Nonlinear regression for analysis of the uptake of KMnO4 from aqueous solutions onto natural marl

The present work aims to evaluate the performance of raw marl collected from the region of Oum El Bouaghi on the elimination of KMnO4 from aqueous solution. The adsorption capacities were studied using the batch technique as a function of pH, initial concentration and temperature. The maximum adsorption for KMnO4 was found to be 83.517% at pH 3.0. When the pH is low (pH<3.0), the uptake of KMnO4 occurs with an electrostatic attraction between the MnO4-ions and the surface proton groups, while at pH ≥3.0-8.0, the formation of complexes with the surface functional groups during the adsorption process and/or cation exchange are responsible for retention of Mn(II) ions onto marl. Experimental adsorption data were modeled with different nonlinear isotherms and kinetic models. Furthermore, statistical errors (SSE, SD, ARE, χ 2, R2 and R2 adj) were calculated to choose the suitable model. Langmuir isotherm was found to be best for fitting the experimental data. The calculated thermodynamic parameters indicated that adsorption process was physical, spontaneous and endothermic in nature. From this work, it was concluded that the natural marl can be used for effective elimination of KMnO4 from aqueous solution and wastewater.

Effect of Water Chemistry on the Uptake of Co(II) on Graphene Oxide Investigated by Batch Technique

The uptake of Co(II) on graphene oxide (GO) by an adsorption process as a function of pH and ionic strength in the absence and presence of humic acid (HA) or fulvic acid (FA) was studied using batch technique. The results indicated that the uptake is strongly dependent on pH but independent of ionic strength. A stimulative effect of HA/FA on Co(II) uptake was found at pH < 7.0, whereas an inhibitory effect was observed at pH > 7.0. Kinetic studies suggest that Co(II) uptake on GO could be described more favorably by the pseudo-second-order kinetic model. The uptake isotherms can be described better by the Langmuir, Freundlich, and D-R models than by the linear model. The thermodynamic data calculated from the temperature-dependent uptake isotherms suggests that the uptake of Co(II) on GO is spontaneous and endothermic. Results of this work are of great importance for the environmental application of GO in the treatment of Co(II) from wastewater and indicated that GO is promising for the natural attenuation of Co(II) and related metal ions from aqueous solution.

Potassium Adsorption Phenomenon in Calcareous Soils of Shahrazur Plain

A laboratory study for adsorption of potassium (K) determination was conducted on six soils located in Sharazur plain from the Kurdistan Region of Iraq in 2021 using the batch technique method. Potassium (K) adsorption isotherms were achieved by equilibrating 5.0 g of soil samples with eight grades of K (0 to 300 mg L-1) as KCl in 50 ml of 0.01M CaCl2 solution. To match the data of adsorption, Freundlich, Langmuir, and Temkin adsorption isotherms were used. The results show that the amount of adsorbed K ranged between (45.78 to 52.49) % added K. The Freundlich model fit the equilibrium K adsorption data better for the Serwan location of soil (silty loam), as demonstrated by a greater coefficient of determination (R2 =0.90). The value of heterogeneity factor 1/n for the Freundlich model ranged from (0.34 to 0.47) kg mg-1, which was less than one. The sorption processes for all of the studied soils were normal adsorption. The constant of the Langmuir isotherm (KL) aligned from (0.107 to o.425) L mg-1. Smaller KL values mean that more adsorbed K would be transformed to a non-exchangeable form, either through the creation of crystalline K or through ion occultation. The RL values indicate the type of isotherm, the values of RL> 1 that means the adsorption nature to be unfavorable. The Temkin equilibrium binding constant (AT) was high for all studied soils except the soils of Bestan Sur and Grdigo locations, the high value of AT indicates high binding energy. The Temkin constant (bT) ranged from (10.46 to 13.47) J mole-1 that was related to the nature of the adsorption energy, a positive value indicates that the adsorption process is exothermic.

