Adsorbents for Removal of Hazardous Metals from waste water and natural water samples: A Review

Wide ranges of low cost adsorbents were used to remove hazardous metal in aqueous solution and wastewater. The low cost adsorbents were usually collected from agricultural waste, seafood waste, food waste, industrial by-product and soil. These adsorbents are readily available in a copious amount. Some of the natural adsorbents appeared as good heavy metal removal, while some were not and require further modifications and improvements to enhance the adsorption capacity. Currently, heavy metals exist in most of the industrial wastewaters and water supplies are among the most severe environmental contaminants. Numerous research works have been conducted in this field, this review includes few potential solution containing papers.

Arsenic Removal from Contaminated Water Using Natural Adsorbents: A Review

More than 170 million individuals have been influenced by arsenic (As) because of the ingestion of As-polluted groundwater. The presence of As in water bodies, particularly groundwater, has been found to become a widespread issue in the past few decades. Because arsenic causes extreme wellbeing impacts, even at a low concentration in drinking water, the innovations of As removal from contaminated water are of significant importance. Traditional strategies, for example, reverse osmosis, ion exchange, and electro-dialysis are generally utilized for the remediation of As-polluted water; however, the high cost and/or sludge production restricts their application in less-developed areas. The utilization of adsorbents acquired from natural materials has been explored as an alternative for the costly techniques for As removal. This paper aims to review the past and current developments in using naturals adsorbents or modified natural materials for arsenic removal and show the different parameters, which may influence the As removal effectiveness of the natural adsorbent, such as contact time, adsorbent dosage, flow rate, pH, reusability, temperature, and influence of others ions.

Effects of Environmental Factors on the Leaching and Immobilization Behavior of Arsenic from Mudstone by Laboratory and In Situ Column Experiments

Hydrothermally altered rocks generated from underground/tunnel projects often produce acidic leachate and release heavy metals and toxic metalloids, such as arsenic (As). The adsorption layer and immobilization methods using natural adsorbents or immobilizer as reasonable countermeasures have been proposed. In this study, two sets of column experiments were conducted, of which one was focused on the laboratory columns and other on the in situ columns, to evaluate the effects of column conditions on leaching of As from excavated rocks and on adsorption or immobilization behavior of As by a river sediment (RS) as a natural adsorbent or immobilizer. A bottom adsorption layer consisting of the RS was constructed under the excavated rock layer or a mixing layer of the excavated rock and river sediment was packed in the column. The results showed that no significant trends in the adsorption and immobilization of As by the RS were observed by comparing laboratory and in situ column experiments because the experimental conditions did not influence significant change in the leachate pH which affects As adsorption or immobilization. However, As leaching concentrations of the in situ experiments were higher than those of the laboratory column experiments. In addition, the lower pH, higher Eh and higher coexisting sulfate ions of the leachate were observed for the in situ columns, compared to the results of the laboratory columns. These results indicate that the leaching concentration of As became higher in the in situ columns, resulting in higher oxidation of sulfide minerals in the rock. This may be due to the differences in conditions, such as temperature and water content, which induce the differences in the rate of oxidation of minerals contained in the rock. On the other hand, since the leachate pH affecting As adsorption or immobilization was not influenced significantly, As adsorption or immobilization effect by the RS were effective for both laboratory and in situ column experiments. These results indicate that both in situ and laboratory column experiments are useful in evaluating leaching and adsorption of As by natural adsorbents, despite the fact that the water content which directly affects the rate of oxidation is sensitive to weathering conditions.

Potential of Kale and Lettuce Residues as Natural Adsorbents of the Carcinogen Aflatoxin B1 in a Dynamic Gastrointestinal Tract-Simulated Model

Adsorption of the carcinogen aflatoxin B1 (AFB1) onto agro-waste-based materials is a promising alternative over conventional inorganic binders. In the current study, two unmodified adsorbents were eco-friendly prepared from kale and lettuce agro-wastes. A dynamic gastrointestinal tract-simulated model was utilized to evaluate the removal efficiency of the sorptive materials (0.5%, w/w) when added to an AFB1-contaminated diet (100 µg AFB1/kg). Different characterization methodologies were employed to understand the interaction mechanisms between the AFB1 molecule and the biosorbents. Based on adsorption results, the biosorbent prepared from kale was the best; its maximum adsorption capacity was 93.6%, which was significantly higher than that of the lettuce biosorbent (83.7%). Characterization results indicate that different mechanisms may act simultaneously during adsorption. Non-electrostatic (hydrophobic interactions, dipole-dipole interactions, and hydrogen bonding) and electrostatic interactions (ionic attractions) together with the formation of AFB1-chlorophyll complexes appear to be the major influencing factors driving AFB1 biosorption.

Efektivitas Kombinasi Kitosan dan Ampas Kopi sebagai Adsorben Alami dalam Menurunkan Konsentrasi Arsen Pada Limbah Cair PT PXI

