found to be the predominant adsorption.

Abstract: Water quality is very important to food processing industry. Water hardness caused by calcium ions in water can affect the properties of food including aroma, texture, flavor and appearance. Chitosan has amino functional groups that can remove metal ions from aqueous solution. However, chitosan can give more effective removal of calcium ions if it is modified with functionalized substance such as thiamine hydrochloride. therefore, the objectives of this study were to synthesize the modified chitosan with thiamine hydrochloride (MCTH) and to determine its efficiency for removal of calcium ion in solution. Chitosan was prepared from crab shells and modified with thiamine hydrochloride at 30 °C. The morphology of both crab-shell chitosan (CSC) and MCTH was characterized by SEM, FTIR and NMR techniques. Batch adsorption experiments were conducted as a function of pH, contacted time and initial concentration of calcium (II) ions. The desorption of calcium(II) ion from both adsorbents was also investigated. The concentration of calcium in solution was measured by FAAS technique. The results indicated that the optimum pH for adsorption was 6.0 for both CSC and MCTH. The adsorption capacity for MCTH (48.31 mg g^-1) was greater than that of CSC (1.52 mg g^-1). The isotherm showed that the adsorption process of calcium (II) ions onto MCTH was fitted to Langmuir isotherm model. Calcium desorption from MCTH was lower than that of CSC.

Abstract: Manganese substituted iron titanate was successfully synthesized and characterized by x-ray diffraction and Fourier transformed infra-red to investigate the composition and to identify the chemical compound of this unique architecture. The materials were tested for adsorption of remazol brilliant blue R (RBBR) aqueous solution. The adsorptions were investigated at different pH which are pH 3, 4, dye concentration and manganese substituted iron titanate dosage. It was found that synthesized manganese substituted iron titanate particles can adsorbed 99% of 100 ppm RBBR dye at pH 2.

Abstract: Selenate removal from mine waters is required to mitigate human and environmental health impacts. In this study, the performance of an inverse fluidised bed reactor (IFBR) for the biological removal of selenate from synthetic mine water (pH 6.0-7.0) was evaluated. A laboratory-scale IFBR was set up with floating biomass carriers. Selenate reducers were enriched from environmental samples and anaerobic sludge. The synthetic medium contained ~10 mM (~1.4 g L^-1) selenate, nutrients and 10 mM ethanol as electron donor. During stable performance the bioreactor achieved 94 % removal of selenate representing a removal rate of 251 mg L^-1 d^-1 at a hydraulic retention time of 5 d. Selenite concentration remained < 1 mg L^-1 during stable performance, and the formation of a red precipitate indicated that selenate was reduced to elemental selenium. The biological selenate reduction generated alkalinity, increasing the wastewater pH from 6.0 to 8.6. The redox potential gradually approached a value ranging from -300 mV to -400 mV against standard hydrogen electrode. Overall, the results showed that the IFBR can be used for removing selenate and acidity from mine waters. Moreover, it has potential to facilitate recovery of elemental selenium. Therefore, the bioprocess provides an opportunity to reduce the costs and liabilities associated with selenium containing mine drainage and the associated environmental impacts.

Abstract: Natural clay (NC) and its surface modified with manganese oxide (MnO-NC) was assessed for removal of Cd (II) ion by batch adsorptive process. The surface modification of NC was chemically prepared with manganese chloride in basic solution by simple procedure, resulting in larger surface area than raw material by about 10-times. FT-IR spectra and SEM photograph showed the unique characteristic of MnO-NC after chemically surface modification with MnO₂ particles successfully set down onto the NC surface. Under optimum conditions as a function of solution pH of 6.0, adsorbent dose of 5 g/L, contact time of 15 min and initial cadmium concentration of 100 mg/L, the adsorption capacity reach to 30.6 mg/g. By comparing with NC, MnO-NC provides higher adsorptive capability than the one by about 30-times. Based on isotherm estimation, the Langmuir adsorption isotherm showed more suitable for both adsorbents with the best correlation coefficient (r²>0.99) than the Freundlich isotherm. The adsorptive kinetics of Cd (II) onto NC and MnO-NC followed the pseudo-second-order.

Abstract: Arsenical water pollution refers to the toxicity of arsenic. The form of trivalent arsenic has been seen as more toxic substances, which will be great improved by the manmade pollution. Compared with other technologies, adsorption is the main method of removal of arsenic pollution, for its higher efficiency and lower cost. Based on the adsorption theory and ion exchange method, the layered double hydroxides material containing ferric iron and manganese (Mn-Fe-LDH) was prepared to remove arsenic in this paper. We have designed some experiments for synthesis of this material. The reaction process and elemental compositions has been studied and the adsorption property of arsenic adsorption onto layered double hydroxides was verified through a series of experiments. Study shows that the Mn-Fe-LDH material can be used as a good adsorbent material for its high removal efficiency. The adsorption capacity of the Mn-Fe-LDH material is not affected by the interference of pH and Cl^-/SO₄^2- ion strength. It was a broad prospect for the development and application of arsenic removal materials.

Abstract: In electrical discharge machining (EDM) process, electrode polarity plays an important role during machining operation. This paper addresses the issues of EDM utilizing the positive and negative tool-electrode polarity to explore the effects on the performance criteria such as material removal rate (MRR), tool wear rate (TWR), surface roughness (SR) and micro-hardness during machining of Ti–5Al-2.5Sn (GradeVI) Ti alloy. The Ti-5Al-2.5Sn alloy was machined using copper-chromium electrode with positive and negative polarity by varying the peak current and pulse-on-time, while the pulse-off-time was kept constant. The result of study suggests that reverse polarity improves the MRR, TWR, SR while normal polarity improves the surface micro-hardness. The peak current has the maximum affect on machining performance for both types of polarities. Further the migration of different elements and formation of compounds on the machined surface was investigated using EDX and XRD analysis.