Congo Red

Physico-chemical investigation on adsorption of congo red, an anionic azo dye by chitosan hydrobeads has been carried out. Adsorption process has been found to be dependant on temperature with optimum activity at 30 °C. Both ionic interaction as well as physical forces is responsible for binding of congo red with chitosan. Theoretical correlation of the experimental equilibrium adsorption data for congo red–chitosan hydrobeads system would be best explained by linearized form of Langmuir isotherm model. The kinetic results follow pseudo second-order rate equation. pH of the experimental solution influenced congo red adsorption inversely, and ∼20.0% of the dye could be desorbed from the loaded beads by changing the pH of the solution to alkaline range (∼pH 12.0). Both sodium chloride and sodium dodecyl sulfate significantly influenced the adsorption process.

Dans les contextes des pays du sud, quels sont les conditions d'accès, les compétences et les usages des
étudiants au niveau secondaire? Cet article présente les résultats d’une enquête effectuée auprès des
étudiants africains et analyse les conditions d’accès, des usages des technologies de l’information et de
la communication (TIC) et de leur diffusion en milieu éducatif au Burkina-Faso et en République
Démocratique du Congo1
. La démarche croise, la territorialité du phénomène et le jeu des acteurs
concernés en milieu éducatif, spécifiquement dans les écoles secondaires. L'article est structuré comme
suit : la première partie présente le cadre théorique ainsi que la méthodologie. La seconde partie de
l’article décrypte les résultats à l’issu de l’enquête effectuée auprès de 1 854 répondants et s’achève
par une discussion. Cette partie traite des coûts d’accès consacrés par les étudiants, les compétences, la
durée moyenne de l’usage d’Internet et dresse un portrait des pratiques en milieu scolaire dans le
contexte des pays subsahariens d'Afrique francophone.
Mots clés : TIC, éducation secondaire, Afrique francophone, Internet

The effluent water of many industries, such as textiles, leather, paper, printing, cosmetics, etc., contains large amount of hazardous dyes. There is huge number of treatment processes as well as adsorbent which are available for the processing of this effluent water-containing dye content. The applicability of naturally available low cast and eco-friendly adsorbents, for the removal of hazardous dyes from aqueous waste by adsorption treatment, has been reviewed. In this review paper, we have provided a compiled list of low-cost, easily available, safe to handle, and easy-to-dispose-off adsorbents. These adsorbents have been classified into five different categories on the basis of their state of availability: (1) waste materials from agriculture and industry, (2) fruit waste, (3) plant waste, (4) natural inorganic materials, and (5) bioadsorbents. Some of the treated adsorbents have shown good adsorption capacities for methylene blue, congo red, crystal violet, rhodamine B, basic red, etc., but this adsorption process is highly pH dependent, and the pH of the medium plays an important role in the treatment process. Thus, in this review paper, we have made some efforts to discuss the role of pH in the treatment of wastewater.

The waste management becomes particular nowadays and waste conversion into valuable materials is one of the promising alternative capable of reducing the resource depletion rate. The performance of lignocel-lulosic residues, pineapple plant stem (PPS) for cationic (Basic Blue 3, BB3) and anionic (Congo Red, CR) dyes removal has been evaluated in a batch process, using different parameters such as, pH, contact time, agitation rate, initial dye concentration and sorbent dosage. The kinetics of both dyes sorption fitted well with pseudo-second order kinetic model. Boundary layer effect and intraparticle diffusion models were applied to study the rate-limiting step. The isotherm data of BB3 could be well described by Freundlich model (r 2 = 0.998) whilst high coefficient of determination of CR obtained from Langmuir (r 2 = 0.999) and Temkin (r 2 = 0.996) models. The maximum sorption capacities for BB3 and CR were found to be 58.983 and 11.966 mg g −1 , respectively under a favourable sorption process. The BB3 and CR adsorption on PPS was found to be exothermic. The result suggests that PPS has higher affinity on cationic than anionic dye. The promising regeneration capability of PPS using acid, implied PPS was a potential biosorbent for BB3 removal.

