The control of aluminium speciation in coagulant composites is the appropriate approach to remove turbidity and natural organic matter from raw water effectively. This suspended matter in water ...affects its organoleptic quality and triggers problems by causing interference with the water treatment process. This study examined the behaviour of composite coagulants polyaluminium chloride-chitosan (PAC-CTS) with different aluminium speciation and polymer ratio to remove oxidizable matter and turbidity residing in surface waters. The fraction of basicity ratio (Al/OH) in the preparation of polyaluminium chloride (PAC) and chitosan (CTS) were simultaneously evaluated and optimized according to aluminium speciation by experimental design. The interaction between PAC and CTS was examined via Al-Ferron timed spectrophotometric approach, theoretical study and fourier transform infrared (FTIR) analysis. Ferron analyses reveal that basicity ratio and CTS fraction affect the distribution of aluminium forms (mononuclear Ala, medium polymeric Alb, colloidal, and high polymeric Alc) in PAC-CTS. The theoretical study showed that Al(OH)2+, Al13, and Al30 species are more reactive than aluminium hydroxide Al(OH)3 at different magnitudes and sites with chitosan. The FTIR analysis confirmed the existence of an interaction between PAC and CTS by revealing a new peak for Al-NH2 stretches. The coagulation performance study of composite coagulant PAC-CTS with different compositions showed that the increase of chitosan and the preponderance of Alb and Alc species compared to Ala are suitable for removing colloidal suspensions. Further, incorporation of PAC with high basicity (74.1%) in 16.3% of chitosan (PAC-CTS1) removed 99.51% of turbidity and 66.66% of oxidizable matter at AlCl3 concentration of 10 mg l−1. However, increasing the percentage of chitosan to 34.1% at the same basicity (74.1%) in the PAC-CTS4 compound was not beneficial for oxidizable matter removal. It was speculated that the improvement in coagulation performance could be achieved by considering the aluminum speciation and polymer content in the composite flocculant PAC-CTS. The present work could be a useful model for synthesizing and studying organometallic interactions in developing new composite coagulants to improve coagulation performance.
Polyaluminum chloride (PAC)/natural polyelectrolyte composite coagulants have received considerable attention recently due to their exceptional properties in drinking water treatment. However, the ...criteria for selecting polyelectrolytes grafted into the PAC to improve coagulation performance are not yet well defined. For this purpose, we have compared the potential of composite coagulant PAC-SA (sodium alginate (anionic polyelectrolyte)) with PAC-CTS (chitosan (cationic polyelectrolyte)) on treatment dam water. The impact of the nature and ratio of polyelectrolytes used was examined as a function of the distribution of aluminum forms in the composite coagulant. The intramolecular interaction between PAC and polyelectrolytes was visualized by FTIR analysis and studied by density functional theory (DFT). The coagulation performance showed that the polyelectrolyte viscosity and aluminum forms distribution significantly affect the removal of turbidity and oxidizable matter. PAC-SA showed a higher removal efficiency of colloidal suspension than PAC-CTS due to alginate’s high viscosity, which improves coagulation via bridging and interparticle entrapment phenomena. The present work highlighted the effect of polyelectrolyte viscosity and aluminum speciation on improving coagulation performance to define promising criteria for developing new composite coagulants.
Composite coagulants of polyaluminum chloride (PAC) and natural polyelectrolytes have attracted considerable attention in recent years due to their outstanding properties in drinking water treatment. ...However, the selection of polyelectrolytes grafted into PAC and aluminum forms distribution in the coagulant composite is under continuous evaluation and update. This study evaluated the effectiveness of new composite coagulants based on polyaluminum chloride (PAC) and sodium alginate (SA) to remove the colloidal matter from dam water. Optimization of the basicity (OH to Al ratios) and the sodium alginate ratio was performed by experimental design to control aluminum speciation in the composites coagulants. The Al-Ferron timed spectrophotometric method, density Functional Theory (DFT), and FTIR analysis were performed to explore PAC and SA’s interaction mechanism. The monitoring of aluminum speciation in the composite coagulant PAC-SA revealed that the basicity and SA ratios in the PAC-SA affected the distribution of aluminum forms (mononuclear Ala, medium polymeric Alb, colloidal, and highly polymeric Alc). The theoretical analysis identified the medium and high aluminum polymer species as the most sensitive species to react with SA. The coagulation performance revealed that the increasing percentage of the SA and the prevalence of Alb and Alc species over Ala species in the PAC-SA are beneficial for turbidity and oxidable matter removal. Incorporating biopolymer (SA) into the PAC reduced the concentration of inorganic coagulant consumed and increased the attraction efficiency of suspended pollutants compared to PAC. At an AlCl
3
concentration of 10 mg.L
−1
, the incorporation of PAC (66.6% of basicity) into 20% of SA removed 99.9% of turbidity and 78.67% of oxidizable matter. This study provided new insights into the intramolecular interaction between PAC and SA and its influence on aluminum’s speciation in the PAC-SA to increase surface water treatment efficiency.