Comparison of Heavy Metals Removal from Aqueous Solution by Moringa oleifera Leaves and Seeds

In this work, biomass obtained from seeds (S-MO) and leaves (L-MO) of the Moringa oleifera plant were used as low-cost biosorbents to remove the Pb(II), Cd(II), Co(II), and Ni(II) from aqueous solutions. The biosorption of the heavy metal ions was done using the batch technique. The effects of contact time (30–1440 min), biosorbent dosage (10–50 g/L) (0.1–0.5 g), and initial concentration of metals (10–500 mg/L) on the sorption capacity of metal ions were investigated. The S-MO and L-MO samples’ characterization was performed using pHpzc, X-ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR). It was found that the pHpzc was notably different between the seeds and leave-derived biosorbents. The removal process’s experimental kinetic data for both S-MO and L-MO were best described by the pseudo-second-order model for all metal ions, with R2 above 0.997 in all cases. Langmuir and Freundlich’s models were also used to analyze the isotherms parameters. Based on the Langmuir model, the maximum sorption capacities (Qm) for L-MO were found as follows: L-MO-Pb > L-MO-Cd > L-MO-Co ≥ L-MO-Ni, and for S-MO, the values of Qm values presented the following order: S-MO-Pb > S-MO-Co > S-MO-Cd > S-MO-Ni.

Kinetic and Equilibrium Studies on the Zinc Adsorption-desorption Characteristics of Some Promising Biochars in Aqueous Solutions

The present research aimed at investigating zinc (Zn) sorption capacity of the biochars derived from apple wood (WB) and rice straw (RB) feedstocks at two 300 and 600°C pyrolysis temperatures (WB300, WB600, RB300 and RB600, respectively) in aqueous solutions. Kinetic and equilibrium sorption experiments were conducted via batch technique. In equilibrium adsorption experiments, the study used the concentration range of 5-200 mg Zn L− 1 and focused on the solution pH effect on Zn adsorption in biochars under the following conditions: unadjusted and adjusted pH (4 and 6) and three ionic strength levels (0.01, 0.03, 0.1 M KNO3). Zinc desorption experiments were conducted under all above mentioned conditions but without pH adjustment at five separate stages. Kinetic data analysis indicated that Zn adsorption in biochars reached the near steady state within 24 hours with the sorption rate order of WB300 < WB600 < RB300 < RB600. The best fitness was superior to both Elovich and exponential rate models. Also, Zn adsorption isotherms in the studied biochars were shown to fit quite well to Langmuir, Freundlich and Dubinin-Radushkevich models. Zn sorption maxima were found to be 4.3, 16.4, 17.9 and 33.3 mg g− 1, on average, for WB300, WB600, RB300, and RB600, respectively. The initial increased pH solution from 4 to 6 caused an increase in Zn adsorption in RB600, RB300 and WB600, however the sorption maxima in WB300 was detected at pH 4. The rise in solution ionic strength from 0.01 M to 0.1 M dropped the Zn adsorption capacity in all the studied biochars. Findings suggested that rice straw derived biochars showed a better performance than woody biochars in Zn sorption and retention from aqueous solutions. In addition, this ability increased with increasing pyrolysis temperature in both types of biochars. Finally, the study revealed that rice straw biochars, produced at high pyrolysis temperatures, can serve as economical and efficient absorbents for Zn removal from aqueous solutions.

Efficient Private Conjunctive Query Protocol Over Encrypted Data

Conjunctive queries play a key role in retrieving data from a database. In a database, a query containing many conditions in its predicate, connected by an “and/&/∧” operator, is called a conjunctive query. Retrieving the outcome of a conjunctive query from thousands of records is a heavy computational task. Private data access to an outsourced database is required to keep the database secure from adversaries; thus, private conjunctive queries (PCQs) are indispensable. Cheon, Kim, and Kim (CKK) proposed a PCQ protocol using search-and-compute circuits in which they used somewhat homomorphic encryption (SwHE) for their protocol security. As their protocol is far from being able to be used practically, we propose a practical batch private conjunctive query (BPCQ) protocol by applying a batch technique for processing conjunctive queries over an outsourced database, in which both database and queries are encoded in binary format. As a main technique in our protocol, we develop a new data-packing method to pack many data into a single polynomial with the batch technique. We further enhance the performances of the binary-encoded BPCQ protocol by replacing the binary encoding with N-ary encoding. Finally, we compare the performance to assess the results obtained by the binary-encoded BPCQ protocol and the N-ary-encoded BPCQ protocol.