Biofilm formation by Salmonella is a serious concern in the food-processing industry and the persistence of the organism in biofilms becomes a constant source of contamination. Since there is zero tolerance for Salmonella in foods, it is important to understand the mechanism of biofilm formation and to prevent the formation. Therefore, this study aimed at investigating the biofilm-forming ability of seafood isolates of Salmonella enterica serovar Weltevreden (S. Weltevreden) under two different nutrient conditions (normal strength trypticase soy broth (TSB) and 1:100 diluted TSB). The role of cellulose production in biofilm formation and in the expression of multicellular behavior (rough, dark, red morphotype: rdar) was investigated. Fourteen isolates of seafood associated S. Weltevreden were studied for biofilm production in polystyrene microtitre plates. Only one (SW49) of 14 was a strong biofilm former on polystyrene template and was able to produce biofilm in both undiluted TSB and 1:100 diluted TSB at 24 h. All others produced moderate or weak biofilms which was higher in 1:100 diluted TSB compared to undiluted medium. All the isolates except one were positive by PCR for the three genes, gcpA (stm1987), adrA (yaiC) and csgD. Gene expression of gcpA, adrA and csgD was studied by real-time PCR with the one strong (SW49) and one representative weak (SW30) biofilm former. In SW49 at 24 h of incubation, the expression of gcpA from biofilm cells was 33 and 36 times higher than from planktonic cells grown in TSB and diluted TSB respectively and at 72 h the expression from biofilm cells was 57 and 61 times higher than that from planktonic cells. Quantification of gene expression did not reveal any significant difference in the expression of csgD and adrA gene. Deletion of gcpA in SW49 resulted in its inability to produce cellulose and consequent inability to bind calcoflour, inability to form rdar colony on Congo Red-agar plates and failure to produce biofilm on polystyrene substrate. The data indicated that, in case of S. Weltevreden, gcpA is critical for activating cellulose synthesis and biofilm formation both in undiluted and diluted TSB. The results of this study suggest the existence of an alternative biofilm regulatory pathway in S. Weltevreden. Role of adrA in cellulose production in nutrient rich medium is known but role of gepA in the above phenomenon is proved in this study. An understanding of the genes involved would help in looking at strategies of repression of the gene to control formation of biofilm.

We aimed to obtain magnesium/iron (Mg/fe)-layered double hydroxides (LDHs) nanoparticles-immobilized on waste foundry sand-a byproduct of the metal casting industry. XRD and ft-iR tests were applied to characterize the prepared sorbent. The results revealed that a new peak reflected LDHs nanoparticles. In addition, SEM-EDS mapping confirmed that the coating process was appropriate. Sorption tests for the interaction of this sorbent with an aqueous solution contaminated with congo red dye revealed the efficacy of this material where the maximum adsorption capacity reached approximately 9127.08 mg/g. The pseudo-first-order and pseudo-second-order kinetic models helped to describe the sorption measurements, indicating that the physical and chemical forces governed the removal process. The severity of water pollution has been resulted from the economic development adopted by human overall the world. The different industries such as textile, plastic, coating, and paper utilize the "dyes" in the different manufacturing stages 1-3 These compounds, even at extremely low concentrations can cause a significant contamination and, consequently, the destroying of the ecosystem elements 4-6. The continuous discharge of water contaminated with poisonous dyes to the environment can be formed a potential threat to the aquatic life and human health especially that the dyes are intrinsically toxic 7,8. Therefore, economical and highly efficient techniques need to be developed for treatment of the contaminated water 9-11. The presently available techniques include photocataly-sis 12 , biodegradation 13 , chemical coagulation 14 , ion exchange 15-17 , and adsorption 18-22. The adsorption is one of the most valuable methods in the treatment of the aqueous solutions because of its high efficiency, ease of operation , low cost of operation, and easy desorption 23-25. The selection or fabrication of the adsorbents is the main operative point of adsorption, where these materials must be highly stable, low cost, environment-friendly, and definitely efficient 26,27. Until date, literatures have been reported different reactive materials containing activated carbon, zeolite, clay, chitosan, montmorillonite, and vermiculite 7. However, several disadvantages of these materials include the high cost, poor adsorption capacity, and low reuse rate, which limits their usage 28,29. Thus, finding more efficient, longer durability and low cost new adsorbents are a difficult but a vital task. Layered double hydroxide (LDH) is a type of layered anionic compound that is joined via a non-covalent bond-an interaction between non-framework interlayer anions and positively charged main lamellar. Its general formula is [M +2 1-x M +3 × (OH) 2 ] x + [An − x/n ·mH 2 O] x − , where, M +3 is a trivalent metal ion such as Fe +3 , Cr +3 , Sc +3 , and Al +3 ; M +2 is divalent metal ions such as Mn +2 , Mg +2 , Ni +2 , and Zn +2 ; An − is an anion that balances the inter-layer charge such as Cl − , OH − , NO 3 − , and CO 3 −2 ; x is the ratio of M +3 / (M +3 + M +2), varying from 0.17 to 0.33 in general 7,30,31. The plenty of hydroxyl groups and the interlayer anions within the LDH can enhance the surface precipitation with metal ions 32. However, the bulk/granular structure of LDHs can limit its adsorption capacity