In this work, we were interested in eliminating the organic and mineral compounds that pose problems in obtaining drinking water using the method of coagulation. These substances are stable in the ...medium due to their colloidal sizes and surface loads, which require appropriate treatment. For this purpose, we explored the removal of colloidal suspension using a coagulant formed by co-precipitation of AlCl
3
.6H
2
O in an alkaline medium. This practice leads to the formation of polymeric species mixtures such as Al
45
O
45
(OH)
45
Cl and Al
2
O
3
.H
2
O after washing. The removal efficiency of mineral and organic matter is evaluated by measuring the turbidity and permanganate index by varying the concentration of the coagulant from 0.04 to 0.4 g.1
−1
. It has been shown that the effectiveness of the treatment had been increased in parallel with the concentration. The preliminary hydrolysis of aluminium leads to a fixation of the pH throughout the concentration range. This character had solved the problem of direct use of aluminium salts (conventional method) resulting in a modification of the pH and subsequently, variable efficiency. The refined coagulant (after washing) reaches the removal of 97% turbidity and almost all oxidisable matter using only a mass of 0.08 g.1
−1
. However, using the crude coagulant (without washing) containing a significant amount of NaCl requires 0.4 g.1
−1
to reach only 87% removal of turbidity as well as 35% of oxidisable matter, with an increase of conductivity compared with that of the refined coagulant.
The adsorptive removal of Malachite Green (MG) by a novel biochar namely Cassava Rind Carbon (CRC) was studied in a batch system. Moreover, Box-Behnken Response Surface Methodology was used to ...optimize operating conditions of the adsorption process. Characterization was done by Thermo Gravimetric Analysis (TGA), Attenuated Total Reflectance Fourier Transform Infra-Red Spectroscopy (ATR/FTIR), Brunauer-Emmett-Teller (BET) surface area, Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and pH zero charge point (pH
). The pseudo-second-order model and Langmuir model provided the best fit for kinetic and isotherm, respectively. The maximum capacity of dye adsorbed was 932.98 mg/g at 25 °C. The influence of temperature, the mass of adsorbent and the concentration of dye was studied. The optimal amount of adsorbed MG was 1,363.58 mg/g corresponding to 50 °C, 5 mg of CRC and 150 mg/L of dye. According to the high performance exhibited by CRC in this study, Manihot esculenta Crantz waste can be used as a better and low-cost biomass for wastewater decolourization.
Our research consists in designing a new system of management and valuation of rainwater with the aim of securing the supply of drinking water.
For this, our study was conducted with a view to the ...collection, storage, treatment, and distribution of rainwater in compliance with the standards in force for use, based on alternative techniques and using modeling software EPA SWMM5, to optimize the dimensioning of the necessary structures.
Thus a case study of the University of Settat in Morocco, with an area of 6.56 Ha, with intense rain of 42 mm/h over a period of 30 min, and an average annual rain of 372 mm/year, the result obtained is very important: a collection of rainwater of 334.8 L/m2/year, towards reservoirs with an overall capacity of 1336.20 m3, to be used to supply toilet flushes, irrigation of surrounding green spaces without the use of drinking water, thus saving drinking water consumption and a significant gain on investment and on the operation of rainwater structures.
Thus, in a limited area, more than 50% can be saved on drinking water consumption, by collecting rainwater, thus securing drinking water consumption in the future in the face of water shortage.
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•New alternative techniques (AT) are proposed for the recovery of rainwater.•By the AT no storm water drainage through the off-site pipe and no rainwater loss.•Building storage tanks on-site With AT to save rainwater for non-potable reuse.•Save more than 50% potable water by non-potable reuse of collected rainwater.•Solutions by the proposed approach are all superior than existing techniques.