Abstrak PXI adalah salah satu perusahaan di Kabupaten Bekasi yang bergerak di bidang jasa layanan laboratorium. Dalam menjalankan kegiatannya, PXI menghasilkan logam arsen ke lingkungan. Keberadaan arsen di dalam air limbah PXI harus segera diselesaikan agar tidak mencemari lingkungan dan membahayakan kehidupan manusia. Metode yang digunakan dalam penelitian ini adalah metode eksperimen dan deskriptif kuantitatif berdasarkan data hasil laboratorium menggunakan instrumen FT-IR, SEM EDX dan AAS. Tahapan penelitian terdiri dari sintesis, karakterisasi dan penggunaan adsorben alami untuk menurunkan logam arsen pada air limbah. Hasil penelitian menunjukkan bahwa penggunaan adsorben alami kitosan dan karbon aktif ampas kopi 1,4 gram dapat menghasilkan efisiensi penurunan logam arsen tertinggi sebesar 86,18% dengan konsentrasi akhir sebesar 0,79 mg/L. Namun hasil tersebut belum memenuhi baku mutu logam arsen yang ditetapkan Peraturan Menteri Lingkungan Hidup Nomor 12 Tahun 2020. Sehingga perlu dilakukan penelitian lebih lanjut untuk meningkatkan efisiensi penurunan logam arsen. Abstract PXI is one of the companies in Bekasi Regency which is engaged in laboratory services. In carrying out its activities, PXI produces arsenic metal into the environment. The presence of arsenic in PXI wastewater must be resolved immediately so as not to pollute the environment and endanger human life. The method used in this study is an experimental and quantitative descriptive method based on laboratory data using FT-IR, SEM EDX and AAS instruments. The research stages consisted of synthesis, characterization and the use of natural adsorbents to reduce arsenic metal in wastewater. The results showed that the use of chitosan natural adsorbent and 1.4 gram coffee grounds activated carbon could produce the highest arsenic metal reduction efficiency of 86.18% with a final concentration of 0.79 mg/L. However, these results do not meet the quality standard for arsenic metal as stipulated by the Regulation of the Minister of the Environment Number 12 of 2020. So it is necessary to do further research to increase the efficiency of reducing metal arsenic.

Adsorption properties of sugarcane bagasse and corn cob for the sulfamethoxazole removal in a fixed-bed column

Natural adsorbents are a good alternative to remove antibiotic residues from wastewater. In this study, the adsorption capacity of sulfamethoxazole (SMX) onto sugarcane bagasse (SB) and corn cob (CC) in a continuous fixed-bed was compared. Brunauer Emmett Teller, Fourier transform infrared (FTIR), Boehm titration, and point of zero charge (pHpzc) were used to characterize both adsorbents. The adsorption capacity (qe) and the removal percentage of SMX (% R) were investigated at different different flow rates (2, 5, and 7 mL min− 1) and adsorbent masses (4 and 6.4 g), and a constant initial concentration of 5 mg L− 1. The results of the characterization showed that SB has a morphology with more dispersed particles and a specific surface higher than CC (2.6 > 1.2 m2 g− 1). Boehm titration indicates that both the surface of SB and CC have a greater amount of acid groups, which is in agreement with FTIR and pHpzc results. The continuous fixed-bed experiments showed that % R and qe of SMX are higher with SB in all the tests. The highest qe and maximum % R was 0.24 mg g− 1 and 74% with SB, and 0.15 mg g− 1 and 65% using CC. In most cases, the qe of both adsorbents decreased with the increase of flow rate and bed height. An analysis suggests that hydrogen bonds could be the main factor favoring the SMX adsorption with SB. Finally, the intraparticle diffusion was the rate-controlling step, predominating the pore-volume diffusion resistance.

A Review on Organic Adsorbents for the Removal of Toxic Metals from Waste Water

The contamination of water due to explosive population growth rate, industrial operations, various toxic components particularly trace metals are affecting on the flora and fauna including on the human well-being. Water is essential requirement for process, developmental activities and all the living being. Due to manmade activities, there is an instant necessity to find different techniques for the removal of toxins in wastewater. Industrial processed effluent contains like nickel, lead, chromium, zinc, arsenic, cadmium, selenium and uranium. So far, a various type efficient methods are available for the removal of heavily metals such as chemical precipitation, ion exchange, reverse osmosis, ultrafiltration, electrodialysis, nanofiltration, coagulation, flocculation, floatation, etc. However available methods have numerous disadvantages like more reagent requirement, random removal of metal ion, generation of toxic sludge etc. At present, treatment of water in the economical process is very important. So the various natural adsorbents were used for the treatment of water. Adsorption techniques being very simple, economical, successful and flexible has become the most ideal methods for removal of toxic metals from wastewater. In this paper reviewed on readily available about 98 published articles (1990-2020) various natural materials as adsorbents for removal of heavy metals from wastewater. It is evident from the review of articles that ion-exchange, adsorption and membrane filtration are the most frequently apprised for the removal of heavy metal in wastewater. As these industries disposes untreated or poorly treated waste water containing toxic metals to the water bodies which in turn affect the human health those who are consuming it causing serious carcinogenic health effects. This review paper presents an overview of different adsorption techniques of heavy metal treatment from several wastewater samples. All of the cited authors and articles give the adsorption kinetics adopting isotherm models. By comparing many research values presented by an earlier number of papers. We draw conclusions for two new adsorption methods first one is with biosorbent and second one with synthetic materials. In this paper an attempt is made to study the effort done by the various researchers those who have made an attempt to treat the toxic waste water by using natural adsorbents and the results are discussed.

Isolation and characterization chitosan from varied crab shell

Crab shells chitosan processing consists of 3 steps, the process is deproteinization,demineralization, and deacetylation. This study aims to produce chitosan with a high yield asan alternative to natural adsorbents and coagulants. This research was conducted using threedifferent raw materials for crab shells, namely mangrove crab shells (K1), small crab shells(K2), and kappa crab shells (K3). In this study, a demineralization process was carried out ondried crab shells using strong acids. Furthermore, deproteination is carried out using a strongbase to obtain chitin and deacetylation with a strong base to produce chitosan. The results ofresearch carried out observations including moisture content, ash content, solubility, and yield.The results of the isolation of the crab shell chitosan obtained the chitosan yields of 31%,32.2%, and 24.5%, respectively.