The present investigation has highlighted the utility of floating aquatic Egyptian hyacinth, which is considered as a significant reason for environmental problems in Nile River, to offer an opportunity to effective disposal of waste and the feasibility of cellulose extraction (16%) utilizing hazard free method. Cellulose was extracted from water hyacinth fiber using mercerization, mercerization-bleaching and Soxhlet extraction method. Dearth of lignin and hemicellulose in all extracted cellulose were affirmed from FTIR spectra. The impact of extraction conditions on crystallinity, aspect ratio and thermal properties of the extracted cellulose is displayed. Mercerization method (5% NaOH) is adequate to obtain cellulose (C-5% NaOH) with high crystallinity (46.9%), high decomposition temperature and high aspect ratio. C-5% NaOH was used for expulsion of crystal violet, Congo red from aqueous solutions by adsorption method. Kinetics models were applied to estimate the rate constant and to depict the equilibrium isotherm for the crystal violet and Congo red adsorption process.

Leaf powder of spear grass, otherwise known as Imperata cylindrica (IC), was used to prepare activated carbon. The Imperata cylindrica activated carbon (ICAC) prepared was used for the removal of Congo red (CR) dye from aqueous solution. Operation parameters such as initial dye concentration, contact time, adsorbent dosage, pH, and temperature were studied in batch systems. Equilibrium was attained in 150 and 180 min at lowest and highest concentrations, respectively. Maximum adsorption was observed at pH 3. Quantum chemical studies suggested that the protonation of aniline groups and minimal molecular size at planar geometry coupled with electrostatic interaction enhances the adsorption at low pH. Adsorption data were tested using pseudo-first-order and second-order reaction kinetics; the latter was found to be more suitable with a coefficient of determination of ≥0.99. The adsorption process fits Langmuir isotherm model better than the Freundlich model, with a maximum monolayer coverage of 313 mgg−1. This study shows that ICAC is effective in removing CR dye from aqueous solutions.

The objective of this work is to study the possibility of eliminating both dyes Methylene Blue (MB) and Congo Red (CR) by adsorption on natural clay of the region of Agadir and determine the different reaction parameters effect on the proceeds. Orientation tests have been carried out in distilled water solutions. The results of the kinetics of adsorption showed that optimal contact time is 60 min; it corresponds to a maximum removal rate of MB and CR respectively of the order of 99% and 75%. Increased adsorbent ratio (0,1 à 2 g / l) improves the removal efficiency of the CR especially dyes for an initial concentration of 10 mg/l. NaNO3 salt and pH of the medium greatly influence the CR of retention. Whatever the reaction parameter tested; it appears that the clay has a good efficiency for the retention of two dyes.

Fine-needle aspiration of abdominal fat pad (FNAFP) is commonly employed for the diagnosis of systemic amyloidosis, a disease with highly variable clinical manifestations, often presenting difficult patient management problems. We evaluated the role of FNAFP particularly in reference to its clinical usefulness. Pathology reports and clinical histories of 91 consecutive cases of FNAFP with Congo red (CR) staining at The Johns Hopkins Hospital (1999–2000) were reviewed. Major emphases were assessment of the clinical utility of the test, correlation with concurrent or subsequent biopsies, and treatment strategies. The primary indications for FNAFP were monoclonal gammopathy (34%), cardiomyopathy (22%), renal insufficiency (20%), neuropathy (8%), plasma cell dyscrasia (6%), and other conditions (10%). Of the 91 patients who underwent FNAFP, the results were as follows; 20 cases (22%) positive; 62 cases (68%) negative; eight cases (9%) insufficient for diagnosis; and one case (1%) equivocal. Of the 20 positive cases, follow-up biopsies were performed on 11 cases, of which six were positive and five were negative for amyloid by CR. Of the 62 negative cases, follow-up biopsies were performed on 19 cases, 14 of which were negative and five positive for amyloid by CR. A follow-up biopsy on the single equivocal case was positive for amyloid by CR. Twenty-one patients positive for amyloid, based on initial or follow-up biopsies, were managed symptomatically without any specific treatment for amyloidosis. One patient, who was specifically treated for amyloidosis by melphalan and dexamethasone, died 1 wk after therapy. Three patients with multiple myeloma and amyloidosis underwent chemotherapy. We conclude that primary clinical indications for FNAFP for amyloidosis are highly variable. An FNAFP result is often not considered clinically conclusive and is followed by further invasive procedures to detect amyloid (55% of our positive and 31% of our negative FNAFP cases were rebiopsied). The estimated sensitivity and specificity of FNAFP were 75% and 92%, respectively. Overall, the reliance on the results of FNAFP depended on the degree of clinical suspicion of the treating physician. Although in the majority of cases diagnosis of amyloidosis did not alter the treatment strategies, a conclusive positive result helped in ruling out other underlying conditions as the cause of patients' symptoms. Diagn. Cytopathol. 2004;30:178–181. © 2004 Wiley-Liss, Inc.