PENYERAPAN ION Pb(II) MENGGUNAKAN ADSORBEN DARI LIMBAH PADAT LUMPUR AKTIF PENGOLAHAN AIR MINUM

Timbal merupakan salah satu polutan yang paling banyak digunakan dalam beberapa kegiatan industri seperti penambangan, peleburan, pemurnian minyak bumi, percetakan, produksi pigmen, dan pembuatan baterai. Permasalahan logam berat dapat ditanggulangi dengan penurunan kadar logam berat menggunakan teknik penyerapan. Salah satu adsorben yang digunakan untuk penyerapan ion Pb(II) adalah limbah padat lumpur aktif dari pengolahan air minum. Penelitian ini bertujuan untuk menggunakan limbah padat lumpur aktif yang di ambil dari sisa pengolahan air minum PDAM Tirta Mayang Jambi dan diaktifasi menggunakan KOH. Adsorben digunakan untuk penyerapan ion Pb(II) dengan metoda penyerapan dilakukan secara statis. Adsorben dikarakterisasi menggunakan FTIR, SEM dan XRF. Ion Pb(II) dalam larutan dianalisis dengan menggunakan metoda Spektrofotometer Serapan Atom (SSA). Parameter penyerapan yang dipelajari adalah pH diperoleh pada pH 5, massa adsorben 0,2 g, waktu kontak 45 menit dan konsentrasi ion Pb(II) adalah 300 mg/L dengan kapasitas adsorbs 25,42 mg/g.ABSTRACT The lead metal is one of the pollutants most widely used in several industrial activities such as mining, smelting, refining petroleum, printing, pigment production, and battery production. Heavy metal problems can be overcome by decreasing heavy metal content using adsorption techniques. One of the adsorbents used for Pb(II) ion adsorption is avtivated sludge solid waste from drinking water treatment. This study aims using activated sludge solid waste from drinking water treatment Local Water Company Tirta Mayang Jambi and activated using KOH. The adsorbent used for adsorption of Pb(II) ion by batch technique. Adsorbents are characterized using FTIR. SEM, XRF. Pb(II) ion in the solution analysis with Adsorption Atomic Spectrophotometer (AAS). The adsorption parameters studied were pH was pH 5, adsorbent mass was 0.2 g, contact time was 45 minute and concentration of Pb(II) ion was 300 mg/L with adsorption capacity was 25.42 mg/g.

Kinetics and Thermodynamics Studies of Copper(II) Adsorption onto Activated Carbon Prepared from Salacca zalacca Peel

Highly porous and stable materials, such as alumina, silica, carbon, zeolite, and bentonite, are well known and have been used as metal ion adsorbents. However, the use of biogenic carbon as adsorbent is relatively rare. The adsorption of copper(II) onto activated carbon extracted from Salcaca zalacca peel was studied. The effect of initial copper concentration, contact time, and a series temperature was studied. Adsorption was carried out in a batch technique. The adsorption equilibrium was reached after 60 minutes of contact time. The adsorption data had a better fitting line for the Langmuir isotherm model. The Langergren and also Ho and Mc Kay equations were used to predict the adsorption kinetics. The adsorption process obeyed a second-order kinetics model. The Thermodynamic parameters were ∆H°= -42.4180 kJ/mol; ∆S°= -0.0843 kJ/mol; ∆G°<0. These values indicated that the adsorption was exothermic and spontaneous. The low ∆G° value revealed that the main mechanism controlling the adsorption process was physisorption.

A Comparative Study on Cu2+, Zn2+, Ni2+, Fe3+, and Cr3+ Metal Ions Removal from Industrial Wastewaters by Chitosan-Based Composite Cryogels

Materials coming from renewable resources have drawn recently an increased attention in various applications as an eco-friendly alternative in the synthesis of novel functional materials. Polysaccharides, with their prominent representative – chitosan (CS), are well-known for their sorption properties, being able to remove metal ions from dilute solutions either by electrostatic interactions or chelation. In this context, we proposed here a comparative study on Cu2+, Zn2+, Ni2+, Fe3+, and Cr3+ metal ions removal from industrial wastewaters by CS-based composite cryogels using batch technique. The composite cryogels consisting of CS embedding a natural zeolite, namely clinoptilolite, were synthesized by cryogelation, and their sorption performance were compared to those of CS cryogels and of acid-activated zeolite. A deeper analysis of thermodynamics and kinetics sorption data was performed to get insights into the sorption mechanism of all metal ions onto sorbents. Based on the optimized sorption conditions, the removal of the above-mentioned ions from aqueous solutions by the composite sorbent using dynamic technique was also evaluated.