Ciprofloxacin (Cipro) incorporation into Li-fluorhectorite (LiFh) clay and its temperaturecontrolled release. with potential pharmaceutical and biomedical applications.Structural characterization of the raw material and the clay-drug composites.Demonstration of the temperature-controlled drug release abilities of a colloidal suspension of the clay-drug composite, following pharmaceutical standards. AbstractClays have shown to be good candidates as drug delivery carriers. In the present paper, we use the temperature-dependent swelling of smectite clays to produce clay-drug composites with sizable drug load capacity. Specifically, we obtain a fluorohectorite-ciprofloxacin (Fh-Cipro) composite, in which a true intercalation of the drug between the clay interlayers has been verified by various experimental techniques. We evaluate the thermally activated drug release from a colloidal suspension of nanosized composite particles in water as well as in synthetic gastric juice from 37 0 C (body temperature) to 85 0 C. The temporal profiles of drug release from the clay fulfil the pharmaceutical standards for these systems. In this work, we have been able to produce a clay-based Temperature Controlled Release System (TCRS) with potential biomedical applications.

The Mexican pulp and paper industry and municipal authorities are facing increasing regulatory and cost-related pressures regarding the handling, treatment and disposal of waste sludge and solid wastes. The dry anaerobic digestion (DASS) is a promising alternative for the co-stabilization of waste sludge, municipal and industrial solid wastes. However, appropriate and fast process start-up is a bottleneck for the dissemination of DASS technology in developing countries. This work aimed at determining a reliable and fast DASS start-up procedure from non-anaerobic inocula for the digestion of a mixture of paper sludge, waste sludge and municipal solid waste. Three types of inoculum were used: cattle manure (CM), soil (S) and waste activated sludge (WAS). Results were analyzed in terms of the stabilization time Te (the time required to develop a full methanogenic regime) and the overall start-up time To (time required to reach at least 25% TS inside the reactor since the inoculation). A factorial experiment was implemented; factors were the inoculum type (five combinations of CM, S and WAS), temperature (35 and 55°C) and loading rate (4.5 and 8.2 g VS/kg.d). Results showed that the fastest start-up was obtained with reactors using inoculum I3 (33% CM, 33% S and 33% WAS) at 55°C and 8.2 g VS/kg.day loading rate. Interestingly, thermophilic regime favoured shorter stabilization times, in spite of the fact that the inocula used were meso- or psychrophilic. Results from DASS reactors that reached steady state after start-up (I3 and I4) showed typical performance responses of 60% removal efficiency (% total VS basis), biogas productivity between 2.7-3.5 NL/kg wrm.day, a in the range 0.3-1.3 and pH around 8. This suggested that the DASS process is a feasible alternative for co-digesting paper-mill sludge, MSW and biosolids.

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Abstract. During the last years, clays have been increasingly explored as hosts for drugs. In the present paper, we have been able to host the non-steroidal anti-inflammatory drug, Tramadol, into the clay Lifluorohectorite (Li-Fh). We preliminary evaluate its incorporation by means of UV spectroscopy and X ray diffraction. Our results indicate that the clay hosts the drug molecule in its interlayer space. We suggest a set of parameters to guarantee an efficient incorporation process. Future studies will concentrate on the release of the drug from the clay nanofluid. PACS

The sodium-modified form of fluorohectorite nanoclay (NaFh) is introduced as a potential drug carrier, demonstrating its ability for the controlled release of the broad-spectrum antibiotic Ciprofloxacin through in vitro tests. The new clay-drug composite is designed to target the local infections in the large intestine, where it delivers most of the incorporated drug thanks to its pH-sensitive behavior. The composite has been conceived to avoid the use of coating technology and to decrease the side-effects commonly associated to the burst-release of the ciprofloxacin at the stomach level. NaFh was obtained from lithium-fluorohectorite by ion exchange, and its lack of toxicity was demonstrated by in vivo studies. Ciprofloxacin hydrochloride (Cipro) was encapsulated into the clay at different values of the pH, drug initial concentration, temperature and time. Systematic studies by X-ray diffraction (XRD), infrared and visible spectrophotometry (FT-IR and UV-vis), and thermal analysis (TGA) indicated that the NaFh host exhibits a high encapsulation efficiency for Cipro, which reaches a 90% of the initial Cipro in solution at 65 oC, with initial concentration of drug in solution of 1.36 x 10−2 mol L-1 at acid pH. XRD revealed that a true intercalation of Cipro takes place between clay layers. TG showed an increased thermal stability of the drug when intercalated into the clay, as compared to the “free” Cipro. IR suggested a strong clay-Cipro interaction via ketone group, as well as the establishment of hydrogen bonds between the two materials. In vitro drug release tests revealed that NaFh is a potentially efficient carrier to deliver Cipro in the large intestine, where the release process is mediated by more than just one mechanism.

The use of natural clays for the removal of dyes from wastewater, an important part of environmental remediation, is desirable due, not least, to their low cost. Palygorskite (PAL), a rigid-structure clay, is a good candidate for use in the elimination of industrial effluents, based on its exceptional adsorptive properties. Recently, a new palygorskite deposit has been discovered in Cuba and its use in the adsorption of dyes has not yet been explored in detail. In the present study, the use of unmodified natural Cuban palygorskite as a host for dyes was evaluated. Congo red (CR) and methylene blue (MB) were the anionic and cationic dyes tested, respectively, because of their wide use and toxicity to the environment. Several physical-chemical parameters were studied in order to establish the best experimental conditions under which to achieve the greatest dye load per gram of clay. Natural mixtures with different percentages of montmorillonite were also tested to evaluate their effect on the adsorption of the dyes. The results indicated that at pH values of ~7–9 and an initial dye concentration of 0.1 mg mL–1, the process was efficient. X-ray diffraction (XRD) analysis proved the surface adsorption of both dyes on the clays. The main interactions involved in the clay-dye system were electrostatic forces and H-bonds. Adsorption of CR seemed to be controlled fundamentally by the palygorskite phase. Such results support the use of this natural clay as an efficient host for the removal of MB and CR from wastewater.

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