A simultaneous removal of Eriochrome Black T (EBT), Indigo Carmine (IC) and Methyl Orange (MO) anionic dyes in ternary mixture onto mixed metal oxides (Mg(Al)O) was studied. Mg(Al)O nanoparticles ...were obtained through one-step by pyrolysis of MgAl-layered double hydroxide compound as precursor. In view of the significant interferences in visible light absorbance, second-order derivative spectrophotometric method was adopted for simultaneous analysis of MO, EBT and IC concentrations. Thermodynamic parameters indicated that the removal of the three anionic dyes were exothermic and spontaneous in nature. Theoretical studies carried out on the dyes structures using density functional theory (DFT) calculations were of use to evaluate the relative electron donating/accepting character of each dye molecule, and are in good agreement with experimental data. Quantum chemical results suggested that MO (N = 4.2414) is more nucleophilic than EBT (N = 3.7960) and IC (N = 3.9797); the assumption has been that MO molecules were favorably adsorbed and interacted first with Mg(Al)O nanoparticles in the mixture media. Moreover, according to the local molecular reactivity results the nitrogen atoms, exhibiting the higher nucleophilic Parr functions PK−, could be the main active sites. In the light of these results, a possible removal mechanism was suggested.
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•Mg(Al)O was obtained by one-step pyrolysis of precursors.•Derivative spectrophotometry was applied for analyzing dyes concentrations.•Dyes molecular structures were studied using DFT/B3LYP/6-31G(d).•Dyes-Mg(Al)O interactions were supported by DFT theoretical results.
Freeze-dried sulfate intercalated layered double hydroxides (LDH) phase was synthetized by coprecipitation method via direct intercalation of sulfate anion. The effect of freeze-drying process on LDH ...properties was investigated. The resulting phase was evaluated for its efficiency in the intercalation of the reactive azo dye, Remazol Brilliant Red F3B (RR-F3B). The freeze-dried phase exhibited a low crystallinity and narrow particle size distribution compared to conventional LDH phases. The freezing step led to highly aggregated nanoparticles with a characteristic distance d003 of 8.12 Å. The preferential arrangement of the intercalated dye species was examined by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses. The results showed that RR-F3B molecules were partially accommodated between the LDH layers as single-layer with horizontal orientation. The effect of drying on morphological and structural properties can be attributed to several stresses during freezing and drying steps.
•Sulfate intercalated LDH was synthetized by coprecipitation followed by freeze-drying process.•Low crystalline freeze-dried phase was produced with staking defaults.•Highly aggregated particles with narrow size distribution was observed.•Partial intercalation of RR-F3B reactive dye with horizontal orientation was suggested.
Purpose: The purpose of this study is to give an insight into the practices of Moroccan industrial companies in the area of managing quality costs. Furthermore, it analyses how the quality costing ...system (QCS) implementation and sophistication differentiate according to a number of variables (size, business market orientation, QMS Maturity...). Design/methodology/approach: In order to achieve this objective, a questionnaire survey has been conducted among a heterogeneous sample of 1000 industrial companies that are operating in the national territory yielding a response rate of 23.4%. This study uses exploratory and chi-square test in the process of answering the above-mentioned questions. Findings: The survey highlighted the limited use of quality costing practices among Moroccan industrial companies. Results indicated that 42.6% of surveyed companies are engaged in QCS while 63.4% of them do not. The primary barrier is the complexity of QCS implementation. Besides, findings pointed out that origin, business activity, business market orientation and QMS maturity level are prominent to QCS implementation (p<0.05). Originality/value: This is one of the first studies to provide an insight into practices of Moroccan industrial companies in the area of managing quality costs. Indeed, several studies were led in different countries but no empirical study has been conducted in Morocco. This will give a clear picture of the situation at the national level. Research limitations/implications: The major limitation of the study is the limited number of respondents. Future researches should be conducted to cover a bigger sample size from manufacturing and services sector as well. Practical implications: The findings provide an insight into the barriers to QCS implementation which can be used as basis to identify ways to overcome these difficulties, to develop guideline and reveal best practices in the implementation of COQ reporting system.
The adsorptive removal of Methylene Blue by a novel bio char namely Cassava Rind Carbon was studied in a batch system. Moreover, several experiments were performed to optimize operating conditions of ...the adsorption process. Thermo gravimetric analysis investigates the thermal behaviour of the raw material. The surface functional groups were identified with Attenuated Total Reflectance Fourier Transform Infra-Red spectroscopy. The carbon surface was also characterised by BET surface area, scanning electron microscopy, X-ray diffraction and zero charge point of pH. Among the three kinetic models used to calculate the adsorption rate constants, the pseudo-second order was the most accurate. The experimental isotherms were analysed and Redlich-Peterson's model provided the best fit. The maximum capacity according to Langmuir model was 565 mg g−1 at 25 °C. The thermodynamic study revealed that the adsorption is endothermic, physical and random. The temperature, the mass of adsorbent and the concentration of dye were the three factors optimized in a Box Behnken Response Surface Methodology, with an optimal amount of adsorbed MB of 771 mg g−1.
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